Manganese(III) and rhenium(II) complexes with bulky 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzoquinonato ligands via carbonyls of corresponding metals

摘要

Four-coordinate complex Mn-III(ISQ-Pr-i)(AP-Pr-i) (1), where ISQ-Pr-i = 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzosemiquinonate anion-radical, AP-Pr-i = 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-amidophenolate dianion, has been prepared by the reaction of Mn-2(CO)(10) with free 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzoquinone (IBQ-Pr-i) in the molar ratio 1:4 in toluene. In contrast to manganese, rhenium carbonyl reacts with o-iminobenzoquinone to form complex Re-II(ISQ-Pr-i)(2)(CO)(2) (2) with the retention of two carbonyls in coordination sphere of rhenium. The complexes have been characterized by IR, UV-Vis, and EPR spectroscopies. Molecular structures of compounds 1 and 2 have been determined by single-crystal X-ray crystallography. Compound 1 is centro-symmetric square-planar molecule with delocalized mixed valent state of AP-Pr-i and ISQ-Pr-i ligands. EPR spectrum of 1 in solid at 300-77 K is typical for manganese complexes with S = 3/2 state. The effective magnetic moment of 1 is 1.96 mu(beta) at temperature 5 K as it was established by variable-temperature magnetic susceptibility measurements. Six-coordinate octahedral complex 2 possesses an S = 1/2 ground state, which is attained via strong intramolecular antiferromagnetic interaction between t(2g), orbital unpaired electron of the low spin Re-II ion and the impaired electron on pi-orbital of the radical ligand. (c) 2005 Elsevier B.V. All rights reserved.