Studies of dirhodium(II) tetra(trifluoroacetate). 5. Remarkable examples of the ambidentate character of dimethyl sulfoxide

The ambidentate character of dimethyl sulfoxide, already known for dirhodium carboxylotes, has been remarkably manifested in new ways. Three novel complexes of dirhodium(II) tetra(trinuoroacetate) with the DMSO ligand, namely, [Rh-2(O2CCF3)(4)]m(DMSO)(n) With m:n = 7:8 (1), 1:1 (2), and 3:2 (3), have been obtained by deposition from the vapor phase, and their crystal structures have been determined by X-ray crystallography. The crystallographic parameters are as follows: for 1, monoclinic space group P2(1)/c with a = 28.261(2) Angstrom, b = 16.059(4) Angstrom, c = 17.636(2) Angstrom, beta = 92.40(4)degrees, and Z = 2; for 2, triclinic space group P (1) over bar with a = 8.915(2) Angstrom, b = 10.592(2) Angstrom, c = 11.916(2) Angstrom, alpha = 84.85(1)degrees, beta = 88.86(1)degrees, gamma = 65.187(8)degrees, and Z = 2; and for 3, triclinic space group P (1) over bar with a = 8.876(2) Angstrom, b = 9.017(2) Angstrom, c = 19.841(3) Angstrom, alpha = 101.91(2)4 beta = 97.144(8)degrees gamma = 100.206(9)degrees, and Z = 1. In the oligomeric molecule of 1, six DMSO ligands bridge seven dirhodium tetra(trifluoroacetate) units in a bidentate fashion via S and O atoms, and two additional DMSO molecules terminate the chain. In the structure of the monoadduct Rh-2(O2CCF3)(4)(DMSO) (2), the dirhodium blocks are bridged through the O atoms of DMSO ligands, forming a one-dimensional polymeric chain. Compound 3 also has an infinite chain structure with the molecules of dimethyl sulfoxide acting in a bidentate mu-DMSO-S,O mode. Every second DMSO molecule is missing in 3, so that two of every three Rh-2(O2CCF3)(4) units are associated through the O atoms of carboxylate groups to give the overall composition [Rh-2(O2CCF3)(4)](3)(DMSO)(2).