Electronic factors affecting metal-metal interactions in early/late heterobimetallics: Substituent effects in zirconium/platinum bis(phosphinoamide) complexes

摘要

The bidentate metalloligand (NMe_2)_2Zr(~iPrNPPh_2)_2 (1) has been synthesized and treated with (COD)PtMe_2 to generate the heterobimetallic Zr/Pt species (NMe_2)_2Zr(~iPrNPPh_2) _2PtMe_2 (2). Complex 2 can be treated with TMSCl to generate the dichloride species Cl_2Zr(~iPrNPPh _2)_2PtMe_2 (3), a useful precursor for generating a range of Zr/Pt complexes featuring different Zr substituents. Upon treatment with lithio or Grignard reagents, Cl(Me_3SiCH_2)Zr(~iPrNPPh_2)_2PtMe_2 (4), (Me _3SiCH_2)_2Zr(~iPrNPPh_2) _2PtMe_2 (5), and Me_2Zr(~iPrNPPh _2)_2PtMe_2 (6) have been synthesized. Complexes 1-6 have been characterized using X-ray crystallography, revealing an unmistakable trend in Pt-Zr distance as a function of the electron-releasing ability of the Zr-bound X-type ligands. In addition, the solid-state structure of 6 reveals isomerization of the chelating metalloligand from a cis to a trans configuration about Pt and an unusual anagostic interaction between one of the Pt-bound Me groups and the electron-deficient Zr center. This isomerization is accompanied by a thermoneutral methyl group exchange process between Zr and Pt.