X-ray crystal and molecular structures of the monomeric 1:1 Adducts of diphenyltin(IV) dichloride and trimethyltin(IV) chloride with 2,6-dimethylpyridine (2,6-lutidine) N-oxide

Article abstract of DOI:10.1021/om00080a012

Diphenyltin(IV) dichloride-2,6-dimethylpyridine N-oxide (I), C₁₉H₁₉Cl₂NOSn, forms colorless crystals, mp 159 °C, in the triclinic space group P1 with a = 9.359 (2) A?, b = 10.534 (2) A?, c = 10.996 (3) A?, α = 97.46 (2)°, β = 114.74 (2)°, γ = 93.26 (2)°, V = 968.8 (3) A?³, Z = 2, and ρ = 1.60 g cm^-3. The structure was determined from 3609 reflections collected on a Nicolet R3 diffractometer with monochromatic Mo Kα radiation and refined to a final R value of 0.0253 for the 3102 reflections included in the least-squares sums. The monomeric complex contains five-coordinated, trigonal-bipyramidal tin with the phenyl rings forming an angle of 124.1 (1)° in the equatorial plane. The ligand oxygen and one of the chlorine atoms occupy the apical positions at an angle of 172.8 (1)°. The sum of the angles subtended at the tin atom in the trigonal plane is 359.0 (3)°. The tin atom is displaced from this plane by 0.1279 (2) A? in the direction of the chlorine atom. The Sn-Cl_eq bond [2.366 (1) A?] is shorter than the Sn-Cl_ax bond [2.471 (1) A?]. The Sn-O distance is 2.296 (2) A?, and the two Sn-C bond distances are approximately equal [2.119 (3) and 2.128 (4) A?]. Trimethyltin(IV) chloride-2,6-dimethylpyridine N-oxide (II), C₁₀H₁₈ClNOSn, mp 106 °C, also crystallizes as colorless crystals in the same space group with a = 8.174 (2) A?, b = 9.599 (2) A?, c = 9.895 (3) A?, α = 115.33 (2)°, β = 105.50 (2)°, γ = 81.45 (2)°, V = 675.7 (2) A?³, Z = 2, and ρ = 1.58 g cm^-3. This structure was solved from 2437 reflections and refined to a final R value of 0.0283 for the 2207 reflections that were used in the least-squares sums. The molecule has the tin atom in a trigonal-bipyramidal geometry with the methyl carbons in the trigonal plane. The Sn-C bond distances are 2.119 (5), 2.120 (4), and 2.125 (6) A?, and the C-Sn-C angles are 114.1 (2), 121.8 (3), and 123.1 (2)°, giving a sum of 358.9 (3)°. The apical Cl-Sn-O angle is 177.4 (1)°, and the tin atom is displaced from the trigonal plane by 0.2357 (2) A? toward the chlorine atom. Both the Sn-Cl and Sn-O distances are larger than those found in structure I [2.533 (1) and 2.400 (2) A?, respectively)]. The angle at the oxygen atom is 125.7 (2)° in I and 130.6 (2)° in II, and the angle formed by the Sn-O-N system and the pyridine N-oxide ring is 86.98 (4)° in I and 84.75 (16)° in II. The N-O distances are 1.346 (4) A? in I and 1.326 (4) A? in II.