The protonation of [Re7H(C)(CO)21]2– with CF3SO3H in dichloromethane solution produces [Re7H2C(CO)21]– which behaves as a strong acid, being completely dissociated in basic solvents. In acetonitrile the compound loses the capping Re(CO)3 unit, giving the octahedral dianion [Re6H2C(CO)18]2–. The [NEt4]+ salt crystallizes in the monoclinic system, space group P21/c(no. 14), with a= 9.394(3), b= 15.669(3), c= 27.983(6)Å, β= 90.87(3)°, and Z= 4. The structure of the anion is closely related to that of the parent compounds [Re7H(C)(CO)21]2– and [Re7C(CO)21]3–, where a carbon-centred monocapped octahedron of rhenium atoms is surrounded by 21 terminal carbonyl ligands, three for each metal. The two hydride ligands have been indirectly located on the basis of potential-energy computations as double bridging, one on an edge of the basal triangle and the other one on an inter-layer edge. The 1H n.m.r. spectra at low temperature show the presence in solution of three isomers (ratio ca. 1 : 1.5 : 10) rapidly exchanging at room temperature. The possible locations of the hydrides in these species are also discussed in the light of the variable-temperature 13C n.m.r. spectra.
Synthesis, Solid State (X-Ray) and Solution (Nuclear Magnetic Resonance) Studies of the Hydridocarbido Carbonyl Cluster Anion [Re7H2C(CO)21]-
MOLINARI, Henriette
1990-01-01
Abstract
The protonation of [Re7H(C)(CO)21]2– with CF3SO3H in dichloromethane solution produces [Re7H2C(CO)21]– which behaves as a strong acid, being completely dissociated in basic solvents. In acetonitrile the compound loses the capping Re(CO)3 unit, giving the octahedral dianion [Re6H2C(CO)18]2–. The [NEt4]+ salt crystallizes in the monoclinic system, space group P21/c(no. 14), with a= 9.394(3), b= 15.669(3), c= 27.983(6)Å, β= 90.87(3)°, and Z= 4. The structure of the anion is closely related to that of the parent compounds [Re7H(C)(CO)21]2– and [Re7C(CO)21]3–, where a carbon-centred monocapped octahedron of rhenium atoms is surrounded by 21 terminal carbonyl ligands, three for each metal. The two hydride ligands have been indirectly located on the basis of potential-energy computations as double bridging, one on an edge of the basal triangle and the other one on an inter-layer edge. The 1H n.m.r. spectra at low temperature show the presence in solution of three isomers (ratio ca. 1 : 1.5 : 10) rapidly exchanging at room temperature. The possible locations of the hydrides in these species are also discussed in the light of the variable-temperature 13C n.m.r. spectra.
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