Preparation and Characterization of N,N-Bridged and/or S,S-Bridged Sexidentate-N2,O2,S2 Cobalt(III) Complexes, Crystal Structure {(3S,8S)-2,2,9,9-Tetramethyl-1,10-dithia-4,7-diazacyclotetradecane-3,8-dicarboxylato}cobalt(III) Bromide

Abstract

Abstract Four kinds of cobalt(III) complexes with N,N-bridged, S,S-bridged, or N,N- and S,S-bridged (cyclo type) sexidentate-N2,O2,S2 ligand containing two d-penicillaminate moieties were newly synthesized. Of these complexes, the crystal structure of the title complex was determined by the X-ray diffraction method. The crystal was orthorhombic, space group P212121, a=16.935(5), b=23.506(7), c=13.057(6) Å, V=5198(3) Å3, Z=8, and the final R value was 0.0685. The ligand coordinates to the cobalt atom as the N,N- and S,S-bridged sexidentate-N2,O2,S2. The absolute configurations of the nitrogen and sulfur donor atoms are S(N),S(N) and R(S),R(S) respectively. The N,N-bridged five-membered ring is the gauche form with the δ conformation and the S,S-bridged seven-membered ring is the twist-chair form with the λ conformation. The other three complexes were characterized by their electronic absorption, 13C NMR, and circular dichroism (CD) spectra. The N,N- and/or S,S-bridged complexes showed the characteristic absorption and CD spectral behavior in the region of 16–24×103 cm−1.