Synthesis of Stable Silicon Heterocycles by Reaction of Organic Substrates with a Chlorosilylene [PhC(N t Bu) 2 SiCl]

Heteroleptic chlorosilylene (PhC(N t Bu) 2 SiCl) ( 1 ) reacts with unsaturated organic compounds under oxidative addition. Reactions of 1 with cyclooctatetraene (COT) and a diimine afford [1+4]‐cycloaddition products 3 and 6 , respectively. In the case of COT, one SiN bond of the amidinato ligand is cleaved, resulting in tetracoordinate silicon, whereas with a diimine a pentacoordinate silicon is formed. Treatment of 1 with ArNCNAr (Ar=2,6‐ i Pr 2 C 6 H 3 ) yields silaimine complex 4 with cleavage of one of the CN bonds. The facile isolation of silaimine complexes is probably due to the kinetic protection afforded by the bulky Ar moiety. When 1 is treated with tert ‐butyl isocyanate, cleavage of the CO bond is observed, which leads to formation of the four‐membered Si 2 O 2 cycle 5 . The same product is formed when 1 is allowed to react with trimethylamine N ‐oxide. When 1 is treated with diphenyl disulfide, cleavage of the SS bond occurs to form 7 . All products have been characterized by multinuclear NMR spectroscopy, EI mass spectrometry, and elemental analysis. In addition, the molecular structures of 3 – 6 have been determined by single‐crystal X‐ray diffraction studies. Collectively, these results suggest that owing to the presence of the lone pair of electrons, the propensity of 1 to undergo oxidative addition is very high.