2-COORDINATE COMPLEXES OF UNIVALENT COINAGE METALS WITH GROUP-5B LIGANDS AND THE CRYSTAL-STRUCTURES OF [AG(AS(C5H9)3)2][CLO4] AND [AG(PPH2(C5H9))2][CLO4]

Twelve complexes of general formula [M(ZR2R′)2]X (M = Ag, Cu, Au; X = BF4, ClO4; Z = As, P) have been isolated and characterized. The stoichiometry is principally determined by the steric properties of the ZR2R′ ligands. For a majority of the complexes, their infrared spectra are indicative of free anions. However, the structural studies detailed below indicate a weak association of the metals with the anions, and demonstrate that neither [Ag{As(C5H9)3}2][ClO4] nor [Ag{PPh2(C5H9)}2][ClO4] contain a linear Z-Ag-Z cation. This substantiates the rarity of the linear ML2 geometry. Crystals of [Ag{As(C5H9)3}2] [ClO4] belong to the monoclinic space group P21/n, with a = 10.162 (4) Å, b = 23.211 (6) Å, c = 14.351 (3) Å, β = 98.37 (2)°, and Z = 4. Anisotropic refinement of all non-hydrogen atoms gave a final, weighed R value of 0.0501. Silver-arsenic bond lengths are 2.480 (2) and 2.482 (2) Å. Ionic interactions give rise to short contacts between the Ag+ ions and ClO4- anions, with the shortest oxygen-silver distance of 2.644 (5) Å. These interactions lead to a nonlinear geometry for the AgAs2 moiety with the As-Ag-As angle bent to 151.2 (1)°. The tertiary phosphine complex crystallizes in the monoclinic space group Pn, with a = 10.574 (6) Å, b = 17.142 (11) Å, c = 18.812 (13) Å, β = 104.34 (5)°, and Z = 4. Anisotropic refinement of all atoms with Z ≥ 6 gave a final weighted R value of 0.0484. The unit cell contains two independent cations. Anion-cation interactions again lead to nonlinear coordination, with P-Ag-P angles of 145.1 (1) or 153.0 (1)°. The Ag-P bonds in the two ions are 2.432 (2) and 2.415 (2) A and 2.419 (2) and 2.397 (2) Å, respectively. An evaluation of the effect that the change in coordination number has on the radius of the Ag(I) ion is given. © 1990, American Chemical Society. All rights reserved.