The structure of boranes B:one sp3 orbital from each boron overlaps a hydrogen's 1s orbital to give a three center bond to which two electrons are assigned(三中心两电子键).(B-H-B bridge) H H H denote: B B H H sp SD 要点：B的杂化方式， 三中心两电子键、氢桥
• The structure of boranes B: one sp3 orbital from each boron overlaps a hydrogen’s 1s orbital to give a three center bond to which two electrons are assigned (三中心两电子键). (B-H-B bridge) denote： H H B B H H H H 要点：B的杂化方式， 三中心两电子键、氢桥
The structure of BHo molecule B:sp3 hybridization Note:a B-B bond 119pm H B 143pm 137pm H 110pm B (a) (b)
The structure of B4H10 molecule 119pm 110pm 137pm 143pm 122。 171pm H B ( b ) B B B B H H H H H H H H H H H ( a ) B: sp3 hybridization Note: a B-B bond
The chemistry properties of boranes ①auto ignition(自燃) B2H6(g+302(g)→B2O3(S)+3H,O(g) △1品=-2034kJ-mol high energy fuel,.virulent(剧毒) with a green flame Borane burning ②hydrolysis B2H6(g)+3H200→2H3B03(S)+6H2(g) △rH=-509.3kJ.mol 水下火箭燃料
• The chemistry properties of boranes ① auto ignition (自燃) high energy fuel, virulent(剧毒） ② hydrolysis with a green flame Borane burning B H (g) 3O (g) B O (s) 3H O(g) 2 6 + 2 ⎯→ 2 3 + 2 B H (g) 3H O(l) 2H BO (s) 6H (g) 2 6 + 2 ⎯→ 3 3 + 2 △ rHm = -509.3kJmol-1 水下火箭燃料 △ rHm -1 = -2034kJmol
3 addition reaction (empty orbit) B,H。+C0→2[HB←C0] B2H6+2NH3→BH2·NH3)2]+BH4] 2LiH+B,H6→2LBH4 2NaH+B2H.→2NaBH, Good reducing agent ④chlorizated by Cl2 B2H.(g)+6C12(g)>2BC13(1)+6HCI △rH=-1376 kJ.mol D
③ addition reaction (empty orbit) B H CO 2[H B CO] 2 6 + ⎯→ 3 ④ chlorizated by Cl2 B H (g) 6Cl (g) 2BCl (l) 6HCl 2 6 + 2 ⎯→ 3 + -1 △ rHm = -1376kJmol 2NaH + B2 H6 ⎯→2NaBH4 2LiH + B2 H6 ⎯→2LiBH 4 + − B H + 2NH ⎯→[BH (NH ) ] +[BH ] 2 6 3 2 3 2 4 :C O: Good reducing agent
2.Oxygen compounds of boron ①Boric oxide(B,O3) Structure:1)atomic crystal m.p 460C 2)amorphism:get soften when TT 02 +H,0 B(amorphism)≥ B203H0 HBO2 +H20 H.BO: Mg or Al metabrie acid-H20上 boric acid 偏硼酸 Preparation: 4Bs)+30,gA2B,0,6 2H,B0,A→B,0,+3H,0
① Boric oxide ( B2O3 ) O2 +H2O B(amorphism) B2O3 H3BO3 Mg or Al -H2O Preparation： 2H BO B O 3H O 4B(s) 3O (g) 2B O (s) 3 3 2 3 2 2 2 3 ⎯⎯→ + ⎯⎯→ + 1）atomic crystal ：m.p 460C 2）amorphism：get soften when T 2. Oxygen compounds of boron Structure： boric acid HBO2 +H2O metaboric acid -H2O 偏硼酸