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

Abstract

The 7-coordinate technetium(III) and rhenium(III) monocapped tris(dioxime) complexes [MX(dioxime)3BR] 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 orth...