C. Foces-Foces

Rhodium(I) complexes with bis(pyrazolyl)methane ligands. Crystal structure of [Rh(COD)(CH2(Pz)2)]ClO4·12 C2H4Cl2

The synthesis and properties of neutral and cationic complexes of general formulae [{RhCl(diolefin)}2(CH2(pz)2)], [Rh(CO)2 (CH2(pz)2)][RhCl2(CO)2], (Rh(diolefin)(CH2(pz)2)]ClO2, [{Rh(diolefin)(PPh3)}2(CH2(pz)2)](ClO4)2, [Rh(CO)2(CH2(pz)2)]ClO4 and [Rh(CO)(CH2(pz)2)(PPh3)]ClO4 are described. The NMR spectra of [Rh(COD)(CH2(pz)2)]ClO4 complexes are discussed. X-ray structural analysis of [Rh(COD)(CH2(Pz)2)]ClO4 · 12C2H4Cl2 is presented; the final R factor is 0.061 for 2436 observed data, recorded with Cu-Kα, not corrected for absorption and with the sample inside a capillary. The Rh atom presents a distorted square planar coordination in a mononuclear arrangement. The COD ring has a twisted boat conformation, and the two halves of the CH2(Pz)2 moiety, which are quite similar to one another, form an angle of 47.2(4)°.

Cyclopentadienylruthenium complexes with chelating diamines and diolefins. Crystal structures of [Ru(nbd)(PPh3)(ϑ-C5H5)]ClO4 and [Ru{(η6-C6H5)Ph2PO}(η-C5H5)]ClO4. A new mode of coordination of triphenylphosphine oxide

Abstract Complexes of the general formulae [Ru(diamine)(PPh 3 )(η-C 5 H 5 )]ClO 4 and [Ru(diolefin)(PPh 3 )(η-C 5 H 5 )]ClO 4 (diamine = ethylenediamine (en), propylenediamine (pn), 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), biimidazole (H 2 bim), bibenzimidazole (H 2 bbzim) and 2-(2′-pyridylbenzimidazole) (Hpybzim); diolefin = 2,5-norbornadiene (nbd), tetrafluorobenzobarrelene (tfb)) have been made by reaction of the complex RuCl(PPh 3 ) 2 (η-C 5 H 5 ) with the diamine or diolefin in the presence of sodiuim perchlorate. A single-crystal X-ray diffraction study of [Ru(nbd)(PPh 3 )(η-C 5 H 5 )]ClO 4 has been carried out. Crystals of the complex are monoclinic, space group P 2 1 / n , with a 18.0576(5), b 14.5070(3), c 10.3186(3) A; β 103.20(6)°. The structure was solved by Patterson synthesis using 4209 observed reflections (2σ( I ) criterion) and refined to a R factor of 0.040. Reaction of RuCl(PPh 3 ) 2 (η-C 5 H 5 ) with oxygen in the presence of sodium perchlorate leads to oxidation of the coordinated triphenylphospine ligands giving the complex [Ru{(η 6 -C 6 H 5 )Ph 2 PO}η-C 5 H 5 )]ClO 4 . In order to establish the structural identity of this compound a single-crystal X-ray diffraction study has been made. Crystals of this complex are monoclinic, space group P 2 1 / c , with a 10.818(5), b 9.4480(3), c 21.0036(19) A; β 90.246(6)°. The structure was solved by Patterson synthesis using 3819 observed reflections (3σ( I ) criterion) and refined to a R factor of 0.036. The ruthenium atom is coordinated in a sandwich fashion by the cyclopentadienyl group and a phenyl ring of the triphenylphosphine oxide ligand. The synthesis of new heteronuclear ruthenium(II)-rhodium(I) complexes of formulae [(η-C 5 H 5 )(Ph 3 P)-Ru(μ-bim)RhY 2 ] x and (η-C 5 H 5 )(Ph 3 P)Ru(μ-bbzim)RhY 2 (Y = CO, Y 2 = diolefin) is also described.

Preparation and X-ray crystal structure of [Ni6{μ-S(CH2)3N(CH3)2}12], a cyclic hexameric homothiolate of nickel

Abstract Highly hygroscopic, black, prism-like crystals separated out from CH3CN solutions containing (Et4N)2NiCl4 and 3-dimethylamino-1-propanethiol at several mole ratios. Crystals of [Ni6{S(CH2)3N(CH3)2}12] are orthorhombic, space group P21212 with a = 30.197(6), b = 29.231(4), c = 10.649(1) A and Z = 4. The Ni6S12 core of each molecular unit constitutes a hexagonal prism whose rectangular faces are NiS4 coordination planes (NiS = 2.19 A; SNiS = 82.2°, 98.05°). Approximate diameters for the Ni6 and S6 rings are 5.85 and 6.60 A, respectively. The allowed molecular symmetry for the Ni6S12 core, D6h, is reduced to D3d when the axial and equatorial SC bonds are included.

Arene-iridium(i) complexes. Crystal structures of [Ir(TFB)(arene)]BF4 (TFB = tetrafluorobenzobarrelene; arene = 1,4-Me2C6H4 or C6Me6)

Abstract The arene-iridium(I) complexes of formula [Ir(TFB)(arene)]BF4 (TFB = tetrafluorobenzobarrelene; arene = C6H4Me2, C6H3Me3, C6H2Me4, C6Me6) have been prepared by treating [IrCl(TFB)2] with AgBF4 in the presence of the corresponding arene. The iridium(I) complexes formed by addition of several types of ligands to [Ir(TFB)(1,4-Me2C6H4)]BF4 in the presence of potassium hydroxide catalyze hydrogen transfer from isopropanol to acetophenone. The crystal structures of [Ir(TFB)(1,4-Me2C6H4)]BF4 and [Ir(TFB)(C6Me6)]BF4 have been solved by standard X-ray single methods. Both compounds have similar R3c symmetry and are pseudoisomorphous with the corresponding rhodium analogues. Lattice constants are: 25.6844(3), 15.9664(2) A, and 26.9123(7), 16.9894(5) A, respectively. Final R factors were 0.037 and 0.033, respectively, for the observed, data. Some deviation from the planarity of the coordinated arene ligands is observed. The C6Me6 ring roughly eclipses the TFB ligand, whereas for the C6H4Me2 derivative the arene and the TFB ligand are staggered.

The influence of the nitro group on the solid-state structure of 4-nitropyrazoles: the cases of pyrazole, 3,5-dimethylpyrazole, 3,5-di-tert-butylpyrazole and 3,5-diphenylpyrazole. I. Static aspects (crystallography and thermodynamics)

We have determined the enthalpies of sublimation of 3,5-di-tert-butylpyrazole (3), 3,5-diphenylpyrazole (4), 4-nitropyrazo1e (5), 3,5-dimethyl-4-nitropyrazole (6), 3,5-di-tert-butyl-4-nitropyrazole (7) and 3,5-diphenyl-4-nitropyrazole (8); those of pyrazole (1) and 3,5-dimethylpyrazole (2) were already known. the effect of the C-substituents (Me, Bu t , Ph and NO 2 ) on the enthalpies of sublimation of pyrazoles and benzenes are additive and linearly related. Moreover, we report the structure of three of these 4-nitropyrazole derivatives, (5), (7) and (8), which have been solved by X-ray crystallography; those of the remaining five compounds were already known

Cationic rhodium tetrafluorobenzobarrelene complexes with diolefin or arene ligands, crystal structures of [Rh(TFB)(arene)] ClO4, (arene = C6Me6, C6H3Me3, C6H4Me2)

Abstract The preparation and properties of complexes of the general formulae [Rh(TFB)(diolefin)]ClO4, [Rh(TFB)(arene)]ClO4 and [Rh(TFB)L2]ClO4, (TFB = tetrafluorobenzobarrelene, L = dimethylsulfoxide and tetrahydrothiophen) are described. The crystal structures of the arene complexes (arene = C6Me6, C6H3Me3 and C6H4Me2) have been solved by X-ray methods. The three compounds crystallize in quite similar lattices: R3c, a = b = 27.122, 26.233, 25.731 and c = 17.079, 16.388, 16.256 A, respectively. δR-plots for about 2000 reflections show the agreement in the refinements carried out up to R-values of 5%, 5% and 4% respectively. The Rh atom is coordinated to the double bonds of the TFB and to the arene ring in all three compounds, but the deviation from planarity of the arene and its relative position with respect to the TFB moiety varies.

Synthesis and hydroformylation reaction of dinuclear rhodium(I) complexes with mixed bridging ligands. X-Ray structure of [Rh2(µ-pz)(µ-SBut)(CO)2{P(OMe)3}2]

The preparation and properties of dinuclear complexes containing one azolate (az) and one t-butylthio group as bridging ligands are described. Bubbling of carbon monoxide through dichloromethane solutions of [Rh2(µ-az)(µ-SBut)(η4-cod)2](cod = cyclo-octa-1,5-diene), followed by addition of phosphorus donor ligands (L) affords the complexes [Rh2(µ-az)(µ-SBut)(CO)2L2]. The crystal and molecular structure of cis-[Rh2(µ-pz)(µ-SBut)(CO)2{P(OMe)3}2](pz = pyrazolate) was determined from a single crystal by X-ray diffraction. Crystals are monoclinic, space group P21, with a= 10.789(2), b= 12.226 0(3), c= 10.431 4(2)A, β= 110.515(1)°, and Z= 2. The final agreement factors were R= 0.036 and R′= 0.044. In the dinuclear complex each rhodium atom is in a distorted square arrangement. The dihedral angle of 63.1(2)° between the two co-ordination planes leads to a bent geometry with a rhodium–rhodium distance of 3.477 0(9)A. The [Rh2(µ-az)(µ-SBut)(CO)2L2] complexes are good precursors for the hydroformylation reaction of olefins under mild conditions.

Arene-rhodium(I) complexes with trimethyltetrafluorobenzobarrelene. Crystal structure of [Rh(Me3TFB)(1,4-C6H4Me2)]ClO4

Abstract The preparation of arene-rhodium(I) complexes of the general formula Rh(Me3TFB)PhBPh3 and [Rh(Me3TFB)(arene)]ClO4 (Me3TFB = trimethyltetrafluorobenzobarrelene; arene = C6H6−nMen (n = 0, 1, 2, 3, 4 or 6); C6H6−nXn (X = F, n = 2 or 6; X = Cl, n = 1 or 2) are described. For arenes of the type C6H6−nXn the dissociation of the coordinated arene (studied by NMR spectroscopy in deuteroacetone) is complete, but for arenes of the type C6H6−nMen it decreases with increasing methyl substitution in the arene ligand. The crystal structure of [Rh(Me3TFB)(1,4-C6H4Me2)]ClO4 has been determined by X-ray diffraction. The compound crystallizes in the Pbca space group, with lattice periodicities of 17.7393(4), 15.7816(3) and 16.0071(3) A. δR-analysis, for the 3953 total recorded reflections, support the refinement carried out to a final R-value of 0.062. The bonding of the arene to the rhodium is η6, with the ring slightly puckered to give a distorted skew conformation.

A model for describing the conformations of flexible 6-membered rings—I : The non-chair conformations

Abstract An empirical model for calculating the torsional angles for flexible 6-membered rings is presented in terms of three independent parameters, two geometrical and one pseudorotation angle. The rings are classified according to four estimators, the fit of the model depending upon their values. Equations are given for defining any conformation by a point in a 2-dimensional pathway. Some examples have been examined in the light of this model.

Conformation of 3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-glucopyrano-[2,1-d]-2-oxazolines

Abstract The crystal and molecular structure of 2-phenyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α- d -glucopyrano)-[2,1-d]-2-oxazoline (2) has been determined. The compound crystallises in the space group P21212 with lattice constants 13.4160(3), 37.4931(14), and 7.7886(1) A, and Z = 8. Direct methods were used in the solution. Least squares refined the model with 3213 observed (with 2σ) reflections down to an R value of 0.053 and Rω 0.060. The pyranoid rings have slightly different conformations, being between skew oS2 and diplanar D0,4. The conformations of 2 and 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α- d -glucopyrano)-[2,1-d]-2-oxazoline in solution have also been investigated by 1H-n.m.r. spectroscopy. The computed best values of the coupling constants have been used with several Karplus-type equations and have been interpreted in terms of a skew oS2 major conformation of the pyranoid ring in each compound.