Dynamic Gold(I) Complexes of Hexa-tert-butyl-octaphosphane

A facile synthesis for {cyclo-(P4tBu3)}2 (1) is reported making the phosphane available for follow-up chemistry. Octaphosphane 1 reacts with [AuCl(tht)] (tht = tetrahydrothiophene) to give a monometallic {[AuCl(1-κ2P2,P4')], 2}, bimetallic {[(AuCl)2(1-κ2P2,P4',κP2')], 3} and trimetallic complex {[(AuCl)3(1-κ2P2,P4',κP2',κP4)], 4} in which up to four phosphorus atoms of the ligand are involved in coordination. In each of these complexes one gold(I) atom is chelated in an unusual distorted T-shaped coordination mode which undergoes a rapid exchange between both donor atoms in solution. This mode of coordination in combination with the flexibility of the phosphane ligand moreover gives rise to an interesting dynamic behavior of the monometallic complex 2 which was elucidated by NMR spectroscopy, X-ray crystallography and DFT calculations.