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Issue 20, 2004
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Synthesis, properties and structures of eight-coordinate zirconium(iv) and hafnium(iv) halide complexes with phosphorus and arsenic ligands

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Abstract

Eight-coordinate [MX4(L–L)2] (M = Zr or Hf; X = Cl or Br; L–L = o-C6H4(PMe2)2 or o-C6H4(AsMe2)2) were made by displacement of Me2S from [MX4(Me2S)2] by three equivalents of L–L in CH2Cl2 solution, or from MX4 and L–L in anhydrous thf solution. The [MI4(L–L)2] were made directly from reaction of MI4 with the ligand in CH2Cl2 solution. The very moisture-sensitive complexes were characterised by IR, UV/Vis, and 1H and 31P NMR spectroscopy and microanalysis. Crystal structures of [ZrCl4{o-C6H4(AsMe2)2}2], [ZrBr4{o-C6H4(PMe2)2}2], [ZrI4{o-C6H4(AsMe2)2}2] and [HfI4{o-C6H4(AsMe2)2}2] all show distorted dodecahedral structures. Surprisingly, unlike the corresponding Ti(IV) systems, only the eight-coordinate complex was found in each system. In contrast, the ligand o-C6H4(PPh2)2 forms only six-coordinate complexes [MX4{o-C6H4(PPh2)2}] which were fully characterised spectroscopically and analytically. Surprisingly the tripodal triarsine, MeC(CH2AsMe2)3, also produces eight-coordinate [MX4{MeC(CH2AsMe2)3}2] in which the triarsines bind as bidentates in a distorted dodecahedral structure. There is no evidence for seven-coordination as found in some thioether systems.

Graphical abstract: Synthesis, properties and structures of eight-coordinate zirconium(iv) and hafnium(iv) halide complexes with phosphorus and arsenic ligands

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Article information


Submitted
14 Jun 2004
Accepted
30 Jul 2004
First published
01 Sep 2004

Dalton Trans., 2004, 3305-3312
Article type
Paper

Synthesis, properties and structures of eight-coordinate zirconium(IV) and hafnium(IV) halide complexes with phosphorus and arsenic ligands

W. Levason, M. L. Matthews, B. Patel, G. Reid and M. Webster, Dalton Trans., 2004, 3305
DOI: 10.1039/B409051A

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