Cm. Barnes et al., STRUCTURAL AND SPECTROSCOPIC STUDIES OF 2 PHASES OF THE ORGANOMETALLIC CHAIN POLYMER [RU-2(MU(2)MU(2)ETA(2)-O2PME2)(2)(CO)(4)](N), Inorganic chemistry, 36(25), 1997, pp. 5793-5798
The microcrystalline organometallic coordination polymer [Ru-2{mu(2):m
u(2):eta(2)-O2PMe2}(CO)(4)](n) which results from the oxidative additi
on of dimethylphosphinic acid to triruthenium dodecacarbonyl has been
structurally characterized by X-ray powder diffraction, lambda = 1.149
49(1) Angstrom, at 295 and 50 K. At roam temperature the crystallites
have a monoclinic unit cell with the space group C2/c with lattice co
nstants a = 18.0792(3) Angstrom, b = 9.0626(2) Angstrom, c = 10.0372(2
) Angstrom, beta = 112.107(1)degrees, and Z = 4; the final refinement
of 52 variables converged to R-p, R-wp, R-F, and R-F2 of 8.2, 10.8, 4.
6, and 8.3%, respectively, for data collected between 4 and 60 degrees
(2 theta). At 50 K the phase is described by a triclinic unit cell, s
pace group P (1) over bar, and is characterized by the lattice constan
ts a = 9.8639(6) Angstrom, b = 8.9290(6) Angstrom, c = 9.8870(5) Angst
rom, alpha = 115.051(3)degrees, beta = 108.587(5)degrees, gamma = 92.0
15(5)degrees, and Z = 2; the final refinement of 102 variables converg
ed to and R-p, R-wp, R-F, and R-F2 of 8.3, 12.4, 1.5, and 3.0%, respec
tively, for data collected between 3 and 74 degrees (2 theta). The tra
nsition between the two crystalline phases has been determined by diff
erential scanning calorimetry to occur at circa 220 K, and the most pr
onounced difference in the environment of the chains, as determined by
variable-temperature LR spectroscopy, is in the rho(PCH3) modes for t
he bridging dimethylphosphinate ligands.