X-ray Crystal and Molecular Structure of the Dimeric 1:1 Dimethyltin(IV) Dichloride Adduct with Diphenylcyclopropenone, 2, at 138 +/- 2 K

Article abstract of DOI:10.1021/ja00384a019

Dimethyltin(IV) dichloride-diphenylcyclopropenone, C34H32Cl4O2Sn2, forms colorless crystals, mp 111 deg C, in the monoclinic space group C2/c with a = 17.049 (16) Angstroem, b = 10.027 (10) Angstroem, c = 19.834 (16) Angstroem, β = 96.00 (6)<*>, V = 3372 Angstroem³, Z = 4, ρ_calcd = 1.678 g cm^-3.The structure was determined by the heavy atom method from 4890 reflections measured at 138 +/- 2 K on the Enraf-Nonius CAD/4 automatic diffractometer with monochromatic Mo Kα radiation to a final R value of 0.0296 for the 4251 reflections included in the least-squares sums.The dimeric molecule contains six-coordinated tin with the oxygen atom of the ligand and one chlorine atom in a trans position making a Cl(1)-Sn-O angle of 172.32 (5)<*>.The angle made by the methyl groups is opened to 142.2 (1)<*>, and the octahedron is completed by a roughly trans Cl(2)-Sn-Cl(1') angle of 166.10 (2)<*>.The Sn2Cl2 ring is formed by bonded and bridging Angstroem> connections.The tin atom lies 0.0266 (2) Angstroem above the plane formed by the carbons of its two methyl groups, its terminally bonded chlorine , and the chlorine atom bridged to it , in the direction of the Cl(1) atom.The shortest bond is made to the terminal chlorine .The distances in the Sn<-O=C system <2.380 (2) and 1.239 (3) Angstroem, respectively> reflect a normal carbonyl unit, but the intraring distances, d(C=C) and d(C-C) <1.376 (3) and 1.397 (3), 1.402 (3) Angstroem, respectively>, and C-C(O)-C angle <58.9 (2)<*>> reflect a more delocalized situation than in the free diphenylcyclopropenone.The ligand system is relatively flat, with the phenyl rings tilted out of the plane of the cyclopropanone system by 2.5<*> and 8.4<*>.The angle formed by the ligand oxygen and three-carbon ring and the plane containing the C=O->Sn system is 11.7 (2)<*>.The Sn2Cl2 ring is almost flat, being bent through dihedral angles of 2.25 (3)<*>.The sum of the internal angles is 359.94<*>, with the acute angles at the tin atoms 77.26 (2)<*> and open angles at the chlorines 102.71 (2)<*>.Each monomeric unit is related to its other half by a twofold axis.