Synthesis and Structure of Di-n-Butyltin Pyridine-2-phosphonate-6-carboxylate

Abstract

The crystal structure of di-n-butyltin pyridine-2-phosphonate-6-carboxylate, [C14H24NO6PSn]2, features centrosymmetric dimers disposed about a central Sn2O2 core. The phosphonate carboxylate dianion is μ2-tetradentate, coordinating one tin atom via one of the phosphonate oxygen atoms, the pyridine nitrogen atom, and one of the carboxylate oxygen atoms; the latter atom also coordinates the second tin atom of the dimer. The remaining positions in the seven-coordinate, distorted pentagonal bipyramidal geometry are occupied by a water molecule and two n-butyl groups that occupy axial positions. The lattice is stabilized by hydrogen-bonding contacts leading to an arrangement of parallel, orthogonally related chains of dimeric units. In methanol solution, the dimer is involved in a dissociation equilibrium that is fast on the NMR time scale.

Di‐n‐butyltin(IV) derivatives of bis(carboxymethyl)benzylamines: synthesis, NMR and X‐ray structure characterization and in vitro antitumour properties

“…Chemical shifts calculated from aromatic chemical shift increments of compound 1 and toluene are given in parentheses; b = broad. 27 Lowering the temperature from 303 to 213 K confirms this proposal, as the single 117 Sn resonance decoalesces into several signals. For all four compounds, the low-temperature spectrum, from either the diluted or the concentrated solution, comprises: (i) a residual signal (ca 15%) in the range À110 to À117 ppm, characteristic for the five-coordinate species of Scheme 2; (ii) a more intense signal (ca 35%) around À282 ppm (À321 ppm for 2), which indicates a coordination expansion through aggregation to a structure with only one type of tin; this suggests a dimer of the type previously described, 27 where the O-Sn oxygen coordinates a neighbouring tin with generation of a four-membered Sn 2 O 2 cyclic core; (iii) a set of four equally intense resonances (ca 50% in total) in the range À320 to À335 ppm, suggesting the existence of an additional species in more aggregated form, necessarily at least a tetramer, with four diastereotopic tin atoms, probably due to the low symmetry of the monomeric unit.…”

Self‐Assembly of Organotin(IV) Moieties with the Schiff‐Base Ligands Pyruvic Acid Isonicotinyl Hydrazone and Pyruvic Acid Salicylhydrazone: Synthesis, Characterization, and Crystal Structures of Monomeric or Polymeric Complexes

“…The magnitude of ∆ν [ν as (COO) -ν s (COO)] is 237 and 193 cm -1 , and therefore indicates the presence of mono-and didentate carboxyl groups. [20] Moreover, the magnitude of ∆ν (231-285 cm -1 ) for complexes 2-12 indicates that the carboxylate ligand functions as a monodentate ligand in these complexes. [20] These conclusions are supported by the results of X-ray diffraction studies.…”

“…In this connection it is relevant to note the Sn-N bond lengths found in other crystal structures of organotin complexes containing a pyridinecarboxylate ligand. [20,26] For instance, in the dicarboxylate tetraorganostannoxane {[(nBu) 2 Sn(2-pic)] 2 O} 2 the two Sn-N bond lengths are 2.550(5) Å and 3.150(5) Å, [26] and in the linear polymer [(PhCH 2 ) 3 Sn(OO 2 CC 5 H 4 N-4)] the Sn-N distance is 2.563 Å. [20] The Sn2 atom is bonded to the carboxyl oxygens O1 and O2, with Sn2-O1 and Sn2-O2 bond lengths of 2.594(8) and 2.388(10) Å, respectively.…”

“…[20,26] For instance, in the dicarboxylate tetraorganostannoxane {[(nBu) 2 Sn(2-pic)] 2 O} 2 the two Sn-N bond lengths are 2.550(5) Å and 3.150(5) Å, [26] and in the linear polymer [(PhCH 2 ) 3 Sn(OO 2 CC 5 H 4 N-4)] the Sn-N distance is 2.563 Å. [20] The Sn2 atom is bonded to the carboxyl oxygens O1 and O2, with Sn2-O1 and Sn2-O2 bond lengths of 2.594(8) and 2.388(10) Å, respectively. Thus, the Sn2 atom is surrounded by C31 and C37 of the two trans phenyl groups along the axial direction while O1, O2, O6, N4, and O4 form the equatorial plane.…”

Crystal structure of bis{(ethanol)[2-(salicylhydrazono)propionato]-di(2-fluorobenzyl)tin(IV)},[(FC6H4CH2)2Sn(C2H5OH)(C10H8N2O4)]2

“…Studies on diorganotin(IV) complexes of caiboxylic acid having carboxylate ligands with additional donor atom, such as nitrogen, revealed new structural types which may lead to complexes with different activities [1][2][3]. In line with these developments, we have recently reported some diorganotin complexes of pyruvic acid isonicotinyl hydrazone [4], In the title complex, the Sn atom exists in a seven-coordinate environment in which one ethanol molecule, two tridentate pyruvic acid salicylhydrazone ligands, and two trans o-fluorobenzyl groups coordinate to each Sn center (figure, top).…”