Synthesis and structural characterisation of group 10 metal(ii) gallyl complexes: Analogies with platinum diboration catalysts?

Cameron Jones, David P. Mills, Richard P. Rose, Andreas Stasch

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Abstract

Reactions of the anionic gallium(i) heterocycle, [:Ga([N(Ar)C(H)]2)] (Ar = C6H3Pri2-2,6), with a variety of mono- and bidentate phosphine, tmeda and 1,5-cyclooctadiene (COD) complexes of group 10 metal dichlorides are reported. In most cases, salt elimination occurs, affording either mono(gallyl) complexes, trans-[MCl(Ga([N(Ar)C(H)]2))(PEt3)2] (M = Ni or Pd) and cis-[PtCl(Ga([N(Ar)C(H)]2))(L)] (L = R2PCH2CH2PR2, R = Ph (dppe) or cyclohexyl (dcpe)), or bis(gallyl) complexes, trans-[M(Ga([N(Ar)C(H)]2))2(PEt3)2] (M = Ni, Pd or Pt), cis-[Pt(Ga([N(Ar)C(H)]2))2(PEt3)2], cis-[M(Ga([N(Ar)C(H)]2))2(L)] (M = Ni, Pd or Pt; L = dppe, Ph2CH2PPh2 (dppm), tmeda or COD). The crystallographic and spectroscopic data for the complexes show that the trans-influence of the gallium(i) heterocycle lies in the series, B(OR)2 > H > PR3 ∼ [:Ga([N(Ar)C(H)]2)] > Cl. Comparisons between the reactivity of one complex, [Pt(Ga([N(Ar)C(H)]2))2(dppe)], with that of closely related platinum bis(boryl) complexes indicate that the gallyl complex is not effective for the catalytic or stoichiometric gallylation of alkenes or alkynes. The phosphaalkyne, ButCP, does, however, insert into one gallyl ligand of the complex, leading to the novel, crystallographically characterised P, N-gallyl complex, [Pt(Ga([N(Ar)C(H)]2))(Ga(PC(But)C(H)[N(Ar)]C(H)N(Ar)))(dppe)]. An investigation into the mechanism of this insertion reaction has been undertaken.

Original languageEnglish
Pages (from-to)4395-4408
Number of pages14
JournalDalton Transactions
Issue number33
DOIs
Publication statusPublished - 3 Jul 2008

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