The crystal and molecular structures of R2SnCl2(1,10-phenanthroline), R = iPr, Cy, CH2Ph and R2 = Me, Ph: a comparison between solid state and theoretical structures

Abstract

Abstract The crystal and molecular structures of four diimine adducts formed between R2SnCl2 [R = iPr, Cy, CH2Ph; and R2 = Me, Ph] and 1,10-phenanthroline have been determined at room temperature. The colorless crystals of R = iPr are monoclinic, space group P21/c with unit cell dimensions a = 8.261(2) Å, b = 15.125(3) Å, c = 15.804(2) Å, β = 104.82(1), Z = 4 and D x = 1.586 Mg m−3. The yellow crystals of R = Cy are monoclinic, space group P21/n with unit cell dimensions a = 10.474(1) Å, b = 16.167(2) Å, c = 14.341(3) Å, β = 101.46(1)°, Z = 4 and D x = 1.496 Mg m−3. Orange crystals of R = CH2Ph are monoclinic, space group P21/n with unit cell dimensions a = 10.356(3) Å, b = 17.540(2) Å, c = 13.817(9) Å, β = 105.93(5)°, Z = 4 and D x = 1.519 Mg m−3. The colorless crystals of R2 = Me, Ph are monoclinic, space group P21/n with unit cell dimensions a = 9.118(2) Å, b = 11.023(2) Å, c = 18.712(2) Å, β = 93.03(1), Z = 4 and D x = 1.634 Mg m−3. The structures were solved by direct methods and each refined by a full-matrix least-squares procedure to final R = 0.045 using 2200 reflections for R = iPr; to R = 0.043 using 2644 reflections for R = Cy; to R = 0.045 using 2576 reflections for R = CH2Ph; and to final R = 0.036 for 2538 reflections for R2 = Me, Ph. The solid state structures of R2SnCl2(phen) feature distorted octahedral tin atom geometries with a trans disposition of the R substituents. A systematic trend to longer Sn–Cl and Sn–N distances with decreasing Lewis acidity is found, however, with a relatively large spread of values which is often correlated in the case of Sn–Cl with C1…H interactions. The structures of R2SnCl2(phen) have also been investigated employing ab initio methods at the Hartree-Fock SCF level of theory so that a correlation may be made between the R2SnCl2(phen) structures in the presence and absence of crystal packing effects. The calculated structures are generally more symmetric suggesting that there is no inherent chemical reason for a lack of symmetry in the solid state. Further, generally there is an elongation of Sn-ligand distances in the gas phase structures. These two key observations point to the importance of crystal packing effects on molecular geometry as well on the derived interatomic parameters.