Crystal and molecular structure of 5-t-butyl-5-aza-2,8-dithia-1-stanna(II)bicyclo[3.3.01,5]octane. Identification of two different geometries along the dissociation-inversion pathway

The crystal and molecular structure of 5-t-butyl-5-aza-2,8-dithia-1-stanna(II)bicyclo[3.3.0 1,5 ]octane [Sn(SC 2 H 4 ) 2 NC 4 H 9 ] 2 have been determined from three-dimensional X-ray data. The crystals are monoclinic, space group P 2 1 / c , with cell dimensions: a 14.104(2), b 21.911(4), c 11.624(2) A, β 98.73(1)°, Z = 6. The final R is 0.040 for the 4279 observed reflections. The unit-cell contains four asymmetric dimers (dimer a ) and two centrosymmetric dimers (dimer b ), each dimer forms a four-membered Sn 2 S 2 ring in which the sulfur atoms are three-coordinated. The SnN distances in the two dimeric forms are significantly different (namely, 2.64 and 2.75 in dimer a , 2.97 A in dimer b ). The lengthening of the SnN distances involves the shortening of the bridging tin—sulfur bonds (2.99 and 2.79 in a , 2.71 A in b ). The coordination around the three different Sn atoms is hemispherical.