M. Tschinkl et al., Transmetalation as a route to a cyclic heteronuclear bifunctional Lewis acid containing tin and gallium, ORGANOMETAL, 19(10), 2000, pp. 1826-1828
The reaction of equimolar quantities of 1,8-bistrimethylstannylnaphthalene
(1) and GaCl3 in toluene yields a stannagallacycle, namely, bis(mu-1,8-napt
halenediyl) (mu-chloride)methyltin (IV) chlorogallium(III) (2). Compound 2
is insoluble in solvents of low polarity and has been characterized by EA,
MSCI, and X-ray analysis. The Latter revealed the existence of a folded eig
ht-membered dimetallacycle as well as the presence of a chloride ligand bri
dging the two metals. When. treated with pyridine, formation of a soluble b
is(pyridine) adduct (3) occurs. Compound 3 has been characterized by EA and
H-1, C-13, and S-119, NMR spectroscopy. As shown by X-ray single-crystal a
nalysis of 3, the central eight-membered dimetallacycle of the molecule has
remained intact on going from 2 to 3. Compound 3 does not feature a bridgi
ng chloride, and its structure is that of a Lewis acid-Lewis base adduct in
which two independent pyridine molecules coordinate the metal centers.