Reactive Intermediate Chemistry

1022 INDEX

Cyclopentane-1,3-diyls, ground-state calculations, 996–997

Cyclopentanone

carbon atom deoxygenation, 491–492 carbene formation, 491–492

femtosecond time scale Norrish I intermediate, 914

trimethylene/tetramethylene diradicals, 915–916

Cyclopentanylidene, carbon atom deoxygenation, 491–492

Cyclopentene, carbon atom reactions, 475–477 Cyclophane diarylcarbenes, preequilibrium

mechanism, 396

Cyclophane diphenylcarbenes, laser flash photolysis, 412–413

1,2-d2-Cyclopropane, femtosecond time scale, reaction dynamics, 900–902

Cyclopropanation

carbene synthesis, diazo compounds, 573–575

Fischer-type carbenes, 579–580 metal carbene synthesis, 567

ring opening stereochemistry, 989–997 stable singlet carbenes, 350–354

Cyclopropane

bond angle deformation, 724–725 electronic spectra, 736

femtosecond time scale, trimethylene/ tetramethylene diradicals, 915–916

NMR spectra, 736 organic radical ions

nucleophilic capture, 257–259

protic, ionic, and polar solvents, 251–256 strained ring cations, 221–228

ring opening, double bond additions, 431–434

singlet carbenes philicity, addition, 285

stepwise addition vs. concerted reaction, 294–297

stereomutation, 989–992

strained hydrocarbon reactivity, 733–735 Cyclopropenation, carbene synthesis, diazo

compounds, 573–575 Cyclopropene

carbon-alkene reactions, 474 cycloaddition reactions, 733 dimerization, 731–732

Cyclopropenylsilylene, silylene isomerization, 666–668

Cyclopropyl carbanions, stereochemistry and racemization, 73–74

Cyclopropylcarbene carbene mimics, 310–314

stepwise addition vs. concerted reaction, 297 Cyclopropylcarbinyl radical

homolytic fragmentation, 151–153 nonclassical structure, 11–12

Cyclopropylfluorocarbene, intramolecular reactions, 305–306

Cyclopropylidene

carbon-alkene reactions, 473–477 steric effects, 382

Cyclopropyl radical, structure, 122 Cycloreversion, radical cations, 237–239 Cyclotetrasilanes, metal-induced a-elimination

reactions, 658–660 Cyclotrigermanes, cyclotrisilanes/

cyclotrigermanes, 656–657 Cyclotrisilanes

metal-induced a-elimination reactions, 658–660 single bond silylene insertions, 673–675 thermolysis and photolysis, 656–657

Cytostatics enediynes, 742

p-benzyne, 754–759 future research, 785

D2SO4 cyclopropane cleavage, 734–735

Data acquisition and processing, nanosecond laser flash photolysis, 851–852

De Broglie wavelength, femtosecond laser pulses, 905–906

Debromination, plumbylene compounds, 701–705

Decay kinetics, nanosecond laser flash photolysis, 869

Decay rate constants, triplet carbenes, TRIR UV-vis (TRUV-Vis) spectroscopy, 394

Dechlorination, germylene synthesis, 695–696 Deep tunneling, elevated temperatures,

421–422 Dehalogenation

dialkylsilylene synthesis and isolation, 684–687

matrix isolation, 825

4-Dehydroanilium ion, distonic structure, 232

1,4-Dehydrobenzene, femtosecond time scale, 910–911

Dehydrohalogenation, matrix isolation, 825 Dehydropyridinium, carbon atom reactivity, 484 Delocalization

cubyl cation formation, 985–987 triplet polynuclear aromatic carbenes,

448–449

EST values, triplet carbenes electronic effects, 379–380

reaction/generation mechanisms, 383–384 singlet-triplet energy gap, 377

steric effects, 379, 381–383

E values, singlet carbenes, philicity of additions, 283–285

GST values, triplet carbenes

hydrogen abstraction, laser flash photolysis (LFP), 412–413

singlet-triplet energy gap, preequilibrium mechanism, 305–400

ms region, non-Kekule´ molecules, zero-field splitting, 172–173

Density functional theory (DFT) o-benzyne, substituent effects, 759–760 p-benzyne, 755–759

carbon acidity-carbanion basicity, sp3 carbanions, hybridized C–H bonds, 80–86

electronic structure calculations, 967 wave function calculations, 977–979

hetarynes, 781–782

N-heterocyclic carbenes (NHC), 360–362 matrix isolation, infrared spectroscopy,

833–836 m-benzynes, 749–752

substituent effects, 761–762 nitrenium ion classification, 594–595

aryland heteroarylnitrenium ions, 606–611 infrared/Raman spectra, 636–638

organic radical ions, 261–262

singlet carbenes, philicity of additions, 283–285 triplet carbenes, singlet-triplet energy gap,

solvent effects, 401–402 wave function calculations

comparisons with, 979–981 functionals, 979

Deoxygenation

benzene-carbon atom reactivity, 482–484 carbon atom reactivity, 486–492

alcohols and ethers, 486–488

carbene formation from carbonyl compounds, 470, 488–492

carbon-alkene reactions, 475 nitrosobenzene, phenylnitrene from, 492

Deoxyguanosine, nitrenium ions, DNA damaging mechanisms, 641–644

2-Deoxyxylolactone, carbene insertion reactions,

577 Deprotonation reactions

matrix isolation, 824

nitrenium ions, photochemical initiation, 616–618

INDEX 1023

stable singlet carbenes

p-electron-donating heteroatom substituents (D-C-D), 338–340

single electronically active heteroatomic substituents, 346–347

tertiary amine radical cations, 259 Destabilization patterns, carbon acidity-carbanion

basicity, sp3 carbanions, hybridized C–H bonds, 83–86

Desulfurization, carbon-lone pair reactions, 493 Detection system

nanosecond laser flash photolysis, 850–852 picosecond lasers, 876–878

Deuteration

singlet carbenes, intramolecular insertion reaction, 306

stable singlet carbenes, cyclopropanation, 351– 354

triplet carbenes, hydrogen abstraction, product studies, 404–405

(E)-b-Deutero-a-methylstyrene, double bond additions, 431–434

Deuterium complexes, singlet carbenes, carbon– hydrogen insertions, 299–302

Deuterium isotope effects carbon-alkene reactions, 474 hydrogen tunneling, 417–421 triplet carbenes

abstraction-recombination insertion, 404 excited state reactivity, 438–439

b-Deuterium isotope effect, isotopic perturbation, 12–13

Deuterium-substituted reactants, femtosecond time scale, 922

DFT-MRCI technique, matrix isolation, 838 Diacetoxyiodobenzene, metal nitrenes, organic

synthesis, 583–586 Diacylperoxide

matrix isolation, 817–818

radical initiation, thermolysis, 140–142 Diadamantylcarbene

steric effects, 382

laser flash photolysis, 429 Diadamantylsilylene, silylene multiple

bond addition acetylenes, 675–677 olefins and dienes, 677–680

Diagnostic reagents, triplet carbenes, hydrogen atom tunneling, 415–416

Dialkylcarbenes, singlet carbene addition, carbene mimics, 312–314

Dialkylgermylenes, stable, synthesis, 691–692 Dialkylplumbylene, 700–705

1024 INDEX

Dialkylsilylene, synthesis and isolation, 684–687 Dialkylstannylene, 696–699

Diaminocarbenes

dimerization reactions, 349–350

stable singlet carbenes, Lewis acids and bases reactions, 355–358

stable singlet carbene, 334–335 Diaminoplumbylene, 699–705 Dianthryl(9-anthryl) carbene

triplet polynuclear aromatic carbenes, 448–449 ultraviolet-visible spectroscopy, 391

Diarylcarbene

structural chemistry, 522

triplet polynuclear aromatic carbenes, 448–449 Diarylgermanes

metal-induced a-elimination reactions, 659–660 photolysis, 655–656

Diarylgermanone, 695–696 Diarylgermylenes

kinetic stabilization, 695–696 stable, synthesis, 692–694

2,5-Diaryl-1,5-hexadiene, radical cation, 245–246 1,1-Diarylmethylenecyclopropane, radical cation,

245–246

Diarylmethyl cations, carbocation reactivity, nucleophilic additions, 26–28

Diarylnitrenium ion, rearrangement/elimination, 620–621

Diarylplumbylene, 700–705

Diarylsilylene, overcrowded, generation and reaction, 687–689

Diarylstannylene, 696–699 Diazabicyclo[2.2.1]hept-2-ene

deazetization, 953–955 diradicals, 916

Diazene, non-Kekule´ molecules, electron spin resonance (ESR), 168

1,1-Diazene, aminonitrenes, 544–547 Diazenium diolates, oxonitrenes, 547 Diazirines

carbene mimics, 308–314 matrix isolation, 815–816

triplet carbene reactions, 383–384 Diazoacetoacetates, metal carbene synthesis, 567 Diazo compounds

carbene synthesis, catalytic methods, 572–579

carbon atom generation, 469 carbene mimics, 308–314 carbonyl compounds

carbonylnitrenes, 513–515 decomposition catalysis, metal carbene

synthesis, 565–567

high-spin polycarbenes, 452

singlet carbenes, carbene mimics, 308–314 stable singlet carbenes

Curtius bis(carbene)-acetylene, 332–334 single electronically active heteroatomic

substituents, 342–347

triplet carbenes, reaction mechanisms, 383–384

matrix isolation, 816

triplet carbene reactions, 383–384 a-Diazo compounds, silylene isomerization,

665–668 Diazomethane

matrix isolation, 815–816

singlet carbenes, stepwise vs. concerted addition, 293–297

Diazosilane, single bond silylene insertions, 674–675

Diazotetrazole, carbon atom generation, 469 Dibenzocycloheptadienylidene

laser flash photolysis, 412–413

tunneling reactions, elevated temperatures, 422

Dibenzofuran radical cations, bimolecular reactions, 254–256

Dibromoplumbanes, 701–705 1,3-Dibromopropane, femtosecond time scale,

908–910 Dibromosilane, 686

Dicarbomethoxycarbenes, stable singlet carbenes, singlet vs. triplet ground state, 332

Dications, nitrenium ion generation, 612–614 spectroscopic analysis, 632

Dichloroarylgermanes, photolysis and thermolysis, 657

Dichlorocarbene

addition and insertion reactions, 274 carbon atom deoxygenation, 490–492

singlet carbenes, carbon–hydrogen insertions, 300–302

stepwise vs. concerted reactions, 295–297 Dichlorodiarylsilanes, photolysis and thermolysis,

656–657 Dicyclopentadienyllead(II) compounds,

699–705

9,10-Didehydroanthracene, p-benzyne, 755–759 Didehydroazepine

fluoro-substituted phenylnitrenees, 536–538 phenylnitrene computational chemistry,

527–528

Didehydroindenes, cytostatic analysis, 769–773 Didehydrophenyl cations, hetarynes, 777–782 Didehydrotoluene biradical, 771–773

Diels-Alder reactions. See also Retro-Diels-Alder reactions

alkenes, trimethylene-methane (TMM) derivatives, 180

organic radical ions, bimolecular reactions, 249–250

Dienes, silylene reactions, 677–680 1,3-Dienes

germylene multiple bond additions, 683 silylene thermal elimination, 654

Difference spectra, matrix isolation, 830, 831–832 Differential activation parameters, triplet carbenes

hydrogen atom transfer, 421–422 tunneling reactions, elevated temperatures,

421–422

Diffraction images, femtosecond time scale, structural determinations, 919–920

Diffuse basis function, LCAO-MO approximation, 972–973

Diffuse reflectance, nanosecond laser flash photolysis, 868

Diffusional rate constant, radical structures, termination, 157

Diffusion controlled rate, triplet carbenes excited state spectroscopy, 435–436 laser flash photolysis, 427–429 preequilibrium mechanism, 395

Diffusion limit

carbocation reactivity, nucleophilic addition, 26–28

nucleophilic substitution, azide ion at benzylic carbon, liberated reaction intermediate ionization and trapping, 50

Difluorocarbene, singlet carbenes, 278–279 1,1-Difluorocyclopropane, stereochemistry,

992–994 2,2-Difluoropropane-1,3-diyl, ground-state

calculations, 996–997 Difluorovinylidene, singlet carbenes, philicity of

addition, 283–285 1,2-Digermacyclobutane, germylene multiple

bond addition, 680 Digermadithiolanes, germylene multiple bond

additions, 683 Digermanes, photolysis, 655–656 Digermene dissociation, 693–694

Dihydroxylation, nitrenium ion, 623–624 a-Diimines, germylene multiple bond additions,

683 a-Diketones

germylene multiple bond additions, 683 silylene multiple bond additions, 682–683

Dimeric structures

INDEX 1025

cleavage mechanism, unimolecular reactions, 239

persistent triplet carbenes, 440–441 p-dimer radical cations, 247 s-dimer radical cations, 247

Dimerization

persistent triplet carbenes, 440–441 stable singlet carbenes

reactivity and mechanisms, 347–350 single electronically active heteroatomic

substituents, 341–347 strained hydrocarbons, 731–732

Dimesitylcarbene

dimesitylketone oxide, 425–426 excited state spectroscopy, 437–438 persistent triplet carbenes, 440–441 preequilibrium mechanism, 396

triplet diphenylcation protection, 443–444 Dimesityldioxirane, matrix isolation studies, 426 2,2-Dimesitylhexamethyltrisalne, single bond

silylene insertions, 672–673 Dimesitylketone oxide, triplet carbene reactions,

425–426

Dimesitylsilanone-epoxide adducts, single bond silylene insertions, 672–673

Dimesitylsilylenes, matrix-isolated structures, 663–665

Dimethoxycarbene, nucleophilicity, 283–285 1,2-Dimethoxy-1,1,2,2-tetramethyldisilane, silylene multiple bond addition,

675–677

Dimethylacetylene, silylene multiple bond addition, 675–677

1,3-Dimethylbenzotriazolium ion, DNA damaging reactions, 610–611

2,3-Dimethyl-1,3-butadiene

germylene multiple bond addition, 680 silylene-isonitrile complexes, 690–691 silylene multiple bond addition, olefins and

dienes, 677–680

2,3-Dimethylbutane (DMB), phosphorylnitrene, 518–520

2,3-Dimethyl-1-butene, bimolecular reactions,

247 Dimethylcarbene

carbene mimics, 308–314 intramolecular insertion reaction, 306

1,1-Dimethylcyclopropane, singlet carbenes, carbene mimics, 308–314

Dimethyldiazirine, carbene mimics, 309–314 5,5-Dimethyl-2,3-dimethylene-1,3-

cyclopentanediyl, singlet-triplet separation, 184

1026 INDEX

2,4-Dimethylenecyclobutane diyl, non-Kekule´ molecules, electron spin resonance (ESR), 170

2,3-Dimethylene-1,3-cyclohexadiene singlet-triplet separation, 184 triplet ground state, 183

1,8-Dimethylenenaphthalene, electron spin resonance (ESR), 170

Dimethylgermylene, single bond insertions, 670–671

2,5-Dimethyl-2,3,4-hexatriene, germylene multiple bond addition, 680

2,2-Dimethyl-1-oxa-2-silacyclopentane, single bond silylene insertions, 671–673 1,2-Dimethyl-3-phenylcyclopropane, radical

cation reactions, 251 2,6-Dimethylphenylnitrene

azirine cyclization, 535–536 intersystem crossing, 534

1,1-Dimethyl-2-phenyl-3-trimethylsilyl-1- silacyclopropene, silylene multiple bond addition, 675–677

Dimethylsilanone, single bond silylene insertions, 671–673

Dimethylsilylene, polysilane/oligosilane generation, 654–655

1,2-Dimethylspiropentanes, stereomutation calculations, 995–996

Dimethylsulfoxide (DMSO), carbon aciditycarbanion basicity, condensed-phase measurements, 87–90

gas phase vs., 93–94 ion-pair acidities, 91–93

Dinaphthl(1-naphthyl)carbene

triplet polynuclear aromatic carbenes, 448–449

ultraviolet-visible spectroscopy, 390–391 1,3-Dioxa-2-silacyclopentane-4-enes, silylene

multiple bond additions, 682–683 Dioxasilirane, electronic spectra, 664–665 Dioxirane structures, matrix isolation studies,

424–425

(Dip2Si)C60, silylene multiple bond addition, 679–680

Diphenoxyphosphorylnitrene, electron spin resonance (EPR) spectra, 519–520

Diphenylacetylene (DPA), picosecond spectroscopy, 890–891 1-(N,N-Diphenylamino)pyridinium ion,

photochemical initiation, 617–618 1,4-Diphenyl-1,3-butadiene (DPB), picosecond

spectroscopy, 888–889 Diphenylcarbenes (DPC)

alkyl protection, 441–444 double bond additions, 431–434

ESR, zero-field splitting, 385–388 excited states, 435

product studies, 434–435 spectroscopic analysis, 435–437

triplet/excited reactivity differences, 438–439 fluorescence spectroscopy, 391

halogen protection, 444–447 hydrogen abstraction

hydrogen atom tunneling, 414–416 laser flash photolysis (LFP), 408–413 product studies, 403–405

hydrogen atom transfer kinetics, 416–417 laser flash photolysis, 408–409

oxygen reactions, 426–427

laser flash photolysis, 428–429 tetramethylpiperidine N-oxide (TEMPO),

430–431

rates and activation parameters, 285–289 remote substituent effects, 386 singlet-triplet energy gap

preequilibrium mechanism, 395–400 solvent effects, 401–402 surface-crossing mechanism, 400–401

trifluoromethyl protection, 447–448

tunneling reactions, elevated temperatures, 422 ultraviolet-visible (UV-vis) spectroscopy,

390–391

1,2-Diphenylcyclopropane, intra-pair reactions, 242–246

Diphenyldiazomethane (DDM)

excited states, product studies, 434–435 preequilibrium mechanism, 395

1,2-Diphenylethene (stilbene), excited states, 886–887

1,1-Diphenylethylene, organic radical ions, bimolecular reactions, 246–250

Diphenylfulvene, distonic radical anions, 231–234

1,6-Diphenyl-1,3,5-hexatriene (DPH), picosecond spectroscopy, 889–890

1,3-Diphenyl imidazolidin-2-ylidenes, stable singlet carbene, 334–335

Diphenylmethyl cation

laser flash photolysis, 408–409 protic solvent lifetimes, 21

Diphenylmethyl radicals fluorescence spectroscopy, 391 triplet carbenes, ultraviolet-visible

spectroscopy, 390–391 Diphenylnitrenium ion, time-resolved infrared

spectra, 636–638

N,N-Diphenylnitrenium ion, singlet-state reactions, p nucleophiles, 625–628

Diphenylsilylenes, thermal elimination, 653–654 2,3-Diphenyltetrasilane, silylene multiple bond

addition, 676–677 Diplumbene, 702–705

Dirac ‘‘ket,’’ wave function calculations, Hartree-Fock calculations, 969–970

1,3-Diradicals, hyperconjugation reaction, cyclopropane ring opening stereochemistry, 989–997

Diradical compounds femtosecond time scale

Norrish I intermediate, 912–914 oxyalkyl diradical, 917 retro-Diels-Alder reactions, 918 trimethylene/tetramethylene, 915–916

trimethylene, femtosecond time scale, 901–902

Direct dynamics calculations cyclopropane stereochemistry, 992 femtosecond time scale, trimethylene/

tetramethylene diradicals, 916 Direct observation

nitrenium ion detection, 638–640 non-Kekule´ molecules, 171

organic radical ion detection-identification, 213–214

triplet carbenes, 384–385

Direct photolysis, triplet carbenes, 433 Discrete intermediate, nucleophilic substitution,

azide ion at benzylic carbon, cumyl derivatives (X-2-Y) borderline reactions, 55–57

Disilacyclohexadiene, silylene multiple bond addition, 675–677

Disilanylsilylene, branched cyclic silylsilanes, 657–658

Disilaoxetane, 684–687

Disilenes, thermal dissociation, 687–689 1,1-Disilylcyclopropanes, stereomutation

calculations, 994–995 Disjoint biradicals

non-Kekule´ molecules, parity-based predictions, 192–194

tetramethyleneethane, 182–183 Disproportionation

organic radical ions, like charge reactions, 260–261

radical termination reactions, 156–157 Disrotation

cyclopentane-1,3-diyl ground state calculations, 997

INDEX 1027

cyclopropane stereochemistry, 990–997 1,1-difluorocyclopropane, 993–994 1,2-dimethylspiropentanes stereomutation,

996

Dissociation energies, overcrowded diarylsilylenes, 687–689

Distannene, 694 Distonic radical ions

bimolecular reactions, 242 intra-pair reactions, 240–246 structural analysis, 229–234 unimolecular reactions, 239

Distributed feedback dye laser (DFDL), picosecond lasers, infrared absorption spectroscopy, 883–885

Di-tert-butylsilylene, single bond silylene insertions, 674–675

Di-tert-butylthioketene, germylene multiple bond additions, 683

Dithiacarbenes, nucleophilicity, 284 Di(triptycyl)carbene, steric effects, 382 Divalent radicals, structural properties, 123 DNA damaging reactions

arylnitrenium ion mechanisms, 640–644 nitrenium ions, 597–598

aryland heterarylnitrenium ions, addition to bases, 609–611

photochemical initiation, 617–618 spectroscopic analysis, 633–634 ultraviolet-vis spectra, 635–636

DNA radicals

heterolytic fragmentation, 155 photoreactivation, 239

Dodecamethylsilicocene, synthesis and isolation, 684–687

Donor-acceptor complex

single bond silylene insertions, 668 stable ion chemistry, 5–6

Double bond additions (DBA)

carbon atom-alkene reactivity, 473–477 carbon atom-aromatic compound reactivity,

carbon–hydrogen bond insertion, 486 triplet carbenes, 431–434

Double hydrogen abstraction, triplet carbenes basic principles, 403

hydrogen atom tunneling, 415–416 Double methylene rotations

cis isomers, 994

cyclopropane stereochemistry, 991–997 Double rotation mechanism, cyclopropane stereochemistry, 990–997

Double-zeta/triple-zeta basis sets, LCAO-MO approximation, 972–973

1028 INDEX

Doubly excited electron configuration, MP2 calculation, 975

Doubly-linked radical cations, bimolecular reactions, 248–249

Doubly occupied orbitals, triplet carbenes, electronic effects, 378–379

Dowd-Chow mechanism, trimethylene-methane (TMM), ring closure chemistry, 176

Dunning’s correlation-consistent (cc) basis set, electronic structure calculation, 973

Dye lasers, picosecond systems, 878–880 Dynamic correlation

CASSCF/CASPT2 calculations, 977 cubyl cation formation, 985–987

hydrogen abstraction, 988

ring expansion reactions, electronic structure calculations, 983–985

Dynamic Jahn-Teller distortion, strained ring compound radical ions, 221–228

E1cB reaction, carbanion intermediates addition reaction, 101–103 elimination reaction, 97–101

E2 reaction, carbanion intermediate elimination reaction, 97–101

E/D ratio, triplet carbenes

electron paramagnetic resonance spectroscopy, 385–390

zero-field splitting, carbenic substituents, 386

Effective interelectronic distance, non-Kekule´ molecules, electron spin resonance (ESR), 173

Effective magnetic moment, non-Kekule´ molecule magnetic susceptibility, 191–192

Electric discharges, radical ions, matrix isolation, 821–823

Electrochemical oxidation, nitrenium ion generation, 618–619

Electrocyclic ring opening, electronic structure calculations, 983–985

Electromagnetic radiation, reactive intermediates, 814

Electron affinities

carbon acidity-carbanion basicity, 96–97 singlet carbenes

philicity in addition, 283–285 structure and bonding, 274–279 triplet carbenes, hydrogen tunneling,

418–421

Electron correlation calculations Pauli exclusion principle, 968 tetramethyleenethane, 182

wave-function calculations, 973–977 configuration interaction (CI) calculations,

974–977

perturbation theory calculations, 974–975 Electron density, Hohenberg-Kohn/Kohn-Sham

theorems, 978

Electron donation, cyclopropane stereochemistry, 990–997

Electron-donor groups, triplet carbenes, 378–379

Electron-electron repulsion imidogen, 505–506 wave-function calculations, 968

Electron free-spin factor, non-Kekule´ molecule magnetic susceptibility, 192

Electronic absorption

organic radical ions, bifunctional/distonic radical ions, 231–234

p bond homolysis/heterolysis, picosecond spectroscopy, 893–894

Electronic configuration, triplet carbenes, 377–378

Electronic effects, triplet carbenes, 378–379 theoretical predictions, 379–380

Electronic integrity, persistent triplet carbenes, 441 Electronic magnetic moments, chemically induced

dynamic nuclear polarization (CIDNP) effects, triplet carbenes, 406

Electronic multiplicity, non-Kekule´ molecules, 194

Electronic spectra

silylenes and germylenes, 662–665 strained hydrocarbons, 736

Electronic stablization, stable singlet carbenes, singlet vs. triplet ground state, 331–332

Electronic states

nitrenium ions, parent, alkyland halonitrenium ions, 603–606

triplet carbenes, 377–378 Electronic structure

reactive intermediates

basic principles, 962–963 Born-Oppenheimer approximation,

967–968

cubyl cation formation, 985–988 cyclopropane ring opening stereochemistry,

989–997

density functional theory (DFT) calculations, 977–979

enthalpy predictions, 965–966

free energy/isotope effect predictions, 966 geometric predictions, 964–965 qualitative models, 966–967

ring expansion reactions, phenylcarbene, phenylnitrene, and phenylphosphinidene, 982–985

spectra predictions, 964 wave-function calculations, 968–977

DFT calculations vs., 979–980 electron correlation calculations,

973–977

configuration interaction (CI) calculations, 974–977

perturbation theory calculations, 974–975

Hartree-Fock theory, 969–970

linear combination of atomic orbitalsmolecular orbital (LCAO-MO) calculation, 970–973

stable singlet carbenes, transition metal catalysis, 359–362

Electron localization function (ELF) analysis, stable singlet carbene state, p-electron- donating-electron-withdrawing heteroatom substituent (D-C-W), 337–338

Electron nuclear double resonance (ENDOR) spectroscopy

organic radical ions, strained ring cations, 226–228

radical identification/characterization, 131–132 Electron paramagnetic resonance (EPR)

spectroscopy acylnitrenes/carbonylnitrenes, 514–515 azobenzene formation, 517–518 carboethoxynitrene, 516–517 halogen-protected diphenylcarbenes, 445–447 organic radical ions, 1,5-Hexadiene systems,

229 phenylnitrene, 524–525

phosphorylnitrene, 519–520 triplet carbenes

electronic effects, 378–379 excited states, 437–438

hydrogen atom transfer kinetics, 416–417 matrix isolation characterization, 385–390

Electron photodetachment photoelectron spectroscopy, trimethylenemethane (TMM), singlet-triplet separation, 177–179

Electron spin resonance (ESR) 2-methylenecyclopentane,1,3-diyls, 179–181 non-Kekule´ molecules

biradical/radical pairing, 173

Curie’s law, ground-state multiplicity, 174 matrices, 172–174

randomly oriented samples, 168–170 structural properties, 171

INDEX 1029

zero-field splitting, immobilizing media, 172–173

organic radical ions

bifunctional/distonic radical ions, 231–234 chemical properties, 207–209 detection-observation, 212–214

intra-pair reactions, 244–246

like charge radical ion reactions, 259–261 n donors, 218

p-donors, 215–218 s donors, 219–221

strained ring cations, 221–228 pentamethylenepropane (PMP), 193–194 m-quinone derivatives, 187–188

radical compounds, identification/ characterization, 128–131

singlet-triplet equilibrations, 307–308 tetramethylenebenzene (TMB), 186–187 tetramethyleneethane (TME), 181–185

Electron transfer organic radical ions

anionic radical reactions, 257–258 bifunctional/distonic radical ions, 231–234 bimolecular reactions, 249–250

cation reactive intermediates, 236 like charge radical ions, 260–261

protic, ionic, and polar solvents, 255–256 unimolecular reactions, 236–239

radical closed-shell structures, 143–144 radical ion generation, 211

Electron-withdrawing groups (EWGs) carbocation reactivity, 29–30

carbon acidity-carbanion basicity, sp3 carbanions, hybridized C–H bonds, 81–86

nucleophilic additions, carbanion intermediates, alkenes, 101–103

nucleophilic substitution

aromatic substitution, carbanion intermediates, 104

1-phenylethyl derivatives, 44–45 ring-substituted cumyl derivatives, 47–48

stable singlet carbenes p-electron-donating-electron-withdrawing

heteroatom substituent (D-C-W), 335–338 singlet vs. triplet ground state, 331–332

triplet carbenes, 379 preequilibrium mechanism, 397

Electrophiles

carbocation reactivity, carcinogenesis, 33–34 cyclopropane/cyclobutane reactions, 733–735 metal carbene synthesis, 563–564

singlet carbene addition philicity, 279–285

1030 INDEX

Electrophiles (Continued)

reaction rate constants and activation, 287–289

transition state symmetry, 290–291

stable singlet carbenes, dimerization reactions, 347–350

Electrophilicity parameter

carbocation reactivity, Mayr’s scale, 28–29 halogen-protected diphenylcarbenes,

445–447 triplet carbenes

hydrogen tunneling, 418–421 laser flash photolysis, 413

Elimination reactions

carbanion intermediates, 97–101 nitrenium ions, singlet-state elimination,

619–621

radical structures, addition-elimination reactions, 155–156

thermally induced silylene a-elimination and photoextrusion, 652–660

a-Elimination reactions

metal-induced silylene reactions, 658–660 thermally induced silylene a-elimination and

photoextrusion, 652–660 Emission spectroscopy

non-Kekule´ molecules, structural properties, 171

triplet carbenes

excited state, 434–435 oxygen reactions, 426–427

Empty p orbitals, 433–434 Enantioselectivity, carbene synthesis

diazo compounds, 573–575 insertion reactions, 576–577

ring closing metathesis (RCM), 581 Encounter frequency,

2-methylenecyclopentane,1,3-diyls, 182 Enders-type carbene, dimerization reactions, 348–

350

Endo systems, 2-norbornyl cation, 10–12 Enediynes

o-benzynes, 742 p-benzyne, 752–759 hetarynes, 780–782 m-benzynes, 747–752

Energetics

carbon atoms, 465

organic radical ions, research issues, 261–262

Energy conservation, trimethylenemethane (TMM), electron photodetachment photoelectron spectroscopy, 178

Energy dissipation, radical ions, matrix isolation, 822

Energy separation. See also Singlet-triplet separation

Energy transfer, nanosecond laser flash photolysis, 867–868

Enolates, gas-phase carbanion reactions, bimolecular nucleophilic substitution, 110

(–)-Enterolactone, carbene insertion reactions, 577 Enthalpy predictions

electronic structure calculations, 965–966 strain energy experiments, 718–719

Entropy

electronic structure calculations, free energy differences, 966

singlet carbenes

addition rate constants and activation parameters, 288–289

intermolecular insertions, 301–302 intramolecular reactions, 303–306

Epimerization, cis isomers, 994

Epoxides, single bond silylene insertions, 672–673 Equilibrium, isotopic perturbation, 12–13 Equilibrium constants

carbocations, 4

silylenes and germylenes, singlet/triplet ground states, 662

triplet carbenes

preequilibrium mechanism, 397

TRIR UV-vis (TRUV-Vis) spectroscopy, 394 ‘‘Escaped products,’’ triplet carbenes, hydrogen

atom abstraction, 403 Esters, nitrene derivatives, 515–517

Et3B, radical initiation, thermolysis, 142 Ethers

carbon acidity-carbanion basicity, condensedphase measurements, 87–88

carbon atom deoxygenation, 486–488 single bond silylene insertions, 669–671

Ethylene, germylene multiple bond addition, 680 Exchange interaction, tetramethyleneethane,

182–183 Exchange operator

Hartree-Fock calculations, 969–970 wave function calculations, functionals,

978–979

‘‘Exchange repulsion,’’ triplet carbenes, 377–378 Excited states

conjugated pi systems, picosecond lasers, 886–891

diphenylacetylene, 890–891 1,4-diphenyl-1,3-butadiene, 888–889 1,2-diphenylethene (stilbene), 886–887

1,6-diphenyl-1,3,5-hexatriene, 889–890 singlet/triplet carbenes, 320–321

triplet carbenes, 434–439 geometry, 437–438 product studies, 434–435

reactivity differences, 438–439 spectroscopic studies, 435–437

Exo substrates, 2-norbornyl cation, 10–12 Exothermicity properties, singlet carbenes singlet-triplet equilibration, 307–308

stepwise vs. concerted addition, 291–297 Expander, matrix isolation apparatus, 803–804 Extinction coefficients, nanosecond laser flash

photolysis, 865–868

Faraday balances, non-Kekule´ molecules, magnetic properties, 191–192

Favorskii rearrangement, carbanion intermediates, 107–108

Femtosecond laser pulses, uncertainty principle, 905–906

Femtosecond time scale chemical studies, 920–921 coherence, 904–906 reaction dynamics, 900–902

representative dynamics, 906–918 cyclobutanone photolysis, 914 1,4-cyclohexadiene to benzene, 911 1,4-dehydrobenzene, Bergmann

rearrangement, 910–911 1,3-dibromopropane, 908–910 formylalkyl radical intermediates, 917 methyl iodide, 908

Norrish type-1 cleavages, 911–914 oxyalkyl diradical intermediates, 917 retro-Diels-Alder reactions, 917–918 sodium iodide, 906–907 trimethylene/tetramethylene diradicals,

915–916

structural determinations, 919–920 time-resolved femtosecond dynamics,

903–904

Femtosecond transition state spectroscopy (FTS), 902

Fermi-resonances, matrix isolation, 831–832 Ferromagnetic spin alignment, triplet polynuclear

aromatic carbenes, 452 Fingerprint region, infrared absorption

spectroscopy, picosecond lasers, 884–885 First-order kinetics, trimethylene-methane

(TMM), 175–176 Fischer-type carbenes

synthetic versatility, 579–580

INDEX 1031

transition metal complexes carbene synthesis, 567–569 electronic structure, 359–362

Flash photochemistry

femtosecond time scale, 901–902 tetramethylenebenzene (TMB), 187 triplet carbenes, room-temperature, 392

Flash vaccuum pyrolysis (FVP) o-benzynes, 745–747 didhydroindenes, 773 matrix isolation, 818 m-benzynes, 752

phenylcarbene rearrangement, incarcerated carbene chemistry, 315–317

Flow cryostat, matrix isolation, 803–804 Flowing-after glow measurements, carbanion

intermediates, gas phase reactions, bimolecular nucleophilic substitution (SN2), 109–110

Flow systems, nanosecond laser flash photolysis, 869

Fluorene, phenylcarbene rearrangement, incarcerated carbene chemistry, 315–317

9-Fluorenyl cation carbocation reactivity

flash photolytic generation, 19–21 nucleophilic additions, 27–28

laser flash photolysis, 412–413 Fluorenylidene

addition rates and activation parameters, 285– 289

laser flash photolysis, 412–413 singlet carbenes, rates and activation

parameters, 285–289 triplet carbenes

EPR spectroscopy, 385–386

hydrogen abstraction, laser flash photolysis (LFP), 412–413

Fluorescence detected magnetic resonance (FDMR), organic radical ions

bimolecular reactions, 247–250 detection-identification, 213

Fluorescence quenching, triplet carbenes, excited states, 436–437

Fluorescence spectroscopy picosecond systems, 880–881

p bond homolysis/heterolysis, 893–894 streak camera detection, 880 time-correlated single-photon counting,

880–881 triplet carbenes

excited states, 436–437 matrix isolation, 391