Triorganotin(IV) derivatives of umbelliferone (7-hydroxycoumarin) and their adducts with 1,10-phenanthroline: synthesis, structural and biological studies

New triorganotin(IV) derivatives of the general formula R₃Sn(Umb) (where, R = Me, n-Bu and Ph; Umb = umbelliferone anion) have been synthesized using sodium salt method. Further, the adducts of the general formula R₃Sn(Umb) · phen (where R = Me and Ph; phen = 1,10-phenanthroline) have also been synthesized by the interaction of the triorganotin(IV) derivatives of umbelliferone with 1,10-phenanthroline. The bonding and coordination behavior of these derivatives are discussed on the basis of IR, NMR (¹H, ¹³C and ¹¹⁹Sn), and ¹¹⁹Sn Mössbauer spectroscopic studies. These investigations indicate that umbelliferone acts as a monoanionic bidentate ligand in R₃Sn(Umb) coordinating through O(7) and O(1) in the solid-state. These polymeric R₃Sn(Umb) derivatives (where R = Me and n-Bu) have been proposed to have a trans-trigonal bipyramidal geometry with the three R groups in equatorial positions, while the axial positions are occupied by a phenolic oxygen and the O(1) atom from the adjacent molecule. A pseudotetrahedral geometry has been suggested for Ph₃Sn(Umb). A distorted octahedral geometry around tin has been proposed for R₃Sn(Umb) · phen, in which umbelliferone anion acts as a monodentate ligand coordinating through phenolic oxygen O(7). The newly synthesized derivatives have been assayed for their anti-inflammatory, cardiovascular and anti-microbial activities. The average LD₅₀ values >1000 mg kg⁻¹ of these derivatives indicate their safety margin. Among all the compounds tested, Ph₃Sn(Umb) · phen has been found to show potent anti-inflammatory activity with low mammalian toxicity and mild hypotensive activity.     

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.     

Preparation and structural studies on diorganotin(IV) complexes of N-nitroso-N-phenylhydroxylaminates

Diorganotin(IV)-complexes of the N-nitroso-N-phenylhydroxylaminates (hereinafter cupf), Et₂Sn(cupf)₂ (1), Bu₂Sn(cupf)₂ (2), {[Bu₂Sn(cupf)]₂O}₂ (3), t-Bu₂Sn(cupf)₂ (4) and Oc₂Sn(cupf)₂ (5, 6) were prepared and characterised by FT-IR and Mössbauer spectroscopic measurements. The binding modes of the ligand were identified by FT-IR spectroscopy, and it was found that the ligand is coordinated in chelating or bridging mode to the organotin(IV) center. The ¹¹⁹Sn Mössbauer and FT-IR studies support the formation of trans-O_h (1-6) structures. The X-ray diffraction analysis of 4 revealed that the tin centre is in a skew-trapezoidal geometry defined by four donors derived from the cupferronato ligands and two carbon atoms from the tin-bound ^tbutyl substituents. The ¹¹⁹Sn NMR investigations indicate that in solution 4 retains its hexacoordinated nature.     

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.     

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, spectroscopic characterization and in vitro antimicrobial activity of diorganotin(IV) dichloride adducts with [1,2,4]triazolo-[1,5-a]pyrimidine and 5,7-dimethyl-[1,2,4]triazolo-[1,5-a]pyrimidine

The heterocyclic ligands [1,2,4]triazolo-[1,5-a]pyrimidine (tp) and 5,7-dimethyl-[1,2,4]triazolo-[1,5-a]pyrimidine (dmtp), react with diorganotin dichlorides giving the addition compounds Me₂SnCl₂(tp)₂, Et₂SnCl₂(tp)₂, Me₂SnCl₂(dmtp)₂, Et₂SnCl₂(dmtp)₂, Bu₂SnCl₂(dmtp), Ph₂SnCl₂(dmtp). The organotin:ligand stoichiometry goes from 1:2 to 1:1 by increasing the steric hindrance of the organic groups bound to tin. The compounds have been characterized by means of infrared, ¹¹⁹Sn Mössbauer and ¹H AND ¹³C NMR spectroscopy.The ligands presumably coordinate to tin classically through the nitrogen atom at the position 3. The 1:1 complexes adopt trigonal bipyramidal structures, with the organic groups on the equatorial plane and the ligand in the apical position. All-trans octahedral structures are inferred for the 1:2 complexes, except for Et₂SnCl₂(tp)₂, characterized by a skew-trapezoidal structure.¹¹⁹Sn Mössbauer measurements, at room temperature, in concomitance with DFT calculations, performed on isomeric structures of R₂SnCl₂(tp)₂ (R = Me, Et), allowed us to conclude that the all-trans octahedral coordination induces self-assembly in the solid state, possibly accomplished through π-π stacking interactions among the planar ligands coordinated to the organotin(IV) compound, while the skew-trapezoidal structure attributed to Et₂SnCl₂(tp)₂, induces the formation of monomeric adducts in the solid state.In vitro antimicrobial tests showed that [n-Bu₂SnCl₂(dmtp)] has interesting properties as anti Gram-positive and antibiofilm agent.     

Tin(IV), Monomethyltin(IV), and Dimethyltin(IV) Complexes with thiol sulfur and heterocyclic nitrogen donors: Molecular dynamics and structure by 119Sn mössbauer spectroscopy

The molecular dynamics of the complexes Sn(SPyN)₄ ( 1 ), SnCl₂(SPyN)₂ ( 2 ), MeSn(SPy)₃ ( 3 ), MeSnCl(SPyN)₂ ( 4 ), Me₂Sn(TCy)₂ ( 5 ), Me₂SnCl(TOx) ( 6 ), and Me₂Sn(TUr) ( 7 ) [HSPy = 2-mercaptopyridine; HSPyN = 2-mercaptopyrimidine; HTCy = 2-thiocytosine; HTOx = 8-thioquinoline; H₂TUr = 2-thiouracil] has been investigated by variable temperature ¹¹⁹Sn Mössbauer spectroscopy. The area under the resonant peaks has been determined as function of temperature, from which Debye temperatures and cut-off frequencies, as well as recoil-free fractions (Lamb Mössbauer factor) and mean square displacements of ¹¹⁹Sn, have been calculated. By fingerprint procedures on the basis of literature data, monomeric structures are attributed to complexes ( 1 )–( 4 ) and ( 6 ), while ( 5 ) and ( 7 ) lie in the borderline monomersmonodimensional polymers. The results are discussed on the basis of known crystal and molecular structures. The nature of the environment of tin atoms has been simulated by point-charge model calculations of nuclear quadrupole splitting parameters; molecular structures are proposed for complexes ( 5 )–( 7 ), where no X-ray diffractometric data are available.     

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.     

Structural and spectral studies of 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one and its diorganotin(IV) complexes

Two diorganotin(IV) complexes of the general formula R₂Sn[Ph(O)CCH-C(Me)N-C₆H₄(O)] (R = Ph, 1a; R = Me, 1b) have been synthesized from the corresponding diorganotin(IV) dichlorides and the ligand, 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one (1) in methanol at room temperature in presence of triethylamine. Both compounds have been characterized by elemental analyses, IR and ¹H, ¹³C, ¹⁵N, ¹¹⁹Sn NMR spectra. The structures of the free ligand and the complexes have been confirmed by single crystal X-ray diffraction. There are three independent molecules in the crystal structure of the ligand 1 and in all three the O-bound proton is transferred to the imine nitrogen and makes an intramolecular N-H?O hydrogen bond with the carbonyl oxygen. In turn this makes an intermolecular hydrogen bond with the phenolic H atom. The crystal structure of 1 is trigonal and a new polymorph; triclinic and monoclinic forms have already been published. In 1a, the central tin atom adopts distorted trigonal-bipyramidal coordination geometry whereas in dimeric 1b it is distorted octahedral when including the intermolecular Sn-O(phenolic) bond [2.7998(20) Å]. The δ (¹¹⁹Sn) values for the complexes 1a and 1b are −306.6 and −127.9 ppm, respectively, thus indicating penta-coordinated Sn centres in solution.     

Solubility, dissociation and complexation with Nd(III) and Th(IV) of oxine, thenoyltrifluoroacetone and 1,10-phenanthroline in 5.0 m NaCl

Equilibria in the system of Nd(III) and Th(IV) with 8-hydroxyquinoline (oxine), thenoyltrifluoroacetone (HTTA) and 1,10-phenanthroline (phen) in 5.0 m NaCl solution have been investigated by spectroscopy and potentiometry. The solubility and deprotonation constants of the three organics were measured to be: pK_s = 3.09 ± 0.01, pK_a1 = 5.82 ±0.02, pK_a2= 10.00 ±0.01 for oxine; pK_s = 2.49 ± 0.01, pK_a1 = 6.47 ±0.03 for HTTA; pK_s = 2.86 ± 0.02, pK_a2 = 5.82 ± 0.05 for phen. The stabilities of the corresponding metal complexes are in the order M(oxine) > M(TTA) > M(phen), where M = Nd(III), Th(IV). For all three organic ligands, the Th(IV) complexation is stronger than that of Nd(III).     

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.     

Structure and spectroscopy of diorganotin(IV) complexes derived from N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide

Three new diorganotin(IV) complexes of the general formula R₂Sn[3-(OMe)-2-OC₆H₃CHN-NC(O)Ph] (R = Ph, Ia; R = Me, Ib; R = n-Bu, Ic) have been synthesised from the corresponding diorganotin(IV) dichlorides and the ligand, N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide in methanol at room temperature in the presence of trimethylamine. All the complexes have been characterized by elemental analysis, IR and ¹H, ¹³C, ¹⁵N, ¹¹⁹Sn NMR spectra, and their structures have been confirmed by single crystal X-ray diffraction analysis of one representative compound Ia. Complex Ia crystallises in the orthorhombic system, space group Pna2₁ with a = 12.424(5), b = 9.911(5), c = 18.872(5) Å; Z = 4. The ligand N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (H₂L) coordinates to the metal centre in the enolate form via the phenolic O, imino N and enolic O atoms. In Ia, the central tin atom adopts a distorted trigonal bipyramidal coordination geometry with the oxygen atoms in axial positions, while the imino nitrogen atom of the Schiff base and the two phenyl groups occupy the equatorial sites. The δ(¹¹⁹Sn) values for the complexes Ia, Ib and Ic are −327.3, −151.7 and −187.2 ppm, respectively, thus indicating penta-coordinated Sn centres in solution.