Higher Coordinate Gold(I) Complexes With The Weak Lewis Base Tri(4-Fluorophenyl) Phosphine. Synthesis, Structural, Luminescence, And Dft Studies

The structures and spectroscopic properties of two high coordinate gold(I) phosphine complexes with the TFFPP=tri(4-fluorophenyl)phosphine ligand are reported. Synthesis in a 1:3 metal to ligand ratio provided the compound [AuCl(TFFPP)(3)] (2) that crystallize in the PT space group, where the asymmetric unit consists of three independent molecules. In all three sites, two sets of bond angles display distinctly different ranges. The three P-Au-P angles have average values of 117.92,degrees 117.57 degrees, and 114.78 degrees for sites A, B, and C, with the corresponding P-Au-Cl angles of 98.31 degrees, 99.05 degrees, and 103.38 degrees, respectively. The chloride ion coordinates as the fourth ligand, at the corresponding Au-Cl distance of 2.7337, 2.6825, and 2.6951 angstrom for the three sites. This distance is longer by 0.40-0.45 angstrom than the Au-Cl distance found in the mono TFFPP complex 1 (2.285 angstrom) indicating a weakening of the Au-Cl interaction as the coordination number increases. In compound 3, [Au(TFFPP)(3)]Cl center dot 1/2CH(2)Cl(2).H2O, the structure consists of three phosphine ligands bound to the gold(I) atom, but the exists as uncoordinated counter anion. The structural differences observed in the two complexes are attributable to crystal-packing effects caused by the introduction of H-bonding as well as enhanced infra and inter-molecular pi-interaction in 3. The photoluminescence of the complexes compared with that of the ligand show ligand centered emission perturbed by the metal coordination. Theoretical DFT studies conducted on these complexes supports assignments of the electronic transitions observed in these systems. (C) 2015 Elsevier B.V. All rights reserved.