The transition elements (d block) and inner transition e.ppt

thetransitionelements dblock andinnertransitionelements fblock intheperiodictable transitionmetalchemistryonestrikingcharacteristicoftherepresentativeelementswasthattheirchemistrychangesmarkedlyacrossagivenperiodasthenumberofvalenceelectronschanges thechemicalsimilaritiesoccurmainlywithintheverticalgroups incontrast thetransitionmetalsshowgreatsimilaritieswithinagivenperiodaswellaswithinagivenverticalgroup why transistionmetalschemistry electronconfigurationthisdifferenceoccursbecausethelastelectronsaddedtothetransitionmetalelementsareinnerelectrons delectronsforthed blocktransitionmetalsandfelectronsforthelanthanidesandactinides theseinnerdandfelectronscannotparticipateinbondingasreadilyasthevalencesandpelectrons thus thechemistryoftransitionelementsisnotasgreatlyaffectedbythegradualchangeinthenumberofelectronsasisthechemistryoftherepresentativeelements alsonotethatthetransitionmetalsdonotextendallthewayacrossthed blockbecausethegroup12elements zinc cadmium andmercury arenotnormallyconsideredtobetransitionelements becausetheird orbitalsarefull thegroup12elementshavepropertiesthataremorelikethoseofmain groupmetalsthantransitionmetals solution electronconfigurationsoftransitionmetalatoms ions a zristhesecondelementinthe4dseries kr 5s24d2 b visthethiredelementinthe3dseries ar 4s23d3 informingv3 threeelectronsarelost two4sandone3d sov3 isad2ion ar 3d10 c moliesbelowcringroup6b 6 soweexpectthesameexceptinconfigurationasforcr thus mois kr 5s14d5 informingtheion molosestheone5sandtwoofthe4delectronstobecomea4d3ion kr 4d3 transitionmetals electronconfigurationwritetheelectronconfigurationforthefollowingtransitionmetals ions a crb ptc tc 4d ir e ru 4f mo 2g co 3 transitionmetalchemistrysowhatcharateristicscanweexpectwithtransitionelements 1 variableoxidationstatesexceptforthefirst lastcolumn thecentralgrouphavingthemostvariety 2 allthed blockelementsaremetals mostofthese d metals aregoodelectricalconductors malleable ductile andlustrous generally theirmeltingandboilingpointsarehigherthanthoseofthemain groupelements theyare hard metalsexceptforzn 3 thelowoxidationstateionsaregenerallygoodreducingagents theyundergooxidation andall3delementsreduceh exceptcu recalltheactivityseries m mn ne theperiod4transitionmetals transitionmetalchemistry 4 theatomicradiiofthesecondrowofd metalsaretypicallygreaterthanthoseinthefirstrow theatomicradiiinthethirdseries period6 however areaboutthesameasthoseinthesecondrowandsmallerthanexpected thiseffectisduetothelanthanidecontraction whichisthedecreaseinradiusalongthefirstrowofthef block thisdecreaseisduetotheincreasingnuclearchargealongtheperiodcoupledwiththepoorshieldingabilityofthef electrons whenthed blockresumes atlutetium theatomicradiushasfallenfrom224pmforbariumto172pmforlutetium 3d 4d 5d horizontaltrendsinkeyatomicpropertiesoftheperiod4elements transitionmetalchemistry 5 periodicitytheatomicradiusdecreasesacrossaperiodreachingaconstantsizeduetoshieldingbytheotherelectrons electronegativitygenerallyincreasesacrossaperiodslightly ionizationenergygraduallyincreasesacrossaperiod atomicsizeandoxidationstatehasamajoreffectonthenatureofbonding ionicbondingismoreprevalentforloweroxidationstateionsandcovalentbondingispreferredforthehigherstates verticaltrendsinkeypropertieswithinthetransitionelements generalpropertiesoftransitionmetalionssc scandium rareonearth foundinelectronicdevicessc3 ti titanium 0 6 bymassonearth lowdensity highstrength tio2isanopaquematerialusedasapigment ti h2o 63 isapurplesolution v vanadium 0 025bymass usedinalloys asacatalystv2o5vo2 5 yellowvo2 4 bluev3 3 blue greenv2 2 violetcr chromium hard brittle lustrous formsaninvisibleoxidecoating manycoloredcompounds mostcommonoxidstates 2 3 6cr2 chromous brightblue powerfulreducingagentcr3 cr2o3 darkgreensolidthatdissolvesinwater cr h2o 6 2cr6 chromic oxidizingagent cro42 cr2o72 mn manganese 0 1 bymass usedtoproducehardsteel mn h2o 62 islightpink andmno4 isdeeppurple astrongoxidizingagent fe iron 4 7 bymass whitelusterous fairlysoft andhighlyreactive fe h2o 63 isayellowsolutionthatisquiteacidic generalpropertiesoftransitionmetalionsco cobalt relativelyrare hard bluish whitemetalusedtomakealloys co h2o 62 isrosecolored ni nickel abundant silver whitemetalwithhighelectricalcu h2o 6 isgreenzn zinc colorlesssolutions whitelustrous activemetal mainoreissphalerite znfe s reducingagent tarnishesrapidly 90 isusedtogalvanizesteel zn2 transitionmetalchemistry indepth informingioniccompoundswithnonmetals thetransitionmetalsexhibitseveraltypicalcharacteristics 1 variousoxidationstatescanbefounddependingontheplacementofthetransitionmetals elementsattheendsofeachrowoccurinonlyoneoxidationstateotherthanzero exception mercury mostotherelementshaveatleasttwooxidationstatesotherthanzero andelementsclosertothecenterofeachrowhavethewidestrangeofoxidationstates furthermore elementsinthesecondandthirdrowsaremostlikelytoreachhigheroxidationstatesthanthoseinthefirstrow transitionmetalchemistry indepth 2 anelementwithahighoxidationislikelytobeagoodoxidizingagent compoundsthatcontainthetransitionmetalelementinalowoxidationstateareoftengoodreducingagents 3 cationsareoftencomplexions speciesinwhichthetransitionmetalionissurroundedbyacertainnumberofligands moleculesorionsthatbehaveaslewisbases thesecomplexeshavethreemajorcomponents acentralmetalatom ligands andcounterions identifyeachcomponentinthefollowingcomplexes k4 fe cn 6 co nh3 6 br3wewillstudytheseinmoredetaillater orbitaloccupancy mostcommonstatesinboldface someoxidationstatesofmanganese aqueousoxoanionsoftransitionelements oneofthemostcharacteristicchemicalpropertiesoftheseelementsistheoccurrenceofmultipleoxidationstates 4 mosttransitionmetalcompoundsarecolored becausethetypicaltransitionmetalioninacomplexcanabsorbvisiblelightofspecificwavelengthsduetoanunpairedd orbitalelectronorelectrons exceptions mno4 ispurpleandcro4 2isyellow complementarycolorsappearinthecolorwheelshownbelow wecanseefromthecolorwheelthat ifforinstance asubstancelooksblue asdoescopper ii sulfatesolution thenitisabsorbingorangelight 580to620nm transitionsbetweend orbitalsorbetweentheligandsandthemetalatomincomplexesgiverisetocolor moreover transitionmetalcompoundsthatdonotexhibitcoloreitherhaveanemptyd orbital sc3 orti4 orafilledone zn2 anartist swheel thebrightcolorsofchromium vi compounds colorsofrepresentativecompoundsoftheperiod4transitionmetals titaniumoxide sodiumchromate potassiumferricyanide nickel ii nitratehexahydrate zincsulfateheptahydrate scandiumoxide vanadylsulfatedihydrate manganese ii chloridetetrahydrate cobalt ii chloridehexahydrate copper ii sulfatepentahydrate metalcomplexesandcoordinationcompoundsspeciessuchas co nh3 5cl 2thatareassembliesofacentralmetalionbondedtoagroupofsurroundingmoleculesorionsarecalledmetalcomplexesormerelycomplexes ifthecomplexcarriesanetcharge itisgenerallycalledacomplexion compoundsthatcontaincomplexesareknownascoordinationcompounds themoleculesorionsthatsurroundthemetalioninacomplexareknownasligands ligandscoordinate orbond toametalatomoriontoformacoordinatecovalentbond noticethatthisbondisdifferentthananordinarycovalentbond whereelectronsaresharedbetweentwojoiningspecies inthecoordinatecovalentbond bothelectronsusedtogeneratethebondarepropertyoftheligandandnotthemetal asaturatedcomplexfullfillsthe18e rule componentsofacoordinationcompound ligandsarenormallyeitheranionsorneutralpolarmolecules everyligandhasatleastoneunsharedpairofvalenceelectronstodonate furthermore theycanbrokendownintothefollowingcategories monodentateligandexamples bidentateligandexamples polydentateligandexamples whentheseligandsarebonded chelated toaparticularmetal wecandefinethecoordinationnumberasthenumberofdonoratomstowhichthemetalisbonded somemorebidentateligands co32 carbanatono3 nitratoso42 sulfato namesofmonodentate aqua ammine fluoro chloro cyano thiocyano hydroxo nitro considereachcoordinationcomplexlistedbelowandanswerthefollowingquestions whatistheoxidationstateofthemetal whatisthetotalnumberofvalenceelectronsaroundthemetal determinethecoordinationnumberforeachcomplex d isthecomplexsaturatedorunsaturated e areanyligandspolydentate ifso identifytheseligands 1 cocl2 en 2 5 cr edta 2 cr ox 3 3 3 zncl4 2 4 ni cn 5 3 namingcoordinationcompounds1 innamingsalts thenameofthecationisgivenbeforethenameoftheanion forexample in co nh3 5cl cl2 wename co nh3 5cl 2 beforecl 2 withinacomplexionormolecule theligandsarenamedbeforethemetal ligandsarelistedinalphabeticalorder regardlessofchargeontheligand prefixes seerule 4below thatgivethenumberofligandsarenotconsideredpartoftheligandnameindeterminingalphabeticalorder consideronceagainthe co nh3 5cl 2 ion nametheammonialigandfirst thenthechloride followedbythemetal pentaamminechlorocobalt iii 3 thenamesoftheanionicligandsendintheletter o whereasneutralonesordinarilybearthenameofthemolecules specialnamesaregivenforh2o aqua nh3 ammine co carbonyl andno nitrosyl forexample fe cn 2 nh3 2 h2o 2 wouldbenameddiamminediaquadicyanoiron iii ion 4 greekprefixes di tri tetra penta andhexa areusedtoindicatethenumberofeachkindofligandwhenmorethanoneispresentasshownintheexamplesabove iftheligandalreadycontainsagreekprefix asinethylenediamine orifitispolydentate i e abletoattachatmorethanonebindingsite thenthefollowingprefixesareusedinstead 2 bis 3 tris 4 tetrakis 5 ifthecomplexisananion itsnameendsin ate ifthesymbolofthemetaloriginatesfromalatinname thenthelatinstemisusedinsteadforexample thecompoundk4 fe cn 6 isnamedpotassiumhexacyanoferrate ii commonlatinstemlistings inparentheses copper cuprate iron ferrate tin stannate lead plumbate 6 theoxidationnumberofthemetalisgiveninparenthesesinromannumeralsdirectlyfollowingthenameofthemetal problem solution writingnamesandformulasofcoordinationcompounds a whatisthesystematicnameofna3 alf6 b whatisthesystematicnameof co en 2cl2 no3 c whatistheformulaoftetraaminebromochloroplatinum iv chloride d whatistheformulaofhexaaminecobalt iii tetrachloro ferrate iii a thecomplexionis alf6 3 six hexa fluorines fluoro aretheligands hexafluoro aluminumisthecentralmetalatom aluminate aluminumhasonlythe 3ionsowedon tneedromannumerals sodiumhexafluoroaluminate writingnamesandformulasofcoordinationcompounds b therearetwoligands chlorineandethylenediamine dichloro bis ethylenediamine thecomplexisthecationandwehavetouseromannumeralsforthecobaltoxidationstatesinceithasmorethanone iii theanion nitrate isnamedlast dichlorobis ethylenediamine cobalt iii nitrate 4nh3 br cl cl pt4 pt nh3 4brcl cl2 6nh3 co3 4cl fe3 co nh3 6 cl4fe 3 name draweachofthefollowingcompoundslistedbelow a nh4 ptcl3 nh3 b co nh3 6 aucl4 2c cr oh 2 nh3 4 brd co en 3 3 e na2 ptcl2 ox 2 f feoh h2o 5 cl2g sodiumtetrahydroxoaluminateh potassiumhexacyanoferrate ii i dicarbonatodifluorocobalt iii perchloratej hexapyridinenickel ii bromide coordinationcompoundsandtheirisomersthegeometry orshape ofatransitionmetalcomplexdependsonthecoordinationnumberandnatureofthemetalion thefollowingtableoutlinesthevarioustypicalgeometriesalongwithexamplesofeach coordinationnumbershapeexamples2linear cucl2 ag nh3 2 aucl2 4squareplanarmostd8metalions somecanbetetrahedral ni cn 4 2 pdcl4 2 4tetrahedralmostd10metalions cu cn 4 3 cdcl4 2 6octahedral ti h2o 6 3 co en 3 3 makesureandnotethesimilaritywiththemolecularshapesinvseprtheory valencebondtheoryrecallvalencebondtheoryfromlastsemester whereatomicorbitalsmixtoformmolecularorbitals andhybrization orhybridorbitals results splinear sp2trigonalplanar sp3tetrahedral inordinarycovalentcompoundstheorbitalsoverlapwithone 1 fromeachatom atomicorbitalsethybridorbitalsetelectronicgeometrys ptwosplinears p pthreesp2trigonalplanars p p pfoursp3tetrahedrals p p p dfivesp3dtrigonalbipyramidals p p p d dsixsp3d2octahedral valencebondtheoryforcoordinationcomplexestheligands lewisbases donateelectronstothemetal lewisacids toformthecovalentbondinthecomplexresultinginamixingofthes p dorbitalsofthemetal incoordinatecovalentbondstheligandorbital containing2e s overlapswiththeunoccupiedorbitalofthemetal thenumber typeofmetalionhybridorbitaloccupiedbytheligand slonepairofelectronsdeterminesthegeometryofthecomplex valencebondtheory cr nh3 6 3 hexaamminechromium iii ionayellowcomplexisparamagnetic usevalencebondtheorytoexplainthebondingandmagneticpropertiesofthecomplex d3 p s cr3 d andconsider6 nh3thereforeneed6equivalentbonds hybridization dddddspppthe3dmetalelectronsareunhybridizedthusparamagneticandtheligandelectronsfitintotheleftoverhybridizedd2sp3orbitalsofthemetal cn 6thusoctahedral hybridorbitalsandbondingintheoctahedral cr nh3 6 3 ion valencebondtheory ni cn 4 2 usevalencebondtheorytoexplainthebondingandmagneticpropertiesoftheabovecomplex d8 p s ni2 d andconsider4 cnthereforeneed4equivalentbonds hybridization dddddspppthe3dmetalelectronsareunhybridizedthusdiamagneticandtheligandelectronsfitintotheleftoverhybridizeddsp2orbitalsofthemetal cn 4andsquareplanar describe zn oh 4 2 hybridorbitalsandbondinginthesquareplanar ni cn 4 2 ion hybridorbitalsandbondinginthetetrahedral zn oh 4 2 ion importanttypesofisomerismincoordinationcompounds atomsconnecteddifferently differentspatialarrangement coordinationisomersligandandcounter ionexchange linkageisomersdifferentdonoratom geometric cis trans isomers diastereomers differentarrangementaroundmetalion opticalisomers enantiomers nonsuperimposablemirrorimages coordinationisomers pt nh3 4cl2 no2 2 pt nh3 4 no2 2 cl2 linkageisomers co nh3 5 no2 cl2isanorangesolidcalledpentaamminenitrocobalt iii chloride co nh3 5 ono cl2isaredcompoundknownaspentaamminenitritocobalt iii chloride nco cyanatoocn isocyanatos c n thiocyanato justlikeinourstudyoforganicchemistry thereexistisomerswithtransitionmetalcomplexes orcompoundswiththesamechemicalformulabutdifferentproperties wewillfocusbrieflyongeometricisomers orcis trans whenatomsorgroupsofatomsarearrangeddifferentlyinspacerelativetothecentralmetalion considerthefollowingexample cis pt nh3 2cl2 versustrans pt nh3 2cl2 thecis isomerhastheidenticalligandsnexttoeachother thetrans isomerhastheidenticalligandsacrossfromoneanother pleasenotethatthisgeometricalarrangementcanhaveseriousbiologicaleffects forinstance itwasdiscoveredthatthecis isomerisahighlyeffectiveantitumoragent whilethetrans isomerhasnoantitumoractivityoreffect geometric cis trans isomerism enantiomersopticalisomerism nonsuperimposableimages inanoctahedralcomplexion opticalisomersusuallycontainchiralcenters asymmetricalcenters chiralmoleculescanrotatetheplaneoflight thusopticallyactive d dextrorotatoryrightl levoratatoryleft plan solution determiningthetypeofstereoisomerism a pt nh3 2br2 b cr en 3 3 en h2nch2ch2nh2 determinethegeometryaroundeachmetalionandthenatureoftheligands placetheligandsinasmanydifferentpositionsaspossible lookforcis transandopticalisomers a pt ii formsasquareplanarcomplexandtherearetwopairofmonodentateligands nh3andbr cis trans thesearegeometricisomers theyarenotopticalisomerssincetheyaresuperimposableontheirmirrorimages determiningthetypeofstereoisomerism continued b ethylenediamineisabidentateligand cr3 ishexacoordinatedandwillformanoctahedralgeometry sincealloftheligandsareidentical therewillbenogeometricisomerismpossible themirrorimagesarenonsuperimposableandarethereforeopticalisomers drawallthestereoisomersforthefollowing cis co nh3 4cl2 trans co nh3 4cl2 pd nh3 2 no2 2 fe c2o4 2 oh2 2 crystalfieldtheoryrecallvalencebondtheory whereatomicorbitalsmixtoformmolecularorbitals andhybrization orhybridorbitals results whileimportant thistheoryfailstogiveinsightintothecolorsofcoordinationcompoundsandtheirmagneticproperties instead weturntocrystalfieldtheory whichhighlightstheeffectsonthed orbitalenergiesofthemetalionasaligandapproachestoformacoordinatecovalentbond themodelassumesthatacomplexionformsasaresultofelectrostaticattractionsbetweenthetransitionmetalcationandthenegativechargeoftheligands intheisolatedmetalion thedorbitalshaveequalenergiesdespitetheirdifferentorientations crystalfieldtheoryhowever inanelectrostaticfieldofligands thedelectronsarerepelledunequallybecausetheyhavedifferentorientations becausetheseligandsmovealongthex y andzaxes theyapproachdirectlytowardthelobesofthedx2 y2anddz2orbitalsandbetweenthelobesofthedxy dyz anddxzorbitals asaresult theelectronsinthedx2 y2anddz2orbitalsexperiencestrongerrepulsionsthanthoseinthedxy dyz anddxzorbitalsandthusliehigherinenergy therefore wecanillustratethesplittingofthed orbitalenergiesofanoctahedralfieldofligandsinthefollowingmanner thefived orbitalsinanoctahedralfieldofligands crystalfieldtheorythesplittingoforbitalenergiesiscalledthecrystalfieldeffect andtheenergydifferencebetweentheegandthet2gorbitalsiscalledthecrystalfieldsplittingenergy theeglevelinvolvesdz2 dx2 y2andisalongthebondaxis thet2glevelinvolvesdxy dxz dyzandbondingliesbetweentheligandorbitals splittingofd orbitalenergiesbyanoctahedralfieldofligands disthesplittingenergy crystalfieldtheorydifferentligandscreatecrystalfieldsofdifferentstrength therebycausingthed orbitalenergiestosplitdifferently astrong fieldligandleadstoalarger splitting aweak fieldligandleadstoasmaller splitting colorinatransitionmetalcomplexarisesduetotwomainfactors oxidationstateofthemetalionandtypeofligand theeffectofligandonsplittingenergy orbitaloccupancyforhigh andlow spincomplexesofd4throughd7metalions high spinandlow spincomplexionsofmn2 crystalfieldtheoryligandcolorarisesbecauseasubstanceabsorbsonlycertainwavelengthsofincomingwhitelight thespectrochemicalseriesisarankingofligandsintermsoftheirabilitytosplitd orbitalenergies considerthefollowingspectrochemicalseries i br cl f oh h2o scn nh3 en no2 cn coweakfieldligand smaller strongfieldligand larger longerwavelength shorterwavelength highspinlowspin thespectrochemicalseries foragivenligand thecolordependsontheoxidationstateofthemetalion foragivenmetalion thecolordependsontheligand plan solution identifyingcomplexionsashighspinorlowspin theelectronconfigurationoffe2 givesusinformationthattheironhas6delectrons thetwoligandshavefieldstrengthsshownin drawtheorbitalboxdiagrams splittingthedorbitalsintoegandt2g addtheelectron