Assignment of the E,Z configurational isomers of platinum complexes of N,N-dialkyl-N '-acyl(aroyl)thioureas by means of triple resonance H-1/C-13/Pt-195 PFG correlation NMR spectroscopy

摘要

Unsymmetrical, dialkyl-substituted N,N-dialkyl-N'-acyl(aroyl)thioureas show E,Z configurational isomerism at room temperature in solution, which is also expressed in the existence of cis-[Pt(ZZ-L-S,O)(2)], cis-[Pt(EZ-L-S,O)(2)] and cis-[Pt(EE-L-S,O)(2)] complexes derived from these ligands. These configurational isomers were assigned by means of a double magnetization transfer H-1/C-13/Pt-195 correlation NMR experiment, despite the fact that the long-range (5)J(Pt-195, H-1) and (4)J(Pt-195, C-13) scalar couplings are not directly observable in their H-1 and C-13 spectra at high field. Depending on the ligand structure, the relative amounts of cis-[Pt(ZZ-L-S,O)(2)], cis-[Pt(EZ-L-S,O)(2)] and cis-Pt(EE-L-S,O)(2)] complexes are in the ranges 40-42% ZZ, 46-47% ZE and 12-13% EE. The cis-bis[N-methyl-N-(tert-butyl)-N'-(2,2-dimethylpropanoyl)thioureatolplati num(II) complex is found to occur exclusively as the ZZ isomer. Copyright (C) 2003 John Wiley Sons, Ltd. [References: 8]