Abstract: Cyclic silazanes which are particularly useful for the formation of silicon nitrides have the general formula: ##STR1## wherein Me represents methyl (CH.sub.3), n=3-6, x=0-1 and y=0.25-1. These N-methylhydridosilazanes are a convenient source of silicon nitride by chemical vapor deposition to form films for masking layers and dielectric coatings with reduced levels of silicon carbide contamination in the silicon nitride. Low molecular weight, linear polymers of the N-methylhydridosilazanes are also useful in the preparation of silicon nitrides by evaporation from liquid solutions and subsequent pyrolysis and are particularly useful for infiltration of refractories. Particularly preferred compounds of the invention are 2,6 di-N-methyl-1,3,5,7-tetramethylcyclotetrasilazane; 2,4,6,8-tetra-N-methyl-1,5-dimethylcyclotetrasilazane and their polymeric derivatives.