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syn − anti Conversion in Octahedral Bis(β‐diketonato)diorganotin(IV) Derivatives Containing Fluorinated 4‐Acyl‐5‐pyrazolonato Donors
Author(s) -
Pettinari Claudio,
Marchetti Fabio,
Cingolani Augusto,
Gindulyte Asta,
Massa Lou,
Rossi Miriam,
Caruso Francesco
Publication year - 2001
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200108)2001:8<2171::aid-ejic2171>3.0.co;2-i
Subject(s) - chemistry , octahedron , molecular geometry , bond length , ligand (biochemistry) , stereochemistry , dissociation (chemistry) , tin , crystallography , steric effects , trigonal bipyramidal molecular geometry , coordination sphere , crystal structure , octahedral molecular geometry , density functional theory , medicinal chemistry , computational chemistry , molecule , organic chemistry , receptor , biochemistry
Six‐coordinate organotin derivatives L 2 SnR 2 [L = 3‐methyl‐1‐(4‐trifluoromethylphenyl)‐4‐R 3 ‐C=O‐5‐pyrazolonato (R 3 = CH 3 , L = L 1 ; R 3 = C 6 H 5 , L = L 2 ; R 3 = CF 3 , L = L 3 ; R = CH 3 , n ‐C 4 H 9 , C 6 H 5 )] have been synthesized and characterized by analytical and spectroscopic ( 1 H, 13 C, 119 Sn, and 19 F NMR, IR) techniques. Partial dissociation of one ligand in chloro‐hydrocarbon solvents gives rise to cationic five‐coordinate L‐(solvent)‐diorganotin(IV) complexes. The X‐ray crystal structure of bis[4‐benzoyl‐3‐methyl‐1‐(4‐trifluoromethylphenyl)pyrazolon‐5‐ato]diphenyltin ( 6 ) shows the metal in a distorted octahedron (skewed trapezoidal bipyramidal) with the two β‐diketonato donors in syn positions, a C−Sn−C bond angle of 165.2(2)° and two sets of tin−oxygen bonds [2.141(5) and 2.139(3) Å for Sn−O(pyrazolonato) and 2.250(4) and 2.272(5) Å for Sn−O(acyl)]. Surprisingly, the recently reported dimethyltin derivative has the anti configuration, in contrast to expectations based on all previous experience. Large scale Hartree−Fock (HF) and Density Functional Theory (DFT) calculated structures for the anti configuration of bis[4‐benzoyl3‐methyl‐1‐(4‐trifluoromethylphenyl)pyrazolon‐5‐ato]dimethyltin show good agreement with the experimental structure obtained from X‐ray methods. The hypothetical syn configuration of bis[4‐benzoyl‐3‐methyl‐1‐(4‐trifluoromethylphenyl)pyrazolon‐5‐ato]dimethyltin was also studied theoretically and both methods also predict characteristic structural features, such as: (from HF) a C−Sn−C bond angle of 150.0°, Sn−O(pyrazolonato) bond lengths of 2.088 and 2.084 Å and Sn−O(acyl) bond lengths of 2.385 and 2.401 Å. Results from the syn calculated structures suggest that intramolecular repulsive F ··· F interactions contribute to the syn − anti conversion.