Macrobicyclic d-metal tris-dioximates obtained by cross-linking with p-block elements—VII. Clathrochelate tris-dioximates of cobalt(III) formed by tin tetrachloride

Abstract Clathrochelate complex acids of the general composition H[CoD 3 (SnCl 3 ) 2 ] (where D 2− 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, 1 H, 13 C { 1 H}, 119 Sn, 59 Co NMR and 119 Sn Mossbauer spectra. A “macrocyclic” effect increases the ligand field effect by the formation of a tin-containing clathrochelate structure which has been found using 59 Co 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 119 Sn 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[CoDm 3 (SnCl 3 ) 2 ]·2C 6 H 6 single crystals (space group C 2/ c, a = 14,657(3), b = 13.823(3), c = 16.837(3) A, β = 98.11 (1)°, V = 3377(2) A 3 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°) is close to that estimated earlier from the 59 Co 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.