STANNACYCLOHEXANES AND SPIRO-TIN COMPOUNDS WITH A STANNOLE OR A STANNOLENE GROUP

1,1-Diethynyl-1-stannacyclohexane (5) was prepared, and its reaction w ith triethylborane or 9-isobutyl-9-borabicyclo[3.3.1]nonane gave the c orresponding spiro-tin compounds 6 and 7 with a stannole fragment, The molecular structure of the derivative 7 was determined by X-ray analy sis (triclinic, space group P (1) over bar; a = 835.2(7), b = 1117.5(2 ), c = 1165.6(2) pm; alpha = 72.05(3), beta = 74.32(3), gamma = 50.61( 3)degrees). Treatment of 6 with trimethyltin ethoxide gave at first qu antitatively the spiro-tin compound 8 with a 2-stannolene unit which r earranges upon heating into the spiro-tin compound 9 with a 3-stannole ne unit, The reaction of 7 with trimethyltin butoxide gave quantitativ ely another tetracyclic compound 10, analogous to 8, All compounds wer e characterised by H-1, B-11, C-13 and Sn-119 NMR data. Numerous coupl ing signs (n)J((SnH)-Sn-119-H-1) and (n)J((SnC)-Sn-119-C-13) and (2)J( (SnSn)-Sn-119-Sn-117) were determined by 2D(13)C/H-1 and Sn-119/H-1 he teronuclear shift correlations. Compound 7 was studied by solid-state C-13 and Sn-119 CPMAS NMR. This revealed the presence of a second crys talline phase in the bulk of the solid material, as confirmed by powde r X-ray diffraction data. Sn-119 CPMAS NMR spectra of 7 show resolved scalar Sn-119-B-11 coupling ((3)J((SnB)-Sn-119-B-11) = 68 +/- 5 and 65 +/- 5 Hz).