通过有机配体界定的锌的磷酸化合物拓扑结构(晶(9)

FanandHanson

Figure6.(a)Crystalstructureofcompound6withatomlabelingscheme.Thermalellipsoidsaredrawnat50%probability.(b)Polyhedralrepresentationofthe2Dsheetin6(Zn:blue.P:yellow).(c)Packingdiagramofcompound6.

containbothphosphoricacidandimidazolehaveflexibilityinthelocationofprotonsrequiredforchargebalance.Thoughtheexactmechanismintheaufbauprocessisfarfrombeingunderstood,itiscertainthattheligandandsolutionpHplayimportantroles.

Intheligandmodifiedzincphosphatestructuresreportedhereandintheliterature,thereappearstobeacompetitionbetweennitrogendonoratomsandphosphateoxygenforzinccoordinationsites.Thus,onecanenvisionalternativestruc-turesformanyligand/metalcombinations.Forexampleanalternativefor3couldhavebeenformedbytheadditionalcoordinationofthezincatomintheterminalringsofthetriple4-ringwithconcomitantdeprotonationoftheL2.ThiscouldleadtostructureAasillustratedinScheme2.Suchastructureremainshypothetical.

Theincorporationofmultifunctionalligandsintozincphosphateframeworksisapowerfulrouteforthesynthesisofinorganic/organichybridmaterials.Imidazoleandbenz-imidazolegroupsareeffectivecompetitorswithphosphateionsforzinccoordinationsites.Thisleadstothecleavageofzincphosphatephasesintofragmentsthatincluderings,chains,andsheets.Themannerinwhichtheinorganicfragmentscanbeputtogethertoformhybridmaterialsis

Scheme2.PossibleTransformationoftheChainObservedin3ToGiveaHypotheticalChainof4-RingsLinkedbyZincAtoms(Zn:Pink.P:Yellow)

a

a

Pendantphosphategroupson4-ringsareomittedforclarity.

dictatedbytheligandandthecoordinationrequirementsofthefragments.Fromthestructuresdescribedabove,itappearsthattheinorganicpiecesin1,2,4,and5arecloselyrelatedasillustratedinScheme3.Startingfromthecommonlyobserved4-ring,two4-ringsmaylinktogethertogenerateatriplefused4-ringandtriple4-ringsmaycondensefurthertogiveladdersorstairsteps.Alternatively,thetriple4-ringmayopenuptogeneratesingle8-ringssuchasthoseobservedin1.Thelinkingof8-ringsalongone

direction

7006InorganicChemistry,Vol.44,No.20,2005