CO的分子轨道能级图 co 40 LUMO 2n 2p 2p 2π 一2力 HOMO 50 3 2s 1π 水 gll'. 2s -.l-15 9 C CO 图」C0分子轨道的能级图 (1σ)2(2o)2(36)2(4σ)2(1π)4(5o)2 一个0键 C- :C三O: 两个π键 11
CO 的分子轨道能级图 一个σ键 :C O: 两个π键 (1σ)2 (2σ)2 (3σ)2 (4σ)2 (1π)4 (5σ)2 11
金属羰基化合物的反馈键(back bond)生成示意图 M CO的HOMO为o给体（碱） CO的LUMO为π受体（酸） 12
CO的HOMO为V给体(碱) CO的LUMO为S受体(酸) 金属羰基化合物的反馈键(back bond)生成示意图 12
MOLECULAR ORBITALS NITRIC OXIDE-NO NO的分子轨道能级图 62p □h 个个个 个个2p 115pm 2p 一个σ键， 田四 一个π键， T2p 一个三电子π键 02s 117pm/ 2s 136 YNo =1687cm-1 弯曲型 2s 185.9 2.4P 2s C1236.Ru2 243.y173.8 N62 YNo =1845cm- 直线型 ground state NO (1σ)2(2o)2(3o)2(4σ)2(1π)4(5o)2(2π)1 13
(1σ)2 (2σ)2 (3σ)2 (4σ)2 (1π)4 (5σ)2 (2π)1 一个σ键， 一个π键， 一个三电子π键 13 NO 的分子轨道能级图 1 1845 J NO cm 1 1687 o J NO cm 136 116.2 173.8 242.4 243.4 236.5 185.9 117pm O P N Cl P O N Ru 弯曲型 直线型
Electron Counting Schemes for Common Ligands Ligand Method A Method B 2(:H) Method A:Donor Pair Method F Cl.Br.I 2(:X:) Fe(II) 6 electrons OH 2(::H) n5-C5H57 6 electrons CN 2(:CN:~) 2(CO) 4 electrons CH3 2(:CH3) 2 electrons NO(bent M-N-O) 2(:N=) Total =18 electrons CO,PR3 2 NH3,H2O 2 CRR'(carbene) 3 HC=CH2 2 2 =0,=S 4(:9:2,5:2)1 2 NO (linear M-N-O) 2(:N=O:*) 3 n3-C3Hs 2(C3H5) i Fe atom 8 electrons =CR(carbyne) 3 in5-CsHs 5 electrons ≡N 6(N3) 12(CO) 4 electrons butadiene 4 1 electron n5-CsHs 6(CsH5） 5 Total 18 electrons n5-CsHs 6 6 Method B:Neutral Ligand Method n7-CjHz 6(CH,*) 14 (Donor pair) (Neutral ligand)
14 (Donor pair) (Neutral ligand) Phnp z
NOTE:In applying the 18-electron rule,metal ions are always considered to be zero-valent,not the formal oxidation state! [Ni(CO)4] [Fe(CO) [Cr(CO)] Ni(0)= d10 Fe(0)= da Cr(0)= d6 4XC0= 8 5x CO 10 6XC0=12 18e 18e 18e To obey the 18-electron rule,many carbonyl complexes are anions or cations: [V(CO)] [Mn(CO)]* [Fe(Co)42- V(0)=d5 Mn(0)=d7 Fe(0)=d8 6C0=12e 6C0=12e 4C0=8e 1- =+1e 1+ =-1e 2- -2e =18e =18e =18e Formal oxidation Formal oxidation Formal oxidation 15 state V(-I) state Mn(I) state Fe(-II)
To obey the 18-electron rule, many carbonyl complexes are anions or cations: NOTE: In applying the 18-electron rule, metal ions are always considered to be zero-valent, not the formal oxidation state! 15