FURTHER STUDY OF ESTERTIN TRICHLORIDES, Cl3SnCH2CH2CO2R. LEWIS ACIDITY TOWARDS ACETONITRILE. CRYSTAL STRUCTURE OF Cl3SnCH2CH2CO2Pr-i

Article abstract of DOI:10.1016/0022-328X(86)80148-6

Crystals of Cl3SnCH2CH2CO2Pr-i are orthorombic, space group P2₁2₁2₁ with a 9.638(6), b 10.004(7) and c 12.848(8) Angstroem.The tin atom is five-coordinate with two chlorines and carbon equatorial and the remaining chlorine and the carbonyl oxygen axial, in a distorted trigonal-bipyramidal arrangement: (Sn-Cl)_ax 2.389(3), average (Sn-Cl)_eq 2.320(2), Sn-C 2.142(9), Sn-O 2.337(5) Angstroem.Apart from the equatorial chlorine and the terminal carbons in the isopropyl group, all non-hydrogen atoms are essentially coplanar.The molecule approaches C_2v symmetry although not constrained to do so by the crystallographic space group.In MeCN solution, the compounds Cl3SnCH2CH2CO2R (I, R = Me, Pr-i, C6H4X (X = p-MeO, H, p-Cl, o-MeO) or C6H3Cl2-2,4) form as equilibrium mixtures of 1/1 and 2/1 MeCN/1 complexes; the chelate ring is broken in the 2/1 complexes.Equilibrium constants indicate that the strength of the intramolecular Sn-O coordination I increases with the electron releasing ability of the R group.