Synthesis and properties of gold alkene complexes. Crystal structure of [Au(bipyoXyl)(η2-CH2CHPh)](PF6) and DFT calculations on the model cation [Au(bipy)(η2-CH2CH2)]+?

Dalton Transactions Pub Date: 2006-10-02 DOI: 10.1039/B610657A

Abstract

Unprecedented 16-electron gold(I) olefin complexes of general formula [Au(bipyR,R′)(η2-olefin)](PF6) and [Au2(bipyR,R′)2(μ-η2:η2-diolefin)](PF6)2 (bipyR,R′ = 6-substituted-2,2′-bipyridine) have been prepared by reaction of dinuclear gold(III) oxo complexes [Au2(bipyR,R′)2(μ-O)2](PF6)2 with the appropriate olefin. The X-ray crystal structures of two mononuclear complexes (olefin = styrene) show in-plane coordination of the olefin and a C[double bond, length as m-dash]C bond distance considerably lengthened with respect to the free olefin. The spectroscopic properties of the complexes are discussed and compared with those of analogous d10 metal derivatives. Both structural and spectroscopic information indicate a substantial contribution of π-back-donation to the Au–olefin bond in the three-coordinate species. Theoretical calculations carried out at the hybrid-DFT level on the model compound [Au(bipy)(η2-CH2[double bond, length as m-dash]CH2)]+ show excellent agreement with the experimental findings giving in addition an estimate of a π-back-bonding contribution higher than that of the σ-bonding.

Graphical abstract: Synthesis and properties of gold alkene complexes. Crystal structure of [Au(bipyoXyl)(η2-CH2 [[double bond, length as m-dash]] CHPh)](PF6) and DFT calculations on the model cation [Au(bipy)(η2-CH2 [[double bond, length as m-dash]] CH2)]+
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