Quantum chemistry : the challenge of transition metals and coordination chemistry ; [proc. of the NATO Advanced Research Workshop and the 40. Internat. Meeting of the Soc. de Chimie Physique: The challenge of transition metals and coordination chemistry,

Over the last twenty years, developments of the ab initio metho­ dologies and of the computing capacities have progressively turned quantum chemistry into a predictive tool for molecular systems involving only light elements. The situation appears less advanced for systems containing transition metal elements where specific difficulties arise, like those 1inked to the quasi-degeneracy of the lowest atomic states. Correlation effects, which are important only for quantitative accuracy in the treatment of molecules made of light elements, need sometimes to be considered even for a qualitative des­ cription of transition metals systems (like the multiple metal-metal bond). The treatment of atoms of a high atomic number has necessited the development of model potential methods. These difficulties ex­ acerbate for systems containing several trans ition atoms a correct description of the dichromium molecule Crz still represents a challenge to quantum chemists. Yet many advances have been made recently in the theoretical treatment of these systems, despite the fact that our understanding still remains disparate with a variety of models and methodologies used more or less successfully (one-electron models, explicitly correlated ab initio methods, density functional formalisms). For these reasons, a NATO Advanced Research Workshop was organized to review in detail the state-of-the-art techniques and at the same time the most common applications. These encompass many fields including the spectroscopy of diatomics and small aggregates, structure and reactivity problems in organometallic chemistry, the cluster­ surface analogy with its implications for heterogeneous catalysis and the description of extended structures. Front Matter....Pages i-ix Accurate Studies on the Structure and Reactivity of Transition Metal Complexes and Clusters....Pages 1-14 The Importance of Atomic and Molecular Correlation on the Bonding in Transition Metal Compounds....Pages 15-35 The Electronic Structure of Transition Metal Atoms and Diatoms Through Pseudopotential Approaches....Pages 37-51 Spectroscopic Characterization of Bonding in Diatomics and Small Transition Metal Aggregates....Pages 53-65 Low-Lying Electronic States of ScH, tih and VH According to MRD-CI Calculations....Pages 67-78 Energy-Adjusted Pseudopotentials for Transition-Metal Elements....Pages 79-89 Spectroscopic Studies of Copper Complexes....Pages 91-100 Scandium Atom Interacting with Diatomic Groups....Pages 101-117 The Nature of the Bonding in the Transition Metal Trimers....Pages 119-134 Electronic Structure and Reactions of Transition Metal Complexes Using Effective Core Potentials....Pages 135-141 Correlation Effects in the Ground and Ionized States of Transition Metal Complexes....Pages 143-157 Analysis of σ-Bonding, π-(Foack)Bonding and the Synergic Effect in Cr(CO) 6 . Comparison of Hartree-Fock and Xα Results for Metal-CO Bonding....Pages 159-177 Applications of the LCGTO-Xα Method to Transition Metal Carbonyls....Pages 179-187 Quantitative Results and Qualitative Analysis by the Hartree-Fock-Slater Transition State Method....Pages 189-198 Xα Electronic Structure of Transition Metal Halides: Calculation of Ligand-Field Multiplet States....Pages 199-207 Complementary Spherical Electron Density Model for Co-Ordination and Organometallic Compounds....Pages 209-224 Theoretical Analysis of Bonding Properties in Transition Metal Complexes. Ligand Substitution Effects....Pages 225-233 Topology of Potential Energy Surfaces: The Complementarity of mo and VB Approaches....Pages 235-252 Applied MO Theory: Organometallic Structure and Reactivity Problems....Pages 253-276 CO Activation and Reactivity in Organometallic Chemistry: Theoretical Studies....Pages 277-299 Structural Distortions and Activation of a C-H Bond in D o Electron Deficient Alkyl Transition Metal Complexes....Pages 301-317 Stereochemistry and Metal-ligand Interaction of Group VIII Low-Valent Transition Metal Complexes. An ab-initio MO and Energy Decomposition Analysis Study....Pages 319-331 Stabilization of Phosphinidene and Phosphirene by Complexation on Phosphorus. Theoretical and PE Studies....Pages 333-340 Molecular Orbital Calculations on Metallocenes with Unusual Geometries....Pages 341-350 Transition State for Carbonyl and Olefin Insertion Reactions....Pages 351-361 Theoretical Aspects of the Photochemistry of Organometallics....Pages 363-375 Electronic Structure of Metallloporphyrins. Ab Initio CI Calculations....Pages 377-390 Multiple Metal-Metal and Metal-Carbon Bonds....Pages 391-401 Design of Ferromagnetically Coupled Polymetallic Systems: Toward the Molecular Ferromagnets....Pages 403-412 A Spectroscopic and Magnetic Investigation of M 4 X 4 Clusters: Localized or Itinerant Electrons?....Pages 413-424 Moving from Discrete Molecules to Extended Structures: A Chemical and Theoretical Approach to the Solid State....Pages 425-443 Cluster-Surface Analogy: New Developments....Pages 445-464 Cluster Model Calculations of the Interaction of H and CO with Small Pd Clusters....Pages 465-475 Theoretical Study on the Catalytic Activities of Palladium for the Hydrogenation Reaction of Acetylene....Pages 477-487 Theoretical Study of the Successive Hydrogenation of Small Platinum Clusters....Pages 489-499 Back Matter....Pages 501-530 Proceedings of the NATO Advanced Research Workshop (40th International Meeting of the Société de Chimie Physique), Strasbourg, France, September 16-20, 1985 Proceedings of the NATO Advanced Research Workshop (40th International Meeting of the Societe de Chimie Physique), Strasbourg, France, September 16-20, 1985