Synthesis and structure of mixed carboxylate-aminopyridinate and -amidinate complexes of dimolybdenum and ditungsten

• We describe new Mo2 and W2 complexes with quadruple M−M bonds.
• Complexes [Mo2(O2CR)4] (R = CF3, Me) and [W2(O2CCF3)4] are used as precursors.
• One or two aminopyridinate or amidinate ligands can substitute carboxylate groups.
• Complexes [M2(O2CR)2(N^N)2] are useful synthetic precursors.

We describe in this paper the synthesis and structural characterization of dimolybdenum and ditungsten complexes with MM bonds derived from the metal–metal bonded tetracarboxylates [M2(O2CR)4] and incorporating one or two bulky aminopyridinate or amidinate ligands. The new compounds were isolated in good yields from reactions of the [Mo2(O2CR)4] (R = CF3, Me) and [W2(O2CCF3)4] metal precursors with the lithium salts of several aminopyridinate and amidinate ligands. They have formulations [M2()(O2CR)3] or [M2()2(O2CR)2] ( = bridging aminopyridinate or amidinate ligand) and were identified by microanalysis and common spectroscopic techniques. Nine of the newly reported complexes were additionally characterized by X-ray crystallography.

Sequential displacement of carboxylate groups from the core MM in the molecules of M2(O2CR)4 (M = Mo, W) by bidentate N-donor aminopyridinate and amidinate ligands.Figure optionsDownload as PowerPoint slide