METAL-METAL COOPERATION VIA 1,1'-BIS(DIPHENYLPHOSPHINO)FERROCENE (DPPF) .1. STRUCTURALLY DISTINCTIVE SILVER(I) DPPF COMPLEXES OF NITRATO AND CARBOXYLATO LIGANDS IN VARIABLE COORDINATION MODES - CRYSTAL-STRUCTURES OF [AG(NO3)(DPPF)]22CHCL3, [AG2(HCO2)2(DPPF)3].2CH2CL2, [AG2(CH3CO2)2(DPPF)]2, AND AG2(C6H5CO2)2(DPPF)

Reaction between AgNO3 and 1,1'-bis(diphenylphosphino)ferrocene (dppf) gives the dimeric [Ag(NO3)(dppf)]2 (1). In the presence of Na+X-, where X=CH3CO2, C6H5CO2, and HCO2, [Ag2(CH3CO2)2(dppf)]2(2), [Ag2(C6H5CO2)2(dppf)] (3), and [Ag2(HCO2)2(dppf)3], (4), respectively, are formed. X-ray crystallographic studies of these compounds revealed that they are all structurally distinct. Compound 1 consists of an unprecedented {Ag2(mu-dppf)2} metallacyclic framework stabilized by two "semibridging-semichelate" nitrato ligands. Compound 2 consists of a chair-conformation arrangement of four tetrahedral Ag(I) centers interlinked by two bridging syn-dppf, and two chelate-bridging (mu2-(eta2-O, eta1-O')) and two triply bridging (mu3-(eta2-O, eta1-O')) acetato ligands. Compound 3 consists of two trigonal planar Ag(I) moieties triply bridged by dppf (syn) and two benzoato fragments. Both 2 and 3 are examples of molecules stabilized by only bridging ligands. The structure of 2 may be viewed as a dimer of 3. Compound 4 uniquely contains a unidentate formato ligand and both chelating (syn) and bridging (anti) dppf in a dinuclear framework. Molecules 1, 2, and 4 are centrosymmetric. The structures of 2-4 illustrate the variability of carboxylates in their ligation modes, their abilities to stabilize 18- and 16-electron silver(I) in its tetrahedral and trigonal planar geometries, and their influence on the nuclearity of the complexes. All the structures demonstrate the adaptability of dppf in its coexistence with ligands of much smaller bite size. Crystal data: for 1, space group = P2(1)/n (No. 14), a = 13.908 (5) angstrom, b = 15.626 (9) angstrom, c = 18.674 (9) angstrom, beta = 102.07 (2)-degrees, Z = 2, 3579 reflections, R = 0.079; for 2, space group = P2(1)/n (No. 14), a = 10.373 (2) angstrom, b = 17.593 (5) angstrom, c = 19.754 (8) angstrom, beta = 100.66 (2)-degrees, Z = 2, 4580 reflections, R = 0.042; for 3, space group = Pbca (No. 61), a = 10.532 (2) angstrom, b = 18.851 (9) angstrom, c = 41.74 (2) angstrom, Z = 8, 3059 reflections, R = 0.0312; for 4, space group = C2/c (No. 15), a = 41.79 (1) angstrom, b = 10.70 (1) angstrom, c = 24.73 (1) angstrom, beta = 110.43 (3)-degrees, Z = 4, 3986 reflections, R = 0.070.