Bonding Energetics in Organometallic Compounds

Downloaded by 80.82.77.83 on June 1, 2018 | https://pubs.acs.org Publication Date: June 25, 1990 | doi: 10.1021/bk-1990-0428.ix002

Author Index Allison, J., 263 Armentrout, Peter Β., 18 Beauchamp, J. L., 34 Bowers, Michael T., 34 Brennen, William R., 148 Christ Jr., Charles S., 70 Coffin, Virginia L., 148 Copenhaver, Ann S., 84 Dearden, David V., 34 Dias, A. R., 205 Diogo,H.P.,205 Drago, Russell S. Eyler, John R., Franz, James, Α., 113 Freiser, Ben S. Gonzalez, Alberto Α., 133 Griller, D., 205 Halpern, Jack, 100 Harrison, J. F., 263 Hedden, David, 159 Hoff, Carl D., 133 Khalsa, G. Rattan K., 133 Klassen, Jane K., 195 Koenig, T., 113 Kubas, Gregory J., 133 Kunze, K., 263

Lichtenberger, Dennis L., 84 Marks, Tobin J., 159, Marks, Tobin J., 1,159 Martinho Simôes, J. Α., 205 Mavridis, Α., 263 Minas da Piedade, M. E., 205 Mukerjee, Shakti L., 133 Nolan, Steven P., 159 Pearson, Ralph G., 251 Richardson, David E., 70 Ryan, Matthew F., 70 Scott, T.W., 113 Selke, Matthias, 195 Sharpe, Paul, 70 Sherry, AlanE., Somorjai, G. Α., 218 Sorensen, Amy Α., 195 Stair, Peter C , 239 Stern, David, 159 Tschinke, Vincenzo, 279 van Koppen, Petra, A. M>, 34 Wayland, Bradford B., Yang, Gilbert K., 195 Zhang, Kai, 133 Ziegler, Tom, 279

Affiliation Index California Institute of Technology, 34 Exxon Research and Engineering Company, 113 Instituto Superior Téchnico, 205 Lawrence Berkeley Laboratory, 218 Los Alamos National Laboratory, 133 Michigan State University, 263 National Research Council of Canada, 205 Northwestern University, 1,159,239 Pacific Northwest Laboratories, 113 Purdue University, 55

The University of Chicago, 100 University of Arizona, 84 University of Athens, 263 University of California, 34,218,251 University of Florida, 70,75 University of Miami, 133 University of Oregon, 113 University of Pennsylvania, 148 University of Southern California, 195 University of Utah, 18

Subject Index Absolute electronegativity-Co/i/waa/ values for electron transfer in reaction of olefins with low-spin Ni atoms, 253,254* Absorbed photochemical energy, 7 Acid properties of chemically modified Mo(100) desorption activation energy vs. proton affinity, 245,247/

Absolute electronegativity definition, 251-252 experimental values for molecules, 252 illustration in orbital energy diagram, 253,257/ role in covalent bonding of metals and hydrogen, 260-261

295 Marks; Bonding Energetics in Organometallic Compounds ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

BONDING ENERGETICS IN ORGANOMETALLIC COMPOUNDS


296

Acid properties of chemically modified MoilOOy-Continued measured desorption activation energies, 245,246/ Mo(100) surfaces used for chemisorption experiments, 244/ thermal desorption spectra, 244-245 Acid sites on chemically modified Mo surfaces acid properties of Mo(100), 244-247 effective Mo oxidation state, 241/^42^43/ hydrogenolysis of methylcyclopropane, 248/249 surface geometry, 241 surface polarizability, 242,244,246/ Activation parameters, distinction between apparent and observed parameters, 126 Adiabatic electron affinities, 75 Adiabatic ionization potentials, 75 Adsorbate coverage, measurement, 11 Adsorbate-induced restructuring of surfaces carbon-induced restructuring of Ni, 229 catalytic reactions, 233,237 dynamic lattice model, 229,233-236 rigid lattice model, 226,229,230-231/ sulfur-induced restructuring of Fe, 233 sulfur-induced restructuring of Ir, 233 Alkyl homolytic-transition metal bond dissociation processes, thermodynamics and kinetics, 100-111 Ammonia, discrepancy in equilibrium constant as determined by Haber and Nernst, 218 Andrade energy, definition, 116 Anionic ligands, bonding,256^58-259/^60 Atomic metal anions, determination of proton affinities, 58 Auger parameter, definition, 242

Β 2:1 Base adducts, use of ECW model, 188-189 Bases in organometallic chemistry, £ and C parameters, 184/ Batch calorimetry in determination of thermodynamic properties, 6 Bis(cyclopentadienyl) metal complexes, enthalpies of formation, 207,208/ Bond disruption enthalpy, definition, 3 Bond dissociation energy(ies) definition, 2-3 from kinetic measurements macroscopic description, 101-102 microscopic description, 102-103,104-105/ metal-ligand, in complexes, 195-203 Bond dissociation enthalpies, metal-C and metal-H, from classical and nonclassical calorimetric studies, 205-216 B

Bond dissociation processes, transitionmetal-alkyl, 100-111 Bondenergy(ies) definition, 3 metal-ligand and metal-metal, determined with FTMS, 55-68 periodic trends in transition metal complexes, 279-289 problems in obtaining thermodynamic information, 84 related to absolute electronegativity and hardness, 251-261 relationships with ionization energy, See Ionization energy-bond energy relationships transition metal complexes, periodic trends by density functional theory, 279-290 Bond enthalpy definition, 3 description of contributions, 4 organolanthanide-li gand, metal and ancillary coordination effects, 159-173 Bond enthalpy term, determination, 208-209 Bond homolysis reactions accuracy of Halpern procedure, 127,129 dissociation energy determination, 127 observed rate constants, 127 temperature dependence of rate constants, 127,128/ Bond order approximation, definition, 85-86 Bond strength, definition, 3 Bond thermolysis in solution free energy and enthalpy, 114,119/ steps required for description, 113 Bonding in charge-transfer complexes, Mulliken description, 176 of anionic ligands bond energies, 259/ hardness parameters, 258/^59 HSAB principle, 256

B

C Cage combination rate constants, effect of temperature, 129 Cage effects, correspondence between transition state and hydrodynamic models, 129 Cage pair intermediates bond homolysis reactions, 126-129 chemical model, 113-114 definition, 113 effect on activation parameters for free radical recombination, 115-116

Marks; Bonding Energetics in Organometallic Compounds ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

297


INDEX Cage pair intermediates-Continued free radical self-termination, 121-122,125/ free radical trapping reactions, 122-126 radiation boundary model, 117-120 Calorimetric measurements bond dissociation energy determination, 107-108 classical and nonclassical, metal-C and metal-H bond dissociation enthalpies, 205-216 organometallic systems, 175-193 Carbon, binding to transition metals, periodic trends, 18-32 Carbon monoxide orbital energy diagram, 253,257/ π orbitals, 256,257/ reductive coupling NMR and IR parameters, 155-156,157/ reaction(s), 153 reaction for insertion into dimetal ketone unit, 155 reactivity studies with tetramesitylporphyrin, 156-157 selectivity, 156 thermodynamics, 153-155 thermodynamic studies of hydrogénation and reductive coupling by rhodium(II) rx^hyrins, 148-157 Catalytic reactions, adsorbate-induced restructuring to explain properties, 233,237 Cation-anionreactions,ECW model, 189-191 Cationic metal-ligand bonds, bond energy determination, 57 Charge-transfer complexes, Mulliken description of bonding, 176 Chemically activated species with wellcharacterized internal energies kinetic energyreleasedistributions, 41 qualitative potential energy diagrams for H, and CH loss, 43,44^,45 thermochemical properties, 41,43/ Chemically activated systems with facile reverse reaction examples, 45,46/47,48/ kinetic energyreleasedistribution, 45-47 schematic representation of potential energy surface, 47,48/ Chemically modified Mo surfaces, acid properties of Mo(100), 244-247 effective Mo oxidation state, 241-243 hydrogenolysis of methylcyclopropane, 248/249 surface geometry, 241 surface polarizability, 242,244,246/ Chromium complexes, binding to Ν and H, thermodynamic and kinetic studies, 133-146 4

OJML calculation of bond energies, 281/ configuration, 281-282 energies for frontier orbitals, 282/ Classicalreactionsolution calorimetry advantages, 205 limitations, 205 Mo-C bond dissociation, 206-210 Nb-C bond dissociation, 207-210 Clean surfaces,relaxationand reconstruction, 229,232f Co=NH% bond strength, 277 CoNHj, configuration, 276 Cobalt ion-4igand bond energies, correlation to organic bond energies, 2931/ Cobalt-alkyl complexes, macroscopic description of bond dissociation energy determination fromkinetic measurements,101-102 Cobalt-carbon bond energies, use of ECW model, 186-187,188/ Combustion calorimetry, use in determination of thermodynamic properties, 4-5 Competitive collision-induced dissociation determination of bond strengths to ion center, 60,63 spectrum, 60,62f,63 Complex ions, gas-phase thermochemistry, 70-82 Complexes, transition metal, periodic trends in bond energies, 279-290 Coordination, effects on organolanthanide-ligand bond enthalpies, 159-173 Coordinatively unsaturated transition metal complexes, limitations of quantitative data for metal-ligand bond strengths, 195 CpMnCCO)^, metal-ligand bond strengths, 196,198/,20qf Cr , calculation of bond energies, 280/,281 CriCO),, coordination of cis- and transcyclooctene, 199,201/,202f CrfCO)^, plot of observed rate constants vs. cyclooctene concentration, 201,202/ Cr(CO) , enthalpic and kinetic data for substitution with olefins, 199,201/ Cross section, definition, 19 Cyclooctene, coordination to Cr(CO) 199^01/^02/ (CyclopentadienyOjZrCHj* absolute Zr-R bond dissociation enthalpies, 73-74 chemistry, 72 relative CPjZr-R bond energies, 72-73 Cyclopropyl free radical, trapping, 124,126/,128/ 2

6

r

D D , stopped-flow kinetic study of displacement from complex, 136 2


298


ctf-Decalin, fractional cage efficiencies, 118,120/ Density functional theory description, 251 periodic trends in bond energies of transition metal complexes, 270-290 properties characterizing atoms, molecules, radicals, and ions, 251 Desorption rates, measurement, 11 Dimer cleavage enthalpies, use of ECW model, 185-186 Dimethyl metal ions, bond energies, 28-29 Dinuclear hydrocarbon activation, 172 Displacement of Hj, D , and N from complex, stopped-flow kinetic study, 136,141/ Disruption enthalpies, definition, 4 Dynamic lattice model of surfaces adsorbate-induced restructuring, 229,233,234-236/ relaxation and reconstruction at clean surfaces, 229,232/ stepped surfaces, 229


2

2

Ε ECW model of organometallic systems 2:1 base adducts, 188-189 advantages, 179 applications, 178-179 cobalt-carbon bond energies, 186-187,188/ comparison to other acid-base theories, 177-178 Δχνβ. basicity order, 182,183/ dimer cleavage enthalpies, 185-186 donor orders vs. acid, 180,181/ equation, 176 estimation of trends in HOMO-LOMO separation of donor and acceptor, 177 heterogeneous catalysts, 191-193 parameter determination, 176-177 philosophy, 178-179 plots employing reference acids and bases, 179-183 reactions of cations and anions, 189-191 Effective Mo oxidation state MoQdyJ surface binding energies and oxidation states, 241/.242 vs. modifier electronegativity, 242,243/ vs. oxygen coverage, 242,243/ Electrochemical techniques in studying metal-metal bond energies, 8 Electron affinity, definition, 75 Electron attachment to gas-phase metal complexes experimental results, 76,77-78/ free energy ladder for attachment to metal complexes, 76,78/

Electron attachment to gas-phase metal complexes-Continued free energy ladder for attachment to metallocenium ions, 76,77/ heterolytic bond enthalpies, 80,81/ mean bond dissociation enthalpies and differential solvationfreeenergies for metallocenes, 76.79/.80 reaction, 75 thermochemical applications of energies, 76,79/,80,81/ thermochemical cycles for attachment, 76,81/ thermochemistry, 75 Electronegativity, absolute, See Absolute electronegativity Electronic chemical potential, 251 Electrostatic covalent model, qualitative, parameter determination, 176-177 Endothermic ion-molecule reactions bond energy determination, 63-64 error limits, 64 reactions, 63-64 Enediolates, formation, 153 Enthalpy, bond, See Bond enthalpy Enthalpy of atomization, definition, 3 Enthalpy of coordinate bond formation, equation, 176 Equilibrium bond dissociation energy, definition, 3 Equilibrium measurements bond dissociation energy determination, 106-107 Fourier transform MS gas-phase ligand binding energies, 60,61/ ion abundances vs.time,58,59/,60 reaction, 58 Equilibrium techniques, use in studying metal-ligand bonding energetics, 7 Ethylene hydrogénation, use of adsorbate-induced restructuring to study, 237 molecular structure before and after thermal decomposition, 220,223/ stepwise decomposition on flat and stepped surfaces, 220,225/ Exothermic ion-molecule reactions bond strengths, 56 canonic and neutral metal-ligand bond energy determination, 57 multiply charged metal ion bond energy determination, 57-58 rate, 56 relative and absolute metal-ligand bond energy determination, 57 Exothermic reactions, use in studying metal-ligand bond enthalpies, 9-10


INDEX


F First-row transition metal ions, gas-phase chemistry with nitrogen-containing compounds, 267-277 Flowing afterglow techniques, use in studying ion-molecule reactions, 10 Fourier transform MS gas-phase thermochemistry of organometallic and coordination complex ions, 71-81 methods for determining metal-ligand and metal-metal bond energies, 55-67 organometallic reaction energetics, 35 Fractional cage efficiency cis-decalin, 118,120/ definition, 115 temperature dependence, 115 Fractional number of electrons transferred between two molecules correlation with π bonding, 255-256 determination, 252 values for bonding in metal carbonyls, 254255/256 values for electron transfer in reaction of olefins with low-spin Ni atoms, 253 Free radical recombination, effect of cage pair intermediates on activation parameters, 115-116 Free radical self-termination calculated activation entropy vs. reciprocal temperature, 121,125/ temperature dependence, 121-122 Free radical trapping reactions activation parameters, 123-126 fractional cage efficiency, 123-124 schematicrepresentation,122-123 trapping of cyclopropylmethyl free radical, 124,126/,128/ trapping of 5-hexenyl radical, 124,125/ Frontier orbital energies, definition, 252 Frontier orbital theory, 252

G Gas-phase chemistry offirst-rowtransition metal ions with nitrogen-containing compounds, 267-277 Gas-phase metal complexes, electron attachment, 75-81 Gas-phase techniques, use in studying metal-ligand bond energies, 8-9 Gas-phase thermochemistry of organometallic and coordination complex ions chemistry of (cyclopentadienyOjZrCH,*, 71 description of Fourier transform ion cyclotron resonance MS, 71-72

Gas-phase thermochemistry of organometallic and coordination complex ions-Continued electron attachment to gas-phase metal complexes, 75-81 entropy effects, 80 experimental procedure, 71-72 Guided ion beam MS apparatus, 18-19 chemical systems for measurement of metal-ligand bond energies, 1920/ conversion of intensities to cross sections, 19 data analysis, 20-21 future developments, 32

H Halogen(s) experimental and calculated bond dissociation energies for diatomic, 87,89/ experimental ionization correlation diagram, 87,88/ relationship between bond energy and ionization energy, 87,89 Halogen acids experimental and calculated dissociation energies, 89,90/,91 relationship between bond energy and ionization energy, 89-91 Hard and soft acids and bases, 251 Hardness definition, 251 experimental values for molecules, 252 local values, 252 values for anionic bases, 258/259-260 values for electron transfer in reaction of olefins with low-spin Ni atoms, 253254/ Hard-soft acid-base (HSAB) principle, 256 Hartree-Fock-Slater local exchange expression, gradient correction, 279 Heat flux calorimetry, use in determination of thermodynamic properties, 6 Heterogeneous catalysts, use of ECW model, 191-193 5-Hexenyl radical,freeradical trapping, 124,125/ Homolytic transition metal-alkyl bond dissociation, olefin formation, 108,109-110/ Hydrogen binding to ( P R ^ C O ) , , 135-139 binding to transition metals, periodic trends, 18-32 enthalpies of binding, 144-145



300

Hydrogen-Continued entropies of binding, 144-145 formation of stable complexes with transition metals, 133-134 kinetics of reaction with [P(C H ) ] W(CO),(py), 145,146/ reaction profile for oxidative addition, 145,146/147 stopped-flow kinetic study of displacement from [Ρ(0 Η ),]^(^>),(Ι.), 136,141 thermal desorption on flat, stepped, and kinked surfaces, 220,225/ Hydrogen molecule bond order approximation, 85-86 molecular bond dissociation and ionization diagram, 85,88/" relationship between bond energy and ionization energy, 85-87 Hydrogen-deuterium exchange, effect of flat vs. stepped surfaces on reaction probability, 220,226,227/ Hydrogénation of CO by Rh(II) porphyrins, 148-157 6

n 3 2


6

η

I Ion cyclotron resonance MS equilibrium measurements, 58-61 metal-ligand bond energies, 8-9 organometallic reaction energetics, 35 Ionization energy examples of use in thermodynamic cycles, 84-85 relationships to bond energy correlation diagram of calculated vs. measured bond dissociation energies, 91-92,93/ equation, 91 general relationships, 91,92/,93/ halogen(s), 87,88/89/ halogen acids, 89,90/,91 hydrogen molecule, 85-87,88/ measured and calculated bond dissociation energies for diatomics, 91,92/ multiple bonds, 92,93/94/ organometallics, 95-97 salts, 91 Ion-molecule gas-phase techniques, use in studying metal-ligand bond energies, 9

Κ Kinetic energy of ion, influencing factors, 63 Kinetic energy release distribution analysis application, 36

Kineticenergy release distribution analysis-Continued complex reactions, 39 hypothetical reaction surfaces, 36,38/ practical considerations in calculations, 41 simple bond cleavage, 36 type I surfaces using phase space theory, 39-40 Kinetic energy release measurements, description, 35 Kinetic measurements, bond dissociation energy determination, 101-105 Kinetic techniques, use in studying metal-ligand bonding energetics, 7-8 Kinetics of binding Ν and Η to complexes of Cr, Mo, and W, 133-146 of transition-metal-alkyl homolytic bond dissociation processes, 100-111 L Laser ionization-Fourier transform MS, advantages for study of gas-phaseion-molecule reactions, 55 LCo(CO) calculation of bond energies, 281-282,283/ configuration, 283 energies for frontier orbitals, 282f LSD/NL computational details, 280 metal-ligand bond strengths in C1 ML and LCo(CO) systems, 281/,282£283/ metal-metal bond strength of Cr , Mo , and W ,280/^81 relative strengths of metal-hydrogen and metal-methyl bonds, 28334/28536/ thermal stability and kinetic lability of metal-carbonyl bond, 286-290 4

3

4

2

2

2

M Manganese carbonyl ions bond dissociation energies, 47,49/ kinetic energy release distributions for CO loss, 49,50/ quantitative studies, 47,49/,5Qf unimolecular decomposition rate constants, 49,5Qf Mass spectrometric appearance potential method, use in studying metal-ligand bond energies, 10-11 Mass spectrometric techniques, developments for study of low-pressure gas-phase reactions of ionic species, 263


301


INDEX Mean bond dissociation energy, definition, 3-4 (MejC^jLn thermochemistry bond disruption enthalpies, 161,163/, 164 bond enthalpies for mono- vs. trihalides, 164,166/ bond enthalpies for mono- vs. triiodides, 164,165/ enthalpies for iodides, 161,162/ iodide formation reaction, 161 Metal(s) effects on organolanthanide-ligand bond enthalpies alkoxide-hgand bond enthalpies, 168-170 alkyne-ligand bond enthalpies, 169 allyl-ligand bond enthalpies, 169,170/ amide-ligand bond enthalpies, 169 comparison to actinide and group 4 complex bond enthalpies, 171 effect of size on reactivity, 164 experimental materials, 160-161 implications for trivalent organoeuropium chemistry, 171-172 thermodynamic anchor points, 161-166 surface structure, 239-240 See also entries under Transition metal Metal carbonyls, bonding, 254255/ Metal hydride ions, bond energies, 2425/ Metal hydride neutrals, bond energies, 2426/27/ Metal methylidene ions, bond energies, 28-29 Metal methyl ions and neutrals, bond energies, 28 Metal surface, modification of geometric and electronic structure, 240 Metal-alkyl bond energies, 283284/285286/ Metal-alkyl radical combination reactions, rate constants, 103,104/ Metal-carbon bond dissociation enthalpies from classical and nonclassical calorimetric studies, 205-216 Metal-carbonyl bond calculated bond energies, 287288/ CO dissociation energy, 289/290 mean bond energies, 287/289 orbital configurations, 286-289 thermal stability and kinetic lability, 286-290 Metal-hydrogen bond dissociation enthalpies from classical and nonclassical calorimetric studies, 205-216 energies, 283-286 order of bond strength, 261 role of electronegativity in covalent bonding, 260-261 Metal-ligand bond determination of bond enthalpy term, 208-209

Metal-ligand bonàr-Continued dissociation energies in CpMnCCO)^ and Cr(CO),(olefin) complexes bond strengths in CpMn(CO),L, 196,198/200/" coordination of cis- and /ra/u-cyclooctene toCr(CO) ,199201/202/^ energy diagram for photochemical CO substitution, 195-196,197/ enthalpies of reactions, 196 experimental procedure, 195 plot of photoacoustic data for photolysis, 196,197/ relative energies from equilibrium studies, 198-19920(y size of Mn-heptane interaction, 203 van't Hoff plot of equilibrium data, 19920QT energies determined with FTMS, 55-68 dimethyl metal ions, 28-29 future developments, 32 ion bonds, 2425/ metal hydride neutrals, 2426/27/ metal methylidyne ions, 29 metal methyl ions and neutrals, 28 multiple, 28 related to bond order, 2930-31/ Metal-ligand bond strengths in CpMnCCO)^ enthalpic and kinetic data, 196,198/ plot of observed rate constant vs. ligand concentration, 198200/" reaction, 196 Metal-metal bond energies, determined with FTMS, 55-68 Metal-metal radical combination reactions, rate constants, 103,104/ Metal-methyl bonds bond energies, 283284/285286/ orbital configuration, 285 Metallocenes, mean bond dissociation enthalpies and differential solvation free energies, 76,79/,80 Metalloformyl complexes formation criteria, 151,153 thermodynamic values, 151 ^-Metalloformyl species, formation criteria, 151 Methylcyclopropane hydrogenolysis acid function on catalyst, 249 experimental conditions, 249 turnover frequency vs. oxygen coverage, 248/249 Methylsilanes, silicon-hydrogen bond dissociation enthalpies, 210-211212-213/ Mn(CO) ., relationship between bond energy and ionization energy, 95-97 5

5



302

Mo , calculation of bond energies, 280/31 Molybdenum complexes, binding to Ν and H, thermodynamic and kinetic studies, 133-146 Molybdenum surfaces, chemically modified acid properties of Mo( 100), 244/3536-247/ effective Mo oxidation state, 241/3233/ hydrogenolysis of methylcyclopropane, 24^249 surface geometry, 241 surface polarizability, 242,244,246/ Molybdenum-carbon bonddissociation enthalpies effect of size of n-alkyl chain, 206-210 measurement, 207-208 values, 209/30 M-R bond disruption enthalpy, definition, 4 Multiple metal-ligand bonds, bond energies, 28 Multiple transition state coupling by dynamical constraints effect on kinetic energy release distributions, 51,52/53 schematic representation of potential energy surface, 52/^3 Multiply charged metal ions bond energy determination, 58 reaction with methane, 57-58


2

Ν Neutral metal-ligand bonds, bond energy determination, 57 NH, relative energies, 26839/ NHj, relative energies, 26839f NH,, orbital energy diagram, 25337/ Niobium-carbon bond dissociation enthalpies formation enthalpies of bis(cyclopentadienyl) metal complexes, 207,208/ measurement, 207-208 values, 209/30 Nitrogen binding to (PR^M(CO) , 134-140 binding to transition metals, periodic trends, 18-32 enthalpies of binding, 144-145 entropies of binding, 144-145 experimental and calculated bond dissociation energies, 94/ experimental ionization energy correlation diagram, 92,93/94 π orbitals, 25637/ relationship between bond energy and ionization energy, 92,94 s

Nitrogen-Continued relative energies, 26839/ stopped-flow kinetic study of displacement from [P(C H UW(CO),(L), 136,141/ Nitrogenfixation,key molecules, 134 Nitrogen-containing compounds, gas-phase chemistry withfirst-rowtransition metal ions, 263-277 NO, chemistry with transition metal ions, 265-266 Nonclassical reaction solution calorimetry advantage, 206 description, 205-206 silicon-hydrogen bond dissociation enthalpies in methyl- and silylsilanes, 210-21 1 3 2 / 3 3 silicon-hydrogen bond dissociation enthalpies in phenylsilanes, 213,214/35 Nonpolar organic compounds, reaction with transition metal ions, 264 t

n

Ο Olefins electron transfer in reaction with low-spin Ni atoms, 25334/ formation accompanying homolytic transition metal-alkyl bond dissociation, 108,109-110/ One-electron redox sequences, description, 5-6 Organolanthanide-ligand bond enthalpies, metal and ancillary coordination effects, 160-172 Organolanthanide-ligand complexes, development, 159 Organometallic compounds determination of ionization energy of Mn(CO),-, 95-96 development of thermodynamics, 2-3 gas-phase thermochemistry, 70-81 relationship between bond energy and ionization energy, 95-97 Organometallic chemistry, development, 1-2 Organometallic reaction(s), development and application of techniques for gas-phase studies, 34-35 Organometallic reaction energetics diagram of reaction coordinate, 35,37/ experimental techniques, 35 product kinetic energy release distributions analysis, 36,38-41 chemically activated species, 41-45 chemically activated systems with facile reverse reaction, 45-48


INDEX

303


Organometallic reaction energetics-Con/maed effect of multiple transition state coupling, 51,52^53 expérimental methods, 36 future measurements, 53 quantitative studies of ions formed with broad range of internal energies, 47,49/^QT role of excited electronic states, 51 schematic representation of apparatus, 36,37/ thermochemical properties of neutrals, 49,51 Organometallic systems, ECW approach, 175-193 Organometallic thermochemistry, progress in characterization, 18

Ρ π bonding correlation with fractional number of electrons transferred, 255-256 π* orbitals of CO and N ,256257/ Palladium, orbital energy diagram, 253257/ [P(C H ) ] M(CO) complexes, equilibrium measurements for N and binding, 135-140 [PCC^UWCCO), absolute bond strengths, 142,144 enthalpies of ligand binding, 135,137/ relative bond strengths of ligand addition, 142,144 [P(C H )J W(CO) (py), kinetics of reaction withHj, 145,146/ [ P i q H J J W(CO) (N ), stopped-flow kinetic study of Hj, D , and N displacement, 136,141/ Periodic trends in bond energies of transition metal complexes, 279-289 in transition metal bonds, 18-32 Phase space theory analysis of kinetic energy release distri butions for type I surfaces, 39-40 fraction of ions decomposing in the second field-free region, 39-40 Phenylsilanes, silicon-hydrogen bond dissociation enthalpies, 213214/215 Phenylthiyl radical activation parameters for diffusive separation and combination of collisional cage pairs, 118,120/ free radical self-termination, 121-122,125/ radiation boundary model, 117-118,119/.120/ 2

6

n

3

2

3

2

6

n

2

3

2

3

2

2

2

Photochemical cage pairs, chemical model, 116-117 Photodissociation bond dissociation energy determination, 64-65,66-67/ reaction, 64 techniques in studying metal-ligand bond enthalpies, 10 Platinum, crystal faces, 220224/" Polar organic compounds chemistry of alkyl cyanides with transition metal ions, 265 chemistry of amines with transition metal ions, 266-267 chemistry of nitroalkanes with transition metal ion, 265-266 mechanism for reaction with transition metal ions, 264 reaction with transition metal ions, 264 Porphyrins, rhodium(II), thermodynamic studies of hydrogénation and reductive coupling of CO, 148-157 (PR^jMCCO),, preparation, 134 Promotion energy, definition, 24 Proton bracketing, canonic and neutral metal-ligand bond energy, 57 Pulsed, time-resolved photoacoustic calorimetry, use in determination of thermodynamic properties, 6-7

R Radiation boundary model cage combination efficiency, 117-118 models for phenylthiyl cage pairs, 118,119/ Reaction energetics, determinedfromproduct kinetic energy release distributions, 34-54 Reductive coupling of CO by Rh(II) porphyrins, 148-157 Relative M-R bond disruption enthalpies, definition, 5 Restructuring of surfaces, adsorbate-induced carbon-induced restructuring of Ni, 229 catalytic reactions, 233237 dynamic lattice model, 229233-236 rigid lattice model, 226229230-231/ sulfur-induced restructuring of Fe, 233 sulfur-induced restructuring of Ir, 233 Reversible bond homolysis, reaction, 122 Rhodium(II) porphyrins, thermodynamic studies of hydrogénation and reductive coupling of CO, 148-157 Rigid lattice model of surfaces insensitivity, 226229 low-energy electron diffraction surface crystallographic determination of surface structure, 229231/



304

Rigid lattice model of surfaces-Continued model of heterogeneous solid surface with different surface sites, 22638/ scanning tunneling microscopic image of graphite-adsorbed layer, 226,230/ Rough surfaces crystal surfaces of platinum, 22034/ decomposition of ethylene, 22035/ effect on probability of H-D exchange, 2203637/ scheme of catalytic reaction that requires turnovers, 22638/ thermal desorption of hydrogen, 220,225/


S Salts, relationship between bond energy and ionization energy, 91 Sc*, relative energies, 26839/ Sc* reaction with NH, energetics, 27435/ exothermicity, 276 relative energies of Sc*, N, NH, and NH , 26839/ *Sc-^IH bond strength, 276 ScN*, 268-272 ScNH*. 272-273 ScNH,*, 273-274 ScNH,*, 274 ScN* calculated properties of states, 270/32 *Δ state,26830 orbital occupancy vs. intemuclear distance, 268,269/ Π state, 268 *Φ state, 270 potential energy curves of states, 27031/ estate, 270 ScNH* Π state, 272 estate, 272-273 Sc*-NH bond strength, 272-273 ScNH,* bond dissociation energy, 274 first excited state configuration, 273 ground-state configuration, 273-274 ScNH,*, geometry, 274 σ donor strength order reversals for Lewis acids, 175-176 scales, 175 Silicon-hydrogen bond dissociation enthalpies in methyl- and silylsilanes carbon-X enthalpies vs. electronegativity ofX,21132/ constancy, 210-213 negligible effect of methyl groups, 210-211 2

2

4

2

2

Silicon-hydrogen bond dissociation enthalpies in methyl- and silylsilancs-Continued silicon-X enthalpies vs. electronegativity of X, 21132/ in phenylsilanes effect of phenyl group, 213 experimental procedure, 213-214 values, 214/35 Silylsilanes, silicon-hydrogen bond dissociation enthalpies, 210-21132-213/ Single metal-ligand bonds, bond energies, 243/ Single-crystal surfaces photography, 2 0 0 3 1 / use in surface science studies, 220 Softness, definition, 251 Solution reaction calorimetry, use in determination of thermodynamic properties, 5-6 Solvent, effect on bond dissociation energies, 105,106/ Stepped surfaces, occurrence, 229 Surface(s) clean, relaxation and reconstruction, 22932/ Mo, chemically modified acid properties of Mo(100), 244-247 effective Mo oxidation state, 241-243 hydrogenolysis of methylcyclopropane, 248/249 surface geometry, 241 surface polarizability, 242,24436/ Surface modification of metals, for physical and chemical effects, 240 Surface polarizability Auger parameter, 242 polarization relaxation energy of substrate, 242 surface relaxation energy vs. oxygen coverage, 244,246/ Surface restructuring, adsorbate-induced, 218-237

Τ Tandem MS, 35 Tetravalent organoactinide complexes, reactions for determination of bond disruption enthalpies, 160 Thermal activation discovery, 220 spectra for chemisorbed hydrocarbons, 22032f Thermochemistry, gas-phase, organometallic and coordination complex ions, 70-82



INDEX

305

Thermodynamics of binding Ν and Η to complexes of Cr, Mo, and W, 133-146 of hydrogénation and reductive coupling of CO by rhodium(II) porphyrins bond energy-thermochemical relationships, 148,149-150t CO reductive coupling, 153-157 reactions, 148 thermodynamic values, 151,152t of organometallic substances, development, 2 of transition-metal-alkyl homolytic bond dissociation processes, 100-111 Tîme-resolved photoacoustic calorimetry, use in determination of enthalpies and quantum yields, 195 Transition metal(s) bonding with H, C, and N, 18-32 complexes, periodic trends in bond energies, 279-290 Transition metal ion(s), first-row gas-phase chemistry with alkyl cyanides, 265 gas-phase chemistry with amines, 266-267 gas-phase chemistry with nitroalkanes, 265-266 reaction of Sc with NH3,267-268 Transition metal ion-ligand bonds, dissociation energies, 21,22-23t Transition metal-alkyl homolytic bond dissociation processes calorimetric measurements, 107-108 comparison of bond dissociation energies determined by different methods, 108t definition of bond dissociation energy, 100

Transition metal-alkyl homolytic bond dissociation processes-Continued equilibrium measurements, 106-107 macroscopic description of bond dissociation energy determination from kinetic measurements, 101-102 microscopic description of bond dissociation energy determination from kinetic measurements, 102-103,104-105/ olefin formation, 108,109-110/ reactions, 100-101 solvent effects, 105,106/ Tungsten complexes, binding to Ν and H, thermody namic and kinetic studies, 133-146 Two-electron redox sequences, description, 5-6

V Vanadium ion-ligand bond energies, correlation to organic bond energies, 29,30/ Very low pressure pyrolysis kinetic techniques, use in studying metal-ligand bond energies, 11

+

W

W , calculation of bond energies, 280/281 WCCOyPiyHj, NMR measurements of kinetic and thermodynamic parameters of interconversion of dihydride and dihyrogen forms, 142,143/,/ 2

Production: BethAnn Pratt-Dewey Indexing: Deborah H. Steiner Acquisition: Cheryl Shanks Elements Typeset by Hot Type Ltd., Washington, DC Printed and Bound by Maple Press, York, PA Paper meets minimum requirements ofAmerican National Standard for Information Sciences-Permanence ofPaperfor Printed Library Materials, ANSI Z39.48-1984 @


Bonding Energetics in Organometallic Compounds

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