Issue 27, 2012

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

Abstract

A series of mixed oxidation state compounds, [{Rh2(acam)4}33-X)2nH2O (Hacam = acetamide; X = Cl, n = 4 (1·4H2O); X = Br, n = 10 (2·10H2O); X = I, n = 10 (3·10H2O)) and [{Rh2(pram)4}33-X)2]·6H2O (Hpram = propionamide; X = Cl (4·6H2O), Br (5·6H2O), I (6·6H2O)) 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 Rh2 units and halide ions lie at the corners. Complexes 1·4H2O, 4·6H2O, 5·6H2O and 6·6H2O have three independent Rh2 units, in which there are two Rh25+ and one Rh24+. 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 Rh24+ unit is greater than that to the Rh25+ units. This suggests that there exists pinning of the oxidation states by water molecules. In the structures of 2·10H2O and 3·10H2O, all of the Rh2 units are crystallographically equivalent. In these structures, eight of the 10 water molecules form a honeycomb-like network between the {Rh2(acam)4}3X2 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.

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

Supplementary files

Article information

Article type
Paper
Submitted
26 Aug 2011
Accepted
12 Mar 2012
First published
29 Mar 2012

Dalton Trans., 2012,41, 8242-8251

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

Y. Fuma, O. Miyashita, T. Kawamura and M. Ebihara, Dalton Trans., 2012, 41, 8242 DOI: 10.1039/C2DT11609J

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