Advances in Inorganic Chemistry: Inorganic Reaction Mechanisms (AIC) (Advances in Inorganic Chemistry)

477 Pages·2003·5.14 MB·English

by  Colin D. Hubbard

PREFACE
I am especially honoured to have been appointed the Editor of
Advances in Inorganic Chemistry, and to be associated with a highly
cited, very successful series. The series began in 1959, edited by H.J.
Emele¤us and A.G. Sharpe, and at that time included reviews on
Radiochemistry.WithVolume 31, ProfessorA.G. Sykes assumed theedi-
torshipandextendedtheareaofinteresttoincludebioinorganicstudies.
He prefaced that issue with an outline of his views on the aims of the
series, and (paraphrasing) he intended to continue to provide a forum
for scholarly and critical reviews by recognized experts, rather than
seeking to catalogue each and every event.Those opinions and other
comments were very appropriate then and remain so, now and in the
future.
Contributionswillbesolicitedbytheeditor,whowillalsobeguidedby
theEditorialAdvisoryBoard.Issuesonthematictopicswill ingeneral
involve a co-editor as a specialist in that particular ¢eld. Suggestions
forsubjectsforreviewsinthefuturewillbewelcomeatanytime.Ofpar-
ticular interest will be reviews of rapidly developing areas that do not
necessarily ¢t into traditional subject sub-areas, thus appealing to
newer readers and researchcolleagues. It is felt that a presentation of
diverse topics will assist in creative thinking and help to ensure that
the overall subject of Inorganic Chemistry continues to develop and
thrive.Inthisrespect,IwouldliketowelcomethenewAdvisoryBoard
membersandwilllookforwardtointeractingwiththem.
Tohonour theaccomplishmentsofProfessorGeo¡Sykes,both in his
own research, principally in mechanistic studies in Inorganic and
BioinorganicChemistry,andaseditorofthisseries,thepresentvolume
onInorganicReactionMechanismsisdedicatedtohim.ThePublisher’s
note in Volume 53 referred to the high impact factor as a re£ection
of the high standards set and the quality of the contributing authors.
I echo these comments and personally acknowledge Professor Sykes’
xi
xii PREFACE
signi¢cant contributiontothe successofthe series. Iam delighted and
feel privileged to succeed illustrious editors and will endeavour to
matchtheirhighstandards.
For my ¢rst volume as Editor, I have invited Professor Colin D.
Hubbard (University of Erlangen-Nu« rnberg, Erlangen, Germany and
University of New Hampshire, Durham, NH, USA) as co-editor.
ProfessorHubbardstudiedchemistryattheUniversityofShe⁄eld,and
obtained his PhD with Ralph G.Wilkins. Following post-doctoralwork
at MIT, Cornell Universityand Universityof California in Berkeley, he
joinedtheacademicsta¡oftheUniversityofNewHampshire,Durham,
wherehebecameProfessorofChemistryin1979.Hisinterestscoverthe
areasofhigh-pressurechemistry,electrontransferreactions,protontun-
nellingandenzymecatalysis.
The¢rstchapterbyF.A.Dunand,L.HelmandA.E.Merbachisacom-
prehensive account of the mechanism of solvent exchange processes.
Metal complex formation can be controlled by solvent exchange.This
topic, as well as ligand substitution in general, form the subject of the
second chapter by J. Burgess and C.D. Hubbard. Following this, J.H.
Espenson describes‘OxygenTransfer Reactions: Catalysis by Rhenium
Compounds’.The fourth chapter by P.C. Ford, L.E. Laverman and J.M.
Lorkovicisanaccountof thereaction mechanisms of nitricoxidewith
biologically relevant metal centers. In chapter 5, U. Fekl and K.I.
Goldbergdiscuss‘Platinum Involvement in Homogeneous Hydrocarbon
C^H Bond Activation and Functionalization’. Chapter 6 by M.H. Hall
andH.-J.Fanistitled‘DensityFunctionalStudiesofIridiumCatalyzed
Alkane Dehydrogenation’. ‘Recent Advances in Electron Transfer
Reactions’arereportedbyD.M.Stanbury.The¢nalchapterbyI.Fa¤bia¤n
and V. Csorda¤s is on ‘The Kinetics and Mechanism of Metal Ion
CatalyzedAutoxidationReactions’.Ithoroughlybelievethatthesecontri-
butionscoverthepresentadvancesaccomplishedinthegeneralareaof
InorganicReactionMechanisms.
RudivanEldik
UniversityofErlangen-Nu« rnberg
Germany
December2002
CONTENTS
PUBLISHER’SNOTE . . . . . . . . . . . ix
PREFACE . . . . . . . . . . . . . xi
SolventExchange onMetalIons
FRANKA.DUNAND,LOTHARHELMANDANDRE¤ E.MERBACH
I. Introduction . . . . . . . . . . . . 1
II. SolventExchangeonMainGroupMetalIons . . . . . 8
III. SolventExchangeond-TransitionMetalIons . . . . . 16
IV. SolventExchangeonLanthanidesandActinides . . . . . 41
V. Appendix:LigandAbbreviations,Formulae,andStructures . . 52
References . . . . . . . . . . . . 62
Ligand SubstitutionReactions
JOHNBURGESSANDCOLIND.HUBBARD
I. Introduction . . . . . . . . . . . . 72
II. InertOctahedralMIIandMIIIComplexes . . . . . . 75
III. HighOxidationStateComplexes . . . . . . . . 94
IV. Square-PlanarComplexes . . . . . . . . . 96
V. ReactionsatLabileTransitionMetalCenters . . . . . 109
VI. TransitionMetalTrianglesandClusters . . . . . . 126
VII. ReactionsofCoordinatedLigands . . . . . . . 128
References . . . . . . . . . . . . 140
OxygenTransfer Reactions:Catalysis byRhenium Compounds
JAMESH.ESPENSON
I. RheniumCatalysts . . . . . . . . . . 158
II. OxygenAtomTransfer:TheReactionsThemselves . . . . 165
III. KineticsofPyridineN-oxideReduction . . . . . . 166
IV. TheChemicalMechanismofPyridineN-oxideReduction . . . 168
V. DigressiontoLigandExchangeandSubstitution . . . . 173
VI. AdditionalOxygenAtomTransferReactions . . . . . 180
v
vi CONTENTS
VII. OtherOxorhenium(V)CompoundsasCatalysts . . . . . 184
VIII. SulfurAtomAbstraction . . . . . . . . . 187
IX. TheActivationofMolecularOxygen . . . . . . . 190
X. Imido-rheniumCompounds . . . . . . . . . 196
XI. Conclusions . . . . . . . . . . . . 200
References . . . . . . . . . . . . 200
ReactionMechanisms ofNitric Oxidewith Biologically
Relevant MetalCenters
PETERC.FORD,LEROYE.LAVERMANANDIVANM.LORKOVIC
I. Introduction . . . . . . . . . . . . 203
II. FormationofMetalNitrosylComplexes . . . . . . 206
III. ReactionsofMetalNitrosylComplexes . . . . . . 219
IV. ExamplesfromtheChemicalBiologyofMetal
NitrosylComplexes . . . . . . . . . . 237
V. OverviewandSummary . . . . . . . . . 245
VI. ListofAbbreviations . . . . . . . . . . 248
References . . . . . . . . . . . . 250
Homogeneous Hydrocarbon C–HBondActivationand
Functionalization with Platinum
ULRICHFEKLANDKARENI.GOLDBERG
I. Introduction . . . . . . . . . . . . 260
II. ClassicDivisionoftheHydrocarbonFunctionalization
CycleintoThreeParts . . . . . . . . . . 263
III. MechanismsfortheC^HActivationSequence:
FormationofaPt(II)HydrocarbylComplexfromPt(II)andHydrocarbon 264
IV. MechanismsfortheOxidationStep:FromPt(II)-Hydrocarbylto
Pt(IV)-Hydrocarbyl . . . . . . . . . . 299
V. MechanismsfortheFunctionalizationSequence:
Carbon-HeteroatomCouplingtoReleasetheProduct . . . . 306
VI. SummaryandConcludingComments . . . . . . . 311
References . . . . . . . . . . . . 314
DensityFunctionalStudies ofIridiumCatalyzed Alkane Dehydrogenation
MICHAELB.HALLANDHUA-JUNFAN
I. Introduction . . . . . . . . . . . . 321
II. CyclopentadienylIridiumComplex . . . . . . . 323
CONTENTS vii
III. FundamentalSteps . . . . . . . . . . 329
IV. TransferReaction . . . . . . . . . . . 336
V. AcceptorlessReaction . . . . . . . . . . 337
VI. GeometricFactor . . . . . . . . . . . 340
VII. ReactionConditions . . . . . . . . . . 340
VIII. Modelwithtert-butylPhosphine . . . . . . . . 342
IX. AnthraphosRhodiumComplex . . . . . . . . 342
X. Conclusions . . . . . . . . . . . . 343
XI. ComputationalDetails . . . . . . . . . . 344
References . . . . . . . . . . . . 345
Recent Advancesin Electron-Transfer Reactions
DAVIDM.STANBURY
I. Introduction . . . . . . . . . . . . 352
II. Outer-SphereElectronTransferReactions . . . . . . 352
III. RadicalElectron-TransferReactions . . . . . . . 361
IV. ‘‘Small-Molecule’’IntramolecularElectron-TransferReactions . . 369
V. ElectronTransferwithMetalloproteins . . . . . . 372
VI. DoubleElectronTransfer . . . . . . . . . 379
VII. ElectrochemicalElectron-TransferReactions . . . . . 381
References . . . . . . . . . . . . 392
MetalIon Catalyzed AutoxidationReactions:
Kineticsand Mechanisms
ISTVA¤NFA¤BIA¤NANDVIKTORCSORDA¤S
I. Introduction . . . . . . . . . . . . 395
II. GeneralConsiderations . . . . . . . . . 397
III. AutoxidationofL-AscorbicAcid . . . . . . . . 400
IV. AutoxidationofCatecholsandRelatedCompounds . . . . 411
V. AutoxidationofCysteine . . . . . . . . . 426
VI. AutoxidationofSulfur(IV) . . . . . . . . . 431
VII. AutoxidationofMiscellaneousSubstrates . . . . . . 442
VIII. ExoticKineticPhenomena . . . . . . . . . 449
IX. Perspectives . . . . . . . . . . . . 455
References . . . . . . . . . . . . 457
INDEX . . . . . . . . . . . . . 463
CONTENTSOFPREVIOUSVolumes . . . . . . . . 473
PUBLISHER’S NOTE
This special volume of Advances in Inorganic Chemistry, with the
thematictitleInorganicReactionMechanisms,isthe¢rstvolumetobe
publishedundertheauspicesoftheneweditor,ProfessorRudivanEldik.
A Dutch national, Professor van Eldik studied chemistry at
PotchefstroomUniversityinSouthAfrica,wherehegainedhisD.Sc.in
1971. After a number of years working abroad, he was appointed
ProfessorofChemistryatPotchefstroomin1979.In1982hereceivedhis
HabilitationattheUniversityofFrankfurtwherehewasGroupLeader
at the Institute for Physical Chemistry between 1980 and 1986. From
1987 to1994 he was Professorof Inorganic Chemistryat the University
of Witten/Herdecke, Germany and was then appointed to his present
position as Professor of Inorganic and Analytical Chemistry at the
Universityof Erlangen-Nˇrnberg in Germany. Inthe intervening years
he has travelled widely, being aVisiting Professor at the University of
Utah in the USA, the University of Canterbury in New Zealand, Ben
Gurion University in Israel and at the moment is Wilsmore Visiting
ProfessorattheUniversityofMelbourneinAustralia.
Aproli¢c author, Professor van Eldik has been responsible for some
580 papers in refereed journals, and four books as editor or co-editor.
Hiscurrentresearchintrestsaretheapplicationofhighpressuretechni-
ques in mechanistic studies; metal-catalyzed autoxidation processes;
and bioinorganic studies. As such he is eminently quali¢ed to edit the
prestigiousAdvancesinInorganicChemistry.Wearecon¢dentthatheis
aworthysuccessor to Professor Geo¡ Sykes and that he will maintain
thehighstandardsforwhichtheseriesisknown.
ix
SOLVENT EXCHANGE ON METAL IONS
FRANK A. DUNAND, LOTHAR HELM and ANDRE´ E. MERBACH
Institutdechimiemole´culaireetbiologique,Ecolepolytechniquefe´de´ralede
Lausanne,EPFL-BCH,CH-1015Lausanne,Switzerland
I. Introduction
A. GeneralAspects
B. ExperimentalMethods
C. ClassificationofMechanisms
D. TheVolumeofActivation
II. SolventExchangeonMainGroupMetalIons
A. GeneralCharacteristics
B. DivalentMainGroupIons
C. TrivalentMainGroupIons
III. SolventExchangeond-TransitionMetalIons
A. GeneralCharacteristics
B. DivalentFirst-RowTransitionMetals
C. TrivalentFirst-RowTransitionMetals
D. SecondandThirdRowOctahedralComplexes
E. EffectofNon-LeavingLigands
F. Square-PlanarComplexes
IV. SolventExchangeonLanthanidesandActinides
A. TrivalentLanthanides
B. DivalentEu(II)
C. Actinides
V. Appendix:LigandAbbreviations,Formulae,andStructures
References
I. Introduction
A. GENERALASPECTS
Solvent exchange reactions on metal cations are among the most
simplechemicalreactions:asolventmoleculesituatedinthe¢rstcoordi-
nation shell of the ion is replaced by another one, normally entering
from the second shell. They are generally considered as fundamental
reactionsfor metalionsin solution,sincetheyconstituteanimportant
step in complex-formation reactions on metal cations.The reaction is
1
ADVANCESININORGANICCHEMISTRY (cid:1)2003ElsevierScience(USA)
VOLUME54ISSN0898-8838 Allrightsreserved.
2 F.A.DUNANDetal.
FIG.1. Meanlifetimesofaparticularwatermoleculeinthefirstcoordinationsphere
ofagivenmetalion,(cid:1) ,andthecorrespondingwaterexchangerateconstants,k
H2O H2O
at298K.Thefilledbarsindicate directlydeterminedvalues,andtheemptybars
indicatevaluesdeducedfromligandsubstitutionstudies.
symmetrical: reactants and reaction products are identical, which has
importantdrawbacksinthedeterminationoftherateconstants.
Theratesofsolventexchangevarywidelywiththenatureofthecation
and, to a lesser extent, with that of the solvent. As an example Fig. 1
showsthatk ,theexchangerateconstantforwatermolecules,covers
H2O
nearly20ordersof magnitude.Atthe‘‘slowend’’ofthelabilityscalethe
mean life time of a water molecule in the 1st coordination shell of
[Ir(H O) ]3+, (cid:1) (=1/k ) is about 290 years (1), whereas at the other
2 6 H O HO
extremethesho2rtestmea2nlifetimeis2(cid:1)10(cid:2)10s(=200ps)directlymeas-
uredon [Eu(H O) ]2+ (2).Variationof therate constant with solvent on
2 7
the same metal ion is less pronounced and generally below 2 orders of
magnitude. Strong back-bonding from the metal to solvent molecules,
however, can slow down the exchange process by several orders of
magnitude,asobservedforexamplefor[Ru(MeCN) ]3+(3).Itistherefore
6
convenient to divide the discussionof solvent exchange into categories
ofmetalions.
SOLVENTEXCHANGEONMETALIONS 3
The¢rstcategoryincludesthemaingroupions,whichexhibitingen-
eral, for a given ionic charge, increasing exchange rate constants, k ,
ex
with increasing ionic radius. This is nicely illustrated by the water
exchange on Al3+, Ga3+ and In3+, all being six-coordinate, with a rate
increase of more than 6 orders of magnitude. Solvent exchange on
mono-valent alkaliand large divalent alkali-earth ions is very fast and
the exchange rate constants can only be deduced from complex-forma-
tionreactions(4,5).
The second category is the d-transition metal ions. Their solvent
exchangepropertiesarestronglyin£uencedbytheelectronicoccupancy
of their d orbitals. This is best illustrated by the 1st row transition
metal ions. On the basis of their ionic radii, r , they should all show
M
labilities similar to Zn2+ for the divalent ions and similar to Ga3+ for
the trivalent ones. However, the water exchange rates varyby 7 and15
orders of magnitude, respectively, depending largely on the electronic
con¢guration of the metal ion. Within this category, square-planar
complexesconstituteaspecialsub-category.
The third category is thehighcoordination numberlanthanides and
actinides.Thetrivalentlanthanidesshowadecreaseinr withthepro-
M
gressive ¢lling of the 4f orbitals, called the lanthanide contraction.
Sincethe4forbitalsareshieldedbythe¢lled5sand5porbitals,theelec-
troniccon¢gurationhasnoremarkablee¡ectandthereforethevariation
in r and an eventual change in coordination number and geometry
M
determinethelabilityofthe1stcoordinationshell.
Solvent exchange reactions have been reviewed several times in the
last10years.AcomprehensivereviewbyLincolnandMerbachwaspub-
lished in this series in 1995 (6). More recent reviews focused more
onhighpressuretechniquesfortheassignmentofreactionmechanisms
(7^9)oronwaterexchange(10).Thisreviewisafollowupoftheexhaus-
tive Lincoln and Merbach review (6). The main features of solvent
exchangeonmetalionswillbepointedout,takingintoaccountdevelop-
mentsandnewresultsfromthelast10years.
B. EXPERIMENTALMETHODS
Onlya fewexperimental techniques are available to measure solvent
exchange rate constants directly. Nuclear magnetic resonance (NMR)
spectroscopyhasshownthewidestrangeofapplication.Mostexchange
rate constants given in this review were determined by NMR using a
variety of speci¢c methods. A common method is the observation of
NMRlineshape(11).Iftheexchangerateconstantisintherangede¢ned
bythenaturallinewidthoftheNMRresonanceandthereisachemical