Heteronuclear double resonance studies of trisilylphosphine and trisilylstibine

The relative signs of all the coupling constants involving ¹H, ²⁹Si and ³¹P in (²⁸SiH₃)₂P²⁹SiH₃ and (²⁸SiH₃)₂Sb²⁹SiH₃ have been determined by ¹H-{²⁹Si} and ¹H-{³¹P} ‘tickling’ experiments. With the exception of ¹ K(²⁹Si-³¹P), the reduced coupling constants are probably positive over one and three bonds, and negative over two and four bonds.