Spin States in Biochemistry and Inorganic Chemistry Spin States in Biochemistry and Inorganic Chemistry Influence on Structure and Reactivity Editedby MARCELSWART InstitutdeQu´ımicaComputacionaliCata`lisi&DepartamentdeQu´ımica,UniversitatdeGirona,Spain and Institucio´ CatalanadeRecercaiEstudisAvanc¸ats(ICREA),Barcelona,Spain MIQUELCOSTAS InstitutdeQu´ımicaComputacionaliCata`lisi&DepartamentdeQu´ımica,UniversitatdeGirona,Spain Thiseditionfirstpublished2016 ©2016JohnWiley&Sons,Ltd Registeredoffice JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester,WestSussex,PO198SQ,UnitedKingdom Fordetailsofourglobaleditorialoffices,forcustomerservicesandforinformationabouthowtoapplyforpermissiontoreusethecopyrightmaterialin thisbookpleaseseeourwebsiteatwww.wiley.com. TherightoftheauthortobeidentifiedastheauthorofthisworkhasbeenassertedinaccordancewiththeCopyright,DesignsandPatentsAct1988. 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LibraryofCongressCataloging-in-PublicationData Spinstatesinbiochemistryandinorganicchemistry:influenceonstructureandreactivity/editedbyMarcelSwartandMiquelCostas. pagescm Includesbibliographicalreferencesandindex. ISBN978-1-118-89831-4(cloth) 1.Nuclearspin. 2.Freeradicals(Chemistry) 3.Biochemistry. 4.Chemistry,Inorganic. I.Swart,Marcel,1971–editor. II.CostasSalgueiro, Miquel,editor. QP527.S652016 612′.01524–dc23 2015019422 AcataloguerecordforthisbookisavailablefromtheBritishLibrary. ISBN:9781118898314 CoverImagesuppliedbyMarcelSwart. Setin10/12ptTimesbyAptaraInc.,NewDelhi,India. 1 2016 VoorElviraenPoppy PerlaJudit,laMireiail’Ariadna Contents AbouttheEditors xv ListofContributors xvii Foreword xxi Acknowledgments xxiii 1 GeneralIntroductiontoSpinStates 1 MarcelSwartandMiquelCostas 1.1 Introduction 1 1.2 ExperimentalChemistry:Reactivity,SynthesisandSpectroscopy 2 1.3 ComputationalChemistry:QuantumChemistryandBasisSets 4 References 4 2 ApplicationofDensityFunctionalandDensityFunctionalBasedLigandFieldTheory toSpinStates 7 ClaudeDaul,MatijaZlatar,MajaGruden-Pavlovic´ andMarcelSwart 2.1 Introduction 7 2.2 WhatIstheProblemwithTheory? 9 2.2.1 DensityFunctionalTheory 9 2.2.2 LFTheory:BridgingtheGapBetweenExperimentalandComputational CoordinationChemistry 11 2.3 ValidationandApplicationStudies 15 2.3.1 UseofOPBE,SSB-DandS12gDensityFunctionalsforSpin-StateSplittings 17 2.3.2 ApplicationofLF-DFT 21 2.4 ConcludingRemarks 25 Acknowledgments 26 References 27 3 AbInitioWavefunctionApproachestoSpinStates 35 CarmenSousaandCoendeGraaf 3.1 IntroductionandScope 35 3.2 Wavefunction-BasedMethodsforSpinStates 35 3.2.1 SingleReferenceMethods 36 3.2.2 MultireferenceMethods 37 3.2.3 MRPerturbationTheory 39 3.2.4 VariationalApproaches 40 3.2.5 DensityMatrixRenormalizationGroupTheory 40 3.3 SpinCrossover 41 3.3.1 ChoiceofActiveSpaceandBasisSet 41 viii Contents 3.3.2 TheHS–LSEnergyDifference 43 3.3.3 Light-InducedExcitedSpinStateTrapping(LIESST) 45 3.3.4 SpinCrossoverinOtherMetals 47 3.4 MagneticCoupling 47 3.5 SpinStatesinBiochemicalandBiomimeticSystems 50 3.6 Two-StateReactivity 52 3.7 ConcludingRemarks 52 References 53 4 ExperimentalTechniquesforDeterminingSpinStates 59 CaroleDubocandMarcelloGennari 4.1 Introduction 59 4.2 MagneticMeasurements 61 4.2.1 g-AnisotropyandZero-FieldSplitting(zfs) 64 4.2.2 UnquenchedOrbitalMomentintheGroundState 64 4.2.3 ExchangeInteractions 64 4.2.4 SpinTransitionsandSpinCrossover 66 4.3 EPRSpectroscopy 66 4.4 Mo¨ssbauerSpectroscopy 70 4.5 X-raySpectroscopicTechniques 74 4.6 NMRSpectroscopy 77 4.7 OtherTechniques 80 4.A Appendix 81 4.A.1 TheoreticalBackground 81 4.A.2 ListofSymbols 82 References 82 5 MolecularDiscoveryinSpinCrossover 85 RobertJ.Deeth 5.1 Introduction 85 5.2 TheoreticalBackground 85 5.2.1 SpinTransitionCurves 88 5.2.2 Light-InducedExcitedSpinStateTrapping 89 5.3 ThermalSCOSystems:Fe(II) 90 5.4 SCOinNon-d6Systems 93 5.5 ComputationalMethods 95 5.6 Outlook 98 References 99 6 MultipleSpin-StateScenariosinOrganometallicReactivity 103 WojciechI.Dzik,WesleyBo¨hmerandBasdeBruin 6.1 Introduction 103 6.2 “Spin-Forbidden”ReactionsandTwo-StateReactivity 104 6.3 Spin-StateChangesinTransitionMetalComplexes 107 6.3.1 InfluenceoftheSpinStateontheKineticsofLigandExchange 108 6.3.2 StoichiometricBondMakingandBreakingReactions 109 6.3.3 Spin-StateSituationsInvolvingRedox-ActiveLigands 115 Contents ix 6.4 Spin-StateChangesinCatalysis 119 6.4.1 Catalytic(Cyclo)oligomerizations 119 6.4.2 PhillipsCr(II)/SiO Catalyst 121 2 6.4.3 SNS–CrCl Catalyst 123 3 6.5 ConcludingRemarks 125 References 126 7 PrinciplesandProspectsofSpin-StatesReactivityinChemistryandBioinorganic Chemistry 131 DandamudiUsharani,BinjuWang,DinaA.SharonandSasonShaik 7.1 Introduction 131 7.2 Spin-StatesReactivity 132 7.2.1 Two-StateandMulti-StateReactivity 133 7.2.2 OriginsofSpin-SelectiveReactivity:Exchange-EnhancedReactivityandOrbital SelectionRules 137 7.2.3 ConsiderationsofExchange-EnhancedReactivityversusOrbital-Controlled Reactivity 140 7.2.4 ConsiderationofSpin-StateSelectivityinH-Abstraction:ThePowerofEER 142 7.2.5 TheOriginsofMechanisticSelection–WhyAreC–HHydroxylationsStepwise Processes? 146 7.3 ProspectsofTwo-StateReactivityandMulti-StateReactivity 148 7.3.1 ProbingSpin-StateReactivity 148 7.3.2 AreSpinInversionProbabilitiesUsefulforAnalyzingTSR? 150 7.4 ConcludingRemarks 151 References 151 8 MultipleSpin-StateScenariosinGas-PhaseReactions 157 JanaRoithova´ 8.1 Introduction 157 8.2 ExperimentalMethodsfortheInvestigationofMetal-IonReactions 158 8.3 MultipleStateReactivity:ReactionsofMetalCationswithMethane 160 8.4 EffectoftheOxidationState:ReactionsofMetalHydrideCationswithMethane 163 8.5 Two-StateReactivity:ReactionsofMetalOxideCations 164 8.6 EffectofLigands 171 8.7 EffectofNoninnocentLigands 174 8.8 ConcludingRemarks 177 References 178 9 CatalyticFunctionandMechanismofHemeandNonhemeIron(IV)–OxoComplexes inNature 185 MatthewG.Quesne,AbayomiS.Faponle,DavidP.GoldbergandSamP.deVisser 9.1 Introduction 185 9.2 CytochromeP450Enzymes 186 9.2.1 ImportanceofCytochromeP450Enzymes 187 9.2.2 P450ActivationofLong-ChainFattyAcids 188 9.2.3 HemeMonooxygenasesandPeroxygenases 188 9.2.4 CatalyticCycleofCytochromeP450Enzymes 188 x Contents 9.3 NonhemeIronDioxygenases 190 9.3.1 CysteineDioxygenase 191 9.3.2 AlkBRepairEnzymes 192 9.3.3 NonhemeIronHalogenases 194 9.4 Conclusions 197 9.5 Acknowledgments 197 References 197 10 TerminalMetal–OxoSpecieswithUnusualSpinStates 203 SarahA.Cook,DavidC.LacyandAndyS.Borovik 10.1 Introduction 203 10.2 Bonding 204 10.2.1 BondingConsiderations:TetragonalSymmetry 204 10.2.2 BondingConsiderations:TrigonalSymmetry 205 10.2.3 MethodsofCharacterization 206 10.3 CaseStudies 206 10.3.1 Iron–OxoChemistry 206 10.3.2 Manganese–OxoChemistry 212 10.3.3 CautionaryTales:LateTransitionMetalOxidoComplexes 217 10.3.4 EffectsofRedoxInactiveMetalIons 217 10.3.5 Metal–OxylComplexes 218 10.4 Reactivity 218 10.4.1 GeneralConcepts:ProtonversusElectronTransfer 218 10.4.2 SpinStateandReactivity 220 10.5 Summary 220 References 221 11 MultipleSpinScenariosinTransition-MetalComplexesInvolvingRedox Non-InnocentLigands 229 FlorianHeimsandKallolRay 11.1 Introduction 229 11.2 SurveyofNon-InnocentLigands 231 11.3 IdentificationofNon-InnocentLigands 232 11.3.1 X-rayCrystallography 232 11.3.2 EPRSpectroscopy 234 11.3.3 Mo¨ssbauerSpectroscopy 235 11.3.4 XASSpectroscopy 236 11.4 SelectedExamplesofBiologicalandChemicalSystemsInvolvingNon-InnocentLigands 237 11.4.1 Copper–RadicalInteraction 237 11.4.2 Iron–RadicalInteraction 246 11.5 ConcludingRemarks 252 References 253 12 MolecularMagnetism 263 GuillemArom´ı,PatrickGamezandOlivierRoubeau 12.1 Introduction 263 12.2 MolecularMagnetism:Motivations,EarlyAchievementsandFoundations 264 Contents xi 12.3 MolecularNanomagnets(MNM) 265 12.3.1 Single-MoleculeMagnets 266 12.3.2 Single-ChainMagnets(SCM) 268 12.3.3 Single-IonMagnets(SIM) 271 12.4 SwitchableSystems 273 12.4.1 SpinCrossover(SCO) 273 12.4.2 ValenceTautomerism(VT) 273 12.4.3 ChargeTransfer(CT) 275 12.4.4 Light-DrivenLigand-InducedSpinChange(LD-LISC) 276 12.4.5 Photoswitching(PS)ThroughIntermetallicCT 277 12.5 Molecular-BasedMagneticRefrigerants 278 12.5.1 TheMagneto-CaloricEffect,ItsExperimentalDeterminationandKeyParameters 278 12.5.2 MoleculartoExtendedFrameworkCoolersTowardsApplications 280 12.6 QuantumManipulationoftheElectronicSpinforQuantumComputing 282 12.6.1 OrganicRadicals 283 12.6.2 TransitionMetalClusters 284 12.6.3 LanthanidesasRealizationofQubits 285 12.6.4 EngineeringofMolecularQuantumGateswithLanthanideQubits 285 12.7 PerspectivesTowardApplicationsandConcludingRemarks 287 References 287 13 ElectronicStructure,Bonding,SpinCoupling,andEnergeticsofPolynuclearIron–Sulfur Clusters–ABrokenSymmetryDensityFunctionalTheoryPerspective 297 KathrinH.Hopmann,VladimirPelmenschikov,Wen-GeHanDuandLouisNoodleman 13.1 Introduction 297 13.2 Iron–SulfurCoordination:GeometricandElectronicStructure 298 13.3 SpinPolarizationSplittingandtheInvertedLevelScheme 300 13.4 SpinCouplingandtheBrokenSymmetryMethod 300 13.5 ElectronLocalizationandDelocalization 301 13.6 PolynuclearSystems–CompetingHeisenbergInteractionsandSpin-Dependent Delocalization 303 13.7 PreambletoThreeMajorTopics:Iron–Sulfur–Nitrosyls,Adenosine-5′-Phosphosulfate Reductase,andtheProximalClusterofMembrane-Bound[NiFe]-Hydrogenase 303 13.7.1 NonhemeIronNitrosylComplexes 303 13.7.2 Adenosine-5′-PhosphosulfateReductase 310 13.7.3 ProximalClusterofO -TolerantMembrane-Bound[NiFe]-HydrogenaseinThree 2 RedoxStates 315 13.8 ConcludingRemarks 318 13.9 Acknowledgments 319 References 319 14 EnvironmentEffectsonSpinStates,Properties,andDynamicsfromMulti-level QM/MMStudies 327 AlexanderPetrenkoandMatthiasStein 14.1 Introduction 327 14.1.1 EnvironmentalEffects 328 14.1.2 HybridQM/MMEmbeddingSchemes 329 xii Contents 14.2 TheQuantumSpinHamiltonian–LinkingTheoryandExperiment 332 14.3 TheSolventasanEnvironment 335 14.3.1 FourierTransformInfraredSpectroscopy 336 14.3.2 NuclearMagneticResonance 336 14.3.3 ElectronParamagneticResonance 336 14.4 EffectofDifferentLevelsofQMandMMTreatment 338 14.4.1 ConvergenceandCaveatsattheQMLevel 338 14.4.2 AccuracyoftheMMPart 341 14.4.3 QMversusQM/MMMethods 341 14.5 IllustrativeBioinorganicExamples 343 14.5.1 CytochromeP450 343 14.5.2 HydrogenaseEnzymes 349 14.5.3 PhotosystemIIandtheEffectofQMSize 354 14.6 FromStaticSpin-StatePropertiestoDynamicsandKineticsofElectronTransfer 357 14.7 FinalRemarksandConclusions 359 14.8 Acknowledgments 362 References 362 15 High-SpinandLow-SpinStatesin{FeNO}7,FeIV=O,andFeIII–OOHComplexes andTheirCorrelationstoReactivity 369 EdwardI.Solomon,KyleD.SutherlinandMartinSrnec 15.1 Introduction 369 15.2 High-andLow-Spin{FeNO}7 Complexes:CorrelationstoO Activation 372 2 15.2.1 SpectroscopicDefinitionoftheElectronicStructureofHigh-Spin{FeNO}7 372 15.2.2 ComputationalStudiesofS=3/2{FeNO}7 ComplexesandRelated{FeO }8 2 Complexes 375 15.2.3 ExtensiontoIPNSandHPPD:ImplicationsforReactivity 377 15.2.4 Correlationto{FeNO}7 S=1/2 385 15.3 Low-Spin(S=1)andHigh-Spin(S=2)FeIV=OComplexes 386 15.3.1 FeIV=OS=1Complexes:𝜋∗FMO 386 15.3.2 FeIV=OS=2Sites:𝜋∗and𝜎∗FMOs 390 15.3.3 ContributionsofFMOstoReactivity 392 15.4 Low-Spin(S=1/2)andHigh-Spin(S=5/2)FeIII–OOHComplexes 396 15.4.1 SpinStateDependenceofO–OBondHomolysis 396 15.4.2 FeIII–OOHS=1/2Reactivity:ABLM 398 15.4.3 FeIII–OOHSpinState-DependentReactivity:FMOs 399 15.5 ConcludingRemarks 401 15.6 Acknowledgments 402 References 402 16 NMRAnalysisofSpinDensities 409 KaraL.Bren 16.1 IntroductionandScope 409 16.2 SpinDensityDistributioninTransitionMetalComplexes 410 16.3 NMRofParamagneticMolecules 412 16.3.1 ChemicalShifts 413 16.3.2 RelaxationRates 414