Divergent Reactivity of a Cyclic Bis-Hydridostannylene: A Masked Sn(I) Diradicaloid.

Herein, reactivity studies of a cyclic bis-hydridostannylene [(ADC)SnH] 2 (1-H 2 ) (ADC=PhC{(NDipp)C} 2 ; Dipp=2,6-iPr 2 C 6 H 3 ) with various unsaturated organic substrates are reported. Reactions of terminal alkynes (RC≡CH) with 1-H 2 afford mixed acetylide-vinyl-functionalized bis-stannylenes via dehydrogenation and hydrostannylation. Treatment of 1-H 2 with PhC≡CCH 3 gives a unique distannabarrelene via dehydrogenative C (sp3) -H stannylation and hydrostannylation of the C≡CCH 3 moiety. 1-H 2 undergoes dehydrogenative [2+2]-cycloaddition reactions with diphenylacetylene, azobenzene, acetone, benzophenone, and benzaldehyde to form the 1,4-distannabarrelene derivatives. The elimination of H 2 in these reactions suggests the masked-diradical property of 1-H 2 . In fact, these [2+2]-cycloaddition products are also accessible on treatments of the Sn(I) diradicaloid [(ADC)Sn] 2 (1) with appropriate reagents. All compounds have been characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction. Moreover, the catalytic activity of 1-H 2 has been shown for the hydroboration of unsaturated substrates.