Homoleptic anionic complexe methyl ligands

Routes to homoleptic isocyanide complexes have been defined in thf (Scheme 46). Ta L6 (L = xylyl isocyanide) was reduced by ACg (A = K, Cs) to [Ta 1L6]. This anion appears to be octahedral. Its 13C NMR resonance occured at 210 ppm, the most downfield shift observed for a diamagnetic homoleptic isocyanide complex. Reaction with the NO source N-methyl-N-nitroso-/ -to 1 uenes u 1 lbnam ide provided Ta I(NO)L5 whose essentially linear NbNO fragment is consistent with the formal presence of ligand NO+. Direct nitrosylation of [M (CO)6] with 2 eq [NO][PF6] in the presence of L in CH2C12 at — 60 °C provided r/,v-[M (NO)2L4]1,662 The reaction represents a rare example of non-oxidative displacement of all CO ligands from a homoleptic carbonylme-talate. 

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