Hydrogen bonding in crystalline alcohol solvates of the platinum(II) sulfido complex [Pt2( -S)2(PPh3)4]

Abstract

Suspension of [Pt₂( -S)₂(PPh₃)₄] in lower alcohols results in recrystallisation, forming yellow to yellow-orange microcrystals of the solvates [Pt₂( -S)₂(PPh₃)₄]•nROH (R = Me, Et, nBu). The di-ethanol solvate was characterised by means of a single-crystal X-ray diffraction study and 1H NMR spectroscopy. The structure consists of an ethanol molecule hydrogen-bonded in an asymmetric bifurcated fashion to the {Pt₂S₂} group, with the second, disordered ethanol molecule involved in a cooperative hydrogen-bonding interaction with the oxygen of the first ethanol. Thermogravimetric analysis shows that the alcohol is relatively easily lost, regenerating orange, unsolvated [Pt₂( -S)₂(PPh₃)₄]. [Pt₂( -S)₂(PPh₃)₄] readily dissolves in hexafluoro-2-propanol, yielding yellow crystals of [Pt₂( -S)₂(PPh₃)₄]•6(CF₃)₂CHOH on evaporation. Characterisation by X-ray diffraction shows that the structure contains a [Pt₂ ( -S)₂(PPh₃)₄] hydrogen-bonded to a single(CF₃)₂CHOH molecule, with the additional (CF₃)₂CHOH molecules forming a discrete hydrogen-bonded pentameric cluster in the crystal.