Electronic Factors Affecting Metal−Metal Interactions in Early/Late Heterobimetallics: Substituent Effects in Zirconium/Platinum Bis(phosphinoamide) Complexes

Abstract

The bidentate metalloligand (NMe2)2Zr(iPrNPPh2)2 (1) has been synthesized and treated with (COD)PtMe2 to generate the heterobimetallic Zr/Pt species (NMe2)2Zr(iPrNPPh2)2PtMe2 (2). Complex 2 can be treated with TMSCl to generate the dichloride species Cl2Zr(iPrNPPh2)2PtMe2 (3), a useful precursor for generating a range of Zr/Pt complexes featuring different Zr substituents. Upon treatment with lithio or Grignard reagents, Cl(Me3SiCH2)Zr(iPrNPPh2)2PtMe2 (4), (Me3SiCH2)2Zr(iPrNPPh2)2PtMe2 (5), and Me2Zr(iPrNPPh2)2PtMe2 (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.