Unusual Difference in the Reactivity of Seven-Coordinated Mo(II) and W(II) Carbonyl Complexes,[MI 2 (CO) 3 (NCCH 3 ) 2 ] with Derivatised-DPPM,Me 3 SiN=PPh 2 CH 2 PPh 2 †

Abstract

The reaction of [Mo(CO)₃I₂(NCCH₃)₂] with a stoichiometric amount of Me₃SiN=PPh₂CH₂PPh₂ gives an octahedral complex, [Mo₃I(CO)(η²-N=PPh₂CH₂PPh₂)] by the metathetical elimination of Me₃SiI. Interestingly, similar reaction of the analogous tungsten complex gives a seven-coordinated complex, [WI₂(CO)₃(η²-Me₃SiN=PPh₂CH₂PPh₂)] which ultimately hydrolyses to give an amide complex, [W(CO)₃I₂(η²-HN=PPh₂CH₂PPh₂)]. The complexes have been characterised by microanalysis, IR and NMR (¹H and ³¹P) spectroscopic data.