Methylene chain length and coordination geometry in triosmium clusters containing diphosphine ligands. X-Ray crystal structures of >(n = 4 or 5) and 2>

Article abstract of DOI:10.1016/0022-328X(94)05276-H

The bis-acetonitrile compound and the butadiene compound 4-cis-C4H6)> react with dppp to give only (1) .Protonation of 1 with trifluoroacetic acid leads to <(μ-H)Os3(CO)10(μ-dppp)>⁺ (2) with the hydride bridging the same osmium atoms as the dppp.The bridging dppp compound (1) reacts with dppp at 110 deg C to give 1-dppp)(μ-dppp)> (4) whereas under the same conditions reacts with dppm (dppm = Ph2PCH2PPh2) to give (5).Protonation of 5 with trifluoroacetic acid gives <(μ-H)Os3(CO)8(μ-dppm)2>⁺ (6) with the hydride bridging the unsubstituted Os - Os edge.The monoacetonitrile compound reacts with dppp at 0 deg C to give two compounds: 1-dppp)> (7) containing one coordinated and one free phosphorus atom and <2(μ-dppp)> (8) with one dppp ligand bridging two Os3(CO)11 moieties.Solid-state structures for 1, 5 and the previously reported cluster (3) are reported.Compound 1 crystallizes in the space group P2₁2₁2₁ with unit cell parameters a = 11.770(2) Angstroem, b = 16.957(3) Angstroem, c = 21.681(5) Angstroem, V = 4327(2) Angstroem³ and Z = 4.Least-squares refinement of 6118 reflections gave a final agreement factor of R = 0.077 (R_w = 0.087).Compound 3 crystallizes in the space group P2₁/c with unit cell parameters a = 12.361(2) Angstroem, b = 16.804(2) Angstroem, c = 20.935(2) Angstroem, β = 116.66(1) deg, V = 3886(2) Angstroem³ and Z = 4.Least-squares refinement of 2284 reflections gave a final agreement factor of R = 0.028 (R_w = 0.032).Compound 5 crystallizes in the space group Pca2₁ with unit cell parameters a = 21.398(3) Angstroem, b = 15.684(4) Angstroem, c = 18.219(4) Angstroem, V = 6115(4) Angstroem³ and Z = 4.Least-squares refinement of 5376 reflections gave a final agreement factor R = 0.060 (R_w = 0.062).Keywords: Osmium; Clusters; Diphosphines; Chelates; Carbonyl; Methylene