The trimethylplatinum(IV) complexes of a number of dithiocarbamato ligands have been prepared. The complexes are dimeric in the solid state and in solution, with the ligands acting in both a bridging and chelating fashion. Restricted rotation about the ligand CâN bonds in solution leads to the formation of four rotomers. The kinetics of the restricted rotation was measured by a variety of dynamic NMR techniques in the slow and intermediate exchange regimes. Two distinct processes are observed, namely the independent rotation about each CâN bond and correlated rotation about both CâN bonds. The free energies of activation, which are strongly dependent on the nature of the ligand substituents, are in the range 65â88 kJ molâ1 at 298 K. The origins of the barrier to rotation and the effects of the nitrogen substituents are discussed. The crystal structures of fac-[PtMe3(Me2NCS2)]2 and fac-[PtMe3(Ph(H)NCS2)]2 are reported.
已经制备了许多二
硫代
氨基甲酸酯
配体的三甲基
铂(IV)络合物。该复合物在固态和溶液中都是二聚体,
配体以桥联和螯合方式起作用。溶液中
配体 C−N 键的受限旋转导致形成四个旋转异构体。通过多种动态核磁共振技术在慢速和中间交换状态下测量受限旋转的动力学。观察到两个不同的过程,即围绕每个 C-N 键的独立旋转和围绕两个 C-N 键的相关旋转。活化自由能很大程度上取决于
配体取代基的性质,在 298 K 时范围为 65–88 kJ mol–1。旋转势垒的起源和氮取代基的影响为讨论过。报道了 fac-[PtMe3(Me2
NCS2)]2 和 fac-[PtMe3(Ph(H)
NCS2)]2 的晶体结构。