Josep M. Viñas

Benzyne complexes of ruthenium: Models for dissociative chemisorption of benzene on a metal surface. Crystal structures of [Ru4(CO)10(μ-CO)(μ4-PR)(μ4-η4-C6H4)] (R = Ph and CH2NPh2), [Ru5(CO)13(μ4-PPh)(μ5-η6-C6H4)] and [Ru6(CO)12(μ4-PMe)2(μ3-η2-C6H4)2]

Abstract Heating a solution of [Ru 3 (CO) 11 (PPh 3 )] in toluene gives the μ 3 -, μ 4 - and μ 5 -benzyne complexes [Ru 3 (CO) 7 (μ-PPh 2 ) 2 (μ 3 -η 2 -C 6 H 4 )] ( 1a ) (33%), [Ru 4 (CO) 10 (μ-CO)(μ 4 -PPh)(μ 4 -η 4 -C 6 H 4 )] ( 2a ) (50%) and [Ru 5 (CO) 13 (μ 4 -PPh)(μ 5 -η 6 -C 6 H 4 )] ( 3a ) (7%), respectively. The structures of 2a and 3a have been established by X-ray diffraction, revealing that the benzyne in each case is bound to a square of ruthenium atoms by CRu σ-bonds to two adjacent rutheniums, and by η 2 -interactions to the other two atoms of the Ru 4 square. In 3a there is also η 2 -co-ordination to a third ruthenium atom, so that there is η 6 -co-ordination overall. The five metal atoms of 3a are arranged like a step site on a metal (111) surface and the complex can be viewed as a model for the aftermath of benzene CH activation on such a surface. The thermolysis of [Ru 3 (CO) 11 (PPh 2 CH 2 NPh 2 )] gives the μ 4 -PCH 2 NPh 2 analogue 2b of 2a , while from [Ru 3 (CO) 11 (PPh 2 Me)] the new cluster [Ru 6 (CO) 12 (μ 4 -PMe) 2 (μ 3 -η 2 -C 6 H 4 ) 2 ] ( 11 ) is isolated in 11% yield. The structures of 2b and of 11 have been determined by X-ray diffraction; 11 contains two μ 3 -benzyne ligands bound to triruthenium faces of an Ru 6 P 2 cluster. Thermolysis of the tritolylphosphine complexes [Ru 3 (CO) 11 (PAr 3 )](Ar = C 6 H 4 - m -Me or C 6 H 4 - p -Me) affords only analogues of 1 and 2 , containing in each case the μ-C 6 H 3 -4-Me ligand. Heating [Ru 3 (CO) 11 (AsPh 3 )] gives low yields of the arsenic analogues of 2 and 3 in addition to the major product [Ru 2 (CO) 6 (μ-AsPh 2 ) 2 ] (65%). The fluxional behaviour of complexes 1 and 2 , involving benzyne rotation on Ru 3 and Ru 4 centres, respectively, is discussed, and pathways for the formation of 1, 2 and 3 are proposed.

Synthesis and vibrational spectra of[RSHgII]2+(ClO4)2 complexes. Crystal and molecular structure of bis(N-methylpiperidinium-4-thiolato)-mercury(II) perchlorate.

Abstract Hg(II) complexes have been prepared with γ-mercaptoamine ligands 1-methyl-4-mercaptopiperidine (4-MP), 1-methyl-3(mercaptomethyl)piperidine (3-MMP) and 1-methyl-2(2-mercaptoethyl)piperidine (2-MEP) with 1:1 and 1:2 metal to ligand ratios. Infrared and Raman spectra for all these compounds have been recorded and discussed. The spectral features agree with a linear SHgS structure and with the characteristic two-coordination of mercury in all the complexes. The structure of [Hg(4-MP)2](ClO4)2 has been determined by X-ray crystallography. The crystals are orthorhombic, space group C2221 (Z=4) in a unit cell of dimensions a= 13.161 (3) A, b= 6.589 (2) A and c= 24.740 (4) A. Solution of the structure by direct methods led to a final weighted R factor of 0.057 for 1339 independent reflections. The crystal structure consists of discrete [Hg(4-MP)2]2+ cations and ClO4− anions packed in layers paralell to the (100) plane.

Conjugate additions to alkynylalkoxycarbenemetal (Cr or W) complexes

Abstract The addition of different nucleophilic compounds (aliphatic and aromatic alcohols, thiols and phosphines) to alkynylalkoxycarbene complexes has been studied. The reaction with smaller nucleophiles proceeds readily and regioselectively at the β-carbene position. With more substituted nucleophiles the reaction rate slowed down considerably. Addition of a catalytic amount of DBU (1,8-di-azabicyclo[5.4.0]undec-7-ene]) speeded up the reaction and improved the E/Z ratio.

Diolefin and carbonyl rhodium(I) and iridium(I) complexes with phosphine sulphide ligands. Crystal structure of [Rh(COD)(Et2P(S)(S)PEt2)]ClO4

Abstract The preparation and properties of new diolefinic or carbonyl cationic rhodium and iridium complexes with phosphine sulphide ligands of the type [M(COD)L 2 ] n n + or [M(CO) 2 L 2 ] n n + ( n = 1 or 2) (L = Me 3 PS, Et 3 PS and Ph 3 PS, L 2 = Me 2 P(S)(S)PMe 2 , Et 2 P(S)(S)PEt 2 and Ph 2 P(S)(S)PPh 2 ) are described. The complexes have been characterized by elemental analyses, IR spectra, conductance studies and 31 P NMR spectroscopy. Oxidative addition of I 2 gives Ir III complexes. Diolefinic complexes with phosphine sulphide are catalyst precursors in the homogeneous hydrogenation of olefins. The crystal structure of [Rh(COD)(Et 2 P(S)(S)PEt 2 )]ClO 4 has been determined by X-ray diffraction methods. The crystals are monoclinic, space group P 2 1 / c , with a 12.754(1), b 13.333(1), c 13.637(1) A, β 95.30(1)°, Z = 4. The cationic complex [Rh(COD)(Et 2 P(S)(S)PEt 2 )] + is monomeric, with the Rh atom showing a slightly distorted square-planar environment. The cyclooctadiene ligand is coordinated to the metal through its two olefinic bonds, and a bis(diethylphosphine) disulphide group, bonded through its two S atoms, acts as a bidentate chelating ligand.

Synthesis, crystal structure, and spectroscopic characterization of af-dichloro-bd,ec-bis{μ[2-(1-methyl-2-piperidinyl)ethanethiolato]-S,N,μ-S} dipalladium(II)

Abstract The reaction of 2-(1-methyl-2-piperidinyl)ethanethiol with sodium tetrachloro-palladate(II) at pH = 8 yields a yellow precipitate of formula [Pd2(C8H16NS)2Cl2] which crystallized in the orthorhombic space group Pcab with a = 22.050(4) A, b = 14.644(3) A, c = 13.834(3) A, V = 4467(3) A3, and Z = 8. The organic ligands chelate to one Pd atom through the S and N atoms and bridges to another Pd atom through the S atom to form a dimer in which each molecule of the organic ligand has the same chirality. IR, UV—Vis and 1H NMR spectra are presented for this compound.

An efficient synthesis of 3,4-dioxocyclobutenecarboxylate derivatives

Abstract Alkynylalkoxycarbene metal complexes react readily with tetraalkoxyethylenes to give the corresponding [2 + 2] cycloadducts in high yields. From these adducts the title compounds were obtained by DMSO oxidation and final hydrolysis of the acetal groups.

Carbonylation of benzyne at polynuclear ruthenium centres

Carbonylation (1 atm, 25 °C) of [Ru3(CO)7(µ-PPh2)2(µ3-C6H4)] gives [Ru3(CO)8(µ-PPh2)2(µ3-C6H4CO)], arising from linking of µ3-benzyne with one molecule of CO, while [Ru4(CO)11(µ4-PPh)(µ4-C6H4)] and [Ru5(CO)13(µ4-PPh)(µ5-C6H4)] react with CO (50 atm, 60–100 °C) to afford [Ru3(CO)10(µ3-PPh){µ-C6H4(CO)2}] and/or [Ru2(CO)7(µ-P(Ph)C(O)C6H4)], involving linking of µ4- and µ5-benzyne with one or two CO molecules; the structures of the products have been established by X-ray diffraction.

Conjugate addition of alcohols to alkynylalkoxycarbene metal (Cr, W) complexes

Abstract Reaction of alkynylakoxycarbene metal (Cr, W) complexes with alcohols gives the corresponding (2-alkoxyalkenyl)alkoxycarbene metal complexes in moderate to good yields. A high degree of stereo-selectivity is found with linear aliphatic alcohols.

Synthesis and crystal structure of μ-chloro-μ-(diphenylethenyl)hexacarbonyldiiron(FeFe)

Abstract Treatment of PPh 4 [Fe 2 (CO) 6 (μ-CO)(μ-C(Ph)C(Ph)H)] with Me 3 OSbCl 6 gives the chloro-bridged derivative [Fe 2 (CO) 6 (μ-Cl)(μ-C(Ph)C(Ph)H)]. The structure of this compound has been established by X-ray diffraction. The title complex appears to be formed by successive methylation of bridging carbon monoxide and replacement of the methoxycarbyne by the chloride ligand.

An improved route to the synthesis of µ-(alkane- or arene-thiolato)(µ-ethenyl)di-iron complexes. Crystal structure of µ-phenylmethanethiolato-µ-(1,2-diphenylethenyl)-hexacarbonyldi-iron(Fe–Fe)

The reactions of [Fe2(CO)6(µ-Cl)(µ-CPhCHPh)] with LiSR (R = Et, Pri, cyclo-C6H11, Ph, or CH2Ph) lead to the complexes [Fe2(CO)6(µ-SR)(µ-CPhCHPh)]. The structure of the benzyl derivative has been established by X-ray diffraction methods; crystals are monoclinic, space group P21/n with a= 21.383(3), b= 7.098(2), c= 16.856(3), A, β= 95.49(2)°, and Z= 4. The structure was solved and refined on the basis of 2 197 significant counter data, to a final R value of 0.056. The structure consists of Fe2(CO)6 units with benzylthiolato and σ:η2-diphenylethenyl ligands bridging the two metal centres.