Fa. Cotton et al., Studies of dirhodium tetra(trifluoroacetate). 3. Solid state isomers of the compound Rh-2(O2CCF3)(4)(THF) prepared by sublimation, INORG CHEM, 38(21), 1999, pp. 4877-4881
The monoadduct of dirhodium tetra(trifluoroacetate) with THF has been obtai
ned by deposition from the vapor phase. The compound Rh-2(O2CCF3)(4)(THF) c
rystallizes in two isomeric forms, 1 and 2, whose structures have been dete
rmined by X-ray crystallography. The crystallographic parameters are as fol
lows: for 1, triclinic space group P (1) over bar with a = 9.557(2) Angstro
m, b = 10.126(2) Angstrom, c = 11.840(4) Angstrom, alpha = 95.97(2)degrees,
beta = 90.40(2)degrees, gamma = 115.58(1)degrees, and Z = 2; for 2, tricli
nic space group (P) over bar 1 with a 8.6347(3) Angstrom, b = 9.678(1) Angs
trom, c = 13.773(4) Angstrom, alpha = 73.182(5)degrees, beta = 74.622(5)deg
rees, 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 s
ingle 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) Angstrom, and the Rh-O(THF)Ph angle is 111.8(3)degrees.
The crystal structure of 2 is not polymeric. Pairs of Rh-2(O2CCF3)(4)(THF)
units are associated through O atoms of carboxylate groups to produce a di
mer 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) Angstrom, respectively.