Theoretical Study of Singlet, Triplet, and the Quintet States, of (Nitrenoethynyl) Halosilylene

Coupling of a local triplet silylene with a local triplet nitrene with the same spin electrons through an acetylene linkage gives a new brand of high spin quintet intermediates of (nitrenoethynyl)halosilylene (X-C-CºC-N, where X® H, F, Cl, Br), which are rather experimentally hard to find. Placing the same linkage between the local closed-shell singlet silylene (s2p0) and the local triplet nitrene (p1p1) gives triplet minima which are 44-61 kcal/mol more stable than their corresponding quintets. The singlet states are approached through connecting triplet states of silylene and nitrene with the opposite spin electrons. Triplet states identified as ground states, while all singlet, triplet, and quintet states of (nitrenoethynyl)halosilylene species are minimal in their corresponding potential energy surface (PES). Our results are compared at B3LYP, MP2, MP4(SDTQ) levels using 6-311** basis set.