which of the following has the minimum heat of dissociation of N-->B Bond?
A)[(CH3)3N --> BF3]
B)[(CH3)3N --> B(CH3)F2]
C)[(CH3)3N --> B(CH3)2F]
D)[(CH3)3N --> B(CH3)3]

Presence of bulky methyl groups which are electron donating groups make boron less electron deficient and hence weakens the strength of coordinate covalent bond .Bulky groups on N and B create too much of steric repulsion which results in increase in bond length also.Based on the above concept can you answer it now?

Is answer D??