.sigma.-Bonded organic derivatives of a cobalt(III) macrocyclic complex

Preparation of 1,1,5,5-tetraphenyl-3,7-diaryl-1,5-diphosphatetrazocines and 1,1,3,3,5-pentaphenyldiphosphatriazine and the x-ray structure of 1,5-Ph4P2N4C2(C6H4CH3-4)2

“…The cyclocondensation reaction (eq 1) was successful for the preparation of 4a-c from Ph2PCl3,20 but the yields were low (<30%) and, in one case, lb, was also isolated as a minor product. 21 The formation of six-membered rings of types 1 and 2, in addition to 4, has been reported previously for the reaction of Ph2PCl3 with the amidine, RFC(NH)(NH2) (RF = perfluoroalkyl ether).5 The 31P NMR chemical shifts of 4a-c are observed close to 0 ppm. In the case of 4a the 31P NMR resonance is ca.…”

Synthesis, Spectroscopy and Electrochemistry of Cobalt(III) Schiff Base Complexes

“…The ligand field parameter D q x y for Salen complexes was shown to be about 2560cm -1 from the two lowest energy bands of the spectra in ethanol (95%). 22,27 Correlation of ligand field transition (d-d transition) and ligand field strength in the Co(III) Schiff-base complexes show that the ligand field strength increases in the trend, 5-nitroSalen > Salen > 5-MeOSalen. As a result of their functional groups, the σ-donation power of these ligands increases in the reverse trend, thus we assume π-interactions between d orbitals and π* orbitals on the Schiff-base ligands.…”

Preparação e caracterização do complexo cobaloxima e sua utilização na construção de um eletrodo modificado: um experimento eletroquímico no curso de graduação

“…Observouse também no espectro uv-vis uma banda de fraca intensidade em 430 nm que pode ser atribuída a uma transferência de carga da ligação Co-C. Segundo a literatura, a energia da transição de transferên-cia de carga Co-C surge em virtude do aumento do caráter doador dos ligantes equatoriais e axiais. Com o aumento do caráter doador ocorre também o aumento da densidade de carga sobre o cobalto e, desta forma, estabiliza a ligação Co-C. Entretanto, alguns autores preferem atribuir esta banda às transições d-d de campo ligante 7,[13][14][15][16] .…”