Louis J. Farrugia

ORTEP-3 for Windows - a version of ORTEP-III with a Graphical User Interface (GUI)

Computer Program Abstracts The category Computer Program Abstracts provides a rapid means of communicating up-to-date information concerning both new programs or systems and significant updates to existing ones. Following normal submission, a Computer Program Abstract will be reviewed by one or two members of the IUCr Commission on Crystallographic Computing. It should not exceed 500 words in length and should follow the standard format given on page 189 of the June 1985 issue of the Journal [J. Appl. CrysL (1985). 18, 189190] and on the World Wide Web at http://www.iucr. ac. uk/journals/jac/software/. Lists of software presented and~or reviewed in the Journal of Applied Crystallography are available on the World Wide Web at the above address, together with information about the availability of the software where this is known. J. App/. CrysL (1997). 30, 565 ORTEP-3 for Windows a version of ORTEP-III with a Graphical User Interface (GUI)

WinGX suite for small-molecule single-crystal crystallography

The category Computer Program Abstracts provides a rapid means of communicating up-to-date information concerning both new programs or systems and signi®cant updates to existing ones. Following normal submission, a Computer Program Abstract will be reviewed by one or two members of the IUCr Commission on Crystallographic Computing. It should not exceed 500 words in length and should follow the standard format given on page 189 of the June 1985 issue of the Journal [J. Appl. Cryst. (1985). 18, 189± 190] and on the World Wide Web at http://www.iucr. org/journals/jac/software/. Lists of software presented and/or reviewed in the Journal of Applied Crystallography are available on the World Wide Web at the above address, together with information about the availability of the software where this is known.

WinGX and ORTEP for Windows: an update

The WinGX suite provides a complete set of programs for the treatment of small-molecule single-crystal diffraction data, from data reduction and processing, structure solution, model refinement and visualization, and metric analysis of molecular geometry and crystal packing, to final report preparation in the form of a CIF. It includes several well known pieces of software and provides a repository for programs when the original authors no longer wish to, or are unable to, maintain them. It also provides menu items to execute external software, such as the SIR and SHELX suites of programs. The program ORTEP for Windows provides a graphical user interface (GUI) for the classic ORTEP program, which is the original software for the illustration of anisotropic displacement ellipsoids. The GUI code provides input capabilities for a wide variety of file formats, and extra functionality such as geometry calculations and ray-traced outputs. The programs WinGX and ORTEP for Windows have been distributed over the internet for about 15 years, and this article describes some of the more modern features of the programs.

The QTAIM Approach to Chemical Bonding Between Transition Metals and Carbocyclic Rings: A Combined Experimental and Theoretical Study of (η5-C5H5)Mn(CO)3, (η6-C6H6)Cr(CO)3, and (E)-{(η5-C5H4)CF═CF(η5-C5H4)}(η5-C5H5)2Fe2

Experimental charge densities for (C(5)H(5))Mn(CO)(3) (2), (eta(6)-C(6)H(6))Cr(CO)(3) (3), and (E)-{(eta(5)-C(5)H(4))CF=CF(eta(5)-C(5)H(4))}(eta(5)-C(5)H(5))(2)Fe(2) (4) have been obtained by multipole refinement of high-resolution X-ray diffraction data at 100 K. The resultant densities were analyzed using the quantum theory of atoms in molecules (QTAIM). The electronic structures of these and related pi-hydrocarbyl complexes have also been studied by ab initio density functional theory calculations, and a generally good agreement between theory and experiment with respect to the topological parameters was observed. The topological parameters indicate significant metal-ring covalency. A consistent area of disagreement concerns the topology of the metal-ring interactions. It is shown that because of the shared-shell bonding between the metal and the ring carbons, an annulus of very flat density rho and very small wedge rho is formed, which leads to topologically unstable structures close to catastrophe points. This in turn leads to unpredictable numbers of metal-C bond paths for ring sizes greater than four and fewer M-C bond paths than expected on the basis of the formal hapticity. This topological instability is a general feature of metal-pi-hydrocarbyl interactions and means that a localized approach based on individual M-C(ring) bond paths does not provide a definitive picture of the chemical bonding in these systems. However, other QTAIM indicators, such as the virial paths, the delocalization indices, and the source function, clearly demonstrate that for the n-hapto (eta(n)-C(n)H(n))M unit, there is generally a very similar level of chemical bonding for all M-C(ring) interactions, as expected on the basis of chemical experience.

Chiral Schiff base complexes of copper (II), vanadium (IV) and nickel (II) as oxidation catalysts. X-ray crystal structures of [Cu (R-salpn) (OH2)] and [Cu (±-busalcx)]

Abstract Several new complexes of chiral and achiral tetradentate Schiff bases with copper (II), nickel (II) and oxovanadyl (IV) ions have been synthesised and characterised and the structures of [Cu ( R -salpn) (OH 2 )] and [Cu (±-busalcx)] have been elucidated by X-ray analysis. [Cu ( R -salpn) (OH 2 )] is essentially square pyramidal with an unusually long bond [2.494 (4) A] from Cu to the oxygen of the apical water molecule. Molecules are linked by hydrogen bonding between the coordinated water and the salpn oxygens of neighbouring molecules. A long contact between a salpn CH 2 hydrogen and a neighbouring copper atom [H(3B). . .Cu = 2.966 (1) A] might be regarded as a CH···Cu hydrogen bond and completes a pseudo-octahedral coordination about copper. [Cu (±-busalcx)] displays tetrahedrally-distorted planar coordination about the copper atom and has no significant intermolecular contacts. The copper, nickel and vanadyl complexes were screened as homogeneous catalysts for the oxidation by Bu t OOH or H 2 O 2 of PhMeS to PhMeSO. All of them are active catalysts but of the chiral complexes only [Cu ( R , R -busalcx)] produced a reasonable enantiomeric excess (14%). Supporting the complexes on silica improved the enantioselectivity of the less sterically hindered [Cu ( R -salpn) (OH 2 )] ( from 2 to 10%), but diminished that of the more hindered [Cu ( R , R -busalcx)], probably by slowing the reaction to such an extent that the uncatalysed oxidation could compete effectively. Finally [Cu (salen)], [Cu ( R -salpn)] and [Ni ( R -salpn)] were synthesised in the pores of zeolites X and Y. These were shown to be active heterogeneous catalysts for the sulfide to sulfoxide oxidations, but no significant e.e. resulted from the use of the chiral catalysts.

Metal−Metal and Metal−Ligand Bonding at a QTAIM Catastrophe: A Combined Experimental and Theoretical Charge Density Study on the Alkylidyne Cluster Fe3(μ-H)(μ-COMe)(CO)10

The charge density in the tri-iron methoxymethylidyne cluster Fe(3)(μ-H)(μ-COMe)(CO)(10) (1) has been studied experimentally at 100 K and by DFT calculations on the isolated molecule using the Quantum Theory of Atoms in Molecules (QTAIM). The COMe ligand acts as a nearly symmetric bridge toward two of the Fe atoms (Fe-C = 1.8554(4), 1.8608(4) Å) but with a much longer interaction to the third Fe atom, Fe-C = 2.6762(4) Å. Complex 1 provides a classic example where topological QTAIM catastrophes render an exact structure description ambiguous. While all experimental and theoretical studies agree in finding no direct metal-metal interaction for the doubly bridged Fe-Fe vector, the chemical bonding between the Fe(CO)(4) unit and the Fe(2)(μ-H)(μ-COMe)(CO)(6) moiety in terms of conventional QTAIM descriptors is much less clear. Bond paths implying direct Fe-Fe interactions and a weak interaction between the COMe ligand and the Fe(CO)(4) center are observed, depending on the experimental or theoretical density model examined. Theoretical studies using the Electron Localizability Indicator (ELI-D) suggest the metal-metal bonding is more significant, while the delocalization indices imply that both Fe-Fe bonding and Fe···C(alkylidyne) bonding are equally important. The source functions at various interfragment reference points are similar and highly delocalized. The potential-energy surface (PES) for the migration of the alkylidyne group from a μ(2) to a semi-μ(3) coordination mode has been explored by DFT calculations on 1 and the model complexes M(3)(μ-H)(μ-CH)(CO)(10) (M = Fe, 2; Ru, 3; and Os, 4). These calculations confirm a semi-μ(3) bridging mode for the alkylidyne ligand as the minimum-energy geometry for compounds 2-4 and demonstrate that, for 1, both Fe-Fe and Fe···C(alkylidyne) interactions are important in the cluster bonding. The PES between μ(2) and semi-μ(3) alkylidyne coordination for 1 is extremely soft, and the interconversion between several topological isomers is predicted to occur with almost no energy cost. Analysis of the density ρ(r) and the Laplacian of the density ▽(2)ρ(r(b)) in the methoxymethylidyne ligand is consistent with a partial π-bond character of the C-O bond, associated with an sp(2) hybridization for these atoms.

Bismuth(III) thiolates: syntheses and the structures of a neutral thiolate and a thiolato anion

Abstract The synthesis of a range of bismuth(III) arenethiolates and a thiolato anion are described together with two X-ray crystal structure determinations of SC6F5 derivatives.

The synergy between dynamics and reactivity at clusters and surfaces

Can We Put the Cluster-Surface Analogy on a Sound Structural Basis? A.M. Bradshaw. An Atomic View of Diffusion on Metal Surfaces G.L. Kellog. Dynamics of the Desorption of Carbon Monoxide from Size-Selected Supported Platinum Clusters U. Heiz, R. Sherwood, D.M. Cox, A. Kaldor, J.T. Yates Jr. NMR Investigation of Binding of Aromatics at Catalytic Surfaces C. Dybowski, M.A. Hepp. From Molecular Carbonyl Clusters to Supported Metal Particles R. Giordano, E. Sappa, G. Predieri. Cluster Equilibria. Relevance to the Energetics and Reactivity of Surface Bound Fragments T.P. Fehlner. Reactions and Dynamics of Ruthenium Clusters K. Vrieze, C.J. Elsevier. Unusual Ligand Transformations and Rearrangements in Heterometallic Clusters Y. Chi, S.-J. Chang, C.-J. Su. Hydride Mobility and its Relation to Structure and Reactivity in Polymetallic Clusters E. Rosenberg. Structural Variations in Tetranuclear Platinum-Ruthenium Clusters L.J. Farrugia, D. Ellis, A.M. Senior. Intramolecular Exchange in d 9 Metal Carbonyl Clusters R. Roulet. Static and Dynamic Stereochemistry of the Organometallic Cluster Complexes [CpCo)3(mm3-Arene)] H. Wadepohl. NMR Studies on the Dynamic Behaviour in Solution of Rhenium-Platinum Mixed Metal Clusters Containing P-Donor Ligands T. Beringhelli, G.D. Alfonso, A.P. Minoja, R. Mynott. Organometallic Migrations over Clusters and Surfaces M. J. McGlinchey, L. Girard, A. Decken. Structure, Melting and Reactivity of Nickel Clusters from Numerical Simulations J. Jellinek, Z.B. Guvenc. Heterodox Bonding Effects between Transition Metal Atoms S. Alvarez, P. Alemany, G. Aullon, A.A. Palacios, J.J. Novoa. Periodic Hartree-Fock Calculations of the Adsorption of Small Molecules on TiO2 C. Minot, A. Fahmi, J. Ahdjoudj. An Overview of the MO Architectures of Metal Clusters Using Graphic Tools C. Mealli. Molecular Orbital Approach of Skeletal Isomerism and Polyhedral Rearrangements in some Organometallic Clusters J.-Y. Saillard, M.T. Garland, S. Kahlal, J.-F. Halet. Some Old and New Redox Reactions of Polynuclear Organometallic Complexes H. Vahrenkamp. Arene Cluster Compounds B.F.G. Johnson. Silver and Gold Clusters Stabilized by Fe(CO)4 Ligands F. Calderoni, M.C. Iapalucci, G. Longoni, U. Testoni. Reactions of Silylalkanes with Triosmium and Triruthenium Clusters A.A. Koridze.

A combined experimental and theoretical charge density study of the chemical bonding and magnetism in 3-amino-propanolato Cu(II) complexes containing weakly coordinated anions.

The experimental (100 K) and theoretical charge densities in the binuclear complexes [Cu2(ap)2(L)2] (ap = 3-aminopropanolate) 1 (L = nitrite), 2 (L = nitrate), and 3 (L = formate) have been examined. These complexes contain the same centrosymmetric alkoxy-bridged motif, where each strongly Jahn-Teller distorted Cu(II) ion is ligated to three O atoms and one N atom in a square-planar arrangement. This primary coordination sphere is augmented by a long contact with the O atom of a pendant L anion from an adjacent molecule in the crystal lattice. Topological analyses of the experimental and theoretical densities according to the quantum theory of atoms in molecules (QTAIM) are in excellent agreement. Consideration of a number of topological indicators including rho(r), vector differential(2)rho(r), the delocalization indices delta(A,B), and the contour integral(A intersection B) rho(r) of the density over the zero flux surface shared by the two atoms confirms that the Cu-O and Cu-N bonding in the primary coordination sphere has a strong covalent component, but the weak Cu...O interactions are primarily electrostatic in nature. In this first investigation of the source function in a coordination complex, it is shown to provide an insight into the differing electrostatic and covalent contributions to the chemical bonds. The two Cu(II) centers are strongly antiferromagnetically coupled, but the topological analyses indicates the lack of any direct Cu...Cu interaction. The molecular graph suggests an exchange pathway via the bridging O-atoms, thus providing experimental support of the classical superexchange mechanism. Periodic DFT calculations on 2 and 3 show that the intradimer coupling proceeds via spin-delocalization and provide values of the magnetic coupling constants -2 J of 324.5 and 244.8 cm(-1), respectively, which compare well with the previously determined experimental values.

Experimental and Theoretical Charge Density Study of Polymorphic Isonicotinamide−Oxalic Acid Molecular Complexes with Strong O···H···N Hydrogen Bonds

Two polymorphs of the 2:1 molecular complex of isonicotinamide and oxalic acid have been characterized by combined X-ray charge density and single-crystal neutron diffraction studies at 100 K. Both polymorphs show strong O-H...N intermolecular hydrogen bonding between the acid and the pyridine base. As is typical of short, strong hydrogen bonds (SSHBs), the covalent O-H bonds are considerably elongated to 1.161(3) and 1.235(5) A, and the H...N interactions are correspondingly short at 1.398(3) and 1.313(6) A in Forms I and II, respectively. The neutron diffraction data indicate no pronounced H dynamics in the SSHBs, and in the case of Form II the SSHB can be described as quasicentered. In addition to the experimental charge densities, theoretical charge densities have been determined from ab initio calculations within the full periodic environment of the crystalline state. The SSHBs are found to be covalent in nature according to the topological analysis of the experimental and theoretical charge densities and application of the source function. Aside from the SSHBs, moderate N-H...O and weak C-H...O interactions are also present in the molecular complexes, for which hydrogen bond energies are estimated from energy densities and independent ab initio calculations. Finally, an attempt is made to evaluate the intermolecular interactions governing the manifestation of polymorphism in this compound.