Molybdenum dialkyldithiocarbamate

Molybdenum additives By using data from Table 5.15, determine a protective tribofilm formation from the degradation of molybdenum dialkyldithiocarbamate (MoDTC), molybdenum dialkyldithiophosphate (MoDDP) directly and in combination with ZDDPs or sulfur compounds. 

MoDDP MoDTC MOFT MSDS MTAC Molybdenum dialkyldithiophosphate. Molybdenum dialkyldithiocarbamate. Minimum Oil Film Thickness. Material Safety Data Sheets (U.S.). Multiple Test Acceptance Criteria. 

Considerable progress has been made in studying tribofilms in the last decade. A number of important surface and thin film techniques have been developed in recent years, which are contributing to a better understanding of at least some tribochemical processes of boundary lubrication. In recent years, X-ray absorption near edge structure XANES spectroscopy, a powerful technique for tribofilm characterization, was used to identify a layered structure (surface and bulk) of tribofilms. The chemistry of tribofilms generated by the combination of zinc dialkyldithiophosphate (ZDDP) and molybdenum dialkyldithiocarbamate (MoDTC) has been examined. 

Metal dithiocarbamates have been investigated as single-source precursors for MOCVD nanosized particles of metal sulfides, such as PtS and PdS,43 PbS,437,4 8 and Bi2S3,439 and tin sulfide thin films.440 In this respect the termochemistry of dithiocarbamates (periodically reviewed441 144) is important. Molybdenum dialkyldithiocarbamates are highly effective antiwear, antiseize, and antifriction additives for lubricating oils,445 and are used as vulcanization accelerators.446... 

Molybdenum dialkyldithiocarbamates Molybdenum dialkyldithiocarbamates are multifunctional lubricant additives as anti-wear, anti-friction and antioxidants. Molybdenum dialkyldithiocarbamates are also multifunctional antioxidants due to the hydroperoxide decomposing ability of dialkyldithiocarbamates, see Section 4.4.2, and the radical scavenging capacity of molybdenum. The best established structure for molybdenum dialkyldithiocarbamates is a six-coordinate complex of a dinuclear molybdenum centre with each molybdenum bonded to terminal oxygen or sulphur atoms, two bridging oxygen or sulphur atoms and one dialkyldithiocar-bamate ligand. Fig. 4.6 [44] ... 

Fig. 4.6 Structure of dinuclear molybdenum dialkyldithiocarbamate, where X are oxygen and sulphur atoms...

The preparation typically involves a condensation reaction of acidic molybdenum sources such as molybdenum trioxide, molybdic acid and ammonium molybdate with dialkylammonium dialkyldithiocarbamate salts formed in situ by reaction of carbon disulphide and dialkylamine [45]. The extent of sulphurisation of the molybdenum core can be increased by the introduction of sulphurising agents such as sodiumhydrosulphide [46]. Patent literature reports that the greatest antioxidant effect of molybdenum dialkyldithiocarbamates is seen when combined with aminic and phenolic antioxidants [47]. 

Together with dinuclear molybdenum dialkyldithiocarbamates, trinuclear dialkyldithiocarbamates have recently been introduced for lubricant applications, specifically for use in engine oils [48]. These molecules are based upon [Mo3S4]" and [MosSy] cores complexed by four dialkyldithiocarbamate ligands. It has been reported that these products decompose hydroperoxides more effectively than do dinuclear molybdenum dialkyldithiocarbamates. The patent literature discloses trinuclear molybdenum dialkyldithiocarbamates that are most effective as antioxidants when combined with radical scavengers such as organocopper compounds and diphenylamines [49]. 

This exchange leads first to the formation of the mixed products and, in the second step, full ligand exchange takes place to produce molybdenum dialkyldithiophosphate (Mo(ddp)2) and zinc dialkyldithiocarbamate (Zn(dtc)2). The equilibrium in this reaction favors Mo(dtc)2 and Zn(ddp)2 formation, and the... 

Molybdenum bisalkyne complexes form more readily in the pyrrole-/V-carbodithioate ligand system ( pyrroledithiocarbamate ) than in the corresponding dialkyldithiocarbamate systems (88). The pyrrole nitrogen is reluctant to share electron density with the attached CS2 moiety since the aromatic stabilization of the five-membered NC4 ring is lost in resonance form ii. As a result of decreased electron donation from the... 

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