STRUCTURAL CHARACTERIZATION OF BIDENTATE CARBOXYLATE DERIVATIVES OF COPPER(I) BISTRIPHENYLPHOSPHINE

The complexes (Ph(3)P)(2)Cu(carboxylate) (carboxylate = acetate (1), hippurate (2), vinyl acetate (3), fluorenate (4)) have been prepared and their solid-state structures determined crystallographically. The copper(I) center in all four structures exhibits a distorted tetrahedral geometry, with varying degrees of asymmetric bidentate binding of the carboxylate ligand. For example, in complex 2 the hippurate ligand displays the greatest extent of asymmetry with the two Cu-O bond distances differing by 0.234(6) Angstrom. The structures of all four derivatives were each shown to be the same both in the solid-state and in dichloromethane solution based on infrared spectroscopy The magnitude of Delta (v(a)(CO2-)-v(s)(CO2-)) in these copper(I) derivatives, determined to be quite similar to the corresponding ionic values, is used as constituting a diagnosis for asymmetric bidentate binding of the carboxylate ligand. Although all four complexes Lire structurally quite similar, only the fluorenate derivative which affords a resonance-stabilized carbanion upon carbon dioxide extrusion undergoes the decarboxylation reaction. Crystal data for 1: space group P2(1)/c, a = 18.085(5), b = 10.977(2), c = 17.979(5) Angstrom, beta = 115.62(2)degrees, Z = 4, R = 3.91%. Crystal data for 2: space group P ($) over bar 1, a = 9.96(2), b = 14.68(3), c = 14.96(3) Angstrom, alpha = 115.46(14), beta = 97.54(16), gamma = 102.31(15)degrees, Z = 2, R = 5.84%. Crystal data for 3: space group P ($) over bar 1, a = 12.755(3), b = 13.125(2), c = 12.572(2) Angstrom, alpha = 118.85(1), beta = 105.85(1), gamma = 97.65(1)degrees, Z = 2, R = 4.08%. Crystal data for 4: space group P ($) over bar 1, a = 11.554(1), b = 15.217(2), c = 15.285(2) Angstrom, alpha = 63.71(1), beta = 79.08(1), gamma = 75.20(1)degrees, Z = 2, R = 7.6%.