Unusual difference in the reactivity of seven-coordinated Mo(II) and W(II) carbonyl complexes, [Mi(2)(CO)(3)(NCCH3)(2)] with derivatised-dppm, Me3SiN=PPh2CH2PPh2

Abstract

The reaction of [Mo(CO)(3)I-2(NCCH3)(2)] with a stoichiometric amount of Me3SiN=PPh2CH2PPh2 gives an octahedral complex, [Mo-3] (CO)(eta(2)-N=PPh2CH2PPh2)] by the metathetical elimination of Me(3)Sil. Interestingly, similar reaction of the analogous tungsten complex gives a seven-coordinated complex, [WI2(CO)(3)(eta(2)-Me3SiN=PPh2CH2PPh2)] which ultimately hydrolyses to give an amide complex, [W(CO)(3)I-2(eta(2)-HN=PPh2CH2PPh2)]. The complexes have been characterised by microanalysis, IR and NMR (H-1 and P-31) spectroscopic data.