Modeling Marvels: Computational Anticipation of Novel Molecules

293 Pages·2008·5.1 MB·English

by  Errol G. Lewars (auth.)

Modeling Marvels
Errol G. Lewars
Modeling Marvels
Computational Anticipation
of Novel Molecules
123
Prof.ErrolG.Lewars
TrentUniversity
DepartmentofChemistry
1600WestBankDrive
PeterboroughONK9J7B8
Canada
[email protected]
ISBN:978-1-4020-6972-7 e-ISBN:978-1-4020-6973-4
DOI:10.1007/978-1-4020-6973-4
LibraryofCongressControlNumber:2008922296
(cid:2)c 2008SpringerScience+BusinessMediaB.V.
Nopartofthisworkmaybereproduced,storedinaretrievalsystem,ortransmitted
inanyformorbyanymeans,electronic,mechanical,photocopying,microfilming,recording
orotherwise,withoutwrittenpermissionfromthePublisher,withtheexception
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springer.com
Asurveyofavarietyofnovelcompoundswhichhave
beenstudiedtheoreticallybuthavenotyetbeenmade.
Someofthesemoleculesdefyconventionalconceptsof
chemicalbonding;allshouldexhibitnovelproperties.
ToAnneandJohn
Preface
The aim of this book is to survey a number of chemical compounds that some
chemists,theoreticalandexperimental,findfascinating.Someofthesecompounds,
like planar carbon species or oxirene, offer no obvious practical applications;
nitrogen oligomers and polymers, in contrast, have been touted as possible high-
energy-densitymaterials.Whatunitesthisotherwiseeclecticcollectionisthatthese
substancesareunknownandofferachallengetotheoryandtosynthesis.Thatsuch
achallengeexistsisinsomecasesalmostobvioustomostchemists:theinstability
ofnitrogenpolymers,forexample,mightbetakennearlyasanaxiom,tobequan-
tifiedbutnotrefutedbycomputationsandtobesubjectedtoanalmostsuperfluous
(but rather challenging) validation by synthesis. On the other hand, oxirene, the
unsaturatedrelativeoftheprosaicoxirane,presentsnoimmediatelyobviousoddity,
yetthismoleculehasdefiedallattemptsatsynthesisandremainsatheoreticalco-
nundrum, in that it is not certain if it can even exist! I hope that this collection of
quirky molecules will appeal to chemists who find the study of chemical oddities
interestingand,onoccasion,evenrewarding.
Severalpeoplereadvariouschapters;itisapleasuretoacknowledgethehelpful
commentsandsuggestionsof:
ProfessorKarlChriste,UniversityofSouthernCalifornia
ProfessorGernotFrenking,UniversityofMarburg
ProfessorJohnGalbraith,MaristCollege
ProfessorRoaldHoffmann,CornellUniversity
ProfessorBartKahr,UniversityofWashington
ProfessorJoelLiebman,UniversityofMaryland
ProfessorGu¨ntherMaier,Justus-LiebigUniversity,Giessen
ProfessorJosefMichl,UniversityofColorado
ProfessorKurtMislow,PrincetonUniversity
ProfessorKeijiMorokuma,EmoryUniversity
ProfessorLeoRadom,UniversityofSydney
ProfessorDouglasStrout,AlabamaStateUniversity
Peterborough,Ontario,Canada ErrolLewars
October2007
ix
Contents
1 PlanarCarbon ................................................. 1
Introduction .................................................... 1
Dimethanospiro[2.2]octaplane:AComputationalSaga ................ 3
Synthesis....................................................... 9
Conclusions .................................................... 10
Notes.......................................................... 11
References ..................................................... 11
2 PyramidalCarbon.............................................. 13
Introduction .................................................... 13
Pyramidane..................................................... 14
OtherMoleculeswithPossiblyPyramidalCarbon .................... 24
Synthesis....................................................... 25
Conclusions .................................................... 27
Notes.......................................................... 27
References ..................................................... 29
3 Oxirene ....................................................... 31
Introduction .................................................... 31
TheOxireneProblem:History..................................... 33
Oxirenesto1981;Summary..................................... 33
OxirenesAfter1981 ........................................... 39
Synthesis....................................................... 49
Conclusions .................................................... 50
Notes.......................................................... 50
References ..................................................... 50
4 NitrogenPentafluorideandRelatedCompounds................... 53
Introduction .................................................... 53
NitrogenPentafluoride,theOctetRule,andHypervalency ............. 53
ThePredictedPropertiesofNF ................................... 59
5
RelatedNitrogenCompounds ..................................... 61
HypercoordinateCompoundsofOtherNonmetals .................... 62
xi
xii Contents
Synthesis....................................................... 62
Conclusions .................................................... 63
Notes.......................................................... 64
References ..................................................... 64
5 HeliumCompounds ............................................ 67
Introduction .................................................... 67
OverviewoftheChemistryofNeon,Argon,Krypton,Xenon,(Radon) ... 67
HeliumCompounds.............................................. 71
Synthesis....................................................... 77
Notes.......................................................... 78
References ..................................................... 78
6 Tetrahedrane .................................................. 81
Introduction .................................................... 81
CounterfeitChemistry:AFictionalSynthesisofaTetrahedrane ......... 82
RealSynthesesofTetrahedranes ................................... 83
Tetra-t-butyltetrahedrane,Synthesis .............................. 83
Tetra-t-butyltetrahedrane,Properties.............................. 85
Tetrakis(trimethylsilyl)tetrahedrane,Synthesis ..................... 87
Tetrakis(trimethylsilyl)tetrahedrane,Properties..................... 87
Tetrahedranyllithium(andCompoundsDerivedTherefrom) .......... 90
Tetrat-butyltetrahedrane,B3LYP/6-31G*Calculations ................ 94
Tetrakis(trimethylsilyl)tetrahedrane,B3LYP/6-31G*Calculations ....... 94
TheParentTetrahedrane,Calculations .............................. 94
SomeCalculatedPropertiesofTetrahedrane ......................... 96
Synthesis.......................................................100
Notes..........................................................101
References .....................................................102
7 Orthogonene...................................................105
Introduction ....................................................105
Orthogonenes1and4 ............................................107
Synthesis.......................................................110
Conclusions ....................................................112
Notes..........................................................112
References .....................................................113
8 Hexaphenylethane..............................................115
Introduction ....................................................115
Hexaphenylethane:TheClassicalPeriod ............................115
Hexaphenylethane:TheModernPeriod .............................118
Synthesis.......................................................123
ARelatedCompound ............................................126
Conclusions ....................................................128
Contents xiii
Notes..........................................................128
References .....................................................129
9 Ethenedione,C O .............................................131
2 2
Introduction ....................................................131
ElectronicStructureandStabilityofEthenedione .....................131
AttemptstomakeEthenedione ....................................133
SpeciesRelatedtoEthenedione....................................135
Synthesis.......................................................137
Conclusions ....................................................138
Notes..........................................................138
References .....................................................139
10 NitrogenOligomersandPolymers:SuperfuelsorChimeras? ........141
Introduction ....................................................141
ExperimentalResults ............................................142
TheoreticalResults ..............................................148
CyclicN Molecules...........................................148
8
CyclicN Molecules...........................................151
6
CyclicN Molecules...........................................155
4
CyclicPolynitrogenswithSeveralRings ..........................156
AcyclicMolecules.............................................156
Some“Conventional”Polynitrogens..............................157
Synthesis.......................................................159
Conclusions ....................................................159
Notes..........................................................160
References .....................................................160
11 OligomersandPolymersofCarbonDioxideandCO /N ............165
2 2
Introduction ....................................................165
CO Compounds ................................................165
2
CO –N Compounds.............................................171
2 2
Structures(B3LYP/6-31G*)oftheCO –N Compounds(Fig.11.5) .....175
2 2
Decomposition Reactions (B3LYP/6-31G*
and MP2/6-31G*) of the Cyclic CO –N
2 2
Compounds(Fig.11.6)........................................... 175
TheB3LYP/6-31G*ReactionProfiles(Fig.11.6).....................175
TheMP2/6-31G*ReactionProfiles(Fig.11.7) .......................178
Stability of the Acyclic CO –N Compounds
2 2
13a,13b,13c ................................................... 178
Synthesis.......................................................180
TheCO Compounds ..........................................180
2
TheCO – N Compounds.....................................180
2 2
Summary ......................................................182
TheCO Dimeretc.,Stability ...................................182
2