配位化学课件Coordination-Compound1

CoordinationChemistryCoordinationCompound

(MetalComplexes)PartOne

IntroductionandHistoricalDevelopmentPartTwo

TheTheoryofCoordinationCompoundsPartThree

StereochemistryofComplexesPartFive

ComplexIonStabilityPartSix

KineticsandMechanismsofReactionsofCoordinationCompoundsPartfour

PreparationsandReactionsofCoordinationCompounds1-1.IndroductionLet’sreview/gooversomeoftheirpropertiesorcharacteristics:Ataveryearlystage(suchasatyourfirstyearintheclassofinorganicchemistry),thestudentswereintroducedtoaseriesofcompoundsreferredtoas/called:coordinationcompounds

(metalcomplexes)(complexesinbrief).1-3.Nomenclature1-1.Indroduction1-2.HistoricalDevelopmentPartOne

IntroductionandHistoricalDevelopmentSocialismwithChinesecharacteristics.Thatcarismy

property.Propertymanagement,intellectualproperty,mechanicalproperty(1)

Thesecompoundsgenerallycontainacentralion

(usuallyametalion),surroundedbyaclusterofionsormolecules.(2)Thesecomplexestendtoretain/maintaintheiridentity/integrityeveninsolution,althoughpartialdissociationmayoccur.

Identitycard;revealorconceal/coverupyouridentity;territorial

integrity;Amanofmoral

integrity

doesnotfearanyslanderousattack(3)Thesecomplexesmaybecationsoranionsornonionics,dependingonthesumofthechargesofthecentralatomandthesurroundingionsormolecules.

一.

Coordinationcompoundsplayanessentialroleinthechemicalindustryandinourlives.

(1)

In1963Nobelprizeinchemistrywasawardedjointly/togethertoDr.K.

ZiegleroftheMaxPlankInstitute,inGermany,andtoProf.G.NattaoftheUniversityofMilan.Italy.academyaward,financialreward

Theydevelopedanewkindofcatalyst,usingittheycouldpreparethepolymerizationofethyleneunderlowpressure,whichmakesthousandsofpolyethylenearticlescommonplace/ordinary.articlesconsumption(thesearticlesareverycommoninmarket)

ThisZiegler-Nattacatalystforthispolymerizationisjust

acomplexofthemetalsaluminumandtitanium.

(2)Theimportanceofmetalcomplexesbecomesclearwhenonerealizethat:

(A)Chlorophyll

[′klɔ:rəfil]

,whichisvitaltophoto-synthesisinplants(allowsplantstoabsorbenergyfromlight),isamagnesiumcomplex

(B)

Hemoglobin[′hi:mə′gləʊbin],

whichcarriesoxygentoanimalcells,isanironcomplex.Hemoglobininthe

blood

carriesoxygenfromtherespiratoryorgans(lungs

or

gills)totherestofthebody(i.e.thetissues)whereitreleasestheoxygentoburnnutrientstoprovideenergytopowerthefunctionsoftheorganism,andcollectstheresultant

carbondioxide

tobringitbacktotherespiratoryorganstobedispensed/removedfromtheorganism.

dispensableindispensable(necessary);resultantreactant

(C)VitaminB12,isawater-solublevitamin

withakeyroleinthenormalfunctioningofthe

brain

and

nervoussystem,andfortheformationof

blood.Itisoneoftheeight

Bvitamins.

·维生素B12Itisnormallyinvolvedinthe

metabolism

ofevery

cell

ofthehumanbody,especiallyaffecting

DNAsynthesisandregulation/control,butalso

fattyacid

synthesisandenergyproduction.Itisthelargestandmoststructurallycomplicatedvitaminandcanbeproducedindustriallyonlythroughbacterialfermentation-synthesis.

Perniciousanemia恶性贫血inhumanisduetothefailureofabsorptionofvitaminB12VitaminB12

isusedtotreat

vitaminB12

deficiency,

cyanidepoisoning

(hydrogen,potassium,sodiumcyanide).

pernicious/hurtful/deadly/harmful/fatal,smokingis…tohealth.(D)Bloodtonicof红桃K(redspadeK),whichhasbeenavailableinmarket,isalsoanironcomplex.BloodTonicassistthebodytopromotehealthyblood,physicalandmentalpowers,skinandimprovehealthyproductionofbloodinvariousbonemarrow-relatedhealthproblems,especiallyaplasticanemia再生障碍性贫血.Italsocanbeusedasabeautytonicbecausewhenthereissufficientbloodandnutrition,theskin,thecomplexion/look/appearanceandhairwillimproveandproject/showordisplaygoodhealthaswellasretard/delayagingandprolongtheyouthfulnessofthebody.Healthybloodisnotonlynecessaryfornourishingyourbody,butalsoimportantinthehealthydevelopmentofyourmind.Whenbloodqualityisunhealthy,typicalsymptomsarepalecomplexion,dryskin,dizziness,ringingintheears,forgetfulness,insomnia/sleeplessnessandmenstrualdisorderinwomen,prematuregrayhairandmanyotherdisharmonies.

(E)SodiumandcalciumsaltsofEDTA,whichisahighlyeffectiveantidoteortoxicideinpreventingpeoplefromradiatingofradioactiveelements,isancomplex.

(F)

Severalcomplexesofplatinumcanbeusedasstronganti-cancermedicines,whicharebeingexperimented(orused)inclinic.

(3)

Itisalmostcertainthatyouhavealreadyencountered/runacrosscoordinationcompoundsinlaboratoryorelsewhere.Theyareusedextensivelyinqualitativeanalysisasameansofseparatingcertainmetalionsandasameansofpositivelyidentifyingcertainunknownions(particularlymetalions).

intensive/extensivereading,extendedfamilyForexample:Youhaveperhapsperformed(orcarriedout)theexperiment:

“howtoidentifysilverioninsolution?”Youcanstate/accountfor/explaintheprobleminthefollowingway:(i)

Youcanaddchloride[′klɔ:raid]iontothesolution,whichgivesanwhiteprecipitateofsilverchlorideimmediately;

PbCl2orCuClisalsoanwhiteprecipitate;aslightmistakecouldprecipitate/resultinadisaster;makeaprecipitate/cavalier/carelessdecision(ii)

Then,addinganexcessofaqueousammoniatothesolution,theprecipitatecandissolveandbecomeaclearsolution.

(iii)

Butifyoucontinuetoaddanexcessofnitric

[′naitrik]acid,theprecipitatewillappearagain.

Thesebehaviorsareduetotheexistenceofthetwoequilibria

(1)(2):Explain:

(i)Becausesilverchlorideisnotsoluble/insolubleinwater,itdoes,however,dissolveinexcessNH3andformsthestablecomplexion[Ag(NH3)2]+;

(ii)TheadditionofexcessofHNO3totheclearsolutioncausestheequilibrium(2)toshifttotheleft,andsothewhiteprecipitatereappears.

(iii)ItisduetothereductionorlowingofconcentrationofNH3whichhasreactedwithH+toformNH4+.(4)

Theformationofmetalcomplexesisoftenaccompaniedbyverystriking/significantchangesincolor.

Youhavelearnedlotsoftheseexamplesininorganicchemistryanddonealargenumberofexperimentsinlaboratory.

Here,givinganinterestingexample:YoumaybefamiliarwiththeuseofthesolutionsofCoCl2asinvisibleink:Writingdownwiththisalmostcolorlesssolutiononpaper,youcanseethefollowingphenomena:(A)Itisvirtually/actuallyinvisible.(B)Whenbeingheated,thewaterisdrivenoff;thebluecomplexCo[CoCl4]isformed.

(C)Thecolorisnotablyintensesothatthewritingcaneasilyberead.

intensepain/emotion/cold/competition;intense/darkgreen(D)Butonstanding,waterisslowlytakenupbythesurroundingatmosphereandtheoriginalcolorlesscomplex[Co(H2O)6]Cl2isregenerated,whichmakesthewritinginvisibleagain.

(i)Thosephenomenaareduetotheexistingofthefollowingequilibium

(3):

Explain:

(iii)Butthewritingbecomesaverylegible/clearbluecolorwhenthewritingofthepaperisheated,andthenthisdistinctcolorslowlydisappears(orbecomesinvisibleagain).

(ii)Thatistosay,thisdilutedsolutionisalmostcolorless(itisactuallyslightpinkduetothecomplex[Co(H2O)6]2+),whenyouwritesomethingonpaperwiththissolution,itispracticallyinvisible).Theaboveexamples<1><2><3><4>…canpositivelyillustrateourpointthatcoordinationcompoundsarecommon,importantandfrequentlyencountered.

(5)

Ontheotherhand,coordinationcompoundsareextensivelyusedindyingandfinishingindustry.Maybeyouwillencountertheseproblemsinthefuture.

二.Thedirectionofresearchandappliedprospectsofcoordinationcompoundscanbesummarizedasfollows:

1.thesynthesesofneo-typeornew-stylecomplexes

(a)Theinorganic,

(b)metal

(c)polymermaterials

havebeenlistedasthreecurrentmajormaterials.

(A)Theyareextensivelyappliedinmanywaysofhigh-temperature;resistant

(tofire,erosionandoxidation,etc.)materials.

(B)Furthermore,thesynthesesofcomplexesareextremelyemphasizedonfunctionalmaterialssuchasonesoflight;heat;electricity;magnetism.

(A)Thecomplexescanbeusedas

reagents/reactantsintermediates

catalysts

inorganicsyntheticindustry.

2.

Theresearchofcomplexesintothepropertiesoftheutilityandsimulatedperformance

(B)ThedevelopmentandutilityofthesesmallmoleculessuchasN2,CO,HCHO,CH4

istheimportantbasisofcurrentchemicalindustry.

Inthesereactionslargenumbersofcarbonyl

[′kɑ:bənil]

complexesandclustercompoundshavebeenusedtoactivatethesesmallmoleculestoreactwithoxygen.

Theseoxidationreactionscanreleaselargeamountsofenergywhichcanbeusedinmanyways.

(C)Manyorganicligandshaveextensivelybeenusedas

developers(显色剂)，

precipitants(沉淀剂),

extractants（萃取剂）,

titrants（滴定剂）,maskingagents（掩蔽剂）

anti-maskingagent

inelementaryanalysis.

三.Theterm“complexcompounds”isnolongerthemeaningofitself

(A)Untilthebeginningofthelastcenturythenatureofthesematerialswerenotfullyunderstood,andthecompoundswerereferredtoas“complexcompounds”.

(B)Thistermisstillusednowadaysbutfortunatelynolongerforthesamereason.

(C)Afterextensiveresearchonsuchsystems,ourknowledgehassoincreasedthatthesystemsarenolongerconsideredcomplicated.

(D)Infact,theknowledgeofthepropertiesofcomplexesisshowedmoresignificantlyimportantifyouwanttounderstandthechemistryofmetals.1-2.HistoricalDevelopmentStudentsshouldkeepinmindthatscientificdevelopmentusuallycomesfromasomewhat

regularfashion:

(i)Collectasmanyfacts(orasmuchinformation)aspossiblebymeansofmanycarefullydesignedexperiments.1-1.Indroduction1-2.HistoricalDevelopment1-3.Nomenclature(ii)

Attempttoexplainandcorrelateallthefactswithasuitabletheory(oratheoryavailableatthattime).

Studentsshouldalsorememberthatunlikeexperiments,theoriescanbemodified,evenattimes(sometimes)completelydiscardedasmoreandmoreinformationbecomesavailable.1-2-1.Discoveryandproperties

(一).Itishardordifficulttostateexactlywhichcomplexisthefirstonediscovered(andwhen).PerhapstheearliestoneonrecordisPrussionblue:

[KCN•Fe(CN)2•Fe(CN)3](currentformulais[KFe(CN)6Fe]x),

whichobtainedbyanartcolormakerDiesbach,inBerlinatthebeginningoftheeighteenthcentury(~1740).

Itwassaidorreportedthatinordertofindoutakindofbluedye,Diesbachmixed:

severalanimals’skins,bloodandNa2CO3

heatedthemonanironpot,thengotankindofbluecompound,whichiscalledPrussionblue.

Note:

CN–isproducedbythehydrolysisofaminoacids(animals’skins)Usually,thefirstcomplexisconsideredashexaamminecobalt(Ⅲ)chloride,CoCl3•6NH3,discoveredbyTassert(1798,whoisananalyticchemistinFrance).Thisdiscoverymarkedtherealbeginningofcoodinationcompoundbecauseitsuniquepropertiesstimulatedconsiderableinterestandresearchonthesimilarsystemsandcompounds.

stimulate(stimulus,

sting,distinguish)–simulate(similar)Butthiscomplexcouldnotexplainedbythechemicaltheoriesavailableatthattime.

SoitisnecessarytounderstandhowCoCl3andNH3,twostablecompoundsofpresumablysaturatedvalence,couldcombinetogethertomakeanotheryetverystablecompound????

Itisapuzzleandastimulusforchemiststofurtherstudyandresearch.

Buttheanswerwasnottobefounduntilapproximately100yearslater.Duringthatperiodoftime,manysuchcompoundswereprepared;andtheirpropertiesstudied;severaltheorieswereproposedandthendiscarded

Becausetheywereinadequatetoexplainsubsequent/next/followingexperimentaldata.suchaschaintheorybyBlomstrand-Jorgensen—referencethemiddlepartonpage2inyourbook(二).Generally,thepreparationofmetalcomplexesinvolvesthereactionbetweenasaltandsomeotherionsormoleculessuchasH2O,NH3,Cl–(X–),NO2–,NCS–,CN–,……

Forexample:

PtCl2•2NH3/[Pt(NH3)4][PtCl4]

Rrdmannsalt;

Co(NO2)3•KNO2•2NH3/K[Co(NH3)2(NO2)4]

Magnussalt(green).

Atfirst,

eachcomplexwasnamedafterthechemistwhooriginallyprepared.Secondly,thecomplexeswerenamedonthebasisofcolorbecausemanyofthecompoundsarecolored.

Forinstance:

CoCl3•6NH3

luteo/yellowcobalticchloride;

CoCl3•5NH3

purpureo/purplecobalticchloride;

CoCl3•5NH3•H2O

roseo/redcobalticchloride.

Clearly,thesesystemsabovementionedwerenotpracticalandhadtobeabandonedorchanged.

Thecorrespondingnomenclatureofcomplexeswillbediscussedlater.LikethesecomplexesCoCl3•xNH3,theydiffernotonlyintheircolors,butalsointhereactivityoftheirchlorides.Youcanseethisfromthefollowingexperimentalresultsofsuchstudies:

ComlexesnumberofCl–ionsprecipitatedbyAg+CoCl3•6NH33CoCl3•5NH32CoCl3•4NH31Therearetwokindsofchlorides:(i)Onetypeisperhapssimilartothatinsodiumchloride,whichisreadilyprecipitatedasAgCl;

(ii)Theothertypeisheldmorefirmlyandnotprecipitated.(三).Theelectricalconductivityofacomplexsolutioncanalsoprovideusefulinformation

Itcandeterminethenumberofionspresentedinsolutionofdifferentcomplexes.Underthesamecondition(suchasthesameconcentration),comparingtheelectricalconductivityofdifferentcomplexes,wecanestimatethenumberofions

ineachcomplexsolution.ComlexesPtCl4•6NH3

PtCl4•5NH3PtCl4•4NH3molarelectricalConductivity(欧姆obm-1)523404

229estimatedresults(numberofionsinsolution)5[Pt(NH3)4]4+,4Cl–4[Pt(NH3)4]3+,3Cl–3[Pt(NH3)4]2+,2Cl–

Forexample:(四).Anotherimportantpropertyearlyobservedwasthatcertaincomplexesexistinseveraldifferentformsbuthavingthesamechemicalcomposition(whicharecalledisomers).

Forinstance:CrCl3•6H2O:

green

[CrCl2(H2O)4]Cl•H2O

violet

[Cr(H2O)6]Cl3

bluegreen

[CrCl(H2O)5]Cl2•H2OPtCl2•2NH3

Cream(lightyellow)

[Pt(NH3)4][PtCl4](α,βforms)Theydifferinsolubility,chemicalreactivity,etc.In

general:

(i)Itwasnecessarytoaccountforalloftheseexperimentfactsabovewithasuitabletheory.

(ii)Inhistory,severalhypothesesandtheorieswereproposedbutprovedtobewrong,andonlyonetheory……1-2-2．Werner’scoordinationtheory

Ourpresentunderstandingtothenatureofmetalcomplexesisduetotheingeniousinsightoftheperson

AlfredWerner,

professorofchemistryinZurich,Swiss;thewinnerofaNobleprizein1913.In1893,attheageofonly26,heproposedwhatisnowcommonlyreferredtoas“Werner’scoordinationtheory”.Thetheoryhasbeenaguidingprincipleininorganicchemistry.

Itincludesthreemainpostulatesorhypotheses:1.

Mostelementsexhibittwotypesofvalence:

(1)primaryvalence

(correspondingtotheoxidationstate)

(2)secondaryvalence

(correspondingtothecoordinationnumber).

2.

Everyelementtendstosatisfybothitsprimaryandsecondaryvalence.3.

Thesecondaryvalenceisdirectedtowardsfixedpositionsinspace.(thisisthebasisofthestereochemistryofcomplexes)Let’sexplainthemwithexamples:(1)CoCl3•6NH3

primaryvalence3,Ⅲ,Co(Ⅲ)secondaryvalence6(NH3)HereCo(Ⅲ)isalreadysurroundedbysixammonias,sothechlorideions(Cl–)arefartherfromthemetalionandaren’tfirmlybound.

Thusasolutionofsuchcomplexeshasfourions,andthreeCl–arereadilyprecipitatedbyAg+assilverchloride.(2)CoCl3•5NH3primaryvalence2,Ⅱ,Co(Ⅱ)secondaryvalence5(NH3)Accordingtopostulate2,thereareonlyfiveNH3.Soonechlorideionmustserveduelfunctionsforsatisfyingboth.Whenfrontedwith

(3)CoCl3•3NH3

(formulatedas[Co(NH3)3Cl3])

theWerner’stheorypredictedthecompoundwouldnotyieldCl-ionsolution.Theexperimentalresultsconfirmedtheconclusion.

ThisprovedthattheWerner’stheorywasright.

Postulate3ofWerner’stheorydealsspecificallywiththestereochemistryofcomplexes.

Itcorrectlyexplainsmanyofthestructuralfeaturesofcoordinationcompounds.

Oneparticularlyimportantcontributionwas

thedeterminationofthestructureofsix-coordinatedcomplexes.

Beforethediscoveryofxrays,thespatialconfigurationofmoleculeswasdeterminedbycomparingthenumberofknownisomerswiththenumbertheoreticallypossible.

Bythisway(andotherevidencesuchasopticalactivity),itcanprovethatcertainstructureswerewrongandobtainevidenceinsupportofaparticularconfiguration.

Wernersuccessfullyusedthismethodtodemonstratethatsix-coordinatedcomplexeshaveanoctahedralstructure:n☆

planartrigonalprismoctahedralMA5B1111MA4B223(12,13,14)3(12,14,16)2(12,16)MA3B323(123,124,3(123,124,2(123,126)135)126)NOTE:n☆numberofknowncomplexisomers1-3.NomenclatureAcomprehensivesystemofnomenclatureofcoordinationcompoundswasnotpossiblepriortoWerner’scoordinationtheory.

Afterpeoplerealizedthatcoordinationcompoundsareeithersaltsornonionicspecies.Theycoulddeviseasystematicschemefornamingordesignatingthem.Salts

usuallyusingatwo-word

nameNonioniccompounds

usinga

one-wordnameForexample:

[Co(NH3)6]Cl3

Hexaamminecobalt(Ⅲ)chloride(salt)

[Pt(NH3)2Cl2]

Dichlorodiammineplatium(Ⅱ)(nonion)Amongthem,Romannumeralsinparenthesesisusedtoindicateoxidationstatesofthemetallicion/atom.Notice:

theArabicnumeralsⅠ,Ⅱ,Ⅲ….Squarebrackets[];anglebrackets<>;roundbrackets();single“(”or”)”iscalled“parenthesis”or“roundbracket”.

1.orderoflisting(排列)ions:Likenamingasalt,thecationisnamedfirst,andthentheaniononthecontraryofChinesenames.Forexample:

[Cr(NH3)6](NO3)3

hexamminechromium(Ⅲ)nitrate

K2[PtCl6]potassium

hexachloroplatinate(Ⅳ)2.nonioniccomplexes:Likingnaminganonioniccompound,nonioniccomplexesaregivenaone-wordname.Forinstance:

[Co(NH3)3(NO3)3]

Trinitrotriamminecobalt(Ⅲ)

[Cu(CH3COCHCOCH3)2]

bis(acetylacetonato)copper(Ⅱ)(notice:acetylacetonate

乙酰丙酮基)3．Namesofligands:orderofligands:

neutral

ligandsnamedasmolecule;

negative

ligandsendin-o;

positive

ligandsendin

-ium

(rare)

Notice:

en

(NH2CH2CH2NH2)

ethylenediamine;

(C6H5)3P

triphenyphosphine;

Cl

chloro-;

CH3COO-

acetato-

twoexceptionstotherule:

H2Oaquo;

NH3ammine

(otheraminesarespellingwithone“m”)Theligandsinacomplexarearrangedintheorder:

(1)negative→(2)neutral→(3)positiveandinorderofincreasingcomplexity.Examples:[Pt(NH3)4(NO2)Cl]SO4

chloronitrotetraammineplatinum(Ⅳ)sulfate

(NH4)[Cr(NH3)2(NCS)4]

ammonium

tetrathiocyanatodiammine-chromate(Ⅲ)Note:

(i)Beforesimpleligandssuchaschloro-,bromo-,nitro-,oxalato-,…Theprefixesmono-,di-,tri-,tetra-,…areused;

Thecomplexligands

bis,tris-,tetrakis-,…areused.

Examples:

en

ethylenediammine

K3[Al(C2O4)3]

potassium

trioxalatoaluminate

[Co(en)2]2SO4

dichlorobis(ethyldiammine)cobalt(Ⅲ)

(ii)Terminationofnamestheendingofanioniccomplexesis“-ate”(alternatively“-ic”).Examples:

Ca2[Fe(CN)6]calcium

hexacyanoferrate

(Ⅱ)

[Fe(H2O)6]SO4

hexaaquoiron(Ⅱ)sulfate

[Ni(DMG)2]

bis(dimethylglyoximato)nickel(Ⅱ)DMG

dimethylglyoximate,

二甲基乙二肟阴离子)4.oxidationstates:

Theoxidationstateofacentralatomisdesignatedby

aRomannumeral

inparenthesesattheendofthecentralatom.

Forapositiveoxidationstate,nosignisusedbeforetheRomannumeral(mostofcomplexes);butnegativeforminusand0forzero(butveryfew).

Examples:[Co(en)2]2SO4

dichlorobis(ethyldiammine)cobalt(Ⅲ)

Na[Co(CO)4]

sodiumtetracarbonyl

cobaltate

(-Ⅰ)

K4[Ni(CN)4]

potassiumtetracyano

nickelate

(0)

5.bridginggroups: