Linkage isomerization of MSCN(CDOH)(2)(CDO)BMe to MNCS(CDOH)(2)(CDO)BMe (M = Tc, Re). Crystal structures of TcNCS(CDOH)(2)(CDO)BMe, ReNCS(CDOH)(2)(CDO)BMe, and ReSCN(CDOH)(2)(CDO)BMe

摘要

The 7-coordinate technetium(III) and rhenium(III) monocapped tris(dioxime) complexes [MX(dioxime)(3)BR] have been prepared in which the seventh ligand, X, is thiocyanate or hydroxide (M = Tc, Re; R = Me, Et). Both the N- and S-bound thiocyanate linkage isomers are produced during the syntheses, however, the S-bound complex isomerizes to the N-bound analogue. The synthetic routes employed allowed isolation of sufficient quantities of the technetium and rhenium S-bound isomers to be identified; however, full characterization was not possible. The linkage isomerization reaction of TcSCN(CDOH)(2)(CDO)BMe to TcNCS(CDOH)(2)(CDO)BMe was monitored in dichloromethane by UV-visible spectrophotometry, with four isosbestic points observed, consistent with the formation of a single product. The N-bound isomers for both Tc and Re, and the S-bound isomer of Re were characterized by single-crystal X-ray diffraction analysis. The two N-bound complexes were found to be isostructural. TcNCS(CDOH)2(CDO)BMe crystallized in the orthorhombic space group P2(1)2(1)2(1) with a = 15.814(2) Angstrom b = 17.855(3) Angstrom, c = 17.997(5) Angstrom, Z = 8, R = 0.054, and R-W = 0.057. ReNCS(CDOH)(2)(CDO)BMe crystallized in the orthorhombic space group P2(1)2(1)2(1) with a = 15.795(1) Angstrom, b = 17.843(2) Angstrom, c = 18.014(3) Angstrom, Z = 8, R = 0.054, and R-W = 0.073. In both cases two independent molecules per unit cell were observed. ReSCN(CDOH)(2)(CDO)BMe crystallized in the monoclinic space group P2(i)/c with a = 10.0866(6) Angstrom, b = 26.301(2) Angstrom, c = 12.4592(7) Angstrom, beta = 100.5(1) deg, Z = 4, R = 0.100, and R-W = 0.141. [References: 46]