Synthesis, structures and oxidative addition reactions of new thermally stable silylenes; crystal structures of [ [formula omitted](CH 2tBu)} 2C 6H 4-1,2] and [( [formula omitted](CH 2tBu)} 2C 6H 4-1,2)(μ-E)] 2 (E = Se or Te)

Abstract

Treatment of the N,N′-dineopentyl-1,2-phenylenediamine 4-RC 6H 3[NH(CH 2 tBu)] 2-1,2 (R = H or Me) with successively two equivalents of n-butyllithium and one of SiCl 4 yields the appropriate N,N′-dineopentyl-1,2-phenylenediaminodichlorosilane Si[{N (CH 2 tBu)} 2C 6H 3-1,2-R-4]Cl 2 (R = H, 1, or R = Me, 2). The thermally stable, yellow, diamagnetic, volatile, crystalline silylene Si[{N (CH 2 tBu)} 2C 6H 3-1,2-R-4] (R = H, 3, or R = Me, 4) is obtained from 1 or 2 by reaction with potassium in refluxing tetrahydrofuran. The silylene 3 undergoes oxidative addition with (i) Mel or EtOH to give [ Si{N (CH 2 tBu)} 2C 6H 4-1,2](X)Y (X = Me and Y = 1. 5. or X = OEt and Y = H. 6), or (ii) a chalcogen E to afford [( Si{N (CH 2 tBu)} 2C 6H 4-1,2)(μ-E)] 2 (E = S. 7. Se. 8 or Te. 9). Spectroscopic data are provided for compounds 1–9 and single crystal X-ray diffraction results for compounds 3, 8 and 9. The average SiN distances are 1.750(4) Å for the silylene 3. 1.719(4) Å for the cyclodisilaselenane 8 and 1.729(3) Å for the cyclodisilatellurane 9, the NSiN′ angles being 88.2(1)° for 3, 93.5(2)° for 8 and 93.7(1)° for 9.