Coordination chemistry of gold(II) complexes

The number of complexes with gold in a formal oxidation state of two have increased considerably and nowadays this oxidation state can be considered nearly as a common state in gold chemistry. This review covers the evolution of the knowledge of this oxidation state from the first dithiocarbamate derivatives [Au-2(S2CNR2)(2)X-2], stable only at very low temperature, to the room temperature stable dinuclear gold complexes [Au-2(L-L)(2)X-2] (L-L = CH2PPh2CH2, CH2PPh2S, C5H4PPh2-2; X = halogen). Although a dinuclear structure with a gold(II)-gold(II) bond supported by two equal bridging ligands were the first and most common, this review shows the present diversity as mononuclear, [Au([9]aneS(3))(2)](BF4)(2), dinuclear with two different bridging ligands, [Au-2(S2CNR2)(CH2PPh2CH2)X-2], with a non-supported metal-metal bond, [Au-2(Ph2PC8H6PPh2)(2)Cl-2](PF6)(2), and polynuclear gold(II) complexes either with chains of only gold centers or with other metals, such as [{(C6F3H2)Au(CH2PPh2CH2)(2)Au}(2)Au-2(CH2PPh2CH2)(2)]ClO4 or [Au2Pt(CH2PPh2S)(4)X-2] (C) 1999 Elsevier Science S.A. All rights reserved.