Raymond Roulet

Homogeneous hydrogenation of aqueous hydrogen carbonate to formate under mild conditions with water soluble rhodium(I)- and ruthenium(II)-phosphine catalysts

Water-soluble rhodium(I)- and ruthenium(II)tertiary phosphine complexes with meta-mono-sulphonated triphenylphosphine (TPPMS) and 1,3,5-triaza-7-phosphaadamantane (PTA) as ligands catalyze the hydrogenation of aqueous HCO3- to HCO2- under mild conditions. No amine additive is needed for good turnovers. CO2 accelerates the reactions with [RhCl(TPPMS)(3)] catalyst; however, it slightly inhibits the reductions catalyzed by [RuCl2(TPPMS)(2)]. Bicarbonate formed in the reaction of limestone with aqueous CO2 can also be used as starting material for formate production. Copyright (C) 2000 John Wiley & Sons, Ltd.

Iron and ruthenium carbonyls of 2,3,5,6-tetrakis(methylene)bicyclo[2.2.2]octane. Crystal and molecular structure of (C12H14)Fe(CO)3

Abstract The reaction of 2,3,5,6-tetrakis(methylene)bicyclo[2.2.2]octane (1a) with Fe 2 (CO) 9 yields the two (η 4 -1,3-diene)Fe(CO) 3 isomers (2: exo; 3:endo) together with two bimetallic isomers (C 12 H 14 )[Fe(CO) 3 ] 2 (4:endo-exo; 5:diexo). The reaction of 1a with Ru 3 (CO) 12 yields the endo-(C 12 H 14 )Ru(CO) 3 (6) and endo, exo-(C 12 H 14 [Ru(CO) 3 ] 2 (7) complexes as the main products. The molecular structure of 3 has been determined by X-ray crystallography. The Fe(CO) 3 group is in the endo position with respect to the roof-shaped tetraene. The ligand is bound through one diene group to two basal positions of a tetragonal pyramidal Fe(CO) 3 L 2 moiety. Hydrogen atom positions have been determined (final residual R = 0.029). The dimensions for the 1,3-butadieneirontricarbonyl system, as found in this and 41 other structures, are summarized and discussed statistically. In this study the weighted averages for all structures show the threeCC distances to be of equal length and the FeC (inner) distance to be shorter than the FeC (outer) distance. The deviations of H(Z) and H(E) atoms from the butadiene plane, as found in this and 6 other structures having an exocyclic unsubstituted 1,3-diene group, are also discussed. Neither thermal epimerization of iron nor epimerization catalyzed by H + were found for complexes 2 – 7 whose structures in solution were deduced from their 1 H and 13 C NMR data on the basis of the known structure of 3.

Amphiphilic organoruthenium oxomolybdenum and oxovanadium clusters

Abstract Para-cymene ruthenium dichloride dimer reacts in aqueous solution with sodium molybdate or sodium vanadate to give the amphiphilic clusters [ (η6-p-MeC6H4i Pr) 4Ru4Mo4O16] (1) and [ (η6-p-MeC6H4i Pr) 4 Ru4V6O19] (4) respectively. The analogous reaction of hexamethylbenzene ruthenium dichloride dimer with sodium vanadate gives [ (η6-C6Me6) 4Ru4V6O19] (5) . The mixed-metal clusters [ (η6-p-MeC6H4i Pr) Ru (η5-C5Me5) 3Rh3Mo4O16] (2) and [ (η6-p-MeC6H4i Pr) 2Ru2 (η5-C5Me5) 2Rh2Mo4O16] (3) are accessible from a mixture of para-cymene ruthenium dichloride dimer and pentamethylcyclopentadienyl rhodium dichloride dimer with sodium molybdate in aqueous solution. The crystal structure analyses of 1 and 4 reveal different framework geometries of the metal oxygen skeletons. 17O NMR spectroscopy and partial charge calculations confirm the presence of three different types of oxygen atoms in 1.

Iron and Molybdenum Carbonyls of 5,6-Dimethylene-7-Oxabicyclo[2.2.1]Hept-2-Ene - Crystal and Molecular-Structure of (C8H8O)Fe2(Co)7

Abstract The photoreaction of 5,6-dimethylene-7-oxabicyclo [2.2.1]hept-2-ene(1) with Fe(CO)5 yields initially the dihapto-tetracarbonyl iron complex (3), which reacts further to give a dihapto-tetracarbonyl-tetrahapto- tricarbonyl complex (C8H8O)Fe2(CO)7 (4) The molecular structure of 4 has been determined by X-ray crystallagraphy. Both the Fe(CO)4 and Fe(CO)3 groups are in exo position with respect to the roof-shaped triene. The ligand is bound through its lone double bond to an equatorial position of a substituted trigonal-bipyramidal Fe(CO)4L moiety and through its diene group to two basal positions of a tetragonal pyramidal Fe(CO)3L2 moiety. Hydrogen atom positions have been determined in the last cycles (final residual R = 0.023). H(Z) atome deviate by 39° from the diene plane away from the metal and H(E) atoms deviate by 11° towards the metal. H atoms of the lone CC double bond deviate by 34° from the C(1)C(2)C(3)C(4) plane away fromthe metal. The structures of complexes 3,4 and(C8H8O)Mo(CO)3 (7) in solution were deduced fromtheir 1H NMR data and the unknown geometries of ligands 1 and 5,6-dimethylenebicyclo[2.2.1] hept-2-ene (2) were simulated by MINDO¦3. Deoxygenation of the ligand is observed in the presence of Fe2(CO)9 in benzene at 60 °C, giving o-quinodimethane complexes 5 and 6, 5 being also obtained by direct thermolysis of complex 4.

Cyanoalkyl complexes of platinum(II). III. Alcoholysis and hydrolysis of the CN group

Abstract Nucleophilic additions of alcohols, thiols and water to the σ-coordinated CN group of cis-[Pt(o-CH2C6H4CN)(PPh3)2]2(BF4)2 give quantitative yields of stable N-bonded iminoether, iminothioether and amide complexes. The proposed mechanism involves a fast replacement of the σ-coordinated CN by the nucleophile HY followed by the intramolecular attack of HY on the ligand in the cis position. π-Coordination of CN to PtII has not been observed. The addition of methanol to other cyanoalkyls did not lead to stable iminoether complexes. The amide complex cis-[Pt(CH2C6H4CONH2)(PPh3)2]2(BF4)2 is converted into the nonionic imide cis-[Pt(CH2C6H4CONH)(PPh3)2]2 in methanolic KOH but it catalyzes for a few cycles the conversion of benzonitrile to benzamide by water under neutral conditions. The imino and isonitrile have a higher trans effect than alkyl groups whereas their trans influence as indicated by 1J(PtP) coupling constants is smaller.

Cyanoalkyl complexes of platinum(II) : II. Uncharged and cationic o-cyanobenzyl complexes

The oxidative addition of o-XCH2C6H4CN to PtL4 yields trans-PtX-(CH2C6H4CN)L2 (L = PPh3, AsPh3a X = Cl, Br). The trans complex is the thermodynamically stable isoer, but cistrans isomerization occurs readily in dichloromethane and is catalyzed by free L. Displacement of L by bidentate phosphorous ligands and insertion of CO in the σ PtC bond occurs readily. Abstraction of X gives a cis cationic complex in which the CN group is coordinated and is prone to nucleophilic attack by alcohols to give stable cis imino ether complexes.

Iron, molybdenum and tungsten carbonyls of 5,6,7,8-tetrakis(methylene)bicyclo[2.2.2]oct-2-ene. Crystal and molecular structure of (C12H12)Fe(CO)3

Abstract The reaction of 5, 6, 7, 8-tetrakis(methylene)bicyclo[2.2.2.]oct-2-ene (1) with Fe29CO)9 yields under various conditions the exo and endo-tetrahaptotri-carbonyliron complexes(2 and3) and the endo, exobis(tetrahaptotricarbonyliron) complex (4); with Fe(CO)39benzalacetone), 2 and the bis(exo-tetrahapto-tricarbonyliron) complex (5) are obtained. The little ligand reacts with M(CO)3(CH3CN)3 (M = Mo, W) giving respectively the hezahapto-tricarbonyl-molybdenum and -tugnsten complex (6, 7). Coordination of all five double bonds of the pentaene is achieved by reacting 2 with Mo9CO)3(CH3CN)3 giving the exo-tetrahapto-tricarbonyliron-hexahapto-tricarbonylmolybdenum complex (8). The structures of complexes 3–8 in solution were deduced from their NMR data and the molecular structure of 2 was determined by X-ray crystallography. The Fe(CO)3 group is in th eexo position with respect to the roof-shaped pentaene. The ligand is bound through one s-cis-butadiene group to two basal positions of a tetragonal pyramidal Fe(CO)3X2 moiety. Hydrogen atom positions were refined in the last cycles (final residual R = 0.023). H(Z) atoms deviate from the diene plane of the coordinated diene away from the metal by ∼42°, whereas H(E) atoms deviate towards the metal by ∼16°. Hybridization at the “inner” carbon atoms as well as at the carbon atoms of the other three double bonds does not differ significantly from sp2. Kinetic study of the cycloaddition reaction of a dienophile to the free 1, 3-diene system of the monometallic complexes shows that the rate with respect to that of the free ligand is not much affected by the presence of the metal.

Hydrido- and hydroxo-cyanoalkyl complexes of platinium(II). Reactivity of the PtH and PtOH bonds towards nucleophiles and electrophiles

Abstract Reactions of the PtH and/or PtC bonds of the hydridocyanoalkyl complexes cis - or trans -PtH[(CH 2 ) n CN]L 2 ( n = 1, 3; L 2 = 2 PPh 3 , Ph 2 PCHCHPPh 2 ) are described, viz. reductive elimination induced by CO, PhCCPh, PEt 3 , PPhMe 2 , cis -Ph 2 PCHCHPPh 2 to give Pt(CO) 2 L 2 , PtL 2 (PhCCPh), PtL 2 , PtL(PPhMe 2 ) 3 , PtL 2 (Ph 2 PCHCHPPh 2 ) (L = PPh 3 ), respectively, and cleavages by acids, halogens and alkyl halides. The monomeric hydroxo complexes cis -Pt(OH)[(CH 2 ) n CN]L 2 were shown to be intermediates in the synthesis of PtH[(CH 2 ) n CN]L 2 from cationic cyanoalkyl complexes in alcoholic NaOH. Their characterisation and the reactions of the PtOH bond with activated methyl groups are reported.

Cationic cyanobenzylpalladium(II) complexes. Synthesis and reactivity of the cyano group towards nucleophiles

Abstract The addition of alcohols, thiols, water and amines to the σ-coordinated CN group of cis -[Pd( o -CH 2 C 6 H 4 CN)L 2 ] 2 (BF 4 ) 2 (L 2 = 2PPh 3 , 1,2-bis(diphenylphosphino)ethene or -ethane) yields stable N-bonded iminoether, iminothioether, amide and amidine complexes,respectively. Thiophenols, ArSH (Ar = p -C 6 H 4 CH 3 , p -C 6 H 4 Br) break the σ-PdC bond, forming o -cyano toluene and complexes of the type [Pd(SAr)L 2 ] 2 (BF 4 ) 2 . The azido complex PdN 3 ( o -CH 2 C 6 H 4 CN)(Ph 2 PCH 2 CH 2 PPh 2 ) is stable in the solid state but in solution it undergoes an intramolecular 1,3-cycloaddition yielding the corresponding tetrazolate complex.

Cyanobenzylpalladium(II) complexes. Synthesis and spectroscopic properties

Abstract The oxidative addition of benzyl, o- , m- and p- cyanobenzyl chlorides to Pd(PPh 3 ) 4 yields trans- PdCl(CH 2 C 6 H 4 Y)(PPh 3 ) 2 (Y= H or CN) (1a-d). In solution, these complexes are in equilibrium with the dimers [PdCl(CH 2 C 6 H 4 Y)PPh 3 ] 2 (2a--d) which are obtained in quantitative yields upon shifting the equilibria by oxidation of the free PPh 3 with H 2 0 2 . PPh 3 in both the monomers and the dimers is readily displaced by bidentate ligands yielding PdCI(CH 2 C 6 -H 4 Y)(L-L) (3). Chloride abstraction from 3 gives dimeric cationic complexes [Pd(o-CH 2 C 6 H 4 CN)(L-L)] 2 (BF 4 ) 2 having a σ-coordinated CN group. Insertion of carbon monoxide in the PdC bonds is quantitative.