Homobinuclear bis-3,6-di-tert-butyl-o-benzosemiquinone and bis-3,6-di-tert-butyl-o-catecholate complexes of PdII and PtII with bridging ligands. Molecular structure of (3,6-Cat)2Pd2L2 (L = dppm and dppy)

Reactions of the binuclear complexes M₂L₂Cl₂ [M = Pt or Pd, L = bis(diphenylphosphino)methane (dppm) or 2-(diphenylphosphino)pyridine (dppy)] with thallium 3,6-ditert-butyl-o-benzosemiquinone (3,6-SQ) in solutions have been studied. The formation of the corresponding bis(semiquinone) binuclear derivatives M₂L₂(SQ)₂ with retention of the metal-metal bond has been established by the ESR method. The average distances between the centers of localization of unpaired electrons, which were determined from the ESR spectral data for the complexes studied, allow conclusions about the parallel arrangement of the semiquinone ligands in skewed conformations in a square-pyramidal coordination sphere of both metal atoms. At room temperature, the biradical complexes are slowly converted to diamagnetic catecholate compounds with cleavage of the M-M bond and with retention of the bridging structure of the dppm and dppy ligands. The structures of catecholate complexes of palladium have been established by X-ray structural analysis.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 464–468, February, 1996.