Yasuhiro Fuma

Change of electrical conductivities between hydrated and dehydrated samples of honeycomb sheet structures with mixed oxidation state paddlewheel dirhodium complexes and halide ions

A series of mixed oxidation state compounds, [{Rh(2)(acam)(4)}(3)(μ(3)-X)(2)]·nH(2)O (Hacam = acetamide; X = Cl, n = 4 (1·4H(2)O); X = Br, n = 10 (2·10H(2)O); X = I, n = 10 (3·10H(2)O)) and [{Rh(2)(pram)(4)}(3)(μ(3)-X)(2)]·6H(2)O (Hpram = propionamide; X = Cl (4·6H(2)O), Br (5·6H(2)O), I (6·6H(2)O)) were synthesized and their X-ray structures were determined. In the crystal structure of all of these complexes, dirhodium complexes and halide ions construct 2-D honeycomb sheet arrangements in which the walls consist of Rh(2) units and halide ions lie at the corners. Complexes 1·4H(2)O, 4·6H(2)O, 5·6H(2)O and 6·6H(2)O have three independent Rh(2) units, in which there are two Rh(2)(5+) and one Rh(2)(4+). In these structures, the water molecules hydrogen bond to O atoms and from the N atoms of the amidate ligands. The number of hydrogen bonds from water molecules to the Rh(2)(4+) unit is greater than that to the Rh(2)(5+) units. This suggests that there exists pinning of the oxidation states by water molecules. In the structures of 2·10H(2)O and 3·10H(2)O, all of the Rh(2) units are crystallographically equivalent. In these structures, eight of the 10 water molecules form a honeycomb-like network between the {Rh(2)(acam)(4)}(3)X(2) honeycomb sheets. The former four structures show very low electrical conductivities of ca. 10(-8) S cm(-1) (room temperature, pellets) and the latter structures have the higher values of ca. 10(-4) S cm(-1). In the former complexes, improvement of the values to 10(-6) S cm(-1) was observed, caused by loss of pinning water.

Variation of hydrogen-bonded networks in hexafluorophosphate salts of amidate-bridged dirhodium(II,III) complexes with axial aqua ligands.

In diaquatetra-mu-acetamidato-kappa(4)N:O;kappa(4)O:N-dirhodium(II,III) hexafluorophosphate, [Rh(2)(C(2)H(4)NO)(4)(H(2)O)(2)]PF(6), and diaquatetra-mu-acetamidato-kappa(4)N:O;kappa(4)O:N-dirhodium(II,III)hexafluorophosphate dihydrate, [Rh(2)(C(2)H(4)NO)(4)(H(2)O)(2)]PF(6).2H(2)O, the cations and anions lie on inversion centers. Diaquatetra-mu-propionamidato-kappa(4)N:O;kappa(4)O:N-dirhodium(II,III) hexafluorophosphate dihydrate, [Rh(2)(C(3)H(6)NO)(4)(H(2)O)(2)]PF(6).2H(2)O, and diaquatetra-mu-butyramidato-kappa(4)N:O;kappa(4)O:N-dirhodium(II,III) hexafluorophosphate, [Rh(2)(C(4)H(8)NO)(4)(H(2)O)(2)]PF(6), crystallize with two crystallographically independent complexes that lie on inversion centers. In all of the structures, the dirhodium units are hydrogen bonded to one another. The hydrogen-bonded networks vary with the alkyl substituents.

A zigzag chain structure in catena-poly[[[tetra-μ-acetamidato-κ4N:O;κ4O:N-dirhodium(II,III)]-μ-chloro] methanol solvate]

In {[Rh2(C2H4NO)4Cl]·CH3OH}n, the cationic dirhodium complex and bridging chloro ligands form a one-dimensional zigzag chain, [Rh2(acam)4(μ-Cl)] (Hacam is acetamide). There is a large difference between the two Rh—Cl distances [2.6076 (14) and 2.5027 (14) A]. Neighboring chains are connected by two N—H⋯O hydrogen bonds per link between the amidate ligands.

Tetra-μ-acetamidato-κ4N:O;κ4O:N-diaqua­dirhodium(II,III) perrhenate

In the title compound, [Rh2(C2H4NO)4(H2O)2][ReO4], the cation lies on an inversion center and the anion on a twofold axis. The cations are connected two-dimensionally by O—H⋯O and N—H⋯O hydrogen bonding. Hydrogen bonds to perrhenate ions connect the two-dimensional sheets.