Synthesis, structural characterization and catalysis of ethyl-substituted indenylnickel(II) halides
摘要:
The reaction of (1-Et-Ind)Li (1-Et-Ind = 1-ethylindenyl) with 1.81 equivalent of Ni(PPh3)(2)Cl-2 in ether, followed by crystallization from CH2Cl2/hexane, affords (1-Et-Ind)Ni(PPh3)Cl (1) in 58% yield. Similar reaction of (1-Et-Ind)Li with 1.81 equivalent of Ni(PPh3)(2)Br-2 in 1,2-dimethoxyethane (DME) affords (1-Et-Ind)Ni(PPh3)Br (2) in 60% yield. The reaction of complex 1 with KI in THF/acetone affords (1-Et-Ind)Ni(PPh3)I (3) quantitatively. Crystal structure analysis revealed that 2 and 3 are isomorphous. The hapticities of the indenyl ligand in these complexes are very similar and significantly distorted from an idealized eta(5) mode to an unsymmetrical eta(3) mode. The complexes are inert toward the insertion of styrene, but are able to catalyze the polymerization of styrene effectively in the presence of PPh3 and NaBPh4. (C) 2004 Elsevier Ltd. All rights reserved.