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

Nitrogen (N) atom in trimethyl amine [N(CH₃)₃] is sp3 hybridised and non bonding electron pair of N is localized. Therefore it is more basic. On the other hand N atom of trisilyl amine [N(SiH₃)₃] is sp2 hybridised. 

This is due to the participation of non-bonding pair of N into pπ-dπ back banding. Due to this delocalization of non-bonding electron pair of N in trisilyl amine it is less basic.

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