29Si and 13C Nuclear magnetic resonance studies of organosilicon chemistry

²⁹Si and ¹³C spin-lattice relaxation times and the corresponding nuclear Overhauser enhancements have been measured for Ph_nSiH_4−n (n = 1, 2, 3), for Ph₂SiHMe and for Ph₂SiCl₂. Thence dipolar and other contributions to the relaxation rates have been separated. The dipolar rates are used to discuss internal rotation about the phenyl-Si bond, and overall motional anisotropy. The value of T₁(Si) for PhSiH₃ is very short and, it is suggested, is dominated by the spin-internal-rotation interaction. Values of chemical shifts and coupling constants are also presented and briefly discussed.