Johann G. Leipoldt

THE CRYSTAL STRUCTURE OF 8-HYDROXYQUINOLINATOCARBONYLTRIPHENYLPHOSPHINERHODIUM(I)

Abstract The crystal structure of 8-hydroxyquinolinatocarbonyltriphenylphosphine, C 28 H 21 O 2 NPRh, was determined from 2995 unique observed reflections obtained with a computer automated diffractometer. The unit cell is triclinic with a = 14.154 A , b = 9.984 A , c = 9.409 A , α = 116.16°, β = 90.09°, γ = 99.60°, Z = 2 with space group P 1 . Refinement of the data with anisotropic thermal parameters converged to R = 4.9%. The compound was prepared by the reaction between [Rh(oxine)(Co) 2 ] and triphenylphosphine. The structure determination shows that the carbonyl group trans to the nitrogen atom of the 8-hydroxyquinolinato ligand was substituted by the triphenylphosphine ligand, which indicate that the nitrogen atom of the chelate ring has a larger trans influence than the oxygen atom.

Octacyano and Oxo- and Nitridotetracyano Complexes of Second and Third Series Early Transition Metals

Publisher Summary This chapter presents a summary on the chemistry of octacyano complexes and oxo- and nitridocyano complexes of molybdenum, tungsten, niobium, tantalum, technetium, and rhenium, with emphasis on the structural and kinetic properties. The octacyano complexes of molybdenum and tungsten are stable and inert toward substitution reactions and are suitable for theoretical studies of redox reactions and application of the Marcus theory. The oxo- and nitridocyano complexes of MO(IV), W(IV), Tc(V) , Re(V), and Os(VI) are good candidates for kinetic studies of substitution reactions with both mono- and bidentate ligands and are of interest in view of the large variations in the observed reactivity. The octacyano complexes of MO(V) and W(V) find excellent use in the oxidation of organic substances that require a mild oxidizing agent. Derivatives of the dioxotetracyano complexes of Mo(IV) and W(IV) can take up dioxygen that leads to the activation of the O2 molecule. Thus, the complexes are candidates as catalysts in oxidation reactions with dioxygen as well as oxygen-transfer reactions. The stereochemistry of octacyano complexes is concerned with the d1 and d2 ions of niobium, molybdenum, and tungsten.

Mechanism for the oxidative addition of lodomethane to carbonyl(N-hydroxy-N-nitrosobenzenaminato-O,O′)triarylphosphinerhodium(I) complexes and crystal structure of [Rh(cupf)(CO)(CH3)(1)(PPh3)]

Abstract Rh(I) complexes, [Rh(cupf)(CO)(PX 3 )] (cupf= cupferrate; PX 3 = PCy 3 , P( o -Tol) 3 , PPh 3 , PPh 2 C 6 F 5 , P( p -ClC 6 H 4 ) 3 and P( p -MeOC 6 H 4 ) 3 ), react with iodomethane to form Rh(III) alkyl compounds. The reaction was studied in the solvents Bz, EtOAc, Me 2 CO, MeOH, CH 3 CN and DMSO having different polarities and donocities. The reaction proceeds through two competing rate determining steps, one of which is first-order in [CH 3 I]. A reaction mechanism, which includes specific solvent effects, is given. The structure determination of [Rh(cupf)(CO)(CH 3 )(I)(PPh 3 )] shows the complex to crystallize in space group P 1 with a =9.912(2), b = 11.534(1), c = 12.514(2) A, α = 67.84(2), β = 84.41(2), γ = 73.15(1)°, Z = 2 and D m = 1.73 g cm −3 . The molecule has distorted octahedral geometry with CH3 and I cis -bonded. Bond distances: RhPI = 2.708(2), RhP = 2.327(4), RhO(hydroxy) = 2.04(1), RhO(nitroso) = 2.175- (9), RhC(carbonyl) = 1.81(2) and RhC(methyl) = 2.08(1) A. Rates for the slow alkyl → acyl conversion in Me 2 CO and CH 3 CN are also given for this complex.

The Crystal structure of the 1:2 phenanthroline adduct of sodium oxotricyano-1,10-phenanthrolinemolybdate(IV)

Abstract The crystal structure of Na[MoO(CN)3(Phen)]· 2Phen was determined from three-dimensional X-ray data. The green crystals are triclinic, space group P 1 with cell dimensions a = 13.354, b = 14.380, c = 9.294 A, α = 93.53, β = 97. 05, γ = 104.93° and containing two molecules per unit cell. The structure was solved from 3353 observed reflections which were obtained from a computer automated diffractometer. The anisotropic refinement converged to R = 0.069 The anion is a distorted octahedron. The MoN distance (2.363(7) A), trans to the MoO bond (1.659(7) A), is significantly 0.189 A longer than the other MoN bond. The mer-arrangement of cyanide ligands has two normal MoCav = 2.17(1) A bond distances and a significant shorter MoC = 2.092(9) A bond trans to the shorter MoN bond. The sodium ion has a distorted trigonal prismatic environment of six N atoms.

The crystal structure of Benzoyl-1,1,1,-trifluoroacetonato(1,5-cycloooctadiene)rhodium(I)

Abstract Benzoyl-1,1,1-trifluoroacetonato(1,5-cyclooctadiene)rhodium I, (Rh(TFBA)(COD)], crystallizes in the monoclinic space group P2/ 1 c with a = 10.966 A , b = 9.817 A , c = 17.004 A , β = 113.2° and Z = 4. The compound was prepared by the reaction between [Rh(TFBA)(CO) 2 ] and cyclooctadiene. 2228 independent observed reflections were used for the structure determination. The final R value for all the reflections was 0.039. The results indicate that the oxygen atom nearest to the phenyl ring has the largest trans -effect.

Kinetics and mechanism of the oxidative addition of iodomethane to β-diketonatobis(triphenylphosphite)rhodium(I) complexes

The kinetics and mechanism of the oxidative addition of CH3I to [Rh(β-diketone)(P(OPh)3)2] complexes was studied in acetone medium at various temperatures. The experimental rate law is R = k[Rh(β-diketone)(P(OPh3)2][CH3I]. The order of the effect of the β-diketone on the reactivity of the complexes is acac >; BA >; DBM >; TFAA >; TFBA >; HFAA indicating that electronegative substituents of the β-diketone decrease the reactivity of the complexes towards oxidative addition reactions. The volume of activation for some of the reactions was determined in various solvents. The large negative values of the volume and entropy of the activation indicated a mechanism which occurs via a polar transition state.

Chemical structure of dicaesium sodium azidooxotetracyanomolybdate(IV)

Abstract The structure of Cs2Na[MoO(CN)4(N3)] was determined by single-crystal X-ray diffraction methods from diffractometer data and refined to R = 0.051. The royal-blue crystals are orthorhombic, space group Pnma, with cell dimensions a = 15.874, b = 7.875, c = 10.371 A, Z = 4. The [MoO(CN)4(N3)]3− ion is a distorted octahedron with the Mo atom displaced 0.28 A towards oxygen from the plane containing four cyano groups. Bond distances found: MoCav = 2.17(1); MoO = 1.70(1); MoN (azido) = 2.29(2) A. The azido chain is linear and bond at an angle of 121(1) ° with Mo. The sodium ion has an octahedral environment, whilst caesium ions display distorted six- and nine-atom environments respectively.

First structural confirmation of different geometrical isomers in the same crystal lattice: the crystal structure of benzoylacetonatocarbonyltriphenylphosphinerhodium(I)

Abstract The first structural confirmation of two different [Rh(BA)(CO)(PPh3)] isomers (BA = benzoylacetonate, CH3(CO)CH(CO)C6H5), namely one with PPh3 cis to the oxygen atom nearest to the phenyl group and the second isomer with PPh3 trans to the oxygen nearest to the phenyl group, in the same crystal lattice is reported. The small influence of the different substituents is illustrated by the near equal RhO, RhP and RhC bond distances in the two different isomers. The structure crystallizes in the triclinic system, space group P 1 with a = 15.625(2), b = 19.138(2), c = 8.891(2) A , α = 95.66(1), β = 74.43(1), γ = 90.52(1)° and Z = 4 . The RhP, RhCO and RhO bond distances for isomer I are 2.249(3), 1.739(14), 2.032(8) and 2.079(8) A. respectively, while the corresponding bond distances for isomer II are 2.248(3), 1.768(14), 2.018(8) and 2.057(7) A, respectively.

THE CRYSTAL STRUCTURE OF THE METHANOL SOLVATE OF 2‐CARBOXYPYRIDINATOCARBONYLTRIPHENYLPHOSPHINERHODIUM(I)

Abstract 2-carboxypyridinatocarbonyltriphenylphosphinerhodium(I) was synthesized by means of the reaction [Rh(Pic)(CO) 2 ] + PPh 3 → [Rh(Pic)(CO)(PPh 3 )] + CO. The crystal structure of this compound was determined from 3031 unique observed reflections obtained with an automated diffractometer. It crystallizes in the triclinic space group P 1 with a = 12.835 A, b = 11.800 A, c = 10.020 A, α = 113.71°, β = 103.55°, γ = 61.19° and with two molecules per unit cell. The final R -value was 4.1%. The carbonyl group trans to the nitrogen atom of the carboxypyridinato ligand was substituted by the PPh 3 ligand. This indicates that the nitrogen atom of the chelate ring has a larger thermodynamic trans effect than does the oxygen atom.

The crystal structure of the acetone adduct oftrans-methyliodo-8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(III)

Summarytrans-Methyliodo-8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(III) was synthesised by means of the oxidative addition of MeI to 8-hydroxyquinolinatocarbonyltriphenylphosphinerhodium(I). The compound crystallizes in the triclinic space group,