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This section lists some binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and some other compounds of molybdenum. For each compound, a formal oxidation number for molybdenum is given, but the usefulness of this number is limited for p-block elements in particular. Based upon that oxidation number, an electronic configuration is also given but note that for more exotic compounds you should view this as a guide only.

In compounds of molybdenum (where known), the most common oxidation numbers of molybdenum are: 6, and 4.

Hydrides

The term hydride is used to indicate compounds of the type M xH y and not necessarily to indicate that any compounds listed behave as hydrides chemically.

Fluorides

Chlorides

Bromides

Iodides

Oxides

Sulfides

Selenides

Tellurides

Nitrides

Carbonyls

Complexes

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Mark Winter, University of Sheffield and WebElements Ltd

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WebElements Periodic Table " Molybdenum " compounds information

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This section lists some binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and some other compounds of molybdenum. For each compound, a formal oxidation number for molybdenum is given, but the usefulness of this number is limited for p-block elements in particular.

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7.1 Local Effects and Dose-Response Relationships

7.1.1 Animals

Inhalation of molybdenum compounds in high concentrations may be irritating to the upper respiratory tract. A few reports on inhalation or intratracheal administration have been published. Pneumoconiosis-like effects in the lungs have been reported in rats and rabbits. In one study, rabbits were given a suspension of powdered molybdenum intratracheally in doses of 70-80 mg/kg. After 9 months, diffuse pneumoconiosis with interstitial pneumonia was observed on histological examination ( Dzukaev, 1970; Mogilevskaya, 1963).

7.1.2 Humans

Pneumoconiosis with X-ray findings and subjective symptoms has been reported in 3 of 19 workers exposed to metallic molybdenum and molybdenum trioxide. Exposure varied between 1 and 19 mg/m ³ for 4-7 years (Mogilevskaya, 1963).

In the U.S.S.R., of 500 workers from a molybdenum and copper mine, many revealed nonspecific symptoms and changes in the CNS. The molybdenum dust levels in the mines were in some cases 10-100 times greater than 6 mg Mo/m ³ -the U.S.S.R. maximum permissible level (Eolayan, 1965).

In 25 workers from a roasting plant in Denver, where molybdenum sulfide is converted to molybdenum oxides, nonspecific complaints have been observed. The most frequent complaints were joint pains, headaches, backaches, and nonspecific hair and skin changes. The exposed workers when compared with the control group demonstrated significant increases in serum ceruloplasmin and milder increases in serum uric acid levels. Hyperuricosuria was not found. Eight-hour time-weighted average of exposure to molybdenum has been calculated to be 9.47 mg Mo/mWalravens ³; the minimum daily body burden of molybdenum has been calculated to be 10.2 mg Mo ( et al., 1979).

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Toxicokinetics

Water-soluble molybdenum compounds are readily taken up through the lungs and the gastrointestinal tract; but insoluble compounds are not. Following absorption, molybdenum is distributed throughout the body with the highest levels generally found in the liver, kidneys, spleen, and bone. Limited data suggest that 25-50% of an oral dose is excreted in the urine, with small amounts also eliminated in the bile. The biological half-life may vary from several hours in laboratory animals to as much as several weeks in humans. The vast majority of molybdenum found in the liver is concentrated in the outer membrane of the mitochondria where it is readily available as a cofactor in enzyme reactions. Molybdenum is excreted rapidly primarily as in the urine as molybdate.

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R.W. KappJr., in Encyclopedia of Toxicology (Third Edition) , 2014

Toxicokinetics

Water-soluble molybdenum compounds are readily taken up through the lungs and the gastrointestinal tract. The rate of gastrointestinal absorption of molybdenum is influenced by its chemical form and the animal species; for example, hexavalent molybdenum is readily absorbed, whereas tetravalent molybdenum is not readily absorbed following oral administration. Water-soluble molybdates, thiomolybdates and oxothiomolybdates, and molybdenum in herbage and green vegetables are absorbed 75-97% by laboratory animals and ruminants. In animals, absorption varies between 75 and 97%, whereas in humans, absorption of molybdenum via the digestive tract after oral intake has been calculated at 28-77%. It is not known whether molybdenum in drinking water is absorbed more rapidly than that contained in food.

Following absorption, molybdenum rapidly appears in the blood, where it binds to α2-macroglobulins in the form of molybdate and is distributed throughout the body, with the highest levels generally found in the liver, kidneys, spleen, and bones. In rodents, molybdenum is distributed mainly to the liver, converted to molybdate with 36-90% of the total dose excreted in the urine, less than 1% in the bile and a minimal amount in the feces. In rabbits and guinea pigs, molybdenum is deposited in the tissues within 4 h after initial high blood and bile levels and eliminated within 72 h by the kidneys. There is no apparent bioaccumulation of molybdenum in human tissues.

The biological half-life of molybdenum is estimated to be up to several weeks in humans, whereas the biological half-time varies from a few hours to several days in small laboratory animals. Data suggest that 25-50% of an oral dose is excreted in the urine, with small amounts eliminated in the bile. More than 50% of molybdenum is excreted primarily through the kidneys, with approximately 6% excreted through the bile when excess molybdenum is present. In rodents, molybdenum compounds are excreted largely in the urine and only to a small extent in feces. The biological half-life may vary from several hours in laboratory animals to as much as several weeks in humans. The vast majority of molybdenum found in the liver is concentrated in the outer membrane of the mitochondria, where it is available as a cofactor in enzyme reactions. Molybdenum intake and excretion are balanced in most nonruminant species, including humans. Molybdenum is excreted rapidly primarily, as in urine, as molybdate.

Molybdenum metabolism is related to copper and sulfur metabolism. In animals, molybdenum interacts in a complex manner with copper and sulfate by a mechanism that is not well understood. Animals on copper-deficient diets are generally more susceptible to molybdenum toxicity than those on copper-adequate diets. The biological half-life varies from a few hours to several days in small laboratory animals and is related to copper and sulfur metabolism. Molybdenum is present in humans, with an average total adult content of 9 mg with blood levels averaged approximately 5 ng ml −1.

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1 Introduction

The impregnated solutions containing cobalt and molybdenum compounds and citric acid (CA) is widely used for high active hydrotreating catalysts preparation, including industrial catalysts. An obvious positive effect of citric acid on the activity of catalysts is explained in variety of ways by different authors. Thus, Fujikawa et al. [1] prescribes the superior catalyst activity to the formation of cobalt citrate complexes, which are thermally stable at temperatures up to 200 °C and contributes the selective formation of the catalyst active component, so called Co-Mo-S phase of type II, described in [2]. Bergwerff et al. [3] reported the formation in a solution of molybdenum citrate complexes. Deposition of these Mo complexes onto Al ₂O ₃ support provides uniform molybdenum distribution along the carrier granule and ensures a high dispersion of MoS ₂ particles, that increases the relative activity of catalyst. In the cited and other papers of mentioned authors, the complex formation between CA and the individual components of the impregnating solution - cobalt or molybdenum was detected, while the formation of bimetallic Co-Mo-CA complexes was not revealed. Earlier Van Veen [4] reported that the positive role of chelating organic ligands consists in the formation of CoMoL compounds in the impregnating solution, whose structure remains unchanged after the drying of the catalyst; moreover the ligands screen metals from the interaction with the carrier. During the sulfidation stage of the CoMoL containing catalysts the Co-Mo-S phase type II is mainly formed, whereas in the catalysts prepared without using of chelating agents the low active Co-Mo-S phase type I is formed. Concerning our experimental results, the reasonable Van Veen's conclusions should be supplemented by the followed statements:

1.

Chelating ligands promotes the coordination of Co towards molybdenum containing anion forming a bimetallic compound with a close proximity of cobalt and molybdenum, that further leads to the selective formation of bimetallic Co-Mo-S phase.

2.

Bimetallic complexes stabilized by chelating ligands, have relatively large size, that does not allow it to penetrate into the narrow pores of the carrier not available for heteroatomic organic molecules of the hydrotreated feedstock.

In the current paper it was demonstrated, that the use of labile bimetallic Co-Mo complexes with a close proximity between Co and Mo in combination with vacuum impregnation of Al ₂O ₃, low-temperature drying (<110 °C) and treatment in H ₂S at 400 °C, allows to obtain uniform catalysts containing fully sulfided particles, corresponding to Co-Mo-S phase of type II. The catalysts obtained reveal high activity in the hydrotreatment of diesel fuel [5]. As it was shown in [6] due to the interaction of ammonium heptamolybdate (AHM), CA, and cobalt acetate the bimetallic Co ₂[Mo ₄(C ₆H ₅O ₇) ₂O ₁₁]*nH ₂O (hereinafter CoMo ₄CA) complex is formed in aqueous solution. CoMo ₄ CA is a good precursor for obtaining of high active hydrotreating catalysts. The linear sizes of this complex allow the localization of the active component predominantly in the wide, accessible for catalysis, pores of alumina [7].

The present paper describes the synthesis of (CoMo ₄CA) in solution from different initial compounds of Co and Mo, and the method for catalyst preparation, ensured the preservation of the (CoMo ₄ CA) complex structure at the support surface. The properties of the catalysts obtained were studied.

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6.9.4 Tungsten Mercury Compounds

The tungsten analogues of many of the molybdenum compounds discussed in Section 6.9.2 are reported in the same references and are included in Table 1 but will not be separately discussed here. ₂W ₂(CO)55-7,59-63 In one particular case, the reactions of [(PPN) ₁₀] with ClHgM (M = MoCp(CO) ₃, WCp(CO) ₃, FeCp(CO) ₂, Co(CO) ₄, Mn(CO) ₅ afforded the complexes [PPNW(CO) ₅HgM] while the analogous chromium dianion could only be obtained for M = MoCp(CO) ₃ and the related [NEt ₄] [Mo ₂(CO) ₈(μ-H)(μ-dppm)] did not undergo this chemistry at all but merely led to symmetrization of the ClHgM species.56

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Workplace Atmosphere Safety

The aerosols of metallic molybdenum, either soluble or insoluble molybdenum compounds and molybdenum silicide, take a predominantly fibrous effect and are related to the third class of danger according to State Standard 12.1.005-88 under the legislation in the CIS [ 37]. The stated average limit value (ALV) of the metallic molybdenum aerosol in the workplace atmosphere as the shift time-weighted average concentration is 0.5 mg/m ³, while the threshold limit value (TLV) is 3 mg/m ³. The ALVs of the insoluble and soluble molybdenum compounds and molybdenum silicide in dust form are 1.0, 4.0 and 4.0 mg/m ³, respectively, while the ALV of soluble molybdenum compounds in the form of condensed aerosols is 2.0 mg/m ³. Molybdenum content in potable water has a toxicological effect and is related to the second class of danger and the TLV is 0.25 mg/L according to CIS State Standard 4630-88 [38].

Molybdenum powder even with particle sizes fraction ≤74 μm in the air is not explosive; the minimum ignition temperature of powder deposits (self-ignition temperature) is 310°C. The products with such characteristics of inflammability and explosion risk are related to the 'Low explosion hazard' class of danger according to the Guide to Legislation and 'Health and Safety' in the European PM Industry [39].

Common techniques are mainly used to prevent pollution and environmental damage during powder manufacture and its processing. Detailed information on health and environment protection measures in such conditions can be found in Section 5.

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6.11.2.1.2.(xv) Compounds with the S₂CPMo core

The coordination chemistry of the adduct S ₂CPR ₃ (R = Me, Et, Cy) and various molybdenum compounds has been explored by Miguel and co-workers. This ligand coordinates in an η ³-pseudoallylic manner to one or two transition metals or to one transition metal and a main group element with formation of an S ₂CPM core. Molecular orbital (MO) analysis of the fluxional behavior of M(S ₂CPMe ₃)(CO) ₂(PMe ₃) ₂ complexes (M = Mo, W) was studied in <1996IC2406>.

The Br-bridged complex of the general formula (CO) ₃M′(μ-Br)(μ-S ₂CPR ₃)M(CO) ₃ (where M′ = Re and M = Mo) was a starting complex for various other species. The complex 32 (Scheme 11, R = Cy) can be reduced with Na/Hg at −78 °C in THF to an anionic species, which by subsequent addition of Ph ₃SnCl gives the yellow complex 33; on warming to room temperature, 33 is reversibly converted into the red compound 34 and an equilibrium of 4/5 of both complexes is reached at room temperature; both compounds were studied by X-ray analyses <1999OM490>. Reduction of 35 with Na/Hg in THF produces the anion Mn bond ( 36 with formation of an MoScheme 12). The addition of ClSnPh ₃ causes migration of the central carbon atom of the S ₂CPR ₃ ligand from Mo to Mn to give compounds ₂CPMn core, which are converted into 37 with the S 38a- 38d on addition of the ligands dmpm or tedip. The same reaction sequence occurs, if two CO groups are replaced in 35 by the chelating ligands dmpm or tedip to give 39a- 39d and 40a- 40d (see Table 3)<1995JOM(492)23>. Further, 35 reacts with NaCCPh and NaCCH to give the acetylene-bridged derivatives Scheme 13), which were characterized by X-ray analyses 41 and 42, respectively, in high yields (<1998JA417>. The Br-bridged complex Scheme 14; the Mo complex (see also compound 43a (M = Mo) is shown in ₂CPW core) was obtained with Mo(CO) ₃(NCMe) ₃ in 90% yield. The complex 43b with S Br Mo arrangement reacts with monodentate ligands to give nearly quantitatively the related complexes 43a with the Mo ₃) is shown 44 or with chelating ligands to produce the complexes <1997JOM(545-546)327>. 45 in 60% and 80% yields, respectively. The crystal structure of 44 (L = PEt

38, 39, 40

R

L-L

a

Cy

tedip

b

Pr i

tedip

c

Cy

dmpm

d

Pr i

dmpm

Reactions of 35 with Br bridge replacement are depicted in Scheme 15. The reaction of 35 with NaOMe in methylenechloride generates 46 in about 80% yield containing an OMe bridge instead of a Br bridge. The OMe bridge can easily be replaced by carbon acids to produce the related complexes 47 in yields between 30% and 60%, while the action of ethanolamine generates 48 in 46% yield. The S-bridged complex 49 was obtained by the reaction of 35 with the salt [HSCH ₂CH(COOMe)NH ₃]Cl in 41% yield; most of the complexes were studied by X-ray analysis <2002OM2979>.

Replacement of the Br bridge by other ligands starting from the dinuclear complex 35 (R = Pr i) is also shown in Scheme 16. Thus, Na/Hg reduction generates the anion 36, which can be converted with PhSeI in THF into red crystals of 50 (82% yield, crystal structure). Similarly, with Ph ₂PCl, brown crystals of 51 (76% yield) were obtained which on heating rearrange and give 52 with the S ₂CPMn core in 86% yield. Heating of 36 and addition of Ph ₃SnCl rearranged to give 53, which was confirmed by an X-ray analysis <1994OM4667>.

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6.11.2.1.2.(xiii) Compounds with the S₂CPMo core

The coordination chemistry of the adduct S ₂CPR ₃ (R = Me, Et, cyclohexyl (Cy)) towards various molybdenum compounds has been explored by the group of Miguel, Carmona and others. This ligand coordinates in a η ³-pseudoallylic manner to one or two transition metals or to one transition metal and a main group element with formation of a S ₂ CPMo core.

The first compound in this series, the dimeric species {Mo(CO) ₂(S ₂CPEt ₃)(PEt ₃} ₂ ( 25), has been detected by Bianchini and prepared either from Mo(CO) ₃(C ₇H ₈) and S ₂CPEt ₃ or from irradiating the η ¹-bonded complex (CO) ₅MoS ₂CPEt ₃ in 60% and 40% yield, respectively <82OM778>. The addition of SnBuCl ₃ to ( 25) leads to ( 26) (69% yield) in which the two sulfur atoms form bridges to the tin atom <92AG81>; the reactions are summarized in Scheme 7.

Red crystals of ( 27) have been obtained by two routes. Starting from MoHCl(CO) ₂(PMe ₃) ₃ the complex is formed in low yield with CS ₂ by elimination of HCl. The compound is also formed in an unusual reaction on heating a solution of Mo(C ₂S ₄)(C ₂H ₄)(PMe ₃) ₃ at 50 °C under 2 atm CO. Alkylation leads to the cationic species ( 28) as depicted in Scheme 8 <92JCS(D)2307, 93IC5569>.

The related mononuclear compound ( 29) is produced in 75% yield by insertion of CS ₂ into the Mo P bond of MoCl(NO)(PMe ₃) ₄. Replacement of Cl and one PMe ₃ by the chelating ligand [S ₂CNMe ₂] − results in the formation of the yellow complex ( 30) in about 50% yield as shown in Scheme 9 <89IC2120>.

Dinuclear compounds, in which the S ₂CPR ₃ group is bridging to another transition metal via the sulfur atoms, have been realized with Mn-, Re-, and Ru-containing fragments. Thus, reaction of (CO) ₃(Br)Mn(S ₂CPR ₃) with Mo(CO) ₃(NCMe) ₃ in THF produces the purple-red complex ( 31) in quantitative yields as shown in Scheme 10 (M = Mn). One CO group at the Mo atom can be replaced by monodentate phosphines to give ( 32) <91JOM(420)C12, 93OM1394>; whereas the action of chelating ligands R ₂PEPR ₂ (E = O, R = Et; E = CH ₂, R = Me, Ph) produce red (93OM1394>. Reduction of ( 33) in 70-80% yield < Hg in THF produces the anion ( Mn bond < 31) with Na93OM2888>. The analogous Re-containing compounds ( 34), probably with formation of a Mo94JOM(467)231>. 31- 34; M = Re) have been obtained <

If the starting complex Mo(CO) ₃(NCMe) ₃ is treated with the cationic species [(η-Me ₆C ₆) ClRuC(S ₂CPCy ₃)]⁺ in THF, ( 35) is formed instantaneously as depicted in Scheme 11. This complex undergoes substitution of one CO group to afford the cationic dicarbonyls ( 36); all compounds have been prepared as the PF ₆− salts <92POL2713>.

A further series of compounds with the S ₂CPMo core is depicted in Equation (7). The reaction of (η ³-allyl)(CO) ₂BrM(η ²-S ₂CPR ₃) (M = Mo, W; R = cyclohexyl, Pr i) with Mo(CO) ₃(NCMe) ₃ in dichloromethane produces a series of four compounds of the type ( 37) with M′ = Mo, M = Mo or W in yields up to 90% <94OM1336>.

(7)

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2.08.4.2.4 Molybdenum

The highest oxidation state of molybdenum is VI. MoF ₆ can be synthesized by direct fluorination of the metal or by other molybdenum compounds such as MoCl ₆. Until recently, it was always assumed that MoF ₆, a d ⁰ system, shows a regular octahedral structure. This is indeed the case at cryogenic temperature as the octahedral structure is the real minimum. However, the intramolecular ligand exchange (trigonal twist) is computed to show a relatively low barrier. Recently, a high-level quantum-chemical investigation on MoF ₆ and other second-period transition-metal hexafluorides to evaluate reliable self-consistent thermochemical data has been reported.

MoF ₆ is a colorless, diamagnetic solid which makes a transformation from cubic to the orthorhombic modification at − 9.6 °C. MoF ₆ is a stronger oxidizer than its heavier homolog WF ₆, because Tl is oxidized by MoF ₆ to Tl III whereas WF ₆ reaches only the oxidation state I of Tl I. Several fluoridomolybdate(VI) complexes such as M[MoF ₇] and M ₂[MoF ₈] (M = Li, Na, K, Rb, Cs [NH ₄]⁺, NO, NO ₂) are formed.

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7.1.1 Animals Inhalation of molybdenum compounds in high concentrations may be irritating to the upper respiratory tract. A few reports on inhalation or intratracheal administration have been published. Pneumoconiosis-like effects in the lungs have been reported in rats and rabbits. In one study, rabbits were given a suspension of powdered molybdenum intratracheally in doses of 70-80 mg/kg.

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Molybdenum is a silvery-white metal that is ductile and highly resistant to corrosion. It has one of the highest melting points of all pure elements - only the elements tantalum and tungsten have higher melting points. Molybdenum is also a micronutrient essential for life.

As a transistion metal, molybdenum easily forms compounds with other elements. Molybdenum comprises 1.2 parts per million (ppm) of the Earth's crust by weight, but it is not found free in nature. The main molybdenum ore is molybdenite (molybdenum disulfide), but can also be found in wulfenite (lead molybdate) and powellite (calcium molybdate).

It is recovered as a by-product of copper or tungsten mining. Molybdenum is mined primarily in the United States, China, Chile and Peru. World production is around 200,000 tons per year, according to the Royal Society of Chemistry (RSC).

Just the facts

Atomic number (number of protons in the nucleus): 42

Atomic symbol (on the periodic table of the elements): Mo

Atomic weight (average mass of the atom): 95.96

Density: 10.2 grams per cubic centimeter

Phase at room temperature: Solid

Melting point: 4,753 degrees Fahrenheit (2,623 degrees Celsius)

Boiling point: 8,382 degrees F (4,639 degrees C)

Number of isotopes (atoms of the same element with a different number of neutrons): 24 whose half-lives are known with mass numbers from 86 to 110.

Most common isotopes: Mo-98 (24.1 percent); Mo-96 (16.7 percent); Mo-95 (15.9 percent); Mo-92 (14.8 percent); Mo-97 (9.6 percent); Mo-100 (9.6 percent); Mo-94 (9.2 percent).

(Image credit: Greg Robson/Creative Commons, Andrei Marincas Shutterstock)

Discovery

The soft black mineral molybdenite (molybdenum sulfide) was often mistaken for graphite or lead ore until 1778 when an analysis by German chemist Carl Scheele revealed it was neither one of these substances, and was in fact, a totally new element. But since Scheele did not have a suitable furnace to reduce the white solid to metal, it would still be a few years before the element was actually identified, according to Chemicool. In fact, Scheele later became known as "hard luck Scheele" because he made a number of chemical discoveries - including oxygen - but the credit was always given to someone else.

For the next few years, scientists continued to assume that molybdenite contained a new element, but it still proved very difficult to identify, since no one had been able to reduce it to a metal. Some researchers did convert it to an oxide, however, upon which when added to water, formed molybdic acid, but the metal itself remained elusive.

Eventually, Swedish chemist Peter Jacob Hjelm ground molybdic acid with carbon in linseed oil to form a paste. The paste allowed for close contact between the carbon and the molybdenite. Hjelm then heated the mixture in a closed crucible to produce the metal, which he then named molybdenum, after the Greek word "molybdos," meaning lead. The new element was announced in the autumn of 1781, according to the Royal Society of Chemistry.

Uses

Most commercial molybdenum is used in the production of alloys, where it is added to increase hardness, strength, electrical conductivity and resistance to wear and corrosion.

Small amounts of molybdenum can be found in a wide variety of products: missiles, engine parts, drills, saw blades, electric heater filaments, lubricant additives, ink for circuit boards and protective coatings in boilers. It is also used as a catalyst in the petroleum industry. Molybdenum is produced and sold as a gray powder, and many of its products are formed by compressing the powder under extremely high pressure, according to the Royal Society of Chemistry.

Due to its high melting point, molybdenum performs incredibly well under very high temperatures. It is particularly useful in products that need to stay lubricated under these extreme temperatures. So in cases where some lubricants and oils might decompose or catch on fire, lubricants with molybdenum sulfides can handle the heat and still keep things moving along.

Molybdenum is the 54th most common element in the Earth's crust.

The molybdenum atom has half the atomic weight and density as tungsten. Because of this molybdenum often replaces tungsten in steel alloys, offering the same metallurgical effect with only half as much metal, according to Encyclopaedia Britannica.

"Big Bertha," the German 43-ton gun used in World War II, contained molybdenum, rather than iron, as an essential component of its steel, because of its much higher melting point.

Molybdenite, or molybdena, is a soft black mineral once used to make pencils. The mineral was thought to contain lead and was often confused for graphite.

Molybdenite is used in certain nickel-based alloys, such as the Hastelloys -- patented alloys that are highly resistant to heat and corrosion and chemical solutions.

Who knew?

Micronutrient

Molybdenum is a micronutrient essential for life, but too much of it is toxic.

Molybdenum is present in dozens of enzymes. One of these important enzymes is nitrogenase, which allows nitrogen in the atmosphere to be taken up and transformed into compounds that allow bacteria, plants, animals and humans to synthesize and utilize proteins.

In humans, molybdenum's main function is to serve as a catalyst for enzymes and to help break down amino acids in the body, according to Drweil.com. In plants, molybdenum is an essential trace element necessary fornitrogen fixation and other metabolic processes.

Molybdenum has the unique quality of being less soluble in acidic soils and more soluble in alkaline soils (it's typically the opposite for other micronutrients). Therefore, molybdenum's availability to plants is quite sensitive to pH and drainage conditions. In alkaline soils, for example, some plants can have up to 500 ppm of molybdenum, according to Lenntech. In contrast, other lands are barren due to a lack of molybdenum in the soil.

Necessary for evolution

Another interesting use for molybdenum is its role in scientific research. Molybdenum is very abundant in the ocean today, but was much less so in times past. This allows it to serve as an excellent indicator of ancient oceanic chemistry. Scientists in the field of biogeology, for example, study the amount of molybdenum in ancient rocks to help estimate how much oxygen may have been present in the ocean and/or atmosphere during a certain time period.

Several years ago, researchers from the University of California, Riverside, suspected that deficiencies in oxygen and molybdenum may have been responsible for a major lag in evolution. They knew that around 2.4 billion years ago, there was an increase in oxygen on the Earth's surface and that oxygen was able to reach the ocean's surface to support microorganisms. However, the diversity of living organisms remained very low. In fact, animals did not appear until almost 2 billion years later - or around 600 million years ago - according to the study press release in Science Daily.

When deprived of molybdenum, bacteria cannot convert nitrogen to a form useful for living things. And if bacteria cannot convert nitrogen quickly enough, then eukaryotes cannot thrive because these single-celled life forms are unable to convert nitrogen on their own, according to Science Daily.

For the study, published in the journal Nature, the researchers measured the levels of molybdenum in black shale, a type of sedimentary rock rich in organic matter and often found deep in the ocean. This helped them estimate how much molybdenum may have been been dissolved in the seawater where the sediment had formed.

Indeed, the researchers found strong evidence that the ocean at this time had been lacking in important molybdenum. This would have had a negative impact on the evolution of early eukaryotes, which scientists believe gave rise to all animals (including humans), plants, fungi and single-celled animals like protists.

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Traci Pedersen - Live Science Contributor

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Molybdenum is a silvery-white metal that is ductile and highly resistant to corrosion. It has one of the highest melting points of all pure elements - only the elements tantalum and tungsten have higher melting points. Molybdenum is also a micronutrient essential for life. As a transistion metal, molybdenum easily forms compounds with other elements.

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by 4.5 percent through 2025. The metal Molybdenum is a silver-gray metal that is usually extracted as a by-product of copper and tungsten mining. It occurs in the minerals wulfenite, powellite and molybdenite, though molybdenite is the main mineral used to produce molybdenum.
Molybdenum has a high melting point of 4,730 degrees Fahrenheit, and because of that characteristic molybdenum uses are many and varied. The metal is usually sold as a gray powder that is compressed under high pressure to make various products.
China, Chile and the US are the three largest producers of molybdenum, and demand for molybdenum is expected to grow
has fared poorly in recent years, but investors hope that its performance will soon improve. To understand molybdenum's prospects moving forward, it is important to be aware of the major molybdenum uses. Here's a brief overview of five.

Metal: Approximately 80 percent of molybdenum is used as an alloying agent in steel

1. Alloys

Structural steel accounts for 35 percent of molybdenum use. Molybdenum improves the strength of steel at high temperatures, and can allow steel to withstand pressures up to 300,000 pounds per square inch. Molybdenum also helps with resistance to chloride corrosion, which is helpful for steel used in pipelines or marine environments.
Another 25 percent of molybdenum is used in stainless steel for pharmaceutical and chemical mills and tanker trucks. Molybdenum is also alloyed with steel to produce drills, saws, jet engines and power-generation turbines. Chrome and molybdenum alloy steel sheets are used in mufflers and other automotive parts.
Molybdenum is also alloyed with cast iron to produce cylinder heads, motor blocks and exhaust manifolds, which allow vehicle engines to run hotter and thereby reduce carbon emissions. The metal is also used in milling and crushing equipment.

Chemical: About 14 percent of molybdenum is used in the chemical industry for catalysts and lubricants

2. Catalysts

Molybdenum uses can also be chemical. For example, the metal is used as as a catalyst in petroleum refineries to help remove sulfur from natural gas and refined petroleum products. The process, known as hydrodesulfurization, involves heat and pressure plus a catalyst containing alumina, molybdenum and cobalt. Occasionally nickel and molybdenum are used instead of cobalt to treat more difficult feedstock. Low-sulfur fuels are cleaner burning, and many countries, including Canada and the US, require vehicles to use ultra-low-sulfur diesel fuel for road vehicles.
Molybdenum also acts as a catalyst in polymer and plastic production.

3. Lubricants

Molybdenum is combined with sulfur to form molybdenum disulfide, which helps two-stroke engines, bicycle coaster brakes, bullets and ski waxes and more. It is also used in greases for ball and roller bearings in the manufacturing, mining and transportation industries.
Molybdenum disulfide can withstand heat and pressure because it is of geothermal origin . The oil-soluble molybdenum-sulfur compounds thiophosphate and thiocarbamate protect engines against wear, oxidation and corrosion.

Other: Less common molybdenum uses include pigments and fertilizer

4. Pigments

Molybdenum is also used in paints and dyes . Zinc molybdate is used in paint primers to inhibit corrosion and stabilize color; for instance, it is used to paint the metal surfaces of boats . Molybdenum oranges are made using lead, lead chromate, lead molybdate and lead sulfate. The paint resists fading in light and weathering over time.
Molybdenum oranges are used in paints, inks, plastic and rubber products and ceramics. Molybdophosphoric acid is used in methyl violet and victoria blue dyes for textiles and paints.

5. Fertilizer

Molybdenum is an essential component of nitrogenase, which is found in nitrogen-fixing bacteria that make nitrogen from the air available to plants. Sodium molybdate is a white crystalline powder used as a fertilizer for plants such as cauliflower and beans to increase crop yields.
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Securities Disclosure: I, Melissa Shaw, hold no direct investment interest in any company mentioned in this article.

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by 4.5 percent through 2025. The metal Molybdenum is a silver-gray metal that is usually extracted as a by-product of copper and tungsten mining. It occurs in the minerals wulfenite, powellite and molybdenite, though molybdenite is the main mineral used to produce molybdenum.

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The Element Molybdenum - Basic Physical and Historical Information

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Molybdenum is contained in the following compounds:

Carbon Nanotubes.

Al2O3

Molybdenum

Platinum

Resin

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Atomic Number: 42

Atomic Weight: 95.95

Melting Point: 2896 K (2623°C or 4753°F)

Boiling Point: 4912 K (4639°C or 8382°F)

Density: 10.2 grams per cubic centimeter

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 5

Protons: 42

Electrons: 42

Neutrons: 54

Element Amount on Earth: Molybdenum comprises 1.2 parts per million (ppm) of the Earth's crust by weight, but it is not found free in nature.

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1. Alloy - Structural steel is responsible for 35 percent of molybdenum use. Molybdenum improves the strength of steel at high temperatures, and can allow steel to withstand pressures up to 300,000 pounds per square inch. Molybdenum also helps with corrosion resistance, which is helpful for steel used in pipelines or marine environments.

2. Catalysts - Molybdenum uses can also be chemical. About 14 percent of molybdenum is used in the chemical industry for catalysts and lubricants. For example, the metal is used as a catalyst in petroleum refineries to help remove sulfur from natural gas and refined petroleum products. The process, known as hydrodesulfurization, involves heat and pressure plus a catalyst with alumina, molybdenum and cobalt.

3. Lubricants - Molybdenum is combined with sulfur to form molybdenum disulfide, which helps lubricate two stroke engines, bicycle coaster brakes, bullets, ski waxes and more. It is also used in greases for ball and roller bearings in the manufacturing, mining and transportation industries.

4. Pigments - Molybdenum is also used in paints and dyes. Zinc molybdate is used in paint primers to inhibit corrosion and stabilize color; for instance, it is used to paint the metal surfaces of boats.

5. Fertilizer - Molybdenum is an essential component of nitrogenase, which is found in nitrogen-fixing bacteria that make nitrogen from the air available to plants. Sodium molybdate is a white crystalline powder used as a fertilizer for plants such as cauliflower and beans to increase crop yields.

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Molybdenum was discovered by Carl Welhelm Scheele, a Swedish chemist, in 1778 in a mineral known as molybdenite (MoS₂) which had been confused as a lead compound. Molybdenum was isolated by Peter Jacob Hjelm in 1781. Today, most molybdenum is obtained from molybdenite, wulfenite (PbMoO₄) and powellite (CaMoO₄). These ores typically occur in conjunction with ores of tin and tungsten. Molybdenum is also obtained as a byproduct of mining and processing tungsten and copper.