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-(-)-sald pen)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, an d 1R,2R-(+)-saldpen R,2R-(+)-diphenyl)ethylenebis(salicylideneaminato) dianion]. As revealed by X-ray crystal structure analyses, these mole cules have a distorted square-pyramidal geometry with a short Mn=N bon d distance (1.52(3) Angstrom for 2). The C(s )compounds have a low-spi n (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 ap proximately 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.