Synthesis, Structure, and Reactivity of <i>β</i>-Diketiminate Complexes of Manganese(II)

Abstract

Reaction of the β-diketiminate lithium salt LLi(OEt2) (1) (L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) with MnCl2 in diethyl ether provided the metalate complex LMn(μ-Cl)2Li(OEt2)2 (3) in high yield. The dimeric compound [LMn(μ-Cl)]2 (4) free of alkaline salt was obtained when the β-diketiminate potassium salt LK (2) was used instead of 1. The substitution reactions of 4 with CpNa, MeLi, and PhLi resulted in the formation of organomanganese complexes LMnCp(THF) (7), [LMn(μ-Me)]2 (8), and LMnPh (9), respectively. The novel ionic compound [LMnCl2][{C(Me)N(iPr)}2CH] (6) was obtained, when the N-heterocyclic carbene {C(Me)N(iPr)}2C was used as a proton acceptor. The first doubly carboxylato-bridged complex with four-coordinate manganese(II), [LMn(μ-O2CMe)]2 (5), was synthesized from the reaction of 2 and Mn(O2CMe)2 in THF. Complexes 3−7 were characterized by single-crystal X-ray structural analysis. The structures show that the β-diketiminate ligand backbone is essentially planar and the metal centers reside in distorted tetrahedral geometry.