Synthesis and spectroscopic studies of new organotin(IV) complexes with tridentate N- and O-donor Schiff bases

The Schiff bases H₂L¹ and H₂L² have been prepared by the reaction of 2-amino-4-chlorophenol with pyrrole-2-carbaldehyde and 2-hydroxy-1-naphtaldehyde, respectively, and HL³ from reaction of 2-(aminomethyl)pyridine with 2-hydroxy-1-naphtaldehyde. Organotin complexes [SnPh₂(L¹)] (1), [SnPh₂(L²)] (2), [SnMe₂(L²)] (3) and [SnPhCl₂(L³)] (4) were synthesized from reaction of SnPh₂Cl₂ and SnMe₂Cl₂ with these Schiff bases. The synthesized complexes have been investigated by elemental analysis and FT-IR, ¹H NMR and ¹¹⁹Sn NMR spectroscopy. In complexes the Schiff bases are completely deprotonated and coordinated to tin as tridentate ligands via phenolic oxygen, pyrrolic, and imine nitrogens in 1, two phenolic oxygens and imine nitrogen in 2 and 3, and phenolic oxygen, imine and pyridine nitrogens in 4. The coordination number of tin in 1, 2, and 3 is five and in 4 is six.     

Synthesis,characterization, and insecticidal activity of new tin (IV) complexes

A three-component reaction of dimethyltin dibromide with imidazo[1,2-a]pyridine, pyridine derivatives, or isoquinoline and allyl bromide in refluxing ethanol affords the ionic complex, bis(1-allylcycloiminium) dimethyltetrabromostannate (II). The reaction involves N-allylation of cycloimine accompanied by the coordination of two bromide ions with the tin atom of dimethyltin dibromide. The complexes have been characterized by infrared and ¹H NMR, ¹³C NMR, and ¹¹⁹Sn NMR studies. The X-ray crystal structure analysis of a complex reveals the tin atom to be hexacoordinated and the dimethyltetrabromostannate (II) anion having octahedral geometry. Some of the complexes tested for their insecticidal activity are found to exhibit strong activity against Tribolium castaneum insect with LC₅₀ ranging from 0.4 to 0.8 ppm.     

Synthesis and characterization of new organotin(IV) complexes with polyfunctional ligands

New mono-, di- and tri-organotin(IV) derivatives containing the neutral bis(2-pyridylthio)methane ligand, [(pyS)₂CH₂] and tris(2-pyridylthio)methane ligand, [(pyS)₃CH] have been synthesized from reaction with SnR_nCl_4−n (R = Me, ⁿBu, Ph and Cy, n = 1-3) acceptors. Mono-nuclear adducts of the type {[(pyS)₂CH₂]R_nSnCl_4−n} and {[(pyS)₃CH]R_nSnCl_4−n} have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear (¹H and ¹¹⁹Sn) NMR spectral data. The ¹H and ¹¹⁹Sn NMR and ESI-MS data suggest for the triorganotin(IV) derivatives a complete dissociation of the compounds in solution. The mono- and di-organotin(IV) derivatives show a greater stability in solution, and their spectroscopic data are in accordance with the existence of six-coordinated RSnCl₃N₂ or R₂SnCl₂N₂ species.     

Tin(IV) and organotin(IV) derivatives of bis(pyrazolyl)acetate: Synthesis, spectroscopic characterization and behaviour in solution.: X-ray single crystal study of bis(pyrazol-1-yl)acetatotri-iodotin(IV) [SnI3(bdmpza)]

Novel heteroscorpionate-containing tin and organotin(IV) complexes, [SnR_nX_3 − n(L)], R = Me, Buⁿ, Ph, or cy; X = Cl, Br or I, n = 0, 1, 2 or 3; L = bis(pyrazol-1-yl)acetate (bpza) or bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza), have been synthesized and characterized by spectral (IR, ¹H, ¹³C and ¹¹⁹Sn NMR, ^119mSn Mössbauer) and analytical data. In [SnI₃(bdmpza)], the ligand is fac-N,N′,O-tridentate, the three iodine atoms thus also fac about the six-coordinate tin(IV) atom. Neutral bpzaH reacts with BuⁿSnCl₃, PhSnCl₃ and SnCl₄ in Et₂O in the absence of base, yielding 1:1 adducts [XSnCl₃(bpzaH)] (X = R or Cl).     

Synthesis, spectral characterization and biological studies of some organotin(IV) complexes of L-proline, trans-hydroxy-L-proline and L-glutamine

New organotin(IV) complexes of the general formula R3Sn(L) (where R=Me, n-Bu and HL=L-proline; R=Me, Ph and HL=trans-hydroxy-L-proline and L-glutamine) and R2Sn(L)2 (where R=n-Bu, Ph and HL=L-proline; R=Ph, HL=trans-hydroxy-L-proline) have been synthesized by the reaction of RnSnCl(4-n) (where n=2 or 3) with sodium salt of the amino acid (HL). n-Bu2Sn(Pro)2 was synthesized by the reaction of n-Bu2SnO with L-proline under azeotropic removal of water. The bonding and coordination behavior in these complexes have been discussed on the basis of IR and 119Sn M?ssbauer spectroscopic studies in the solid-state. Their coordination behavior in solution has been discussed with the help of multinuclear (1H, 13C and 119Sn) NMR spectral studies. The 119Sn M?ssbauer and IR studies indicate that L-proline and trans-hydroxy-L-proline show similar coordination behavior towards organotin(IV) compounds. Pentacoordinate trigonal-bipyramidal and hexacoordinate octahedral structures, respectively, have been proposed for the tri- and diorganotin(IV) complexes of L-proline and trans-hydroxy-L-proline, in which the carboxylate group acts as bidentate group. L-glutamine shows different coordination behavior towards organotin(IV) compounds, it acts as monoanionic bidentate ligand coordinating through carboxylate and amino group. The triorganotin(IV) complexes of L-glutamine have been proposed to have trigonal-bipyramidal environment around tin. The newly synthesized complexes have been tested for their antiinflammatory and cardiovascular activities. Their LD50 values are >1000 mg kg-1.     

Synthesis and structural characterization of ruthenium complexes with 1-aryl-imidazole-2-thione

Treatment of [RuCl₂(PPh₃)₃] with 2 equiv. Himt^MPh (Himt^MPh?=?1-(4-methyl-phenyl)-imidazole-2-thione) in the presence of MeONa afforded cis-[Ru(κ ²-S,N-imt^MPh)₂(PPh₃)₂] (1), while interaction of [RuCl₂(PPh₃)₃] and 2 equiv. Himt^MPh in tetrahydrofuran (THF) without base gave [RuCl₂(κ ¹-S-Himt^MPh)₂(PPh₃)₂] (2). Treatment of [RuHCl(CO)(PPh₃)₃] with 1 equiv. Himt^MPh in THF gave [RuHCl(κ ¹-S-Himt^MPh)(CO)(PPh₃)₂] (3), whereas reaction of [RuHCl(CO)(PPh₃)₃] with 1 equiv. of the deprotonated [imt^MPh]^? or [imt^NPh]^? (imt^NPh?=?1-(4-nitro-phenyl)-2-mercaptoimidazolyl) gave [RuH(κ ²-S,N-imt^RPh)(CO)(PPh₃)₂] (R?=?M 4a, R?=?N 4b). The ruthenium hydride complexes 4a and 4b easily convert to their corresponding ruthenium chloride complexes [RuCl(κ ²-S,N-imt^MPh)(CO)(PPh₃)₂] (5a) and [RuCl(κ ²-S,N-imt^NPh)(CO)(PPh₃)₂] (5b), respectively, in refluxing CHCl₃ by chloride substitution of the RuH. Photolysis of 5a in CHCl₃ at room temperature afforded an oxidized product [RuCl₂(κ ²-S,N-imt^MPh)(PPh₃)₂] (6). Reaction of 6 with excess [imt^MPh]^? afforded 1. The molecular structures of 1·EtOH, 3·C₆H₁₄, 4b·0.25CH₃COCH₃, and 6·2CH₂Cl₂ have been determined by single-crystal X-ray crystallography.     

Synthesis, crystal structure and in vitro antitumor activity of carboxylate bridged dinuclear organotin(IV) complexes

Two novel dinuclear organotin(IV) complexes [n-Bu₂Sn(imda)(H₂O)]₂·Bipy (1) and [n-Bu₂Sn(imda)(H₂O)]₂·Phen (2) [H₂imda = iminodiacetic acid, Bipy = 2,2′-bipyridine and Phen = 1,10-phenanthroline] were synthesised and characterized employing IR, ¹H, ¹³C, ¹¹⁹Sn NMR, and ¹¹⁹Sn Mössbauer spectroscopic and elemental analyses. Single crystal X-ray crystallography of 1 has confirmed that it is a binuclear Sn(IV) species formed via carboxylate bridges where each metal adopted a seven coordinate distorted pentagonal bipyramidal geometry. The iminodiacetate dianion (imda²⁻) acts as a potential tridentate [N,O,O] carboxylate bridging ligand. The packing revealed that the additional α-diimine (Bipy or Phen) does not coordinate to metal ion. However, its presence in the crystal lattice as spacer helps for the formation of a supramolecular framework by bringing the two binuclear species close enough through extensive H-bonding. The in vitro cytotoxicity of compounds 1 and 2 indicate better results than cisplatin against three tumor cell lines investigated.     

Organotin(IV) triazolates: Synthesis and their spectral characterization

Some organotin(IV) triazolates of general formula R_nSn(L)_4 − n (where R = Me, n-Bu and Ph for n = 2; R = Me, n-Pr and n-Bu for n = 3 and HL = 3-amino-5-mercapto-1,2,4-triazole) have been synthesized by the reaction of R₂SnCl₂/R₃SnCl with NaL in 1:2/1:1 molar ratio. Whereas, Oct₂SnL₂ has been synthesized azeotropically by the reaction of Oct₂SnO and HL in 1:2 molar ratio. As good single crystals were not obtained, a large number of experimental techniques, viz. UV/Vis, IR, far-IR, multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR and ¹¹⁹Sn Mössbauer spectroscopic studies, were used to accomplish a definitive characterization and determination of their most probable structures. In these compounds triazole acts as a monoanionic bidentate ligand, coordinating through S_exo and N(4). The IR and ¹¹⁹Sn Mössbauer spectroscopic studies allow us to deduce a highly distorted cis-trigonal-bipyramidal structure for R₃SnL and a distorted skew trapezoidal-bipyramidal structure for R₂SnL₂, in the solid state. However, ¹H, ¹³C and ¹¹⁹Sn NMR spectral studies revealed that weak bonding between tin and N(4) is further weakened in the solution leading to pseudo-tetrahedral/tetrahedral structure.     

Synthesis,spectroscopic and structural studies of 2,2,2-trifluoroethyl phosphorodiamidate complexes with tin(IV) chloride

The two octahedral complexes SnCl₄ · 2(O)P(NR₂)₂OCH₂CF₃ (R = Me (1) or Et (2)) have been prepared from SnCl₄ and the ligands (R₂N)₂P(O)OCH₂CF₃ in chloroform solution. Both adducts have been characterised by (³¹P and ¹¹⁹Sn) NMR, IR spectroscopy and elemental analysis. The NMR data show that the complexes exist as mixtures of cis and trans isomers in solution with the latter isomer being the predominant species. The structure of 1 has been determined by X-ray crystallography. Accordingly, the structure is centrosymmetric and the two ligands are bound trans to each other in the octahedral tin complex. DFT/B3LYP calculations show that trans configuration does indeed lead to the lowest energy species. Comparison of the structural, NMR and theoretical data of both complexes with those related to SnCl₄ · 2L (L = (Me₂N)₃P(O) and (Me₂N)₂P(O)F) further supports the important effects of the nature of the substituents in the ligand on the stereochemistry of the complex formed.     

Synthesis and spectroscopic characterization of new organotin(IV) complexes with bis(3,5-dimethylpyrazol-1-yl)dithioacetate

New organotin(IV) derivatives containing the anionic ligand bis(3,5-dimethylpyrazolyl)dithioacetate [L₂CS₂]^? have been synthesized by reaction of SnR _n X_{4? n} (R?=?Me, Ph, ⁿ Bu or Cy; n?=?1–3) acceptors and Li[L₂CS₂]. Mononuclear complexes of the type [L₂CS₂]R _n SnCl_{4? n ?1}} have been obtained and fully characterized by elemental analyses and FT-IR in the solid state, and by NMR (¹H and ¹¹⁹Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry (ESI-MS) in solution. ESI-MS spectra of methanol solutions of diorganotin derivatives, recorded with fragmentor potentials of 0, 50, 100 and 150?V, show the occurrence at 150?V of peaks attributable to the loss of the CS₂ group from the ligands and the formation of stable tetraorganodistannoxane species.     

Synthesis, characterisation and X-ray structures of diorganotin(IV) and iron(III) complexes of dianionic terdentate Schiff base ligands

Diorganotin(IV) complexes, [SnR₂L] (1)-(4), (R = Me, Ph), of the terdentate Schiff bases N-[(2-pyrroyl)methylidene]-N′-tosylbenzene-1,2-diamine (H₂L¹) and N-[(2-hydroxyphenyl)metylidene]-N′-tosylbenzene-1,2-diamine (H₂L²) have been synthesised. The complexes were obtained by addition of the appropriate ligand to a methanol suspension of the corresponding diorganotin(IV) dichloride in the presence of triethylamine. However, the reaction between the precursor [η⁵-C₅H₅Fe(CO)₂]₂SnCl₂ and the Schiff bases in the presence of triethylamine gave (5) and (6), respectively. The crystal structures of the ligands and complexes have been studied by X-ray diffraction. The structure of [SnR₂L] complexes shows the tin to be five-coordinate in a distorted square pyramidal environment with the dianionic ligand acting in a terdentate manner. In 5 and 6, the iron atom is in a slightly distorted octahedral environment and is meridionally coordinated by two ligands. Spectroscopic data for the ligands and complexes (IR, ¹H, ¹³C and ¹¹⁹Sn NMR and mass spectra) are discussed and related to the structural information.     

Synthesis and solid-state spectroscopic investigation of some novel diorganotin(IV) complexes of tetraazamacrocyclic ligands

The tetradendate macrocyclic ligands, [H₂L-1 = 5,12-dioxa-7,14-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,8-diene] and [H₂L-2 = 6,14-dioxa-8,16-dimethyl-1,5,9,13-tetraazacyclohexadeca-1,9-diene] have been prepared by the condensation reaction of 1,2-diaminoethane and 1,3-diaminopropane, respectively, with ethyl acetoacetate in methanol at room temperature. The diorganotin(IV) complexes of general formula [R₂Sn(L-1)/R₂Sn(L-2)] (R = Me, n-Bu and Ph) have been synthesized by template condensation reaction of 1,2-diaminoethane or 1,3-diaminopropane and ethyl acetoacetate with R₂SnCl₂ (R = Me or Ph) or n-Bu₂SnO in 2:2:1 molar ratio at ambient temperature (35 ± 2 °C) in methanol. The solid-state characterization of resulting complexes have been carried out by elemental analysis, IR, recently developed DART-mass, solid-state ¹³C NMR, ^119mSn Mössbauer spectroscopic studies. These studies suggest that in all of the studied complexes, the macrocyclic ligands act as tetradentate coordinating through four nitrogen atoms giving a skew-trapezoidal bipyramidal environment around tin center. Since, the studied diorganotin(IV) macrocyclic complexes are insoluble in common organic solvents, hence good crystals could not be grown for single crystal X-ray crystallographic studies. Thermal studies of all of the studied complexes have also been carried out in the temperature range 0-1000 °C using TG, DTG and DTA techniques. The end product of pyrolysis is SnO₂ confirmed by XRD analysis.     

Penta- and heptacoordinated tin(IV) compounds derived from pyridine Schiff bases and 2-pyridine carboxylate: Synthesis and structural characterization

The synthesis of the Sn(IV)-complexed, Schiff base derivatives 1a-1l, prepared in one pot by the reaction of 2-amino-4-R-phenol (R = H, Me, Cl, NO₂), 2-pyridinecarboxaldehyde, 2-picolinic acid and dimethyl-, dibutyl-, and diphenyltin oxides, is described. The complexes were characterized by IR, MS, ¹H, ¹³C, ¹¹⁹Sn NMR. Suitable crystals of 1e and 1h enabled us to use X-ray diffraction to determine their molecular structures, which exhibited pentagonal-bipyramidal geometries where the butyl groups occupied the axial positions whereas the nitrogen and the oxygen atoms occupied the equatorial positions. The reaction of the Schiff base 2 with dibutyltin oxide led to the pentacoordinated complex, 2h, through the addition of methanol to the CN bond. An unusual reduction-oxidation reaction took place by the reaction of 2-amino-4-nitro-phenol, dibutyltin oxide and 2-pyridinecarboxaldehyde, which produced the corresponding amine, 3h, and the amide, 4h, tin(IV) derivatives. Both structures were established by X-ray crystallography and exhibited a distorted, bipyramidal trigonal (BPT) geometry.     

Synthesis and biological activity of trinuclear seven-coordinated tin(IV) complexes derived from tridentate ligands and trimesic acid

The synthesis of trinuclear Sn(IV) complexes 5a–h – prepared in a one-pot reaction of 2-amino-4-R-phenol (R=H, Me, Cl, NO₂), 2-pyridine-carboxaldehyde, 1,3,5-benzenetricarboxylic acid (trimesic acid, H₃BTC), and dibutyl and dioctyltin oxides – is described. These compounds were characterized by elemental analysis, mass spectrometry, IR, and multinuclear NMR spectroscopy. The structures of 5a and 5b were also determined by single-crystal X-ray analysis. The trinuclear tin system is formed by bridges through the carboxylate moieties. The metal centers are seven-coordinate and the coordination polyhedron of tin can be depicted as distorted pentagonal-bipyramidal (PBP), where the equatorial plane consists of three oxygens and two nitrogens and the organic groups occupy the axial positions. The work presented here combines the useful properties of Schiff bases and H₃BTC ligands in the formation of organotin(IV) complexes, and investigates the likely antioxidant (DPPH and TBARS) and anti-inflammatory activity (TPA) of the new substances.     

Synthesis, characterization and solution behaviour of phosphoryl complexes of tin tetrafluoride

The preparation and characterization of a series of octahedral complexes [SnF₄L₂] (L = (Me₂N)₃PO (1), L = (R₂N)₂P(O)F; R = Me (2); Et (3) or L = R₂NP(O)F₂; R = Me (4); Et (5)) are described. These new adducts have been characterised by multinuclear (¹⁹F, ³¹P and ¹¹⁹Sn) NMR, IR spectroscopy and elemental analysis. The NMR data particularly the ¹⁹F NMR spectra showed that the complexes exist in solution as mixtures of cis and trans isomers. The solution behaviour of the complexes studied by variable temperature NMR in the presence of excess ligand indicated that, unlike in the SnCl₄ analogues, the ligand exchange at room temperature is slow for 1–3 and fast only for 4 and 5. The metal–ligand exchange barriers in [SnF₄L₂] and [SnCl₄L₂] systems were estimated and compared. The results indicate that in addition to the difference in the Lewis acidity between SnF₄ and SnCl₄ the nature of the substituents (fluorine atoms) on the phosphorus atom of the ligand can contribute considerably to the lability of the complex obtained.     

New diorganotin(IV) derivatives of 7-hydroxycoumarin (umbelliferone) and their adducts with 1,10-phenanthroline

New diorganotin(IV) derivatives of the general formula R2Sn(Umb)2 (where R = n-Bu, n-Oct and Ph; Umb = umbelliferone anion) have been synthesized either by the reaction of R2SnO with umbelliferone under azeotropic removal of water or by the reaction of R2SnCl2 with sodium salt of umbelliferone. Further, the adducts of the general formula R2Sn(Umb)2.phen (where R = n-Bu and n-Oct; phen = 1,10-phenanthroline) have also been synthesized by the interaction of R2Sn(Umb)2 with 1,10-phenanthroline. The bonding and coordination behavior in these derivatives are discussed on the basis of IR and 119Sn M?ssbauer spectroscopic studies in solid state. Their coordination behavior in solution is discussed by the multinuclear (1H, 13C and 119Sn) NMR spectral studies. The M?ssbauer and IR studies indicate that umbelliferone acts as a monoanionic bidentate ligand in R2Sn(Umb)2 coordinating through O(7) and O(1). A distorted octahedral geometry around tin has been proposed for R2Sn(Umb)2 as well as for R2Sn(Umb)2.phen in solid state. The newly synthesized derivatives have been tested for their anti-inflammatory and cardiovascular activities. The average LD50 value >1000 mg kg(-1) of these compounds indicates their safety margin.     

Triorganotin(IV) Derivatives of Bidentate Schiff Bases: Synthesis and Spectral Studies

Abstract

Reaction of tri-n-butyl tin(IV) chloride with the sodium salt of Schiff bases [salicylidene-2-aminopyridine (sapH), salicylidene-2-amino-4-picoline (sapicH), salicylidene-2-methyl-1-aminobenzene (o-smabH), salicylidene-4-methyl-1-aminobenzene (p-smabH), salicylidene-1- aminobenzene (sabH), salicylidene-3-nitro-1-aminobenzene (snabH)] in MeOH-C₆H₆ mixture in 1:1 molar ratio produced complexes of the type [Buⁿ ₃Sn(sb)] (where sb = Schiff bases). All complexes obtained were characterized by elemental analysis (C, H, N, and Sn), infrared (IR), nuclear magnetic resonance (NMR; ¹H, ¹³C, and ¹¹⁹Sn), and TOF-MS spectroscopic studies. These complexes were found to be monomeric, colored viscous liquids and are soluble in polar solvents (methanol, ethanol, DMSO, and DMF). On the basis of ¹¹⁹Sn NMR observations, a five coordination geometry around tin(IV) atom in these complexes is proposed tentatively.     

Synthesis and characterization of tribenzyltin(IV) and dibenzyltin(IV) complexes of 2-{[(2Z)-3-hydroxy-1-methyl- 2-butenylidene]amino}acetic acid: Crystal structure of tribenzyl{2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene] amino}acetato}tin(IV)

Reactions of equimolar quantities of potassium 2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene]amino}acetate, with R _n SnX_4?n (R: benzyl– and n=2 or 3) in methanol yielded products of compositions LHSn(PhCH₂)₃ and LSn(PhCH₂)₂, respectively. The complexes were characterized by microanalysis, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) and ^119mSn Mössbauer spectroscopy. A full characterization of the structure of the complex, tribenzyl{2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene]amino}acetato}tin(IV), was carried out by single crystal X-ray crystallography. The compound exists as centrosymmetric dimers in which two ligand molecules bridge the two tin centres. Each of the tin atoms in the dimeric unit is five coordinate in an approximately trigonal bipyramidal configuration, with carbon atoms in the equatorial positions and oxygen atoms arranged axially.     

Synthesis and Characterization of a Novel Phosph(V)azane-Tin(IV) Complex

Abstract

The reaction of bis(anilino)phosphine oxide (C₆H₅NH)₂P(O)H, 1 with Bu₂ ⁿSnCl₂ in the presence of an excess of triethylamine (TEA) in dry tetrahydrofurane (THF) yields the novel N,O-bonded tin complex Bu₂ ⁿSn[NPh(O)P(H)NPh(HNEt₃)]₂, 2. TEA is used as a base to deprotonate the phosphazane ligand and is separated as Et₃NH⁺Cl^?, whereas HTEA⁺ exists in the final product 2 and act as a charge balancing and H-bond structure–directing agent. This new compound has been fully characterized by means of IR, MS, and multinuclear (¹H, ³¹P, and ¹¹⁹Sn NMR) spectroscopy.