Which is/are the correct statement/s about structure of methyl isothiocyanate (H3CNCS) and Silyl isothiocyanate(SiH3NCO)?

(A) CNC bond angle in H₃CNCS is >120 and hybridization is closed to sp2 

(B) Si-N-C bond angle is 180 in H₃CNCS
(C) Both have Back Bonding 
(D) Skeleton Si-N-C-S is linear but molecule are non planer.

SOLUTION:  

The hybridization of Nitrogen in Methyl isothiocyanate (H₃CNCS) is Sp2. Thus bond angle (< C-N-C) is expected to be 120°. But it is slightly greater than 120° due to resonating structure. The resonating structure has N as sp hybridized. Hence bond angle of the overall structure is found to be about 142°

But in case Silyl isothiocyanate (SiH₃NCO), the structure is found to be (sp hybridized) and planar  due to back bond between Si-N. In which the lone pair of electrons on N are donated to the vacant 3d orbitals of Si through back bonding (2pπ-3dπ back bond).

Hence Options (A, B, D) are correct.