Cyclic silyldiazocompounds, 1-diazo-2,2-diphenyl-4-bromo-1,2-dihydro-2-silanaphthalene, 6-diazo-1,1-dimethyl-2,3,4,5-tetraphenylsilacyclohexa-2,4-diene, and 10-diazo-9,9-dimethyl-9,10-dihydro-9-silaanthracene, were prepared and their spectroscopic properties were determined.