i.BsH1(戊硼烷pentaborane) 网式戊硼烷 Arachno structure three center two electron bond B:sp3hybridization Ψ=CaΨ1+CΨB2+CΨB3 its sepular equation ER-E 6 B B Es-E B =0 B B Ep-E solve seqular equation B E=Eg+28 (bonding) E2 =E3=E8-B (anti-bonding) B 1 向心式中心键 %=后wm+w:+wa） 3center-2electron bonds a bonding orbital ii. B5H11（戊硼烷 pentaborane） 0 E - E E - E E - E its sepular equation : B : sp hybridization three center two electron bond : B B B 1 2 3 3            ca B cb B ca B a bonding orbital ( ) 31 E E (anti - bonding) E 2 (bonding) seqular equation 1 1 2 3 2 3 1 B B B B B E E solve               B B B 3center-2electron bonds 向心式三中心键 Arachno structure 网式戊硼烷