CRYSTAL-STRUCTURE, INFRARED, AND SOLID-STATE CP MAS NMR CHARACTERIZATION OF [(PPH(3))(2)AGO2CH] AND OF [(PPH(3))(2)AGO2CH]CENTER-DOT-2HCO(2)H, A COMPLEX OF THE H-BONDED [H-2(HCO2)(3)](-) SPECIES

Bis(triphenylphosphine)silver(I) formate and its diformic acid adduct, [(PPh(3))(2)AgO2CH]. 2CHO(2)H have been prepared and characterized by infrared spectroscopy, solid state CP MAS C-13 and P-31 NMR spectrosc opy, and single-crystal X-ray diffraction. Crystals of [(PPh(3))(2)AgO 2CH] are isomorphous, with [(PPh(3))(2)CuO2CH] crystallizing as discre te monomeric units in the monoclinic space group C?Jc with a 2-fold cr ystallographic axis of symmetry through the bisector of the P-Ag-P ang le and the anion. The formate anion is symmetrically coordinated to th e silver with an Ag-O distance of 2.425(3) Angstrom. The Ag-P distance is 2.4261(7) Angstrom, and the P-Ag-P angle 127.37(3)degrees. Crystal s of the diformic acid adduct belong to the orthorhombic space group P nma, in which the PPh(3) ligands are related by a crystallographic mir ror plane containing the silver atom, the formate anions, and the two molecules of formic acid. The anion is unsymmetrically coordinated wit h the Ag-O distances of 2.550(7) and 2.713(8) Angstrom, seemingly a co nsequence of strong hydrogen bond formation with each of the formic ac id molecules, with 0 ... 0 distances of 2.56(1) and 2.50(1) Angstrom. Although the Ag-P distance of 2.426(2) Angstrom is unchanged from that of [(PPh(3))(2)AgO2CH], the P-Ag-P angle increases to 147.86(7)degree s, the largest yet recorded for the [(PPh(3))(2)Ag](+) cation. The com pound can be regarded as a complex between the [(PPh(3))(2)Ag](+) cati on and the previously unknown doubly H-bonded [H-2(HCO2)(3)](-) ''trif ormate'' anion. Infrared bands due to this anion are assigned and disc ussed in relation to the metal-ligand and ii-bonding in the complexes. The solid state cross-polarization magic angle spinning (CP MAS) C-13 NMR spectra of [(PPh(3))(2)AgO2CH] shows a single carbonyl peak at 16 9.7 ppm, while for the formic acid adduct, three distinct peaks at 163 .5, 166.1, and 169.4 are observable. Simple doublets arising from (1)J (AgP) coupling are observed in the P-31 solid state NMR spectra of bot h complexes with a line spacing of 432 Hz for [(PPh(3))(2)AgO2CH] and 517 Hz for [(PPh(3))(2)AgO2CH]. 2HCO(2)H.