Synthesis and structure of bulky phosphiniminato complexes of zirconium and hafnium: Aryl groups as 'non-innocent' substituents in electrophilic systems

摘要

Sterically highly hindered phosphiniminato complexes MCl3(NCP) were prepared from MCl4 and Li[NPC] in toluene [M = Zr or Hf, NPC = 4-(BuC6H4C)-C-t(SiMe3)P(Ph)(2)=NC6H2Me3-2,4,6]. Reaction with methyl lithium readily affords the corresponding zirconium and hafniurn trimethyl complexes. The structures of representative zirconium and hafniurn complexes MX3(NPC) (X = Cl, M = Zr, Hf; X = Me, M = Hf) were determined by X-ray diffraction. In all cases the NPC ligand acts as C-N chelate, with an additional bonding contribution from the ipso-carbon atom of the C-bound aryl substituent, which results in a eta(1):eta(2)-coordination mode. The reaction of the hafniurn trimethyl complex with CPh3+ salts of perfluoroarylborate anions results either in the diastereoselective formation of the binuclear cation [{(NPC)HfMe2}(2)(mu-Me)](+) or in the formation of the mononuclear cation [(NPC)HtMe(2)](+), depending on the molar ratio of reagents. (c) 2006 Elsevier B.V. All rights reserved.