The effect of carbon chain length of the diphosphine ligand on the aurophilic interaction. Synthesis and X-ray structural study for a series of Au(I) compounds with Ph2P–R–PPh2 and S-(CH2)n-py ligands

The effect of the carbon chain-length for Ph2P–R–PPh2 (R = –CHdouble bond; length as m-dashCH–, –CH2–CH2–, –CH2–CH2–CH2–, and –CH2–CH2–CH2– CH2–) and S-(CH2)n-pyridine ligand (n = 0 to 2) on the aurophilic interaction has been explored systematically. The effect of the N position in x-mercaptopyridine (x = 2 or 4) toward Au(I) center and/or the SR group was also investigated. X-ray structural study was made for 12 new derivatives. The Au–Au distances are below 3.0 Å for 2-S-pyridine derivatives with Ph2P–CHdouble bond; length as m-dashCH–PPh2 (t-dpen) and Ph2P–CH2–CH2–PPh2 (dppe) ligand and the pyridine N atoms come in close contact with the H atoms of these diphosphine carbon chains. A local coplanar conformation is formed between 2-S-pyridine and Au–P–CH groups for these derivatives. The carbon chain lengths are not too consequential on the induction of aurophilicity. Various infinite and/or dimer structures have been revealed from single crystal X-ray analysis for the present series of compounds.