Synthesis and characterization of N-[2-P(i-Pr)2-4-methylphenyl]2- (PNP) pincer tin(IV) and tin(II) complexes

N-[2-P(i-Pr)(2)-4-methylphenyl](2)(-) (PNP) pincer complexes of tin(IV) and tin(II), [(PNP)SnCl(3)] (2) and [(PNP)SnN(SiMe(3))(2)] (3), respectively, were prepared and characterized by X-ray diffraction, solution and solid state NMR spectroscopy, and (119)Sn M?ssbauer spectroscopy. Furthermore, (119)Sn cross polarization magic angle spinning NMR spectroscopic data of [Sn(NMe(2))(2)](2) are reported. Compound 2 is surprisingly stable toward air, but attempts to substitute chloride ligands caused decomposition.     

Synthesis and characterization of imidocubanes with exocube Ge(IV) and Sn(IV) substituents: [M(mu3-NGeMe3)]4 (M = Sn, Ge, Pb); [Sn(mu3-NSnMe3)]4

The heteroleptic lithium amide, [(Me3Sn)(Me3Ge)NLi.(Et2O)]2 (2), reacts with MCl(2) (M = Sn, Ge, Pb) to yield the corresponding cubane complexes [M(mu3-NGeMe3)]4 [M = Sn (3), Ge (4), Pb (5)]. In an analogous reaction with SnCl2, the lithium stannylamide, [(Me3Sn)2NLi.(Et2O)]2 (1), produces the mixed-valent Sn congener [Sn(mu3-NSnMe3)]4 (6). All imidocubanes contain both di- and tetravalent group 14 metals that are bridged by N. These structures are comprised of M4N4 (M = Sn, Pb, Ge) cores that possess varying distortion from perfect cube geometry. The Pb derivative (5) exhibits enhanced volatility and vapor-phase integrity.     

Diorganotin-based coordination polymers derived from sulfonate/phosphonate/phosphonocarboxylate ligands

The reactions of diorganotin precursors [R(2)Sn(OR(1))(OSO(2)R(1))](n) [R = R(1) = Me (1); R = Me, R(1) = Et (2)] with an equimolar amount of t-butylphosphonic acid (RT, 8-10 h) in methanol result in the formation of identical products, of composition [(Me(2)Sn)(3)(O(3)PBu(t))(2)(O(2)P(OH)Bu(t))(2)](n) (3). On the other hand, a similar reaction of 2, when carried out in dichloromethane, affords [(Me(2)Sn)(3)(O(3)PBu(t))(2)(OSO(2)Et)(2)·MeOH](n) (4). A plausible mechanism implicating the role of solvent in the formation of these compounds has been put forward. In addition, the synthesis of [(Me(2)Sn)(3)(O(3)PCH(2)CH(2)COOMe)(2)(OSO(2)Me)(2)](n) (5) and [R(2)Sn(O(2)P(OH)CH(2)CH(2)COOMe)(OSO(2)R(1))](n) [R = Et, R(1) = Me (6); R = (n)Bu, R(1) = Et (7)] has been achieved by reacting 1 and related diorganotin(alkoxy)alkanesulfonates with 3-phosphonopropionic acid in methanol. The formation of a methylpropionate functionality on the phosphorus center in these structural frameworks results from in situ esterification of the carboxylic group. X-ray crystallographic studies of 1-7 are presented. The structures of 1 and 2 represent one-dimensional (1D) coordination polymers composed of alternate [Sn-O](2) and [Sn-O-S-O](2) cyclic rings formed by μ(2)-alkoxo and sulfonate ligands, respectively. For 3-5 and 7, variable bonding modes of phosphonate and/or sulfonate ligands afford the construction of two- and three-dimensional self-assemblies that are comprised of trinuclear tin entities with an Sn(3)P(2)O(6) core as well as [Sn-O-P-O](2) and/or [Sn-O-S-O](2) rings. The formation of a 1D coordination polymer in 6 is unique in terms of repeating eight-membered cyclic rings containing Sn, O, P, and S heteroatoms. The contribution from hydrogen-bonding interactions is also found to be significant in these structures.     

Recipe for new diorganostannates, [R2Sn(OS(O)2R1)4]2-, bearing alkanesulfonate groups using dialkyl sulfite as the reagent

A one-pot reaction between di-n-propyl/di-n-butyltin oxide, dialkyl sulfite, and triethylamine or tetra-n-alkylammonium iodide proceeds under ambient conditions (110-120 degrees C, 20 h) via sulfur-centered Arbuzov rearrangement to afford the corresponding dianionic tetraalkanesulfonato diorganostannates [R2Sn(OSO2Me)4].2Et3NMe [R = n-Pr (1), n-Bu (2)] as well as [n-Bu(2)Sn(OSO(2)R(1))(4)].(2)R(2)(4)N [R(1) = Me, Et, n-Pr; R(2) = Et (3, 5, and 7), n-Bu (4, 6, and 8)]. X-ray crystal structures of 2 and 3 reveal a monomeric motif of the dianion, with methanesulfonate groups acting as unidentate ligands. The (119)Sn NMR spectral studies suggest the existence of pentacoordinated tin species in solution.     

Synthesis, characterization, and structural studies of mixed-ligand diorganotin esters, [R2Sn(OP(O)(OH)Ph)(OS(O)2R1)]n [R = n-Bu, R1 = Me (1), n-Pr(2); R = Et, R1 = Me (3)] with 1D and 3D coordination polymeric motifs

Mixed-ligand diorganotin esters, [R 2Sn(OP(O)(OH)Ph)(OS(O) 2R (1))] n [R = n-Bu, R (1) = Me ( 1), n-Pr ( 2); R = Et, R (1) = Me ( 3)], have been synthesized by reacting the tin precursors, R 2Sn(OR (1))OS(O) 2R with an equimolar amount of phenylphosphonic acid under mild conditions (room temperature, 6-8 h, CH 2Cl 2). These have been characterized by IR, multinuclear ( (1)H, (13)C{ (1)H}, (31)P, and (119)Sn) NMR, and single crystal X-ray diffraction studies. The asymmetric unit of 1 is comprised of a tetramer with four crystallographically unique tin atoms. The structure reveals a central eight-membered (Sn-O-S-O) 2 cyclic ring with two exocyclic tin atoms, which results from micro 3-binding of the two methanesulfonate groups. The remaining two sulfonates are monodentate and contribute in O...HO(P) hydrogen bonding. The molecular structure is extended into a 3D coordination polymer with the aid of hydrogenphenylphosphonate group on each tin atom, acting in a micro 2-O 2P mode and forms a series of eight-membered (Sn-O-P-O) 2 rings in the structural framework. 2 and 3 are isostructural and represent linear 1D coordination polymers via micro 2-binding mode of both alkanesulfonate and hydrogenphenylphosphonate groups.     

cyclo-CH2[Sn(CI2)CH2Si(Me2)]2O]: synthesis and complexation behaviour of a novel, cyclic, bidentate Lewis acid and its conversion into a tin-containing fluorosilane with intermolecular Si-F...Sn bridges

Acid-catalysed hydrolysis of [CH2[(Sn(Ph2)CH2Si(OiPr)Me2]2] followed by subsequent reaction with mercuric chloride in acetone afforded the novel silicon- and tin-containing eight-membered ring [cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2O] in good yield, the crystal structure of which is reported. 119Sn NMR and X-ray studies indicate that [cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2O] acts as a bidentate Lewis acid towards chloride ions exclusively forming the 1:1 complex [(Ph3P)2N]+[cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2OCl]- upon addition of [(Ph3P)2N]+Cl- . Also reported are the synthesis and structure of [K(dibenzo[18]crown-6)]+[cyclo-CH2(Sn(Cl2)CH2Si(Me2)]2OF]-, the first completely characterised organostannate with a C2SnCl2F- substituent pattern. No ring-opening polymerisation could be achieved for [cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2O] or for its perphenylated derivative [cyclo-CH2[Sn(Ph2)CH2Si(Me2)]2O]. The reaction of [cyclo-CH2[Sn(Cl2)CH2Si(Me2)]2O] with Me3O+BF4- gave the tin-containing fluorosilane [CH2[Sn(Cl2)CH2Si(F)Me2]2], in which the Si-F bond is activated by intermolecular Si-F...Sn interactions in the solid state.     

Synthesis and structures of beta-diketiminatotin(II) halides, an amide and of Sn(=E)[{N(R)C(Ph)}2CH](NR2) (E = S or Se, R = SiMe3)

Treatment of [Li(L1)]2 (1) or K(L2) (2) with SnX2 in Et2O yielded the heteroleptic beta-diketiminatotin(II) halides Sn(L1)Cl (3a), Sn(L1)Br (3b) or Sn(L2)Cl (4), even when an excess of the alkali metal beta-diketiminate was used [L1={N(R)C(Ph)}2CH, L2={N(R)C(Ph)CHC(But)N(R)}, R = SiMe3]. From and half an equivalent each of SnCl2.2H2O and SnCl2, or one equivalent of SnCl2.2H2O, the product was Sn(L3)Cl (5) or Sn(L4)Cl (6), in which one or both of the N-R bonds of L1 had been hydrolytically cleaved; the compound Sn(L5)Cl (7) was similarly obtained from and an equivalent portion of SnCl2.2H2O [L3={N(R)C(Ph)CHC(But)N(H)}, L4={N(H)C(Ph)CHC(But)N(H)} and L5={N(H)C(Ph)}2CH]. The halide exchange between 3a and 3b, studied by two-dimensional (119)Sn{1H}-NMR spectroscopy, is attributed to implicate a (mu-Cl)(mu-Br)-dimeric intermediate or transition state. The 13C{1H}-NMR spectra of or showed two distinct resonances for each group, which coalesced on heating, corresponding to DeltaG(338 K)= 69.4 (3a) or 72.8 (3b) kJ mol(-1). The chloride ligand of was readily displaced by treatment with NaNR2, CF3SO3H or CH2(COPh)2, yielding Sn(L1)X [X = NR2 (8), O3SCF3 (9) or {OC(Ph)}2CH (10)]. Oxidative addition of sulfur or selenium to gave the tin(IV) terminal chalcogenides Sn(E)(L1)(NR2)[E = S (11) or Se (12)]. The X-ray structures of the cocrystal of 3a/3b and of the crystalline compounds 5, 6, 8, 11 and are presented, as well as multinuclear NMR spectra of each of the new compounds.     

Self-assembly of diorganotin(IV) moieties and 2-pyrazinecarboxylic acid: syntheses, characterizations and crystal structures of monomeric, polymeric or trinuclear macrocyclic compounds

A series of diorganotin(IV) compounds of the type [R(2)Sn(pca)Cl](3)(R = CH(3); (n)Bu; C(6)H(5); C(6)H(5)CH(2); Hpca = 2-pyrazinecarboxylic acid), R(2)Sn(pca)(2)(mH(2)O)xnH(2)O (m= 1: R = CH(3), n= 2, R =(n)Bu, n= 0; m= 0, n= 0: R =(n)Bu, C(6)H(5), C(6)H(5)CH(2)) and (Et(3)NH)(+)[R(2)Sn(pca)(2)Cl](-)xmH(2)O (m= 0: R = CH(3), (n)Bu, C(6)H(5)CH(2); m= 1: R = C(6)H(5)) have been obtained by reactions of 2-pyrazinecarboxylic acid with diorganotin(iv) dichloride in the presence of sodium ethoxide or triethylamine. All compounds were characterized by elemental, IR and NMR spectra analyses. Except for compounds, and, the others were also characterized by X-ray crystallography diffraction analyses, which revealed that compounds and were trinuclear macrocyclic structures with six-coordinate tin(IV) atoms, compounds and were monomeric structures with seven-coordinate tin(IV) atoms, compounds and were polymeric chain structures with seven-coordinate tin(IV) atoms and compounds and were stannate with seven-coordinate tin(IV) atoms.     

Reactivity of 2-pyridinecarboxylic esters with cadmium(II) halides: study of (113)Cd NMR solid state spectra and crystal structures of hexacoordinated complexes [CdI(2)(C(5)H(4)NCOOMe)(2)] and [CdI(2)(C(5)H(4)NCOOPr(n))(2)

The series of complexes [CdX(2)(C(5)H(4)NCOOR)] (X = Cl or Br; R = Me, Et, Pr(n)() or Pr(i)()) and [CdX(2)(C(5)H(4)NCOOR)(2)] (X = I; R = Me, Et, Pr(n)(), or Pr(i)()) have been obtained by the addition reaction of esters of 2-pyridinecarboxylic acid to cadmium(II) halides. X-ray crystal structures of two complexes [CdI(2)(C(5)H(4)NCOOR)(2)], R = Me (10) and R = Pr(n)() (12), have been determined. In both cases, the structure consists of discrete neutral monomeric units where the cadmium atom has a distorted octahedral coordination with CdI(2)N(2)O(2) core, two halides being in cis disposition. Structural information is compared with that deduced from (113)Cd CPMAS NMR experiments. Chemical shift anisotropies are discussed in terms of distortions produced in cadmium octahedra. The orientation of the principal axes of (113)Cd shielding tensor is also analyzed and related to the disposition of ligands in the structures of two analyzed compounds.     

New organotin(IV) ascorbates: synthesis, spectral characterization, biological and potentiometric studies

New organotin(IV) ascorbates of the general formulae R(3)Sn(HAsc) (where R = Me , n-Pr, n-Bu and Ph) and R(2)Sn(Asc) (where R = n-Bu and Ph) have been synthesized by the reaction of R(n)SnCl(4-n) (where n = 2 or 3) with monosodium-l-ascorbate. The bonding and coordination behaviour in these complexes are discussed on the basis of UV-Vis, IR, Far-IR, (1)H and (13)C NMR, and (119)Sn Mossbauer spectroscopic studies. L-Ascorbic acid acts as a monoanionic bidentate ligand in R(3)Sn(HAsc) coordinating through O(1) and O(3). The Mossbauer studies together with IR and NMR studies suggest that for these polymeric derivatives, the polyhedron is trigonal bipyramidal around tin with three organic groups in the equatorial positions. In R(2)Sn(Asc), L-ascorbic acid acts as dianionic tetradentate ligand and a polymeric structure with octahedral geometry around tin with trans organic groups has been tentatively proposed. The complexes have been assayed for their anti-inflammatory and cardiovascular activity. Ph(2)Sn(Asc) has been found to show the highest activity among the studied complexes. It is suggested on the basis of potentiometric studies of Me(2)Sn(IV) and Me(3)Sn(IV) systems with L-ascorbic acid that under physiological conditions (pH = 7.0) Me(2)Sn(HAsc)(OH) (approximately 60%), Me(2)Sn(OH)(2) (approximately 40%) and Me(3)Sn(HAsc) (approximately 60%), Me(3)Sn(OH) (approximately 40%), respectively, are existing, which may be responsible for their biological activities.     

Tert-butylamidinate tin(ii) complexes: high activity, single-site initiators for the controlled production of polylactide

The tin(ii) coordination chemistry of two monoanionic N,N'-bis(2,6-diisopropylphenyl)alkylamidinate ligands is described. Complexation studies with the acetamidinate, [MeC(NAr)(2)](-), (Ar = 2,6-(i)Pr(2)C(6)H(3)) are complicated by the side formation of the bis(amidinate) tin(ii) compound, [MeC(NAr)(2)](2)Sn. By contrast, the bulkier tert-butylamidinate, [(t)BuC(NAr)(2)](-), allows tin(ii) mono-halide, -alkoxide and -amide complexes to be isolated cleanly in high yields. Thus, the reaction of [(t)BuC(NAr)(2)]H with (n)BuLi and subsequent treatment with SnCl(2) generates [(t)BuC(NAr)(2)]SnCl, in ca. 70% yield. Reactions of with LiO(i)Pr, LiNMe(2) and LiNTMS(2) afford [(t)BuC(NAr)(2)]Sn(O(i)Pr), [(t)BuC(NAr)(2)]Sn(NMe(2)), and [(t)BuC(NAr)(2)]Sn(NTMS(2)), respectively. The molecular structures of complexes are reported. Complexes, and have been investigated as initiators for the ring-opening polymerisation of rac-lactide: and display characteristics of well-controlled polymerisation initiators, but high molecular weight polymer is observed with due to inefficient initiation, a consequence of the steric bulk of the NTMS(2) unit. Polymerisations with and are faster than for the corresponding beta-diketiminate tin(ii) complexes, consistent with the more open nature of the tin(ii) coordination sphere.     

Cyclic and linear polyferrocenes with silicon and tin as alternating bridges

The synthesis and characterization of ferrocene-based oligomers that contained two different elements (Si and Sn) as alternating bridges is described for the first time. The salt-metathesis reaction of R(2) Si[(C(5) H(4) )Fe(C(5) H(4) Li)](2) (R=Me, Et) with R'(2) SnCl(2) (R'=Me, nBu, tBu) afforded a mixture of oligomers (6(Me) SnMe(2), 6(Et) SnMe(2), 6(Me) SnnBu(2), 6(Et) SnnBu(2), 6(Me) SntBu(2), and 6(Et) SntBu(2)). These oligomers were characterized by (1) H, (13) C, (29) Si, and (119) Sn?NMR spectroscopy and by mass spectrometry. MS (MALDI-TOF) studies of 6(Et) SnMe(2) revealed the presence of linear (l) and cyclic (c) species that contained up to 20?ferrocene moieties. The molecular weights of the polymers were determined by gel-permeation chromatography (GPC) and by dynamic-light scattering (DLS). GPC analysis revealed average molecular weights of 2100-6300?Da with respect to polystyrene as a standard. DLS analysis yielded very similar results. Some compounds, c-(6(Me) SnMe(2) )(1), c-(6(Me) SntBu(2))(2), c-(6(Et) SnMe(2))(1), c-(6(Et) SntBu(2))(2), l-(6(Me) SnnBu(2) )(2), and l-(6(Me) SnnBu(2))(3), which contained up to six ferrocene moieties, were isolated in their pure form either by column chromatography or by crystallization. The Si- and Sn-bridged macrocycles that contained four ferrocene units (c-(6(Me) SntBu(2))(2) and c-(6(Et) SntBu(2))(2)) were structurally characterized by single-crystal X-ray analysis.     

Self-assembly of dialkyltin moieties and mercaptobenzoic acid into macrocyclic complexes with hydrophobic "pseudo-cage" or double-cavity structures: supramolecular infrastructures involving intermolecular C-H...S weak hydrogen bonds and pi-pi interactions

Four novel organotin complexes of two types--[R2Sn(o-SC6H4CO2)]6 (R = Me, 1 x H2O; nBu, 2) and {[R2Sn(m-CO2C6H4S)R2Sn(m-SC6H4CO2)SnR2]O}2 (R = Me, 3; nBu, 4)--have been prepared by treatment of o- or m-mercaptobenzoic acid and the corresponding R2SnCl2 (R = Me, nBu) with sodium ethoxide in ethanol (95%). All the complexes were characterized by elemental analysis, FT-IR and NMR (1H, (3C, 119Sn) spectroscopy, TGA, and X-ray crystallography diffraction analysis. The molecular structure analyses reveal that both 1 and 2 are hexanuclear macrocycles with hydrophobic "pseudo-cage" structures, while 3 and 4 are hexanuclear macrocycles with double-cavity structures. Furthermore, the supramolecular structure analyses show that looser and more intriguing supramolecular infrastructures were also found in complexes 1-4, which exist either as one-dimensional chains of rings or as two-dimensional networks assembled from the organometallic subunits through intermolecular C-H...S weak hydrogen bonds (WHBs) and pi-pi interactions.     

Flexible coordination of the carboxylate ligand in tin(II) amides and a 1,3-diaza-2,4-distannacyclobutanediyl

A series of tin(II) amido complexes possessing m-terphenyl carboxylate ligands have been prepared. These complexes, namely [(Me(3)Si)(2)NSn(mu-O(2)CC(6)H(2)Ph(3))](2), [(Me(3)Si)(2)NSn(mu-O(2)CC(6)H(3)Mes(2))](2), and [(Me(3)Si)(2)NSn(mu-O(2)CC(6)H(2)Mes(2)Me)](2) [Mes = 2,4,6-trimethylphenyl], are the first structurally characterized examples of tin(II) carboxylate complexes exhibiting discrete Sn(2)O(4)C(2) heterocyclic cores. Initial reactivity studies led to the isolation of a 1,3-diaza-2,4-distannacyclobutanediyl, [(Mes(2)C(6)H(3)CO(2))Sn(mu-NSiMe(3))](2). This molecule possesses a Sn(2)N(2) heterocyclic core and it was crystallised as both the CH(2)Cl(2) and Et(2)O solvates. Although the tin atoms in this molecule have a formal oxidation state of 3+, preliminary computational studies on this molecule suggest that it is best described as a ground state singlet. Finally, the X-ray crystal structure of (CH(2)Cl)(Cl)Sn[N(SiMe(3))(2)](2), the product of oxidative addition of CH(2)Cl(2) to Sn[N(SiMe(3))(2)](2), is also presented herein.     

4-amino- and 4-nitrodipicolinatovanadium(V) complexes and their hydroxylamido derivatives: synthesis, aqueous, and solid-state properties

A number of 4-substituted, dipicolinatodioxovanadium(V) complexes and their hydroxylamido derivatives were synthesized to characterize the solid state and solution properties of five- and seven-coordinate vanadium(V) complexes. The X-ray crystal structures of Na[VO2dipic-NH2].2H2O (2) and K[VO2dipic-NO2] (3) show the vanadium adopting a distorted, trigonal-bipyramidal coordination environment similar to the parent coordination complex, [VO2dipic]- (1), reported previously as the Cs+ salt. The observed differences in the chemical shifts of the complexes both in the 1H (ca. 0.7-1.4 ppm) and 51V (ca. 1-11 ppm) NMR spectra were consistent with the electron-donating or electron-withdrawing properties of the substituent groups, respectively. Stoichiometric addition of a series of hydroxylamine ligands (H2NOH, MeHNOH, Me2NOH, and Et2NOH) to complexes 1-3 led to the formation of seven-coordinate vanadium(V) complexes. The X-ray crystal structure of [VO(dipic)(Me2NO)(H2O)].0.5H2O (1c) was found to be similar to the previously characterized complexes [VO(dipic)(H2NO)(H2O)] (1a) and [VO(dipic)(OO-tBu)(H2O)]. While only slight differences in the 1H NMR spectra were observed upon addition of the hydroxylamido ligand, the signals in the 51V NMR spectra change by up to 100 ppm. The addition of the hydroxylamido ligand increased the complex stability of complexes 2 and 3. Evidence for a nonstoichiometric redox reaction was found for the monoalkyl hydroxylamine ligand. The reaction of an unsaturated five-coordinate species with a hydroxylamine to form a seven-coordinate vanadium complex will, in general, dramatically increase the amounts of the vanadium compound that remain intact at pH values near neutral.     

Complexes of germanium(IV) fluoride with phosphane ligands: structural and spectroscopic authentication of germanium(IV) phosphane complexes

The first phosphane complexes of germanium(iv) fluoride, trans-[GeF(4)(PR(3))(2)] (R = Me or Ph) and cis-[GeF(4)(diphosphane)] (diphosphane = R(2)P(CH(2))(2)PR(2), R = Me, Et, Ph or Cy; o-C(6)H(4)(PR(2))(2), R = Me or Ph) have been prepared from [GeF(4)(MeCN)(2)] and the ligands in dry CH(2)Cl(2) and characterised by microanalysis, IR, Raman, (1)H, (19)F{(1)H} and (31)P{(1)H} NMR spectroscopy. The crystal structures of [GeF(4)(diphosphane)] (diphosphane = Ph(2)P(CH(2))(2)PPh(2) and o-C(6)H(4)(PMe(2))(2)) have been determined and show the expected cis octahedral geometries. In anhydrous CH(2)Cl(2) solution the complexes are slowly converted into the corresponding phosphane oxide adducts by dry O(2). The apparently contradictory literature on the reaction of GeCl(4) with phosphanes is clarified. The complexes trans-[GeCl(4)(AsR(3))(2)] (R = Me or Et) are obtained from GeCl(4) and AsR(3) either without solvent or in CH(2)Cl(2), and the structures of trans-[GeCl(4)(AsEt(3))(2)] and Et(3)AsCl(2) determined. Unexpectedly, the complexes of GeF(4) with arsane ligands are very unstable and have not been isolated in a pure state. The behaviour of the germanium(iv) halides towards phosphane and arsane ligands are compared with the corresponding silicon(iv) and tin(iv) systems.     

Organotin(IV) derivatives as biocides: An investigation of structure by IR, solution NMR, electron impact MS and assessment of structure correlation with biocidal activity

A brief account is given of the synthesis, structural chemistry and the antibacterial, antifungal and cytotoxic effects of organotin complexes of 2-[(2,4-dichloroanilinocarbonyl)]benzoic acid. The unimolar and bimolar substitution products have been characterized by elemental analysis and spectral studies, including IR, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR, and mass spectra. The data support the binding of the oxygen atom to the tin atom in [R₂Sn(OOCR’)₂] and [R₃Sn(OOCR’)] (R = Me, Bu, and Ph, R’ = 2-[(2,4-dichloroanilinocarbonyl)]benzoic acid). Based on these studies, with a coordination number of four, a distorted tetrahedral geometry has been proposed for the resulting derivatives in solution. The free ligand (R’/COOH) and its respective tin complexes were tested in vitro against a number of microorganisms to assess their biocidal properties and to correlate them with the structures of the derivatives.     

Synthesis and characterization of tin containing polyhedral oligometallasilsesquioxanes (POMSS)

Tin silicate species have shown good catalytic activity in various oxidation reactions. In an attempt to mimic surface tin species, several tin containing silsesquioxanes have been synthesized. Incompletely condensed silsesquioxanes (c-C5H9)7Si7O9(OH)3 and (c-C5H9)7Si7O9(OSiMe3)(OH)2 were reacted with common tin-precursors, which afforded several silsesquioxane ligated tin compounds. Divalent stannasilsesquioxanes form dimers of the type [(c-C5H9)7Si7O11(OX)Sn]2(X=H, SiMe3) with three-coordinated tin centers. The three-coordinated tin(II) are hydrolytically unstable whereas the octahedrally surrounded tetravalent stannasilsesquioxanes [(c-C5H9)7Si7O11(OX)]Sn(acac)2(X=H, OSiMe3) are hydrolytically robust. An unprecedented anionic trimeric cluster, [[(c-C5H9)7Si7O12Sn]3(mu2-OH)3(mu3-OH)]-[HNEt3]+, stabilized by bridging hydroxyl groups was formed when the product formed upon reacting (c-C5H9)7Si7O9(OH)3 with SnCl4 was slowly hydrolyzed. The stannasilsesquioxanes showed no catalytic activity in oxidation reactions.     

Tetrylenes chelated by hybrid amido-amino ligand: derivatives of 2-[(N,N-dimethylamino)methyl]aniline

Reaction of 2-[(dimethylamino)methyl]aniline with butyllithium, followed by conversion with trimethylsilyl, triphenylsilyl, triphenylgermyl, trimethylstannyl, or tri-n-butylstannyl chloride, gives the corresponding substituted aniline. These compounds were further deprotonated by butyllithium and reacted with germanium, tin, and lead dichlorides, respectively, in both stoichiometric ratios 2:1 and 1:1, providing the target homo- ([2-(Me(2)NCH(2))C(6)H(4)(YR(3))N](2)M) and heteroleptic ([2-(Me(2)NCH(2))C(6)H(4)(YR(3))N]MCl) germylenes and stannylenes, where M = Ge, Sn, Y = Si, Ge, and R = Me, Ph. Unlike all of these cases, the heteroleptic plumbylene can only be obtained with this reaction when the amide is substituted by a trimethylsilyl moiety. Anilines substituted by trimethyltin or tri-n-butyltin moieties gave transmetalation products after the second deprotonation by butyllithium. The trimethyltin-substituted stannylenes could likewise not be obtained by hexamethyldisilazane elimination of (trimethylstannyl)-2-[(dimethylamino)methyl]aniline with 0.5 mol equiv of either bis[bis(trimethylsilyl)amido]tin or {bis[bis(trimethylsilyl)amido]tin chloride}. Products of these reactions are heterocubanes with compositions {[2-(Me(2)NCH(2))C(6)H(4)N]Sn}(4) and [2-(Me(2)NCH(2))C(6)H(4)N](2)(μ(2)-SnMe(2))(2), respectively, and Me(4)Sn or Me(3)SnCl. The structures of trimethylsilyl- and triphenylgermyl-substituted germylenes, stannylenes, and plumbylenes, as well as a number of their precursors, in the crystalline state, were investigated by X-ray diffraction and NMR spectroscopy in solution. Density functional theory methods were used for evaluation of the structures of several compounds.     

Preparation of new monoanionic "scorpionate" ligands: synthesis and structural characterization of titanium(IV) complexes bearing this class of ligand

The preparation of new "scorpionate" ligands in the form of the lithium derivatives [(Li(bdmpzdta)(H(2)O))(4)] (1) [bdmpzdta = bis(3,5-dimethylpyrazol-1-yl)dithioacetate], [Li(bdphpza)(H(2)O)(THF)] (2) [bdphpza = bis(3,5-diphenylpyrazol-1-yl)acetate], and [Li(bdphpzdta)(H(2)O)(THF)] (3) [bdphpzdta = bis(3,5-diphenylpyrazol-1-yl)dithioacetate] has been carried out. Furthermore, a series of titanium complexes has been prepared by reaction of TiCl(4)(THF)(2) with the lithium reagents [(Li(bdmpza)(H(2)O))(4)] (4) [bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate] and 1. Under the appropriate experimental conditions neutral complexes, namely [TiCl(3)(kappa(3)-bdmpza)] (5), [TiCl(3)(kappa(3)-bdmpzdta)] (6), and [TiCl(2)(kappa(2)-bdmpzdta)(2)] (7), and cationic complexes, namely [TiCl(2)(THF)(kappa(3)-bdmpza)]Cl (8) and [TiCl(2)(THF)(kappa(3)-bdmpzdta)]Cl (9), were isolated. Complexes 8 and 9 undergo an interesting nucleophilic THF ring-opening reaction to give the corresponding alkoxide-containing species [TiCl(2)(kappa(3)-bdmpza)(O(CH(2))(4)Cl)] (10) and [TiCl(2)(kappa(3)-bdmpzdta)(O(CH(2))(4)Cl)] (11). A family of alkoxide-containing complexes of general formulas [TiCl(2)(kappa(3)-bdmpza)(OR)] [R = Me (12); R = Et (14); R = (i)Pr (16); R = (t)Bu (18)] and [TiCl(2)(kappa(3)-bdmpzdta)(OR)] [R = Me (13); R = Et (15); R = (i)Pr (17)] was also prepared. The structures of these complexes have been determined by spectroscopic methods, and in addition, the X-ray crystal structures of 3, 7, 10, and 11 were also established.