The chemistry and structure of Chugaev's salt and related compounds containing a cyclic carbene ligand

Abstract

The products of addition of hydrazines, RNH·NH₂, to the cations [M(MeNC)₄]²⁺ have been shown to be carbene complexes of the type [M(C₄H₈N₄R)(MeNC)₂]⁺(M = Pd, R = H, M = Pt, R = H, Me, Ph, or CONH₂), where C₄H₈N₄R is formally the chelating ligand, 3,6-sigma-2,4,5,7-tetra-azaocten-3,3,6-triyl. The two molecules of methyl isocyanide can be replaced by neutral, anionic, or cationic ligands. Neutral complexes M(C₄H₁₀N₄)X₂(X = Cl, Br, l or CN), in which the carbene ligand is protonated, were obtained by treating the cationic species with mineral acid, or by metathesis. The chemical properties and i.r. and n.m.r. spectra of these compounds are discussed.