title: Studies of Dirhodium Tetra(trifluoroacetate). 3. Solid State Isomers of the Compound Rh(2)(O(2)CCF(3))(4)(THF) Prepared by Sublimation.
abstract: The monoadduct of dirhodium tetra(trifluoroacetate) with THF has been obtained by deposition from the vapor phase. The compound Rh(2)(O(2)CCF(3))(4)(THF) crystallizes in two isomeric forms, 1 and 2, whose structures have been determined by X-ray crystallography. The crystallographic parameters are as follows: for 1, triclinic space group P&onemacr; with a = 9.557(2) Å, b = 10.126(2) Å, c = 11.840(4) Å, alpha = 95.97(2) degrees, beta = 90.40(2) degrees, gamma = 115.58(1) degrees, and Z = 2; for 2, triclinic space group P&onemacr; with a = 8.6347(3) Å, b = 9.678(1) Å, c = 13.773(4) Å, alpha = 73.182(5) degrees, beta = 74.622(5) degrees, gamma = 89.76(1) degrees, and Z = 2. Compound 1 is unique as the only extended structure where dirhodium carboxylate molecules are bridged by a single exogenous atom. The oxygen atom of the THF ligand coordinates to the axial positions of two Rh(2) units so that a one-dimensional zigzag chain is formed. The bridging is slightly asymmetric with Rh-O(THF) distances of 2.363(6) and 2.407(6) Å, and the Rh-O(THF)-Rh angle is 111.8(3) degrees. The crystal structure of 2 is not polymeric. Pairs of Rh(2)(O(2)CCF(3))(4)(THF) units are associated through O atoms of carboxylate groups to produce a dimer of dimers. The lengths of the terminal Rh-O(THF) and axial bridging Rh.O(Ac) interactions are 2.214(7) and 2.406(6) Å, respectively.
authors.affiliation: Laboratory for Molecular Structure and Bonding, Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012.
authors.forename: F. Albert
authors.initials: FA
authors.lastname: Cotton
authors.forename: Evgeny V.
authors.initials: EV
authors.lastname: Dikarev
authors.forename: Salah-Eddine
authors.initials: SE
authors.lastname: Stiriba