Anne-Marie Lebuis

Homogeneous Catalytic Hydrosilylation of Pyridines

The color change from yellow to violet allows the formation of the intermediate [Cp2 Ti(SiHMePh)(pyridine)] to be monitored in the reaction of PhMeSiH2 with a pyridine in the presence of the precatalyst [Cp2 TiMe2 ] [Eq. (a)]; the hydride [Cp2 TiH] is postulated to be the key intermediate in the catalytic cycle. The regioselective hydrosilylation of pyridine and also substituted pyridines can be catalyzed by the titanocene [Cp2 TiMe2 ]. R=Me, CO2 Et.

Bisperoxovanadium compounds: synthesis and reactivity of some insulin mimetic complexes☆

Abstract A series of bisperoxovanadium complexes (bpV) of the general formula K3[VO(O2)2(L-L′)] has been prepared and characerized. where L-L′ is a pyridinedicarboxylate (2,3-pdc, 2,4-pdc, 2,5-pdc) or 3-acetatoxypicolinate (3-acetpic). Two structures have been determined: bpV(2,4-pdc), P21, a = 38.187(5) A , c = 11.4088(8) A , β = 90.546(9)° , V = 3093.8(7) A 3 , Z = 8, R/Rw = 0.049/0.055, and bpV(3-acetpic), P1, a = 7.4037(13) A , b = 10.709(3) A , c =10.9569(19) A , α = 110.742(16)°, β = 95.600(19)°, γ = 100.195(19)°, V = 787.4(3) A 3 , Z = 2, R/Rw=0.036/0.026. The oxygen atom of the 2-carboxylate group and the oxo ligand are situated in apical positions of a pseudotrigonal plane formed by the nitrogen atom and the centres of the two peroxo groups. The compounds rapidly oxidize sodium tris(3-sulfonatophenyl)phosphine, in water, to the corresponding oxide. The results are discussed with reference to the reported insulin mimetic activity of this class of compounds.

Homogen katalysierte Hydrosilylierung von Pyridinen

Anhand des Farbwechsels von Gelb zu Violett last sich die Bildung der Zwischenstufe [Cp2Ti(SiHMePh)(Pyridin)] bei der Reaktion von PhMeSiH2 mit einem Pyridin in Gegenwart der Katalysatorvorstufe [Cp2TiMe2] verfolgen [Gl. (a)]; als Schlusselintermediat im Katalysecyclus wird das Hydrid [Cp2TiH] diskutiert. Mit dem Titanocen [Cp2TiMe2] kann die regioselektive Hydrosilylierung von Pyridinen katalysiert werden, die auch substituiert sein konnen. R=Me, COOEt.

The synthesis and structure of the thiosulfonato iron complexes CpFe(CO)2SS(O)2R

Abstract Treatment of the iron polysulfanes (μ-Sx)[CpFe(CO)2]2 (x=3, 4) with sulfonyl chlorides RSO2Cl (R=CF3 (1), CCl3 (2), C6F5 (3)) gave the corresponding iron thiosulfonato complexes CpFe(CO)2SS(O)2R in good yields. Crystal structure for 2: P21/c, a=6.704(2), b=8.933(2), c=22.603(5) A, α=90, β=92.82(2), γ=90°, V=1352.0(6) A3 and Z=4.

Mesitylpseudohalogermanes Mes2Ge(CN)2 and Mes3GeX (X=CN, NCS, N3, NCO and OH; Mes=2,4,6-trimethylphenyl): syntheses, crystal and molecular structures

Abstract The crystal and molecular structures of the mesitylpseudohalogermanes, Mes2Ge(CN)2 (Mes=2,4,6-trimethylphenyl) and Mes3GeX (X=CN, NCS, N3, NCO, or OH), have been determined by X-ray diffraction methods; the isocyanate and hydroxide crystallise as a 1:1 hydrogen-bonded complex. All are covalent monomers free from pseudohalogen bridging, and all except the cyanides and hydroxide are N-bonded to germanium. Each Ge atom is four-coordinate in a distorted tetrahedral geometry, as evident from (mes)Ge(mes) angles between 112 and 120°, which are attributed to the sterically demanding mesityl groups. The greatest distortion is displayed by Mes2Ge(CN)2, for which the NCGeCN angle of 97.8(3)° and (mes)Ge(mes) angle of 119.8(3)° are also consistent with the bulky mesityl groups and the small steric requirements of the cyano groups. The GeNY angles show a distinctive trend, decreasing from 173.3(5)° for the isothiocyanate (Y=CS), through 153.5(5)° for the isocyanate (Y=CO), to 119.0(7)° for the azide (Y=NN), an effect attributed to differences in electronic structure of the pseudohalo ligands. The geometries of the compounds examined here are compared with those of some other tri- and dimesityl-Group 14 metal derivatives as well as related phenylgermanium compounds.

STUDIES IN ARYLTIN CHEMISTRY. PART XIV. CRYSTAL AND MOLECULAR STRUCTURES OF TRIS(O-METHOXYPHENYL)TIN(IV) CHLORIDE, FLUORIDE AND OXIDE

Full crystal structures are reported for the tris( o -methoxyphenyl)tin compounds, ( o -CH 3 OC 6 H 4 ) 3 SnX [X=Cl ( A ), F ( B )] and [( o -CH 3 OC 6 H 4 ) 3 Sn] 2 O ( C ), together with both solid-state and solution (CDCl 3 ) 119 Sn NMR data for B and C as well as (Mes) 3 SnF and [( o -Tol) 3 Sn] 2 O. Compound B like A is monomeric with a similar but not identical arrangement of aryl groups around the tin while NMR data indicate that B has almost the same geometry in solution as in the solid state. The anomalously lower frequency δ ( 119 Sn) value for B is consistent with the more ionic character of the SnF bond compared with other SnX (X=Cl, Br, I) bonds. Compound C is the first (Ar 3 Sn) 2 O with an SnOSn bond angle between 140 and 180°. The comparison of solid-state with solution 2 J ( 119 Sn, 119 Sn) values for C and [( o -Tol) 3 Sn] 2 O suggests that the solid state favours structures having larger SnOSn angles. Reacting C with water gives ( o -CH 3 OC 6 H 4 ) 3 SnOH only in solution, identified by its 13 C and 119 Sn NMR spectra.

The reactions of CpRu(PPh3)2SR with the electrophiles HBF4, [MeSSMe2]BF4 and MeSphth where R=CMe3, CHMe2, 4-C6H4Me and phth=phthalimide

Abstract Reaction of the ruthenium thiolato complexes CpRu(PPh3)2SR (1), where R=CMe3, CHMe2, 4-C6H4Me with HBF4 gave the corresponding thiol complex salts [CpRu(PPh3)2(HSR)]BF4 (2) in very good yields. Treatment of the thiolato complexes with [MeSSMe2]BF4 gave the methyl thioether complex salt [CpRu(PPh3)2SMe2]BF4 (3). Reactions of 1 with MeSphth, where phth=phthalimide, gave CpRu(PPh3)2(phth) (4) and the dimers (μ-SMe)(μ-SR)[CpRu(phth)]2 (5) for R=CMe3 and CHMe2, however, for R=4-C6H4Me the same reaction gave CpRu(PPh3)(phth)(MeSS-4-C6H4Me) (6) and (μ-SMe)(μ-S-4-C6H4Me)[CpRu(S-4-C6H4Me)]2 (7). The crystal structure for 7 was determined: space group P21/c, a=8.805(2), b=13.668(3), c=26.026(6) A, α=90, β=108.86(2), γ=90°, V=2964.0(12) A3 and Z=4.

Reactions of cyclotrigermane and germylenes with carbonyl compounds: Cycloadducts and oligomers

Reactions of germylenes, generated by thermolysis of cyclotrigermanes, or of bulky germylenes, with various α-dicarbonyl compounds are described. They proceed through a radical pathway, as confirmed by ESR measurements, to give different types of compounds. In the reaction of (Mes2Ge)3 with fluorenone, formation of the 2:1 ketone/germylene cycloadduct and of the oxadigermetane, resulting from a transient digermene, occurred. In the case of acenaphthene quinone, we observed the first example of cycloaddition between a digermene and an α-diketone. The X-ray crystal structure of the product shows a drastically distorted six-membered ring system. The formation of oligomeric adducts was observed with parabenzoquinone.

Synthesis and spectroscopic and X-ray structural characterisation of some para-substituted triaryltin(pentacarbonyl)manganese(I) complexes

Abstract A series of para-substituted triaryltin(pentacarbonyl)manganese(I) compounds [(p-XC6H4)3SnMn(CO)5: II, X=CH3; III, X=CH3O; IV, X=CH3S; V, X=F; VI, X=Cl; VII, X=CH3S(O2)] is reported for comparison with the known phenyl analogue I. IR data [ν(CO)] as well as complete 119Sn/55Mn/13C solution NMR results are given for I–VII. Chemical shifts, 119Sn versus 55Mn, except I, correlate well, but have differing single parameter (SP) correlations, 119Sn versus σI and 55Mn versus σ°p. These results are compared with previous SP studies of the 119Sn solution NMR spectra of the series, (p-XC6H4)4Sn and (p-XC6H4)3SnY (Y=Cl, Br, I). Full crystal structures are reported for compounds II–VI. All are similar to that of I, with the Mn(CO)5 moiety being a distorted tetragonal pyramid, and having a quasi-mirror plane through the central C4MnSnC3 skeleton. The Ar3Sn are distorted trigonal propellers with ring torsion angles in the range 30–80°, the exception being IV with one torsion angle of 22°.

Structural and spectroscopic studies of bis(pentacarbonylmanganese)diphenyltin(IV) and bis(pentacarbonylmanganese)diphenyllead(IV)

Solid-state nuclear magnetic resonance and vibrational spectroscopic studies are reported for bis(pentacarbonylmanganese)diphenyltin(IV) and bis(pentacarbonylmanganese)diphenyllead(IV). The solid-state, CP-MAS, 119 Sn and 207 Pb NMR spectra of these complexes each reveal a single asymmetric undecet due to the 1 J 119 Sn‐ 55 Mn and 207 Pb‐ 55 Mn spin‐spin couplings and second-order quadrupole‐dipole effects. The 1 JSn‐Mn and 1 JPb,-Mn values are 139 ^ 1a nd 228^ 1H z; respectively. The 119 Sn and 207 Pb chemical shift anisotropies have been determined. The crystal structure of the tin compound has been re-examined. q 2001 Elsevier Science B.V. All rights reserved.