MACROBICYCLIC D-METAL TRIS-DIOXIMATES OBTAINED BY CROSS-LINKING WITH P-BLOCK ELEMENTS .7. CLATHROCHELATE TRIS-DIOXIMATES OF COBALT(III) FORMED BY TIN TETRACHLORIDE

Clathrochelate complex acids of the general composition H[CoD3(SnCl3)2] (where D2- is the dianion of the corresponding dioxime), which readily form salts with organic amines, have been obtained by template cross-linking of cobalt(III) tris-dioximates of different natures with tin tetrachloride. The clathrochelate structure of the compounds isolated and their composition were confirmed by elemental analysis data, IR, electronic absorption, H-1, C-13 {H-1}, Sn-119, Co-59 NMR and Sn-119 Mossbauer spectra. A ''macrocyclic'' effect increases the ligand field effect by the formation of a tin-containing clathrochelate structure which has been found using Co-59 NMR spectroscopy; this corresponds to the ligand field parameters obtained when examining d-d transitions in the electronic spectra. In the case of the non-symmetrical dioxime, fac and mer isomers of the macrobicyclic complex have been identified. The high symmetry of the tin-containing cross-linking fragments has been established using Sn-119 Mossbauer and NMR spectroscopy. The effect of the nature of the macrobicyclic ligand on the structure and spectral characteristics of clathrochelate complexes are discussed. Monoclinic H[CoDM3(SnCl3)2].2C6H6 single crystals (space group C2/c, a = 14,657(3), b = 13.823(3), c = 16.837(3) angstrom, beta = 98.11(1)-degrees, V = 3377(2) angstrom3, Z = 4) have been obtained by recrystallizing a preliminarily synthesized clathrochelate. The cobalt atom is encapsulated by the macrobicyclic ligand and surrounded by a distorted trigonal antiprismatic coordination of six nitrogens. The distortion angle found experimentally (ca 42.3-degrees) is close to that estimated earlier from the Co-59 NMR parameters. The Co-N bond length (1.90 A) is characteristic of clathrochelate tris-dioximates and is determined by the superposition of the contributions of metal electron configuration and ligand geometry.