Highly reactive and chemoselective cleavage of allyl esters using an air- and moisture-stable [CpRu(IV)(π-C3H5)(2-quinolinecarboxylato)]PF6 catalyst

A new catalytic process for allyl ester cleavage has been developed by using a robust cationic CpRu(IV) π-allyl complex of 2-quinolinecarboxylic acid that can be stored for over six months in air without any loss of catalytic activity. The deprotection of various alcohols and acids can be attained simply with high reactivity and chemoselectivity under mild conditions. Furthermore, with continuous removal of the low-boiling point coproduct, a turnover number of 1 000 000 can be achieved.     

Molecular structure and reactions of [RhH2(C6H5NCHCHNC6H5)(PPh3)2]PF6

The structure of [RhH₂(Ph-DAB)(PPh₃)₂]PF₆ (Ph-DAB = 1,4-phenyl-diaza-1,3-butadiene) has been determined. The complex crystallizes in space group P2₁/n of the monoclinic system, with 4 formula units in a cell of dimensions: a 15.136(1), b 17.842(1), c 17.363(1) Å, β 106.7(1)°. The structural data were refined by full matrix least squares methods to a conventional R index of 0.073 based on those 3309 reflections having I₀ > 3σ(I₀).The coordination polyhedron around the rhodium may be regarded as a distorted octahedron with two hydride hydrogen atoms in cis position and two phosphine ligands bent towards the hydrides, making an angle P¹RhP² of 159.4(1)°. The Ph-DAB acts as a σ,σ′,N,N′-chelating ligand with a planar NCCN skeleton in the same plane as the rhodium.The structure is consistent with the ¹H, ¹³C and ³¹P NMR data. The reactions of the title compound with CO, IMe and MeOOCCCCOOMe has been investigated. In all cases evolution of H₂ was observed.     

Basische metalle : XXXVI. Die synthese stabiler hydrido(olefin)rhodium-komplexe und von[C5H5Rh(PMe3)(η3-CH3CHC6H5)]PF6

The complexes C₅H₅Rh(PMe₃)C₂H₃R′ (R′  H, Me, Ph) and C₅H₅Rh(PR₃)C₂H₄(PR₃  PMe₂Ph, PPrⁱ₃) are prepared by reaction of[PMe₃(C₂H₃R/t')RhCl]₂ or [PR₃(C₂H₄)RhCl]₂ and TlC₅H₅, respectively. They react with HBF₄ in ether/propionic anhydride to form the BF₄ salts of the hydrido(olefin)rhodium cations [C₅H₅RhH(C₂H₃R′)PR₃]⁺(R  Me; R′  H, Me and R  Prⁱ; R′  H). From C₅H₅Rh(PMe₃)C₂H₃Ph and CF₃COOH/NH₄PF₆ the η³-benzyl complex [C₅H₅Rh(PMe₃)(η³-CH₃CHC₆H₅)]PF₆ is obtained. The reversibility of the protonation reactions is demonstrated by temperature-dependent NMR spectra and by deuteration experiments. The complexes C₅H₅Rh(PMe₃)C₂H₃R′ (R′  H, Ph) and C₅H₅Rh(PMe₂Ph)C₂H₄ react with CH₃I in ether to give the salts [C₅H₅RhCH₃(C₂H₃R′)PR₃]I which in THF or CH₃NO₂ yield the neutral compounds C₅H₅RhCH₃(PR₃)I.     

Structure and magnetic properties of the ferromagnetically coupled nickel dimer [Ni(terpy)(NCO)(H2O)]2(PF6)2

Summary The crystal structure of the dimeric [{Ni(C₁₅H₁₁N₃)(NCO)(H₂O)}₂](PF₆)₂ has been determined by x-ray diffraction methods. Crystal data are as follows: P 1,a=11.904(4) Å,b=10.392(4) Å,c=8.531(3) Å, =111.87(2)^o, =90.61(3)^o, =107.37(5)^o, U=926.7(4) ų, Z=2, D_m=1.77(2), D_x=1.78 g. cm^–3, (Mo-K)=12.1 cm^–1, F(000)=494. Least-squares refinement of 1230 reflections with I1.5(1) gave a final R =0.035 (R=0.038). The structure is formed by cationic [{Ni(C₁₅H₁₁N₃)(NCO)(H₂O)}₂]²⁺ and anionic PF ₆ ^– units, linked through hydrogen bonds between the water molecule and the hexafluorophosphate ion. The resulting coordination geometry around each nickel(II) ion is ferragonally elongated octahedral. The N-bridging cyanate groups occupy simultaneously an equatorial position in the coordination sphere of one of the nickel atoms and an axial position in the other. The remaining axial positions are occupied by the water molecules. Powder susceptibility data, between 2.0 and 300 K, show the existence of ferromagnetic exchange between nickel centres. The magnetic parameters are J/K=6.6K, D/K =–17.6 K, zJ/K=0.57 and g-2.21.     

Synthesis and characterization of the bimetallic gold-iridium compoundscis-[IrH(AuPPh3)(dppe)2]PF6 andmer-[IrH(AuPPh3)(CO)(PPh3)3]PF6

Summary The bimetallic complexes [IrH(AuPPh₃)(dppe)₂]X(X=Cl, BPh₄, PF₆ or BF₄) and [IrH(AuPPh₃)(CO)(PPh₃)₃] PF₆ have been synthesized from the corresponding neutral iridium phosphine hydrides and [AuCl(PPh₃)]. The molecular structure of the latter compounds, determined by single-crystal x-ray crystallography, consists of an octahedrally co-ordinated iridium atom and an almost linear P–Au–Ir–P arrangement. The Au–Ir distance is 2.6628(4) Å. The position of the hydride ligand was located in the x-ray structural analysis and istrans to the carbonyl group, which is consistent with the i.r. and n.m.r. spectral data.     

X-ray Crystallographic Study of the Ruthenium Blue Complexes [Ru(2)Cl(3)(tacn)(2)](PF(6))(2).4H(2)O, [Ru(2)Br(3)(tacn)(2)](PF(6))(2).2H(2)O, and [Ru(2)I(3)(tacn)(2)](PF(6))(2): Steric Interactions and the Ru-Ru "Bond Length"

X-ray crystal structures are reported for the following complexes: [Ru(2)Cl(3)(tacn)(2)](PF(6))(2).4H(2)O (tacn = 1,4,7-triazacyclononane), monoclinic P2(1)/n, Z = 4, a = 14.418(8) ?, b = 11.577(3) ?, c = 18.471(1) ?, beta = 91.08(5) degrees, V = 3082 ?(3), R(R(w)) = 0.039 (0.043) using 4067 unique data with I > 2.5sigma(I) at 293 K; [Ru(2)Br(3)(tacn)(2)](PF(6))(2).2H(2)O, monoclinic P2(1)/a, Z = 4, a = 13.638(4) ?, b = 12.283(4) ?, c = 18.679(6) ?, beta = 109.19(2) degrees, V = 3069.5 ?(3), R(R(w)) = 0.052 (0.054) using 3668 unique data with I > 2.5sigma(I) at 293 K; [Ru(2)I(3)(tacn)(2)](PF(6))(2), cubic P2(1)/3, Z = 3, a = 14.03(4) ?, beta = 90.0 degrees, V = 2763.1(1) ?(3), R (R(w)) = 0.022 (0.025) using 896 unique data with I > 2.5sigma(I) at 293 K. All of the cations have cofacial bioctahedral geometries, although [Ru(2)Cl(3)(tacn)(2)](PF(6))(2).4H(2)O, [Ru(2)Br(3)(tacn)(2)](PF(6))(2).2H(2)O, and [Ru(2)I(3)(tacn)(2)](PF(6))(2) are not isomorphous. Average bond lengths and angles for the cofacial bioctahedral cores, [N(3)Ru(&mgr;-X)(3)RuN(3)](2+), are compared to those for the analogous ammine complexes [Ru(2)Cl(3)(NH(3))(6)](BPh(4))(2) and [Ru(2)Br(3)(NH(3))(6)](ZnBr(4)). The Ru-Ru distances in the tacn complexes are longer than those in the equivalent ammine complexes, probably as a result of steric interactions.     

Synthesis,structure, and dissociation equilibrium of [Co(eta5-C5H5)(Se2C6H4)]2, a novel metalladiselenolene complex

A (phenylenediselenolato)cobalt complex dimer, [Co(eta(5)-C(5)H(5))(Se(2)C(6)H(4))](2) (1), was synthesized by a reaction of carbonyl(eta(5)-cyclopentadienyl)diiodocobalt(III) ([Co(eta(5)-C(5)H(5))I(2)(CO)]) with poly(o-diselenobenzene). The structure of 1, determined by single-crystal X-ray crystallography, was found to be located in the space group of P2(1)/c (No. 14), with a = 9.3346(5) A, b = 11.6477(9) A, c = 10.2179(5) A, beta = 111.491(1) degrees, and Z = 2. Covalent Co-Se bonds bridge the metal centers. In solution, dimers and monomers coexist at equilibrium. The dissociation equilibrium constant of 1 in solution was evaluated by (1)H NMR spectra at several temperatures between 20 and 80 degrees C. Dissociation enthalpies/entropies were found to be 50/110, 60/120, and 88 kJ mol(-1)/200 J K(-1) mol(-1) in dimethyl sulfoxide-d(6), benzene-d(6), and chloroform-d(1), respectively.