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=-CH=CH-, -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 Angstrom for 2-S-pyridine derivatives with Ph2P-CH=CH-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. (C) 2004 Elsevier B.V. All rights reserved.