Kevin K. Klausmeyer

Structural characterization of bidentate carboxylate derivatives of copper(I) bistriphenylphosphine

The complexes (Ph3P)2Cu(carboxylate) (carboxylate = acetate (1), hippurate (2), vinyl acetate (3), fluorenate (4)) have been prepared and their solid-state structures determined crystallographically. The copper(I) center in all four structures exhibits a distorted tetrahedral geometry, with varying degrees of asymmetric bidentate binding of the carboxylate ligand. For example, in complex 2 the hippurate ligand displays the greatest extent of asymmetry with the two Cuue5f8O bond distances differing by 0.234(6) A. The structures of all four derivatives were each shown to be the same both in the solid-state and in dichloromethane solution based on infrared spectroscopy. The magnitude of Δ (va(CO2−)-vs(CO2−)) in these copper(I) derivatives, determined to be quite similar to the corresponding ionic values, is used as constituting a diagnosis for asymmetric bidentate binding of the carboxylate ligand. Although all four complexes are structurally quite similar, only the fluorenate derivative which affords a resonance-stabilized carbanion upon carbon dioxide extrusion undergoes the decarboxylation reaction. Crystal data for 1: space group P21/c, a = 18.085(5), b = 10.977(2), c = 17.979(5) A, β = 115.62(2)°, Z= 4, R =3.91%. Crystal data for 2: space group P1, a = 9.96(2), b = 14.68(3), c = 14.96(3) A , a = 115.46(14), β = 97.54(16), η = 102.31(15)°, Z = 2, R=5.84%. Crystal data for 3: space group P1, a = 12.755(3), b = 13.125(2), c = 12.572(2) A, α = 118.85(1), β = 105.85(1), η = 97.65(1)°, Z = 2, R =4.08%. Crystal data for 4: space group P1, a = 11.554(1), b = 15.217(2), c = 15.285(2) A, α = 63.71(1), β = 79.08(1), η = 75.20(1)°, Z = 2, R = 7.6%.

The propensity of alkoxide and aryloxide derivatives of tungsten carbonyls to aggregate in solution. Synthesis and X-ray structures of dinuclear, trinuclear and tetranuclear complexes derived from the MeOW(CO)5− anion

Abstract The complex [Et4N][W(CO)5OMe] (1) has been prepared from the reaction of the photochemically generated W(CO)5THF adduct and [Et4N][OH] in methanol. Complex 1 was shown to undergo rapid CO dissociation in THF to quantitatively provide the dimeric dianion, [W(CO)4OMe]22−. The resulting THF insoluble salt [Et4N]2[W(CO)4OMe]2 (2) has been structurally characterized by X-ray crystallography, with the doubly bridging methoxide ligands being in an anti configuration. Complex 2 was found to subsequently react with excess methoxide ligand in a THF slurry to afford the face-sharing octahedron complex [Et4N]3[W2(CO)6(OMe)3] (3) which contains three doubly bridging methoxide groups. In the absence of excess methoxide ligand complex 2 cleanly yields the tetrameric complex [Et4N]4[W(CO)3OMe]4 (4) which has been structurally characterized as a cubane-like arrangement with triply bridging μ3-methoxide groups and W(CO)3 units. Although complex 3 was not characterized in the solid state, the closely related glycolate derivative [Et4N]3[W2(CO)6(OCH2CH2OH)3] (5) was synthesized and its structure determined by X-ray crystallography. The trianions of complex 5 are linked in the crystal lattice by strong intermolecular hydrogen bonds. Crystal data for 2: space group P21/n, a = 7.696(2), b = 22.019(4), c = 9.714(2) A, β = 92.22(3)°, Z = 4, R = 6.43%. Crystal data for 4: space group Fddd, a = 12.433(9), b = 24.01(2), c = 39.29(3) A, Z = 8, R = 8.13%. Crystal data for 5: space group P212121, a = 11.43(2), b = 12.91(1), c = 29.85(6) A, Z = 8, R = 8.29%. Finally, the rate of CO ligand dissociation in the closely related aryloxide derivatives [Et4N][W(CO)5OR] (R = C6H5 and 3,5-F2C6H3) were measured to be 2.15 × 10−2 and 1.31 × 10−3 s−1, respectively, in THF solution at 5°C. Hence, the value of the rate constant of 2.15 × 10−2 s−1 establishes a lower limit for the first-order rate constant for CO loss in the W(CO)5OMe− anion, since the methoxide ligand is a better π-donating group than phenoxide.

[Bis(2-methyl-1-pyridyl)phenylphosphine-κ2N,P,N′]trichlorochromium(III) acetonitrile solvate

In the title molxadecular structure, [CrCl3{PPh(2-CH2C5H4N)2}]·CH3CN, the CrIII atom exhibits an octaxadhedral coordination geometry, with a tridentate ligand capping one face of the octaxadhedron and three Cl− ions occupying the opposite face.

Characterization of the Initial Intermediate Formed during Photoinduced Oxygenation of the Ruthenium(II) Bis(bipyridyl)flavonolate Complex.

A ruthenium(II) flavonolate complex, [Ru(II)(bpy)2fla][BF4], was synthesized to model the reactivity of the flavonol dioxygenases. The treatment of dry CH3CN solutions of [Ru(II)(bpy)2fla][BF4] with dioxygen under light leads to the oxidative O-heterocyclic ring opening of the coordinated substrate flavonolate, resulting in the formation of [Ru(II)(bpy)2(carboxylate)][BF4] (carboxylate = O-benzoylsalicylate or benzoate) species, as determined by electrospray ionization mass spectrometry. Moderation of the excitation and temperature allowed isolation and characterization of an intermediate, [Ru(II)(bpy)2bpg][BF4] (bpg = 2-benzoyloxyphenylglyoxylate), generated by the 1,2-addition of dioxygen to the central flavonolate ring.