The effects of ring size on ¹⁵N, ¹⁷O, and ²⁹Si n.m.r. chemical shifts and ¹⁵Nâ ²⁹Si, ¹³Câ ²⁹Si, ¹⁵Nâ ¹H, and ²⁹Siâ ²⁹Si coupling constants in cyclosilazoxanes have been studied. The opposite shielding sequence in δ(¹⁵N) and δ(²⁹Si) and the decrease in ¹⁵Nâ ²⁹Si coupling with diminishing ring size are consistent with higher Siâ N bond ionicity (reduced d Ï â p Ï interaction) in smaller rings. The ¹⁷O chemical shift is practically independent of ring size in cyclosiloxanes. It has been proposed that the factors governing the ¹⁷O chemical shift act in opposite directions and are balanced. A linear relationship between Nâ H bond stretching frequency and ¹⁵N n.m.r. parameters (¹⁵Nâ ¹H coupling and ¹⁵N chemical shifts) has been established.