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Showing posts with label Bridge Bonding. Show all posts
Showing posts with label Bridge Bonding. Show all posts

Tuesday, April 26, 2022

Banana Bond or 3C-2e Bond or Bridge bond or structure of B2H6 and Al2(CH3)6:

(1) Formation of 3C-2e bond in B2H6 is best explain by MOT and total number of bond in B2H6 is 6 (3C-2e=2 and 3C-4e=4)

(2) Bridge bonds are longer than terminal bond because at bridge bonds electrons are delocalized at three centres
(3) Bond energy (441kj/mole) of B-H-B bond is greater than bond energy (381 K j/mole) of   B-H bond.
(4) Hybridization of B atom is sp3, so non planer, and non polar (U=0)
(5)  B2H6 Methylated up to B2H2 Me4
(6) B2H6 is hypovalent molecule hence act as Lewis acid and undergoes two type of cleavage when react with Lewis base:

(A) UNSYMETRICAL CLEAVAGE: 
B2H6 Undergo unsymmetrical cleavage with small size strong Lewis base like NH3 NH2Me and NH (Me) 2 etc.

(B) SYMETRICAL CLEAVAGE:
B2H6 undergoes symmetrical cleavage with large size weak Lewis base like PH3, PF3,Me3N , OEt , OMe3, pyridine , THF , Thiophene , SMe2 ,Set2

Related Questions: 

(1) Why aqueous solution of AlCl3 is acidic in nature ?

(2) What happen when aq AlCl3 react with Acid or Base?

(3) Although anhydrous aluminium chloride is covalent but its aqueous solution is ionic in nature. Why?

(4) Why BF3 do not exist as dimer?. Explain.

(5) Why B-F bond length in BF3 is shorter (130 pm) than B-F bond Iength in BF4- (143 pm)?. Explain.

(6) B-F bond length in BF3 is shorter than B-F bond length in (BF4)- why?

(7) When B2H6 is allowed to react with following Lewis bases, then how may given Lewis base form adduct through symmetrical Cleavage of B2H6.

(8) What is product of reaction between diborane (B2H6) and ammmonia (NH3)?

(9) Why methylation of Diborane (B2H6) replace four hydrogen only ?

(10) What is Use of Boric Acid?

(11) What is use of Orthoboric acids?

(12) What is basicity of "Boric acid" ?

(13) Why Boric acid exist in solid state ?

(14) What is structure of solid Ortho Boric acid ?

(15) What is effect of heat on Borax?

(16) What is the structure of trimetaboric acid and trimetaborate ion?

(17) What is the Sodium per borate ,give the structure and its uses?

(18) Why aqueous solution of borax reacts with two moles of acids ?

(19) What is the molecular formula of Borax ?

(20) Why Boric acid become strong acid in the presence of cis 1,2-diol or 1,3-diol ?

(21) Why Borazine is more reactive than benzene towards Electrophic Aromatic substitution reactions ?

(22) Why Borazine (B3N3H6) is also known as inorganic benzene ?.

(23) Four-center two-electron bond (4C-2e Bond): Structure of AlCl3:

(24) What is the difference between the structure of AlCl3 and diborane?

Tuesday, February 9, 2021

Which of the following has only bridge bond? (A) [BeCl2]n (B) [BeH2]n (C) [SnCl2]n (D) [BeH3]2

The compounds (A) and (B) have only bridge bond.
Related Questions:

(1) What is the difference between the structure of AlCl3 and diborane?

How many of the following has only bridge bond ? (a) (BeH2) solid (b) BeCl2) solid (c) Al2Cl2. (d) B2H6 (e) Fe2Cl6 (f) I2Cl6

The options (A) and (B)  or BeH2 solid and BeCl2 solid have only bridge bond and other also have 2c-2e bonds 




Tuesday, February 2, 2021

What is hydrolysis product of BeCl2 with excess water at room temperature?



Related Questions:

(1) What is the difference between the structure of AlCl3 and diborane?

What is structure of Al2Cl6 and also explain bridge bond in Al2Cl6?

AlCl3 dimmerised to Al2Cl6 by 3C-4e bond bridge bond and Al2Cl6 is neither hypovalent nor hypovalent rather its octet is complete. Al2Cl6 contains six bond having two bridge bond(3c-4e) and four bond is (2C-2e).

We will used  MOT here  it cannot act as Lewis acid  due to crowding in spite having vacant d orbital’s however AlCl3 act as Lewis acid.


Monday, January 18, 2021

Consider Al2(OH)6 compound and calculate the value of (X+Y)/Z Where X= total number of two centre-two electrons (2C-2e) bond, Y= total number of three centre-two electron(3C-2e)bonds, and Z=total number of three centre-four electron (3C-4e) bond;

 

Total number of two centre-two electrons (2C-2e) bonds(X)=6

Total number of three centre-two electron(3C-2e) bonds(Y)=4

Total number of three centre-four electron (3C-4e) bond(Z)=2

Hence (X+Y)/Z=(6+4)/2=5

Related Questions:

(1) What is the difference between the structure of AlCl3 and diborane?

(2) What is structural feature of monomeric and polymeric Beryllium halides ?

(3) What is bridge bond ? explaine 3C-4e bridge bond with suitable examples .

(4) What is structure of Beryllium chloride ?

(5) What is the structure of Aluminium tetrahydridoborate (Al(BH4)3) ?

(6) What is structure of Al(CH3)3 and also explain the bridge bonding in Al(CH3)3?

(7) The type of overlap in the bridge bond exist in Al2(CH3)6 is

(8) What is structure of diborane?

(9) What is structure of BeH2 in solid state ?

(10) Consider the structure of Al(CH3)3 given below and select the correct option?

(11) Consider Al2(OH)6 compound and calculate the value of (X+Y)/Z Where X= total number of two centre-two electrons (2C-2e) bond, Y= total number of three centre-two electron(3C-2e)bonds, and Z=total number of three centre-four electron (3C-4e) bond;

Consider the structure of Al2(CH3)3 given below and select the correct option?

(A) x < y

(B) alpha < Beta

(C) Bridge bond is formed by sp3-sp3-sp3 overlap.

(D) All of the correct.

Answer Key: (D)

Related Questions:

 (1) What is structure of diborane?

(2) What is structure of Al(CH3)3 and also explain the bridge bonding in Al(CH3)3?

(3) What is bridge bond ? explaine 3C-4e bridge bond with suitable examples .

(4) What is structural feature of monomeric and polymeric Beryllium halides ?

(5) What is the difference between the structure of AlCl3 and diborane?

(6) What is structure of Beryllium chloride ?

(7) What is structure of BeH2 in solid state ?

What is structure of BeH2 in solid state ?

BeH2 is covalent hydride and having polymeric structure in solid state in which beryllium atoms are bonded together by three centre-two electrons(3c-2e) bridge bond which also know as banana bond and all the H-Be-H bond angle are below 109.28’

But in gaseous BeH2 exist in dimeric form in which Be atoms are sp2 hybridised, planer  and non polar(dipole moment zero).

Related Questions:



What is structure of diborane?

(1)  B2H6 contains 4-Terminal H are bonded by Sigma bond and  remaining 2-H are bridging hydrogen's and of these are broken then dimer become monomer.

(2) Boron undergoes sp3 hybridisation 3 of its sp3 hybridised orbitals contain one( e¯) each and fourth sp3 hybrid orbital is vacant.

(3) 3-(Three) of these sp3 hybrid orbitals get overlapped by s orbitals of 3-hydrogen atoms.

(4) One of the sp3 hybrid orbitals which have been overlapped by s orbital of hydrogen gets overlapped by vacant sp3 hybrid orbital. Of 2nd Boron atom. And it's vice versa.

(5) By this two types of overlapping take place 4 (sp3– s) overlap bonds and 2(sp2 – s – sp3) overlap bonds.


(6) H is held in this bond by forces of attraction from B and This bond is called 3 centred two electron bonds (3C-2e bond) . Also called Banana bonds. Due to repulsion between the two hydrogen nuclei, the delocalised orbitals of bridges are bent away from each other on the middle giving the shape of banana.

(7) The two bridging hydrogens are in a plane and perpendicular to the rest four hydrogen atoms.

ILLUSTRATED EXAMPLE (1): In Diborane

(A) 4 bridged hydrogens and two terminal hydrogen are present

(B) 2 bridged hydrogens and four terminal hydrogen are present

(C) 3 bridged and three terminal hydrogen are present

(D)None of the above

 

ILLUSTRATED EXAMPLE (2): Which one of the following statements is not true regarding diborane?

(A) It has two bridging hydrogens and four perpendicular to the rest.

(B) When methylated, the product is Me4B2H2.

(C) The bridging hydrogens are in a plane and perpendicular to the rest.

(D ) All the B–H bond distances are equal

 

ILLUSTRATED EXAMPLE (3): The structure of diborane (B2H6) contains

(A) Four (2C–2e–) bonds and two (2C–3e–) bonds

(B) Two (2C–2e–) bonds and two (3C–2e–) bonds

(C) Four (2C–2e–) bonds and four (3C– 2e–) bonds

(D ) None of these


ILLUSTRATED EXAMPLE (4): The molecular shapes  of diborane is shown:

Consider the following statements for diborane:

1. Boron is approximately sp3 hybridised

2. B–H–Bangle is 180°

3. There are two terminal B–H bonds for each boron atom

4. There are only 12 bonding electrons available

Of these statements:

(A ) 1, 3 and 4 are correct                  (B) 1, 2 and 3 are correct

(C) 2, 3 and 4 are correct                    (D) 1, 2 and 4 are correct