X-Ray structure analysis of the salts [N(PPh3)2][M4H3(CO)12](M = Ru or Os); confirmation of the existence of discrete structural isomers for a hydridocarbonyl cluster in the solid state
Abstract
X-Ray analysis has shown that the salt [N(PPh3)2][Ru4H3(CO)12] crystallizes in two forms, (1) and (2), which correspond to two different structural isomers (tautomers) of the anion. These have overall geometries of virtual C2[(1)] and C3v[(2)] symmetry, and provide the first confirmation of the existence of such isomers in the solid state. Crystals of (1) and (2) are triclinic, space group P. For (1), a= 17.361(4), b= 11.735(2), c= 12.321(2)Å, α= 94.61 (2), β= 98.44(2), γ= 88.52(2)°, Z= 2; refinement of atomic parameters using 7 210 data converged at R= 0.0473. For (2), a= 15.608(3), b= 15.370(3), c= 11.219(2)Å, α= 99.26(2), β= 103.27(2), γ= 105.72(2)°, Z= 2; refinement of atomic parameters using 10 945 data converged at R= 0.0432. Although three crystalline modifications, (3), (4), and (5), of the corresponding salt [N(PPh3)2][Os4H3(CO)12] were isolated, X-ray analysis has shown that in all three the same isomer of the monoanion, of virtual C2 symmetry, is present. Crystals of the osmium salt (3), which are isomorphous with those of the ruthenium salt (1), are triclinic, space group P
, a= 17.378(4), b= 11.691(2), c= 12.308(2)Å, α= 94.40(2), β= 98.62(2), γ= 88.41(2)°, Z= 2. Modification (4) crystallizes as a 0.5CH2Cl2 solvate, orthorhombic, space group Pna21, a= 17.648(4), b= 19.597(4), c= 15.429(3)Å, Z= 4. Modification (5) is monoclinic, space group P21/c, a= 11.683(2), b= 28.976(4), c= 14.733(3)Å, β= 100.13(2)°, Z= 4. Complete structure analysis was carried out for modification (4) only, for which refinement of atomic parameters using 3 347 data converged at R= 0.0426.