Electronic structures of nitridomanganese(V) complexes

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'-(I S,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) Angstrom for 2). The C(s )compounds have a low-spin (1)A'[a'(x(2-)y(2))](2) ground state. The lowest absorption system (similar to 600 nm) consists of two components that are separated by approximately 4000 cm(-1); these are assigned to (1)A'' --> (1)A'[a'(x(2) - y(2))a'(yz)] (14 900 cm(-1)) and (1)A'' --> (1)A"[a'(x(2 )- y(2))a"(xz)] (18 900 cm(-1)) transitions.