Molecular structures and supramolecular association of chlorodiorganotin(IV) complexes with bis- and tris-dithiocarbamate ligand

Two series of di and trinuclear chlorodiorganotin(IV) complexes derived from bis- and tris-dithiocarbamate ligands have been prepared and structurally characterized. The dinuclear complexes 1-2 of the composition {(R₂SnCl)₂(bis-dtc)} (1, R = Me; 2, R = ⁿBu) have been obtained from R₂SnCl₂ (R = Me, ⁿBu) and the triethylammonium salt of N,N′-dibenzyl-1,2-ethylene-bis(dithiocarbamate). The trinuclear complexes 3-9 with the general formula {(R₂SnCl)₃(tris-dtc)} 3, R = Me, tris-dtc = tris-dtc-Me; 4, R = Me, tris-dtc = tris-dtc-ⁱPr; 5, R = Me, tris-dtc = tris-dtc-Bn; 6, R = ⁿBu, tris-dtc = tris-dtc-Me; 7, R = ⁿBu, tris-dtc = tris-dtc- ⁱPr; 8, R = ⁿBu, tris-dtc = tris-dtc-Bn; 9, R = ^tBu, tris-dtc = tris-dtc-Me) were prepared from R₂SnCl₂ (R = Me, ⁿBu, ^tBu) and the potassium dithiocarbamate salts of (tris[2-(methylamino)ethyl]amine) (tris-dtc-Me), (tris[2-(isopropylamino)ethyl]amine) (=tris-dtc-ⁱPr) and (tris[2-(benzylamino)ethyl]amine) (=tris-dtc-Bn). Compounds 1-9 have been analyzed as far as possible by elemental analysis, FAB⁺ mass spectrometry, IR and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy, and single-crystal X-ray diffraction analysis. The solid state and solution studies showed that the dtc ligands are coordinated to the tin atoms in the anisobidentate manner. In all cases the metal centers are five-coordinate. The coordination geometry is intermediate between square-pyramidal and trigonal-bipyramidal coordination polyhedra with τ-values in the range of 0.32-0.53. For the members of each series characterized in the solid state by X-ray diffraction analysis, different molecular conformations were found. The crystal structures show the presence of C-H?Cl, C-H?S, C-H?π, S?Cl, S?S, Cl?Sn and S?Sn contacts.     

Chiral organotin (IV) carboxylates complexes: Syntheses, characterization, and crystal structures with chiral (S)-(+)-6-methoxy-α-methyl-2-naphthaleneaceto acid ligand

Eight new organotin (IV) carboxylates, (R₃Sn)₄(nap)₄ (R = Me 1, n-Bu 2), [(R₃Sn) (nap)]_n (R = Ph 3, PhCH₂4), (R₂Sn) (nap)₂ (R = n-Bu 5, Ph 6, PhCH₂7) and {[R₂Sn(nap)]₂O}₂ (R = Me 8) (nap = (S)-(+)-6-methoxy-α-methyl-2-naphthaleneaceto anion) have been synthesized. All of the complexes have been characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C and ¹¹⁹Sn) spectra. Among these complexes, complexes 1, 3, 5 and 8 were also characterized by X-ray crystallography diffraction analysis, and the data of X-ray crystallography diffraction indicated that complexes 1, 3 and 5 are new chiral organotin (IV) carboxylates complexes. The structural analyses show that complex 1 has a tetranuclear Sn₄O₈ macrocycle structure, complex 3 has a 1D spring-like chiral helical chain with a columnar channel, complex 5 possesses a dimer structure, and complex 8 has a supramolecular chainlike ladder structure through weak intermolecular non-covalent O^…O interactions.     

Syntheses and crystal structures of diorganotin (IV) moieties with 3-hydroxy-2-pyridinecarboxylic acid

A series of new organotin (IV) complexes with 3-hydroxy-2-pyridinecarboxylic acid (3-OH-2-picH) of two types: R₂SnCl(3-OH-2-pic) (I) (R = Me 1, n-Bu 2, Ph 3, PhCH₂4) and R₂ Sn(3-OH-2-pic)₂ (II) (R = Me 5, n-Bu 6, Ph 7, PhCH₂8)have been synthesized by reactions of diorganotin (IV) dichloride with 3-hydroxy-2-pyridinecarboxylic acid in the presence of sodium ethoxide. All complexes are characterized by elemental analyses, IR spectra and NMR spectra analyses. Among them, complexes 1, 5, 6 and 7 are also characterized by X-ray crystallography diffraction analyses. Complex 1 is a 1D polymeric chain with six-coordinate tin atoms and the packing of complex 1 is stabilized by the C-H?Cl intermolecular weak interactions, thus a 2D network of 1 is formed. Complex 5 is also a 1D polymeric chain with seven-coordinate tin atoms. Complex 6 is a zigzag polymeric chain linked by Sn?O intermolecular weak interactions. Complex 7 is a monomeric complex with distorted octahedral geometry.     

Self-assembly of di- and triorganotin(IV) complexes: Syntheses, characterization and crystal structures of 1D polymeric chain containing O,O-diethyl or O,O-diisopropyl phosphoric acid ligands

A series of organotin(IV) complexes with O,O-diethyl phosphoric acid (L¹H) and O,O-diisopropyl phosphoric acid (L²H) of the types: [R₃Sn · L]_n (L = L¹, R = Ph 1, R = PhCH₂2, R = Me 3, R = Bu 4; L = L², R = Ph 9, R = PhCH₂10, R = Me 11, R = Bu 12), [R₂Cl Sn · L]_n (L = L¹, R = Me 5, R = Ph 6, R = PhCH₂7, R = Bu 8; L = L², R = Me 13, R = Ph 14, R = PhCH₂15, R = Bu 16), have been synthesized. All complexes were characterized by elemental analysis, TGA, IR and NMR (¹H, ¹³C, ³¹P and ¹¹⁹Sn) spectroscopy analysis. Among them, complexes 1, 2, 3, 5, 8, 9 and 11 have been characterized by X-ray crystallography diffraction analysis. In the crystalline state, the complexes adopt infinite 1D infinite chain structures which are generated by the bidentate bridging phosphonate ligands and the five-coordinated tin centers.     

Investigation on coordination modes of organotin(IV) complexes with 6-thiopurine and related ligands

The organotin(IV) complexes R₂Sn(tpu)₂ · L [L = 2MeOH, R = Me (1); L = 0: R = n-Bu (2), Ph (3), PhCH₂ (4)], R₃Sn(Hthpu) [R = Me (5), n-Bu (6), Ph (7), PhCH₂ (8)] and (R₂SnCl)₂ (dtpu) · L [L = H₂O, R = Me (9); L = 0: R = n-Bu (10), Ph (11), PhCH₂ (12)] have been synthesized, where tpu, Hthpu and dtpu are the anions of 6-thiopurine (Htpu), 2-thio-6-hydroxypurine (H₂thpu) and 2,6-dithiopurine (H₂dtpu), respectively. All the complexes 1-12 have been characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectra analyses. And complexes 1, 2, 7 and 9 have also been determined by X-ray crystallography, complexes 1 and 2 are both six-coordinated with R₂Sn coordinated to the thiol/thione S and heterocyclic N atoms but the coordination modes differed. As for complex 7 and 9, the geometries of Sn atoms are distorted trigonal bipyramidal. Moreover, the packing of complexes 1, 2, 7 and 9 are stabilized by the hydrogen bonding and weak interactions.     

Self-assembly syntheses and crystal structures of triorganotin(IV) pyridinecarboxylate: 1D polymers and a 42-membered macrocycle

A series of new triorganotin(IV) pyridinecarboxylates with 6-hydroxynicotinic acid (6-OH-3-nicH), 5-hydroxynicotinic acid (5-OH-3-nicH) and 2-hydroxyisonicotinic acid (2-OH-4-isonicH) of the types: [R₃Sn (6-OH-3-nic)·L]_n (I) (R = Ph, L = Ph·EtOH, 1; R = Bn, L = H₂O·EtOH, 2; R = Me, L = 0, 3; R = n-Bu, L = 0, 4), [R₃Sn (5-OH-3-nic)]_n (II) (R = Ph, 5; R = Bn, 6; R = Me, 7; R = n-Bu, 8), [R₃Sn (2-OH-4-isonic·L)]_n (III) (R = Bn, 9, L = MeOH; R = Me, L = 0, 10; R = Ph, 11, L = 0.5EtOH) have been synthesized. All the complexes were characterized by elemental analysis, TGA, IR and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy analyses. Among them, except for complexes 5 and 6, all complexes were also characterized by X-ray crystallography diffraction analysis. Crystal structures show that complexes 1-10 adopt 1D infinite chain structures which are generated by the bidentate O, O or N, O and the five-coordinated tin centers. Significant O-H?O, and N-H?O intermolecular hydrogen bonds stabilize these structures. Complex 11 is a 42-membered macrocycle containing six tin atoms, and forms a 2D network by intermolecular N-H?O hydrogen.     

Chiral self-assembly of triorganotin complexes: Syntheses, characterization, crystal structures and antitumor activity of organotin(IV) complexes containing (R)-(+)-methylsuccinic acid, (S)-(+)-methylglutaric acid and l-(−)-malic acid ligands

Six new chiral triorganotin(IV) complexes, {(R₃Sn)₂[C₃H₆(COO)₂]}_n (R = Me: 1; Bu: 2), {(R₃Sn)₂[C₄H₈(COO)₂]}_n (R = Me: 3; Bu: 4), and {(R₃Sn)₂[C₂H₄O(COO)₂]}_n (R = Me: 5; Bu: 6) have been prepared by treatment of (R)-(+)-methylsuccinic acid, (S)-(+)-methylglutaric acid and l-(−)-malic acid, with the corresponding R₃SnCl (R = Me, Bu) and sodium ethoxide in methanol. All the complexes were characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and TGA. Except for 3, all of the complexes were also characterized by X-ray crystallography. The structural analyses reveal that complexes 1 and 5 have 2D network structures in which (R)-(+)-methylsuccinic acid and l-(−)-malic acid act as tetradentate ligands coordinated to trimethyltin(IV) ions. Complexes 2 and 4 have 3D metal-organic framework structures in which the deprotoned acids serve as tetradentate ligands. Complex 6 adopts a 1D zigzag chain structure and forms a 2D supramolecular framework through intermolecular C-H?O interactions. In addition, the antitumor activities of complexes 1-6 have been studied. We also have measured the specific rotation of the chiral dicarboxylic acids and the organotin derivatives.     

4,5-Bis[(triorganotin)thiolato]-1,3-dithiole-2-thione, (R3Sn)2(dmit), 4,5-bis[(triorganotin)thiolato]-1,3-dithiole-2-one, (R3Sn)2(dmio), compounds: Crystal structures of (cyclohexyl3Sn)2(dmio), (Ph3Sn)2(dmit) and (Ph3Sn)2(dmio)

The synthesis and crystal structures of 4,5-bis[(triorganotin)thiolato]-1,3-dithiole-2-thione, (R₃Sn)₂(dmit), 1, and 4,5-bis[(triorganotin)thiolato]-1,3-dithiole-2-one, (R₃Sn)₂(dmio), 2, compounds are reported. Compounds, (1 or 2: R = Ph or cyclohexyl, Cy), have been obtained from reaction of R₃SnCl with Cs₂dmit or Na₂dmio. The presence of the two tin centres in (2: R = Ph) is shown in the ¹³C NMR spectrum by the couplings of both Sn atoms to the dmio olefinic carbons with J values of 29.4 and 24.7 Hz. The δ¹¹⁹ Sn values for (1: R = Ph) and (2: R = Ph) differ by about 30 ppm, values being −20.7 and −50.1 ppm, respectively, in CDCl₃ solution. X-ray structure determinations for (1: R = Ph) and (2: R = Ph or Cy) reveal the compounds to have 4-coordinate, distorted tetrahedral tin centres. The dithiolato ligands, dmit and dmio, act as bridging ligands, in contrast to their chelating roles in R₂Sn(dmit) and R₂Sn(dmio). A further difference between R₂Sn(dmit) and R₂Sn(dmio), on one hand, and 1 and 2 on the other, is that intermolecular Sn-S and Sn-O interactions are absent in 1 and 2. However, weak intermolecular hydrogen bonding interactions are found in (1: R = Ph) [C-H?π] and in (2: R = Ph) [C-H?π and C-H?O].     

Synthesis and characterization of aluminum complexes of 2-pyrazol-1-yl-ethenolate ligands

The synthesis and the characterization of some new aluminum complexes with bidentate 2-pyrazol-1-yl-ethenolate ligands are described. 2-(3,5-Disubstituted pyrazol-1-yl)-1-phenylethanones, 1-PhC(O)CH₂-3,5-R₂C₃HN₂ (1a, R = Me; 1b, R = Bu^t), were prepared by solventless reaction of 3,5-dimethyl pyrazole or 3,5-di-tert-butyl pyrazole with PhC(O)CH₂Br. Reaction of 1a or 1b with (R¹ = Me, Et) yielded N,O-chelate alkylaluminum complexes (2a, R = R¹ = Me; 2b, R = Bu^t, R¹ = Me; 2c, R = Me, R¹ = Et). Compound 1a was readily lithiated with LiBuⁿ in thf or toluene to give lithiated species 3. Treatment of 3 with 0.5 equiv of MeAlCl₂ or AlCl₃ yielded five-coordinated aluminum complexes [XAl(OC(Ph)CH{(3,5-Me₂C₃HN₂)-1})₂] (4, X = Me; 5, X = Cl). Reaction of 5 with an equiv of LiHBEt₃ generated [Al(OC(Ph)CH{(3,5-Me₂C₃HN₂)-1})₃] (6). Complex 6 was also obtained by reaction of 3 with 1/3 equiv of AlCl₃. Treatment of 5 with 2 equiv of AlMe₃ yielded complex 2a, whereas with an equiv of AlMe₃ afforded a mixture of 2a and [Me(Cl)AlOC(Ph)CH{(3,5-Me₂C₃HN₂)-1}] (7). Compounds 1a, 1b, 2a-2c and 4-6 were characterized by elemental analyses, NMR and IR (for 1a and 1b) spectroscopy. The structures of complexes 2a and 5 were determined by single crystal X-ray diffraction techniques. Both 2a and 5 are monomeric in the solid state. The coordination geometries of the aluminum atoms are a distorted tetrahedron for 2a or a distorted trigonal bipyramid for 5.     

Organotin biocides: VII . Tri- and diorganotin derivatives of piperazine bis(dithiocarbamic) acid

Eight tri- and diorganotin derivatives of piperazine bis (dithiocarbamic) acid (H₂pdtc) of formulae (R₃Sn)₂pdtc (R = Me, Bu, Ph, cyclo-C₆H₁₁) and R₂Snpdtc (R = Me, Bu, Oct, Ph) have been synthesised, along with (ClBu₂Sn)₂pdtc, a by-product in the synthesis of Bu₂Snpdtc. On the basis of spectroscopic data, compounds of type (R₃Sn)₂pdtc are judged to be monomeric, with the tin atoms in a tetrahedral environment distorted towards five-coordinate cis-S₂SnR₃ each by a weakly bidentate CS₂ group. The diorganotin derivatives are polymeric, with a distorted trans-R₂SnS₄ geometry about the metal. Variable temperature Mössbauer spectroscopic data are presented for (Me₃Sn)₂pdtc and Me₂Snpdtc.     

Structural and conformational analysis of neutral dinuclear diorganotin(IV) complexes derived from hexadentate Schiff base ligands

The synthesis of three hexadentate Schiff base ligands has been carried out, which contain two sets of ONO donor atoms. These were reacted with diorganotin(IV) dichloride derivatives (R = Me, nBu, Ph) to prepare seven dinuclear diorganotin(IV) complexes in moderate yields. Aside from IR and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopic studies, mass spectrometry and elemental analysis, four tin complexes were characterized by X-ray diffraction analysis. The spectroscopic analyses showed that in solution the tin atoms have five-coordinate environments with a distorted trigonal bipyramidal geometry. Each tin atom is coordinated to the nitrogen atom and forms covalent bonds with two oxygen atoms and two carbon atoms. Due to the presence of a methylene group as bridge between the two ONO chelates, the overall molecular structures can have cis or trans conformation, having either mirror or C₂-symmetry. While in solution a fast equilibrium can be supposed, in the solid state different intermediate conformations have been detected. Furthermore, for the dialkyltin derivatives Sn?O intermolecular interactions were found allowing for a dimeric or crinkled polymeric organization, whereas for the diphenyltin derivatives no such interactions were observed.     

Formation and crystal structures of [(alkoxy)bis(pyridin-2-yl)methanolato-N,O,N]tin(IV) complexes

Reactions of bis(pyridin-2-yl)ketone with tin tetrahalides, SnX₄ (X = Cl or Br), or organotin trichlorides, R^′SnCl₃ (R^′ = Ph, Bu or CH₂CH₂CO₂Me), in ROH (R = Me or Et) readily produces RObis(pyridin-2-yl)methanolato)tin complexes, [5: RO(py)₂C(OSnX₃)] (5: R,X = Me,Cl; Et,Cl; Et,Br) or [6: MeO(py)₂C(OSnCl₂R^′)] (R^′ = Ph, Bu, CH₂CH₂CO₂Me). In addition, halide exchange reaction between SnI₄ and (5: R,X = Me,Cl) occurred to give (5: R,X = Me,I). The crystal structures of six tin(IV) derivatives indicated, in all cases, a monoanionic tridentate ligand, [RO(py)₂C(O⁻)-N,O,N], arranged in a fac manner about a distorted octahedral tin atom. The Sn–O and Sn–N bonds lengths do not show much variation amongst the six complexes despite the differences in the other ligands at tin.     

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.     

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.     

Reaction of 1,2-dibromoethane with primary amines: formation of N,N′-disubstituted ethylenediamines RNH-CH2CH2-NHR and homologous polyamines RNH-[CH2CH2NR]n-H

The reaction of primary amines RNH₂ (R: Me, Et, iPr, tBu and Ph) with 1,2-dibromoethane gave N,N′-disubstituted ethylenediamines R-NH-CH₂CH₂-NH-R (1) in yields ranging from 10% (1a; R=Me) to 70% (1d, R=tBu; 1e, R=Ph). Piperazines and N-substituted polyethyleneimines were identified (¹H NMR, ¹³C NMR and EI-MS) as side products of the reaction and isolated by fractional distillation. The piperazines 2 are formed in yields of 3-10% and can be separated from the diamines 1 in all cases, except for R=Me and Ph. The polyamine homologues RNH-[CH₂CH₂NR]_n-H (3-5) were isolated in yields ranging from 0.1% (n=4, R=iPr) to 14% (n=2, R=iPr). The yields of 1 increase with the size of the substituent R, no obvious trend exists for the yields of the side products.     

Self-assembly of triorganotin(IV) moieties with 2,3,4,5-tetrafluorobenzoic acid and 4,4′-bipy, triphenylphosphine oxide or phen: Syntheses, characterizations and supramolecular structures

A series of triorganotin (IV) complexes with 2,3,4,5-tetrafluorobenzoic acid and mixed-ligands of the types: R₃Sn(O₂CC₆HF₄)_m · L (m = 1, L = 0, R = Ph 1; m = 1, L = Ph₃PO, R = Ph 4, Me 5), [R₃Sn(O₂CC₆HF₄)]_m · L (m = 2, L = 4,4′-bipy, R = Ph 2, Me 3; m = n, L = 0, R = Me 6), and [R₃Sn(O₂CC₆HF₄) · (H₂O)]_m · L · C₂H₅OH (m = 2, L = Phen, R = Ph 7, Me 8), (4,4′-bipy = 4,4′-bipyridyl; Phen = 1,10-phenanthroline), have been synthesized by the reaction of triorganotin chloride and 2,3,4,5-tetrafluorobenzoic acid in the presence of mixed-ligands: 4,4′-bipy, triphenylphosphine oxide, or phen. All complexes were characterized by elemental analysis, IR, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopy analysis. Except for 5 and 8, all the complexes were also characterized by X-ray crystallography.     

Synthesis,characterization and crystal structures of 2-[(E)-2-(4-hydroxy-3,5-dimethylphenyl)-1-diazenyl]benzoic acid and its polymeric and monomeric triorganotin(IV) complexes

Three triorganotin(IV) complexes of composition R₃SnLH (R = Me, Bu and Ph and LH = 2-[(E)-2-(4-hydroxy-3,5-dimethylphenyl)-1-diazenyl]benzoate) have been synthesized and characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, and IR spectroscopic techniques in combination with elemental analysis. The crystal structures of the carboxylate ligand HO₂CC₆H₄{NN(C₆H₂-4-OH-3,5-(CH₃)₂)}-o in its neutral form and three triorganotin(IV) complexes, viz., polymeric (R₃Sn[O₂CC₆H₄{N–N(H)(C₆H₂-4-O-3,5-(CH₃)₂)}-o])_n (R = Me (1) and Bu (2)) and monomeric Ph₃Sn[O₂CC₆H₄{N–N(H)(C₆H₂-4-O-3,5-(CH₃)₂)}-o] (3) complexes are reported. The polymeric complexes 1 and 2 exist as extended chains in which the LH-bridged Sn-atoms adopt a trans-R₃SnO₂ trigonal bipyramidal configuration with R groups in the equatorial positions and the axial sites occupied by an oxygen atom from the carboxylate ligand and the phenoxide O atom of the next carboxylate ligand. The Sn atom in complex 3 has a distorted tetrahedral geometry. In all three complexes, the carboxylate ligand is in the zwitterionic form with the phenolic proton moved to the nearby azo nitrogen atom, in contrast to the free carboxylic acid ligand which is in the azo form.     

Synthesis,characterization and crystal structures of 2-[(E)-2-(4-hydroxy-3,5-dimethylphenyl)-1-diazenyl]benzoic acid and its polymeric and monomeric triorganotin(IV) complexes

Three triorganotin(IV) complexes of composition R₃SnLH (R = Me, Bu and Ph and LH = 2-[(E)-2-(4-hydroxy-3,5-dimethylphenyl)-1-diazenyl]benzoate) have been synthesized and characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, and IR spectroscopic techniques in combination with elemental analysis. The crystal structures of the carboxylate ligand HO₂CC₆H₄{NN(C₆H₂-4-OH-3,5-(CH₃)₂)}-o in its neutral form and three triorganotin(IV) complexes, viz., polymeric (R₃Sn[O₂CC₆H₄{N–N(H)(C₆H₂-4-O-3,5-(CH₃)₂)}-o])_n (R = Me (1) and Bu (2)) and monomeric Ph₃Sn[O₂CC₆H₄{N–N(H)(C₆H₂-4-O-3,5-(CH₃)₂)}-o] (3) complexes are reported. The polymeric complexes 1 and 2 exist as extended chains in which the LH-bridged Sn-atoms adopt a trans-R₃SnO₂ trigonal bipyramidal configuration with R groups in the equatorial positions and the axial sites occupied by an oxygen atom from the carboxylate ligand and the phenoxide O atom of the next carboxylate ligand. The Sn atom in complex 3 has a distorted tetrahedral geometry. In all three complexes, the carboxylate ligand is in the zwitterionic form with the phenolic proton moved to the nearby azo nitrogen atom, in contrast to the free carboxylic acid ligand which is in the azo form.     

Simplified synthesis, H, C, N, Sn NMR spectra and X-ray structures of diorganotin(IV) complexes containing the 4-phenyl-2,4-butanedionebenzoylhydrazone(2−) ligand

Two diorganotin(IV) complexes of the general formula R₂Sn[Ph(O)CCH-C(Me)N-NC(O)Ph] (R=Ph, 1; R=Me, 2) have been synthesised from the corresponding diorganotin(IV) dichloride and the ligand 4-phenyl-2,4-butanedionebenzoylhydrazone(2−) (H₂L), derived from benzoyl acetone and benzoyl hydrazide in methanol at room temperature in presence of triethylamine. The syntheses were performed under very mild conditions, at room temperature and without exclusion of air or moisture from the reaction vessel. Previously, rigorous conditions have been considered necessary for these species. The two compounds have been characterised by elemental analysis, IR and ¹H, ¹³C, ¹⁵N, ¹¹⁹Sn NMR spectra, and their structures have been confirmed single crystal X-ray structure analysis. The central tin atom of both complexes adopts a distorted trigonal bipyramidal coordination with two ligand oxygen atoms in axial positions, the nitrogen atom of the ligand and two organic groups on tin occupying equatorial sites. 2 has crystallised with two crystallographically independent molecules in the asymmetric unit. The δ(¹¹⁹Sn) values for the complexes 1 and 2 are −151.5 and −146.8 ppm, respectively, thus indicating penta-coordinated tin centres.     

Diorganotin(IV) derivatives of arylhydroxamic acids: synthesis, properties and antitumor activity

Series of diorganotin(IV) complexes of 4-X-benzohydroxamic acid [X = NH₂ (HL₁), NO₂ (HL₂) or F (HL₃)] formulated as [R₂SnL₂] and [R₂Sn(L)]₂O (R = Me, Et, nBu or Ph) have been prepared and characterized by FT-IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopies, elemental analyses, FAB⁺-MS and melting point determination. They are stable in air, soluble in alcohols and in hydroalcoholic solution and, in some cases, in water. Their in vitro antitumor activity against a series of human tumor cell lines was tested and, in a few of them, is identical to, or even higher than, that of cisplatin. For the mononuclear dialkyltin compounds, the activity generally increases with the length of the carbon chain of the alkyl ligand, being higher for the complexes with benzohydroxamato ligands bearing an electron-acceptor substituent (X = NO₂ or F). No structure-activity relationship based on the Hammett’s σ_p constant, or related ones, has been recognized.