Tris- phosphine reaction with molybdenum

Reaction of [MoCl(S2CNR2)3] (R = Me, Et) with silver triflate afforded diamagnetic [Mo2(dtc)6][OTf]2 which could act as the source of tris(dithiocarbamato)Mo cations in the synthesis of [MoL(dtc)3]"+ (n = 0, L = Cl, I, N3 n = 1, L = O, NCMe, PR3). The molybdenum atom in paramagnetic seven-coordinate [Mo(PMe2Ph)(S2CNEt2)3][OTf has pentagonal-bipyramidal coordination with an apical phosphine ligand. 

While the decomposition products of molybdenum-based initiators may conveniently be removed as molybdates after any metathesis reaction by addition of aqueous base, ruthenium tends to form RUO2, a black insoluble product. The removal of decomposed Ru-sites from any product is best performed by the use of a water-soluble phosphine such as tris(hydroxymethyl)phosphine [182]. Alternatively, addition of triphenylphosphinoxide or DMSO followed by filtration over sihca was reported to be advantageous [183]. For purposes of completeness, the investigations of the actual catalytic cycle in the reaction of Cl2Ru(CHPh)(PCy3)2 with cyclic olefins carried out with substituted cyclobutenes shall be mentioned [184]. 

Models for monodithiolene molybdenum species related to xanthine oxidase and aerobic CODH have been described, e.g. [Mo(S2CgH4)02(SR)] [143]. The synthesis of related species with terminal sulfido ligands would enable assembly of the indicated (dithiolene)Mo02S-CuSR ensembles. The interaction of M0S4 and Cu has received considerable study, motivated by interest in the ability of dietary Mo to inhibit copper uptake in ruminants [144]. Bi-, tri-, tetra-, or higher nuclearity Cu-Mo clusters result from the reaction of MoS and Cu" in the presence of tertiary phosphines, amines, or cyanide [144]. 

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