Synthetic and Structural Studies on the Cyclic Bis(amino)stannylenes Sn[(NR)₂C₁₀H₆‐1, 8] and their Reactions with SnCl₂ or Si[(NCH₂Bu^t)₂C₆H₄‐1, 2] (R = SiMe₃ or CH₂Bu^t)

Abstract

Abstract Treatment of {HNR} 2 C 10 H 6 ‐1, 8 [R = SiMe 3 ( 1 ), CH 2 Bu t ( 2 )] with Sn[N(SiMe 3 ) 2 ] 2 afforded the cyclic stannylene Sn[{NR} 2 C 10 H 6 ‐1, 8] [R = SiMe 3 ( 3 ), CH 2 Bu t ( 4 )]. From 3 and SnCl 2 in THF and crystallisation from toluene, the product was the crystalline tetracyclic compound $Sn(Cl)[\{\overline{N(SiMe_{3})\}_{2}C_{10}H_{6}-1, 8]Sn}Cl$ ( 5 ) as the (toluene) 0.5 ‐solvate. Reaction of 4 with the silylene Si[(NCH 2 Bu t ) 2 C 6 H 4 ‐1, 2] ( 6 ) [abbreviated as Si(NN)] in benzene and crystallisation in presence of Et 2 O furnished the crystalline tricyclic complex Sn[{Si(NCH 2 Bu t ) 2 C 6 H 4 ‐1′, 2′} 2 ‐{(NCH 2 Bu t ) 2 C 10 H 6 ‐1, 8}] ( 7 ) as the Et 2 O‐solvate. Complex 5 slowly dissociated into its factors 3 and SnCl 2 in toluene, but rapidly in THF. Solutions of 7 in C 6 D 6 , C 7 D 8 or THF‐d 8 , studied by multinuclear, variable temperature NMR spectroscopy, revealed the presence of an equilibrium between 8 (an isomer of 7 , in which the skeletal atoms of the eight‐membered ring were $\overline{SnNCCCNSiSi}$ , rather than the $\overline{SnSiNCCCNSi}$ of 7 ) and 4 + 2 Si(NN), with 8 dominant in PhMe but not in THF; additionally 8 was shown to be fluxional and solutions of 8 in C 6 D 6 or C 7 D 8 decomposed to give the silane Si(NN)[(NCH 2 Bu t ) 2 C 10 H 6 ‐1, 8], 6 and Sn metal. The X‐ray structures of 3 , 5 and 7 are presented.