The unhindered silanimines 1,1‐dimethyl‐N‐phenylsilanimine (2) and N‐isopropyl‐1,1‐dimethylsilanimine (10) have been generated by flash vacuum thermolysis of the N‐allylsilanamine 1 and vacuum gas‐solid reaction of the 1‐chlorosilanamine 9, respectively. The silanimines 2 and 10 have been characterized by MS as well as by chemical trapping to yield 3 or dimerization to the cyclodisilazane 11.