Molybdenum complexes tertiary phosphines

The orange complex is air sensitive in the solid state. It is reasonably soluble and stable in THF but decomposes in nonpolar solvents, such as benzene, to give polymeric halogen-bridged products.9 It is paramagnetic with a magnetic moment of 3.63 BM, and its IR spectrum shows a very intense band at about 820 cm-1 due to coordinated THF. Its reactions with tertiary phosphines in THF give a series of molybdenum (III) tertiary phosphine complexes,9 and with trimethyl-silyl azide Mo(V) nitrido complexes are formed.8... 

The electrochemical Generation of Low Valent Molybdenum Tris (Tertiary phosphine) Complexes Interactions with Monophosphines and Molecular Nitrogen... 

Although trialkyl- and triarylbismuthines are much weaker donors than the corresponding phosphoms, arsenic, and antimony compounds, they have nevertheless been employed to a considerable extent as ligands in transition metal complexes. The metals coordinated to the bismuth in these complexes include chromium (72—77), cobalt (78,79), iridium (80), iron (77,81,82), manganese (83,84), molybdenum (72,75—77,85—89), nickel (75,79,90,91), niobium (92), rhodium (93,94), silver (95—97), tungsten (72,75—77,87,89), uranium (98), and vanadium (99). The coordination compounds formed from tertiary bismuthines are less stable than those formed from tertiary phosphines, arsines, or stibines. 

The electrosynthesis of hydride complexes directly from molecular hydrogen at atmospheric pressure by reduction of Mo(II) and W(II) tertiary phosphine precursors in moderate yield has been described as also the electrosynthesis of trihydride complexes of these metals by reduction of M(IV) dihydride precursors [101,102]. Hydrogen evolution at the active site of molybdenum nitrogenases [103] is intimately linked with biological nitrogen fixation and the electrochemistry of certain well-defined mononuclear molybdenum and tungsten hydrido species has been discussed in this context [104,105]. 

The complexes [M(N2)2(tertiary phosphine)4] (M = Mo or W) react with acids in different ways. For example [W(N2)2(PMe2Ph)4l with HC1 or H2S04 in methanol produces 1 mol dinitrogen and up to 2 mol ammonia, whereas the molybdenum counterpart gives only 1 mol of ammonia and 1.5 mol of dinitrogen. Many data have been collected on... 

Zero-valent ruthenium complexes (arene)Ru(PRg)2 (PR3 = tertiary phosphine), isoelectronic with the molybdenum complexes (CgHg)Mo-(PR3)3 182), have not yet been reported. However, the hydride cation (XXVII), isoelectronic with the molybdenum hydride cations [(CgHg)-Mo(PR3)3H] 182), has been obtained from the dissociation of [RuH-(PPh3)JPFg in dichloromethane solution 364). 

Reduction of [Mo CIg] and [Mo ClgX ] anions (X = Cl, Br, or I) by certain tertiary phosphines gave complexes of stoicheiometry MOgClgX3(PR3)3, which are formulated to have an ionic structure [MOgCl8(PR3)g] [Mo Clg]X in which the cation is a derivative of the previously unknown [Mo Clg] cluster. The use of photoelectron spectroscopy to determine structures of metal halide clusters has been reviewed. " A detailed study of the force fields for MojXg anions (X = Cr or Br) has indicated that 6 bonds do not play a significant part in the M—M bond strength of molybdenum halides. ... 

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