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Monday, January 18, 2021

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:

(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 ?

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 2^nd 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

(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.

(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

(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

Sunday, January 17, 2021

Structure of Al2(CH3)3 and also explain the bridge bonding in Al2(CH3)3?

Structural features of Dimer of Al(CH₃)₃:

(1) Total number of 2C-2e bond in these molecule is 22 while their ii two (2) 3C-2e (Al-O-Al )bridge bond.

(2)One vacant orbital of each Alumium atom is involved in sp3 hybridiazation.

(3) All the carbon atoms of –CH3 does not lie in the same plane.

(4) There is eight(8) sp3 hybridised atoms present in this molecule.

(5) There are total 48 bonding electrons are available.

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;

What is the structure of (O2F2) oxygen fluoride

The compound id produced as result of glow dischage through amixture of O₂ and F₂ at -180 to -190 degree (c). As should be expected. O₂F₂ is an extremely reactive fluorinating agent. Under the conditions that produce OF₂, small and O₄F₂ are produced, but these unstable compounds decomposed at liquid nitrogen temperatures.

Why Bond length of O-O is greater in H₂O₂ than O₂F₂?

Electronegativity of F is much more than hydrogen and also hybridization of oxygen atoms in of H₂O₂ and O₂F₂ both have (sp3) same and hence we can apply bent’s rule.

According bent’s rule more eletronegative atoms reduce % s-character (or increases % p-character vice versa) of those hybride orbital in which they attach. So in case of O₂F₂% s-character of those hybride orbital decrease which have flourine while % p-character increases in same way % s-character of remaing hybride orbital inceases and p-character decreases hence its bond length also (bond length is directly proportional to % p-character) decreases. hence O-O bond length in O₂F₂ is shorter thane H₂O₂.

Related Questions:

What is Bent’s rule of hybridization?

Which of the following compound have longest (S=O)bond length , O=SF2, O=SCl2, O=SBr2.

Why Bond length of O-O is greater in H2O2 than O2F2?

How to arrange increasing (C-H) bond length in increasing order and H-C-F bond angle in the given compounds, CH4, CH3F, CH2F2 and CHF3 ?

BENT'S RULE OF HYBRIDISATION:

Oxides of Halogens;

Halogens and oxygen they do not combine directly with oxygen due to high electron affinity of both halogens and oxygen but their oxides with oxygen can be prepared indirectly.

The compounds of oxygen with fluorine are called as fluorides (not a oxide) because fluorine is more electronegative than oxygen. Most of these compounds are endothermic and unstable and are likely to explode resulting in the formation of more stable products.

The compounds of chlorine ,bromine and Iodine with oxygen are called oxide because electronegtivity of oxygen is greater than these. And the common oxides of halogens are X₂O, X₂O₃, X₂O₅, and X₃O₇ (common oxidation state of 17^th group) and uncommon oxides are ClO₂ (+4) and ClO₃/Cl₂O₆ etc.

Flourine	O.S.	Chlorine	Bromine	Iodine
OF₂ &O₂F₂	(+1) /X₂O	Cl₂O	Br₂O
	(+3)/X₂O₃
	(+4)	ClO₂/Cl₂O₄	BrO₂	I₂O₄
	(+5)/X₂O₅			I₂O₅
	(+6)	ClO₃/Cl₂O₆	BrO₃
	(+7)/X₂O₇	Cl₂O₇

All the oxides are powerful oxidizing agents and decompose explosively when they are given mechanical shock or heat.

Structure of chlorine oxides:

Structure of dichlorine heptaoxide:

Avarage oxidation state of Chlorine in Cl₂O₇ is one of the common oxidation state of the chlorine so there is (Cl-O-Cl) Oxy-linkage will be present. And one of oxygen atom is shared by both of chlorine atoms and rest of the oxygen atoms equally distributed.

The whole molecule dichlorine heptaoxide (Cl₂O₇) is non planer and polar and oxygen atom of (Cl-O-Cl) oxy-linkage does not involve in delocalization due to maximum repulsion hence two Cl-O bond have equal length and bond order may be/equal to one while other six Cl=O bond have eqaual bond length

In dichlorine heptaoxide (Cl₂O₇) , two ClO₄ group connected with an oxygen atom which is sp3 hybridised (non planer) and bond angle may be expected 109⦁28’ but actually due to the presence of two lone pair on oxygen atom the Cl-O-Cl bond angle deviated from ideal and it may be greater (119⦁) than ideal bond angle.

Question (1): Number of sigma and pi bonds present in Cl₂O₇ is/ are ....?

Number of sigma and pi bond present in Cl₂O₇ are (8) and (6) repectively.

Question(2):What is the anhydride of HClO4 ?

Cl2O7 is the anhydride of HClO4

Question (3):Number of equivalent Cl-O bond in Cl₂O₇ is/are….

Number of equivalent Cl-O bond in Cl₂O₇ are (2) two.

Question(4):Number of equivalent Cl=O bond in Cl₂O₇ is/are….

Number of equivalent Cl=O bond in Cl₂O₇ are (6) six.

Related Questions:

Which is more basic N(CH3)3 or N(SiH3)3 , explain?

Are all the five bonds of PCl5 equivalent? Justify your answer.