STERIC CONTROL OF TRICOORDINATION IN UNIVALENT COINAGE METAL-COMPLEXES - CRYSTAL-STRUCTURE OF TRIS(CYCLOPENTYLDIPHENYLPHOSPHINE)SILVER(I) TETRAFLUOROBORATE

Eighteen complexes of general formula [M(PR2R′)3]X (M = Cu, Ag, Au; X = BF4, ClO4; R = Ph, Cy, C5H9) have been isolated and characterized. In the majority of cases, the infrared spectra of the anions indicate that they are not coordinated or, at most, very weakly coordinated. Thus three-coordination is indicated. This intermediate coordination number for univalent coinage metals is produced by steric limitations of the tertiary phosphine ligands. The PR2R′ ligands employed are intermediate in size between tricyclohexylphosphine, which forms two-coordinate complexes, and triphenylphosphine, which forms four-coordinate complexes. Crystals of [Ag{PPh2(C5H9)}3] [BF4] belong to the trigonal space group P31c, with a = 13.398 (6) Å, c = 30.509 (10) Å, and Z = 4. The structure refinement converged at R = 0.0551. The structure consists of nonplanar three-coordinate Ag–phosphine complexes and disordered BF4− anions. The silver ions are located on sites of 3-fold symmetry (Ag–P = 2.545 (3) Å, P–Ag–P = 117.4 (1)°). The Ag(PR2R′)3 cations are found in pairs about a single disordered BF4− anion. Weak Ag–BF4 interactions (Ag⋯F = 2.54 (2) Å) induce the deformation of the AgP3 core from planarity. © 1990, American Chemical Society. All rights reserved.