Chlorotris(2,4,6-trimethylphenyl)tin(IV) and its ethanol hemisolvate.

Chlorotris(2,4,6-trimethylphenyl)tin(IV), crystallizes from ethanol as solvent-free needles, [Sn(C(9)H(11))(3)Cl], (I), and as the hemisolvate, [Sn(C(9)H(11))(3)Cl].0.5C(2)H(6)O, (II). The asymmetric unit in (I) has three independent molecules, whereas in (II), there are two [Sn(C(9)H(11))(3)Cl] molecules together with one ethanol molecule. In the unit cell of (II), the ethanol molecules lie in channels between stacks of (Mes)(3)SnCl molecules (Mes is 2,4,6-trimethylphenyl) and each ethanol molecule is disordered (0.50:0.50) over two positions. A comparison of the structures of the title compounds and other (Mes)(3)SnX (X = F, Br or I) systems with those of the triphenyltin analogues shows that the steric requirements of the o-CH(3) groups are met by a flattening of the SnC(3) skeleton and increases in the average Sn-X and Sn-C values. Comparing Sn-X data for (Mes)(3)SnX (X = F, Cl, Br or I) systems with values for the tris(o-methoxyphenyl)tin analogues suggests that the Sn-F distance of 1.961 A in (Mes)(3)SnF may well be characteristic of sterically unhindered four-coordinate Ar(3)SnF systems.