Gold(I) complexes of neutral, anionic, and oxidized bis(diphenylphosphino)acetonitrile

The ligand bis(diphenylphosphino)acetonitrile, (PPh2)2CHCN, (“dppm-CN”), was prepared. The reaction between dppm-CN and [Au(C6F5)(tht)] (tht = tetrahydrothiophene) (molar ratio 1:2) formed an open-ended dinuclear gold(I) complex [(AuC6F5)2(dppm-CN)], 1. The crystal structure showed a linear disposition of dimers with intramolecular Au···Au interactions between the dinuclear units, but despite two distinctly different distances between the gold centers, it is without intermolecular Au···Au interactions. Deprotonation of dppm-CN afforded the anion [(PPh2)2CCN]¯ which reacted with [AuCl(tht)] (molar ratio 1:1) to form a neutral cyclic dinuclear gold(I) complex [Au2{(PPh2)2CCN}2], 2. Complex 2 could also be formed from mono- or bis(phosphine) gold(I) chloride complexes through the making and breaking of Au-P bonds. Reaction between the oxidized, deprotonated form of the ligand, [(P(S)Ph2)2CCN]¯, and [AuCl(PPh3)] (molar ratio 1:1) formed the neutral mononuclear complex [Au(PPh3)(P(S)Ph2)2CCN] 3, with the [AuPPh3]+ fragment bonded to one sulfur atom and a large degree of electron delocalization across the S-P-C-P-S ring. Complexes 1–3 were all obtained in satisfactory yield (70-90%), and analyzed by single crystal X-ray studies, solution 1H and 31P NMR, IR, and elemental analyses.

Graphical abstractThe ligand bis(diphenylphosphino)acetonitrile was used as a neutral and modified anionic and oxidized version in forming mono- and dinuclear gold(I) complexes of the type [(AuC6F5)2(dppm-CN)], 1, [Au2{(PPh2)2CCN}2], 2, and [Au(PPh3)(P(S)Ph2)2CCN] 3.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► First examples of cyclic and open-ended dinuclear gold(I) complexes with dppm-CN ligand. ► Utilizing the dppm-CN ligand in anionic, neutral and oxidized form. ► Unusual intermolecular gold(I)-gold(I) interaction.