Showing papers by "Richard D. Adams published in 1979"

Synthesis and X-ray structure of a formylated octamolybdate cluster [(HCO)2(Mo8O28)]6–

Abstract: Reaction of formic acid with aqueous (NH4)6–[Mo7O24]yields the compound (NH4)3[(HCO)(Mo4O14)]·H2O which has been shown by X-ray crystallography to contain the discrete [(H2Mo8O28)]6– anion; this anion is related to the [H2Mo8O28]6– anion by replacement of its surface-bound protons with formyl groups.

Triosmium cluster compounds containing isocyanide and hydride ligands. Crystal and molecular structures of (. mu. -H)(H)Os/sub 3/(CO)/sub 10/(CN-t-C/sub 4/H/sub 9/) and (. mu. -H)/sub 2/Os/sub 3/(CO)/sub 9/(CN-t-C/sub 4/H/sub 9/)

Abstract: The structures of the compounds (..mu..-H)(H)Os/sub 3/(CO)/sub 10/(CN-t-C/sub 4/H/sub 9/) and (..mu..-H)/sub 2/Os/sub 3/(CO)/sub 9/(CN-t-C/sub 4/H/sub 9/) have been revealed by x-ray crystallographic techniques. For (..mu..-H)(H)Os/sub 3/(CO)/sub 10/(CN-t-C/sub 4/H/sub 9/): a = 9.064 (3), b = 12.225 (3), c = 20.364 (4) A; ..beta.. = 98.73 (3)/sup 0/; space group P2/sub 1//c(C/sub 2h//sup 5/), No. 14; Z = 4; d/sub calcd/ = 2.79 g cm /sup -3/. This compound contains a triangular cluster of three osmium atoms; Os(1)--Os(2) = 2.930 (1) A, Os(1)--Os(3) = 2.876 (1) A, and Os(2)--Os(3) = 3.000 (1) A. There are ten linear terminal carbonyl groups and one linear terminal isocyanide ligand which occupies an axial coordination site. The hydrogen atoms were not observed crystallographically, but their positions are strongly inferred from considerations of molecular geometry. For (..mu..-H)/sub 2/Os/sub 3/(CO)/sub 9/(CN-t-C/sub 4/H/sub 9/): a = 15.220 (8), b = 12.093 (6), c = 23.454 (5) A; space group Pbcn (D/sub 2h//sup 14/), No. 60; Z = 8; d/sub calcd/ = 2.79 g cm/sup -3/. The compound is analogous to the parent carbonyl (..mu..-H)/sub 2/Os/sub 3/(CO)/sub 10/ and has two normal and one short osmium--osmium bonds: Os(1)--Os(2) = 2.827 (1) A, Os(1)--Os(3) = 2.828 (1) A, Os(2)--Os(3)more » = 2.691 (1) A. The isocyanide ligand resides in an equatorial coordination site on osmium Os(2). The hydrogen atoms were not observed but are believed to occupy bridging positions as in the parent carbonyl complex. 2 figures, 7 tables.« less

Hydrogenation of small molecules by transition metal cluster hydrides. Reaction of H/sub 2/Os/sub 3/(CO)/sub 10/ with carbon disulfide

Abstract: H/sub 2/Os/sub 3/(CO)/sub 10/ was refluxed with carbon disulfide for 34 hr. The reaction product was analyzed as H/sub 2/CS/sub 2/(HOs/sub 3/(CO)/sub 10/)/sub 2/ by IR, /sup 1/H NMR, and x-ray crystallography. The molecular structure is illustrated. The nature of the cluster bonding is discussed. Carbon--sulfur bond distances are listed. The cluster reduction has produced a CH/sub 2/S/sub 2//sup 2 -/ unit which might be a precursor to dithioacetal. 1 figure.

Triosmium cluster compounds containing isocyanide and hydride ligands. Crystal and molecular structure of (. mu. -H)(. mu. -eta/sup 1/-C==N(H)(t-C/sub 4/H/sub 9/))Os/sub 3/(CO)/sub 10/

Abstract: The crystal and molecular structure of the compound (..mu..-H)(..mu..-eta/sup 1/-C==N(H)(t-C/sub 4/H/sub 9/))Os/sub 3/(CO)/sub 10/ has been determined by X-ray crystallographic methods. The compound crystallizes in the centrosymmetric monoclinic space group P2/sub 1//n(C/sub 2h//sup 5/):a = 13.651 (4) A, b = 9.156 (4) A, c = 18.275 (5) A, ..beta.. = 111.42 (2)/sup 0/, V = 2126.3 (25) A/sup 3/, Z = 4, rho/sub calcd/ = 2.92 g cm/sup -3/. A uniform triangular cluster of three osmium atoms contains ten linear carbonyl groups and a ..mu..-eta/sup 1/-C==N(H)(t-C/sub 4/H/sub 9/) iminyl ligand. The carbon atom of the iminyl ligand symmetrically bridges one osmium-osmium bond, as is shown by the internuclear separations Os(2)-C(11) = 2.066 (8) A and Os(3)-C(11) = 2.043 (8) A. The iminyl bond, C(11)-N, is double with the C-N distance being 1.298 (10) A.