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如何为分子轨道命名ReviewReviewofatomicorbital(原子轨道CoordinationSymmetryofforceCoordinationSphericalpolarcoordinationWavefunctionSphericalharmonicfunctionYlm(MolecularMolecularOrbitalSymmetryinDiatomic(分子轨道PCoordinationSymmetryofforceCoordinationSymmetryofforceARBZRRaroundthez-axis(关于z-轴旋转对称性LCAOfunctions,withsymmetryaboutthe

rA rALCAOfunctions,angularwavel=1,LCAOfunctions,angularwavel=1, TwoTwoatomsarrangedalongz-axis,combinationofforms M.O.NsinBe3NsinAsinBOnenodearoundthez-axis =Node(=0)aroundthez-BondingOrbital 问题如何命名分子轨

1s,2p3d,成键轨道()还是反键轨道 定义:量子数H原子中(spH原子中(spd=包含分子轴的节面 如何确定分子轨道的?Rotationaroundthez-axiswillRotationaroundthez-axiswillchangetheshapeortheelectrondensitydistributionofthediatomicBRRotationaroundthez-axiswillnotchangetheshapeortheelectrondensitydistributionofthediatomicZAZAzationof ponentofangularLz 0,1,2,Notation: functionfunctionNode01==与角度PropertiesandClassificationofLz 0,1,2,Notation:PropertiesPropertiesandClassificationof Realizationofthetwowaveeiei eiei

Degeneracyof1 …PropertiesPropertiesandClassificationofs–Moleculars–MolecularOrbitalsymmetryinDiatomicpx-py-(dxz-(dyz-dz2– (dxy- (dx2-y2-dx2-y2轨道对“g”and“u”Symmetryin(x(x,y,z)(x,(x,y,z)德文gerade偶德文ungerade奇nter(中心反演Inversionabout “ SymmetryinReflectionaboutthenodeplane节面的镜面反映 分子轨道的类型(分子轨道的类型(命名σAO以“头顶头”方式形成成键轨道σgσu，它们都绕键轴呈圆柱形对称，区别在于有无垂直_于键轴的节_HH2的LUMOσu+=0,关于分子轴无H的HOMO2gπ轨道πu和反键轨道πg它们都有一个包含键轴的节面，区别在π直于键轴的节_乙烯的LUMO:+=1,关于分子轴有1个节

乙烯的HOMO:δAO以“面对面”方式形成成键道δg和反键轨道δu，它们都有两个包_Re2Cl82-中的δ*轨+=2,关于分子轴面有2个节面Re2Cl82-中的δ轨3.43.4HomonuclearDiatomicReviewofmolecularorbitalinhydrogenmolecule 1 1

1J 1J 1Homonucleardiatomicmolecules(同核双原子分子H2,O2, =BA=BAMolecularOrbitalsymmetryinMolecularOrbitalsymmetryinDiatomics–px-py-(dxz-(dyz-dz2– (dxy- (dx2-y2-dx2-y221z, 21z, 2s 2 )y,(2 212)x, 2121)y,(2 212)2x, p2)z,(2 212212ABA2sB12A1sB (1s1s)ABAB2ThemosteffectiveatomicorbitalcombinationsindiatomicIsHe2IsHe2astableIsHe2astable12 1sAB12 1sAB (1s1s) AB22He++4.75eV(458

2.5eV(241定义键级bondorderBO=（成键电子数-反键电子数键 =(N*-

=净成键电子对数

分子中有不成对电子时表现为顺磁性 IsHe2IsHe2astableIsHe2astableAA

(1s1s222 (1s2 B 2He4.75eV(458

2.5eV(241Energylevel 两个因素两个因素••• • ABSequenceforlongbonddiatomicg<EnergylevelO2,2 22Energyleveluu<AABSequenceforshortbonddiatomic

BCNOFE2p-BCNOFE2p-EnergylevelAnalternativewayofunderstandingthedifferentenergylevelBCNOFE2p-The2sand2porbitalsofB,C,NareenergeticallythanthoseofOandF.Sothe2sand2pzmayalsohavelargeoverlaps,whichresul changesinB,C,Ndiatomic

2σu(强反键 ππ2pxσ1σu （1（1）B2（5×2=10电子 (1πu) (1πu)特点：无σ键，只有π1+π1键，BO=1（2）C2：（6×2=12电子 (1πu) (1πu)特点：无σ键，只有π+π键，BO=2，又因弱反1σu不能完全抵销强成键1σg，故BO=2~3。反磁性（3）N2：（7×2=14电子 (1πu) (1πu)注意注意:上述1(1πu)1通常记作(1πu)2,但电子简并轨道;而2清楚地看出简并轨道(1πu)2通常记作(1πu)4.为使初学者暂且用了上述标记特点：σ+π+π，BO=3，反磁性 （4）（4）O2：（8×电子11）KK（σ2s）2(σ*2s）2（σ2pz）KK（σ2s）2(σ*2s）2（σ2pz）2 ）1由于每个π3只相当于半个键，故解释了顺磁性由O分 O O O 键

键长/pm )2 （5）F2：（9×2=18电子GroundGroundstateofneutralandionic2He2doesnotexist,butHe+was24.75eV(4584.75eV(458BondOrder D.E.issmallBondOrder D.E.islarge2However,onlyexistsinflamesoroverheated BondOrder D.E.issmallOnlyexistsinhightemperatureItisparamagnetic,itItisparamagnetic,itisafreeComparisonwithhomonucleardiatomicSymmetryinmoleculesandAttentionRotationaroundz-isstillaquantumInversionaboutthemolecularcenterNo“g”and“u”ReflectionaboutthenodeplanWith“+”and“-”Molecular-orbitalTheoryAlsoAppliestoHeteronuclearDiatomicMolecules异核双原子分子)对成键MO的较大贡献来自电负性较大的原子对反键MO的较大贡献来自电负性较小的原子 引起的能量降低不显著Ground Ground 91.7 91.7 6.11 6.11 1.82 根据能级相近原则，只有

--BO=是名副其实的分子轨道是名副其实的分子轨道其余的基本是F的原子轨道HFVS.“等电子原理 -的分子轨道与N2相似Ground 112.8 11.09Ground 112.8 11.09Ground112.811.090.112 0.112 0.112OCOCCOLookingforthereasonwhyCOisaweakpolar12345C