Electronic Structures of Nitridomanganese(V) Complexes

Abstract

The single-crystal polarized absorption and circular dichroism spectra of the nitridomanganese(V) complexes (salen)Mn⋮N (1), (1S,2S-(−)-saldpen)Mn⋮N (2), and (1R,2R-(+)-saldpen)Mn⋮N (3) have been measured [salen = N,N‘-ethylenebis(salicylideneaminato) dianion, 1S,2S-(−)-saldpen = N,N‘-(1S,2S-(−)-diphenyl)ethylenebis(salicylideneaminato) dianion, and 1R,2R-(+)-saldpen = N,N‘-(1R,2R-(+)-diphenyl)ethylenebis(salicylideneaminato) dianion]. As revealed by X-ray crystal structure analyses, these molecules have a distorted square-pyramidal geometry with a short Mn⋮N bond distance (1.52(3) Å for 2). The Cs compounds have a low-spin 1A‘[a‘(x2 − y2)]2 ground state. The lowest absorption system (∼600 nm) consists of two components that are separated by approximately 4000 cm-1; these are assigned to 1A‘ → 1A‘[a‘(x2 − y2)a‘(yz)] (14 900 cm-1) and 1A‘ → 1A‘‘[a‘(x2 − y2)a‘‘(xz)] (18 900 cm-1) transitions.