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Wednesday, July 3, 2019

Structure of phosphorous trioxide (P4O6) and phosphorous pentaoxide (P4O10) :

Phosphorous is a pentavalent element hence show +3 and +5 oxidation state (d orbital presence).it form two oxide P2O3 (+3) and P2O5 (+5). These oxide of phosphorus exist as dimer in form of P4O6 (+3) and P4O5

Comparative Study of P4O6 and P4O10 :

SN
Properties
P4O6
P4O10
1
Hybridisation (P) atom
 Sp3
Sp3
2
Hybridisation (O) atom
Sp3
Sp3 /Sp2 of Vertex (O)
3
No of Bridge bond (P-O-P)
6
6
4
No of Six member ring
4
4
5
No of Total  (l.p.)
16
20
6
No of Back Bond
0
4
7
No of P(pi)-P(pi) Bond
0
0
8
No of 2P(pi)-3d(pi) Bond
0
4
9
Longer (P-O) Bond
All are equal
12
10
Shorter (P-O) Bond
All are equal
4
11
Bond Length (P-O)
166 pm (Longer)
145 pm (shorter)
12
Bond Angle (O-P-O)
99.5 =100 (smaller)
102 (bigger)
13
Bond Angle (P-O-P)
127 (bigger)
123 (smaller)
14
No of Sigma Bond
12
16
15
No of (Pi) Bond
0
4
16
No of oxygen atom attached with( P)
3

4

Common feature of P4O6 and P4O10 :

(1) Both oxides have closed cage like structure.
(2) Both oxides contain six (P-O-P) Bond.
(3) Both oxide have 4 six member ring.
(4) Both are the anhydride of their respective acids.
(5) Both are Non planer

Explanation of Different Bond length and Bond Angle In P4O6 and P4O10 :
(1) According to "Bent's rule" lone pair electron  prefer to Stay to in those atomic hybrid orbitals have more % s-character.
(2) In case of P4O6 molecules, atomic hybrid orbitals containing lone pair electrons have more (s) character and less (p) character hence shorter bond length while remaining orbitals have less (S) character and more (p) character hence longer bond length (X1) than (X2) in P4O10 .
(3) We know that On increasing % s character in hybrid orbital, the bond length decreases while bond angle increases.
(3) In Case of P4O (O-P-O) bond angle is smaller due to higher p-character in atomic hybrid orbitals than orbital containing (O-P-O) in P4O10. (have more s-character )
For reading more Details about  click on  Bent Rule and Drago’s rule 

Related Questions:



Trisilyl amine, N(SiH3)3 is planar whereas trimethyl amines N(CH3)3 is pyramidal. Explain why?.















1 comment:

  1. Excellent comparison phosphorous oxides thank you so much chemzipper!!

    ReplyDelete