Dialkoxyosmium(IV) porphyrins. Crystal and molecular structures of diethoxy-, diphenoxy-, and bis(2-propanolato)(meso-tetraphenylporphyrinato)osmium(IV)

Abstract

A series of dialkoxyosmium(IV) porphyrins [Os(Por)(OR)2] [Por = TPP (meso-tetraphenylporphyrinato dianion), (MeO)12TPP (meso-tetrakis(3,4,5-trimethoxyphenyl)porphyrinato dianion); R = Me, Et, i-Pr, PhCH2] were synthesized by treatment of [Os(Por)(N2)(THF)] [Por = TPP, (MeO)12TPP] with alcohols in tetrahydrofuran (THF). All these new complexes were characterized by UV-visible, IR, and 1H NMR spectroscopy. The X-ray crystal structures of [Os(TPP)(OEt)2], [Os(TPP)(OCH(CH3)2)2], and [Os(TPP)(OPh)2] have been determined: [Os(TPP)(OEt)2], monoclinic P21/c, a = 9.858 (1) Å, b = 15.646 (4) Å, c = 13.137 (2) Å, β = 106.94 (1)°, Z = 2; [Os(TPP)(OCH(CH3)2)2], triclinic P1, a = 9.812 (1) Å, b = 11.093 (1) Å, c = 11.656 (1) Å, α = 70.83 (1)°, β = 76.08°, γ = 62.06 (1)°, Z = 1; [Os(TPP)(OPh)2], triclinic P1, a = 10.253 (1) Å, b = 10.724 (1) Å, c = 11.958 (1) Å, α = 62.08 (1)°, β = 68.55 (1)°, γ = 79.30 (1)°, Z = 1. The RO-Os-OR axes in all complexes are required to be linear by symmetry with Os-OR distances ranging from 1.909 (4) to 1.938 (2) Å, indicating the presence of dπ(Os)-pπ(O) interactions. The Os-O-C angles for the three complexes are nearly the same, being 127.0 (3)-128.2 (5)°. © 1992 American Chemical Society.