化学竞赛杂化轨道理论课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,18.1 Theory of hybrid orbital,杂化轨道理论,分子轨道理论 价键理论,化学键理论,价电子离域,价电子定域在两原子之间或成为孤对电子,每个原子提供一个价电子和一个轨道重叠成键,18.1 Theory of hybrid orbital,1,Each,bond arises from the overlap of an H1,s,orbital with one of the O2,p,orbitals.This model suggests that the bond angle should be 90,which is significantly different from the experimental value.,104.5,C,2v,O,H,H,2s,2p,Pure p orbitals,2s,2p,O,2H,H,2,O,O,H,H,Why do atomic orbital need hybridization?,为什么要杂化？,Each bond arises from the ov,2,sp,3,2s,2p,O,2H,O,*,sp,3,Linus Pauling,Hybridization(1931),sp32s2pO2HO*sp3Linus PaulingH,3,Simplified MO diagram of diatomic molecules,分子轨道理论,Energy,2s,2s,1,g,1,u,2p,2p,2,g,2,u,1,u,1,g,p,z,HOMO,LUMO,N,2,:,KK(3),2,(4),2,(1),4,(5),2,Simplified MO diagram of diato,4,Hybridization of 2s and 2p 2s,和,2p,的杂化,Boundary surfaces of,(a)2s+2p,(b)2s-2p,Hybridization of 2s and 2p 2,5,Energy diagram for X,2,:(a)with hybridization and(b)without 2s-2p,z,hybridization.The 1s orbitals are left out.,(a),(b),Energy diagram for X2:(a)wit,6,2.Construction of hybrid orbitals,杂化轨道的构造,If we begin with,n,AOs,we must end up with,n,orbitals after hybridization.,n,个原子轨道杂化得到,n,个杂化轨道,All,n,hybrids are equivalent except for directionality,same energy.,所有的杂化轨道能级相同，但方向不同,2.Construction of hybrid orbi,7,a.sp hybridization(linear species)sp,杂化，直线型,One s and one p AO mix to form a set of two hybrid orbitals.,sp,=180,linear,Normalization and orthogonality,a.sp hybridization(linear s,8,1s,1s,2 H,Hybridization,The promotion energy can be considered a part of the energy required to form hybrid orbitals.,The overlap of the hybrid orbitals on Be with the 1s orbitals on the H atoms gives two Be-H(sp)-1s,bonds oriented 180from each other.,Be*(sp),2s,2p,Be,Be*,BeH,2,sp,2p,1s1s2 HHybridizationThe promot,9,One s and two p(p,x,and p,y,)AOs mix to form a set of three hybrid orbitals.,b.sp,2,hybridization(trigonal planar),sp,2,杂化，平面三角形,sp,2,D,3h,=120,triangular,f=1.991,，,=1/3,h1,h2,h3,x,y,One s and two p(px and py)AO,10,A trigonal planar molecule and sp,2,hybridization:the bonding in BH,3,2s,2p,B,B*,BH,3,sp,2,hybrid,p,orbital,1s,1s,1s,3 H,B*,sp,2,2p,A trigonal planar molecule and,11,h1,h2,h4,h3,z,One s and 3 p AOs mix to form a set of four hybrid sp,3,orbitals.,sp,3,hybrides(tetrahedral),sp,3,杂化，四面体,h1h2h4h3zOne s and 3 p AO,12,CH,4,2s,2p,1s,1s,1s,1s,C,4 H,C*,sp,3,C*(sp,3,),This gives four sp,3,orbitals that are oriented in a tetrahedral fashion.The overlap of the sp,3,hybrid orbitals on C with the 1s orbitals on the H atoms gives four C-H(sp,3,)-1s,bonds oriented 109.5 from each other.,CH42s2p1s1s1s1sC4 HC*sp3C*(sp,13,h1,h2,x,y,h3,h4,h5,z,dsp,3,(sp,3,d)hybrides(trigonal bipyramidal),dsp,3,(sp,3,d),杂化，三角双锥,The bond lengths will not be the same because there is more d contribution to the axial hybrid orbitals.,h1h2xyh3h4h5zdsp3(sp3d),14,h1,h2,x,y,h3,h4,h5,z,The bond lengths will not be the same because there is more d contribution to the axial hybrid orbitals.,平面和轴向轨道是不等价的。,In the case dsp,3,the axial bond length is shorter,While it is longer in the case sp,3,d,（,dsp,3,杂化,轴向键长较短，,sp,3,d,杂化则较长,h1h2xyh3h4h5zThe bond len,15,PF,5,3s,3p,P,P*,3d,P*(,sp,3,d),3d,We need hybrid orbitals suitable for bonds to 5 atoms.,n,s and,n,p combinations can only provide four,so we need to use,n,d orbitals,(if they are available),.,3d,z,2,3p,z,3p,y,3p,x,3s,sp,3,d,z,2,The appropriate mixture to form a trigonal bipyramidal arrangement of hybrids involves all the,n,s and,n,p orbitals as well as the,n,d,z,2,orbital.,PF53s3pPP*3dP*(sp3d)3dWe need,16,Valence bond theory treatment of a trigonal bipyramidal molecule:the bonding in PF,5,F,2s,2p,F,2s,2p,F,2s,2p,3d,P*(,sp,3,d),F,2s,2p,F,2s,2p,The overlap of the sp,3,d hybrid orbitals on P with the 2p orbitals on the F atoms gives five P-F(sp,3,d)-2p,bonds in two sets:the two,axial,bonds along the z-axis(180 from each other)and three,equatorial,bonds in the xy plane(120 from each other and 90 from each axial bond).,This means that the 5 bonds are not equivalent!,Valence bond theory treatment,17,Square planar:D,4h,h,1,x,y,h3,h,2,h4,Eg.Ni(CN),4,2-,dsp,2,hybrides(square planar),dsp,2,杂化，平面四边形,Square planar:D4hh1xyh3h2,18,5,1,2,3,4,6,x,y,z,d,2,sp,3,(sp,3,d,2,)hybrides(Octahedral),d,2,sp,3,(sp,3,d,2,),杂化，八面体,512346xyzd2sp3(sp3d2)hybride,19,SF,6,The overlap of the sp,3,d,2,hybrid orbitals on S with the 2p orbitals on the F atoms gives six S-F(sp,3,d,2,)-2p,bonds 90 from each other,that are equivalent,.,You can figure out the normalization coefficients.,3d,z,2,3p,z,3p,y,3p,x,3s,sp,3,d,2,3d,x,2,-y,2,3s,3p,S,S*,3d,S*(,sp,3,d,2,),3d,F,F,F,F,F,F,SF6The overlap of the sp3d2 hy,20,Hybridization schemes,sp,n,d,m,gives a“complete”set of hybrid orbitals for“any”geometry.,sp,Linear,直线,sp,2,Trigonal planar,平面三角形,sp,3,Tetrahedral,四面体,sp,3,d(d,z,2,),Trigonal bipyramidal,三角双锥,sp,3,d(d,x,2,-,y,2,),square-based pyramidal,四方锥,sp,3,d,2,Octahedral,八面体,sp,2,d,Square planar,平面四边形,Hybridization schemesspndm giv,21,Valence bond theory treatment of,p,-bonding,p,-,键