Formation of paramagnetic metallacyclobutadienes by reaction of diaminoacetylenes with molybdenum alkylidyne complexes

Abstract

The reactions of the molybdenum alkylidyne complex [MesCMo{OCMe(CF₃)₂}₃] (1) with the diaminoacetylenes R₂NCCNR₂ (2, NR₂ = 4-methylpiperidinyl; 3, NR₂ = NEt₂; Mes = 2,4,6-trimethylphenyl) afforded the metallacyclobutadiene (MCBD) complexes 4 and 5. In contrast to all other MCBD complexes, 4 and 5 are paramagnetic and best described as Mo(IV) species containing an anionic diaminodicarbene of the type [(R₂N)CC(Mes)C(NR₂)]⁻.