Simple two-coordinate acyclic silylenes, SiR2, have hitherto been identified only as transient intermediates or thermally labile species. By making use of the strong a-donor properties and high steric loading of the B(NDippCH)(2) substituent (Dipp = 2,6-(Pr2C6H3)-Pr-i), an isolable monomeric species, Si{B(NDippCH)(2)}{N(SiMe3)Dipp}, can be synthesized which is stable in the solid state up to 130 degrees C. This silylene species undergoes facile oxidative addition reactions with dihydrogen (at sub-ambient temperatures) and with alkyl C-H bonds, consistent with a low singlet-triplet gap (103.9 kJ mol(-1)), thus demonstrating fundamental modes of reactivity more characteristic of transition metal systems.