F. Ortega et al., TUNGSTORHENATE HETEROPOLYANIONS .2. SYNTHESIS AND CHARACTERIZATION OFENNEATUNGSTORHENATES(V), ENNEATUNGSTORHENATES(VI), AND ENNEATUNGSTORHENATES(VII), Inorganic chemistry, 36(10), 1997, pp. 2166-2169
The tungstorhenate(V) heteropolyanion [W9ReO32](5-) has been isolated
as guanidinium and cesium salts from reaction of [ReO2(PPh3)(py)(3)]() with sodiom tungstate. Crystallographic analysis of black Cs-5[W9ReO
32]. 3H(2)O [triclinic, P1 or P1; a = 10.194(1), b = 11.503(2), c = 9.
682(1) Angstrom: alpha = 100.55(1), beta = 115.81(1), gamma = 99.13(1)
degrees; Z = 1], based on 3743 reflections, shows the anion to be isos
tructural with decatungstate, [W10O32](4-). Refinement in P1 led to re
liability indices R = 0.084, R-W = 0.046. Electrochemical investigatio
n revealed the existence of Re-VI and Re-VII analogues, which were hyd
rolytically unstable in aqneous solution but which were isolated as cr
ystalline tetra-n-butylammonium and tetra-n-heptylammonium salts, resp
ectively, from nonaqueous solvents. The tetra-n-butylammonium salts of
[(W9ReO32)-O-VI](4-) and [W10O32](4-) were shown to be isomorphous by
X-ray powder diffraction. Simulation of the Q-band ESR spectrum of [(
W9ReO32)-O-VI](4-) (polycrystaline solid solution in [W10O32](4-)) gav
e g(x) = 1.69(1), g(y) = 1.730(2) and 10(4)A(x)(Re-185,Re-187, I = 5/2
) = (-)252(10), 10(4)A(Y) = (-)398(10), 10(4)A(z) = (-)653(5) cm(-1).
The orthorhombic ESR spectrum proves that the Re atom occupies one of
the eight equivalent ''equatorial'' sites in the decatungstare structu
re.