Different Coordination Modes of a Tripod Phosphine in Gold(I) and Silver(I) Complexes

Abstract

The following gold(I) and silver(I) complexes of the tritertiary phosphine 1,1,1- tris(diphenylphosphinomethyl)ethane, tripod , have been synthesised: Au₃(tripod)X₃ [X = Cl(1), Br(2), I(3)]; [Au₃(tripod)₂Cl₂]Cl (4); Au(tripod)X [X = Br(5), I(6)]; Ag₃(tripod) (NO₃)₄ (7), Ag(tripod)NO₃ (8). They were characterized by X-ray diffraction (complexes 2, 3 and 4), ³¹P NMR spectroscopy, electrospray and FAB mass spectrometry and infrared spectroscopy. Complexes 2 and 3 show a linear coordination geometry for Au(I), with relatively short Au-P bond distances. Complex 3 has a Au•••Au intramolecular distance of 3.326 $\stackrel{\text{°}}{\text{A}}$ , while complex 2 had a short Au•••Au intermolecular interaction of 3.048 $\stackrel{\text{°}}{\text{A}}$ . Complexes 4-6 were found by ³¹P NMR spectroscopy studies to contain a mixture of species in solution, one of which crystallised as [Au₃(tripod|)₂Cl₂]Cl which was shown by X-ray diffraction to contain both tetrahedral and linear Au(I), the first example of a Au(I) complex containing such a mixture of geometries. The reaction of [Au₃ (tripod)Cl₃] (1) with tripod led successfully to the formation of [Au₃(tripod|)₂Cl₂]⁺ and [Au₃(tripod)₂Cl₃]⁺ and [Au₃(tripod|)₃Cl]²⁺. The silver(I) complexes, 7 and 8 appear to contain linear and tetrahedral Ag(I), respectively.

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