Syntheses and Characterization of Organotin(IV) Complexes Derived from 2‐Mercapto‐1,3,4‐thiadiazole

Four organotin complexes of the types [(Ph₃Sn)(C₂HN₂S₂)] ( 1 ), [(CH₃)₃Sn(C₂HN₂S₂)]_n ( 2 ), [(Bu₂Sn)(C₂HN₂S₂)₂] ( 3 ), and [(Me₂Sn)₄(C₂HN₂S₂)₂(µ ₃‐O)₂(C₂H₅O)₂] ( 4 ) have been obtained by 2‐mercapto‐1,3,4‐thiadiazole and triorganotin chloride or diorganotin dichloride. All the complexes were characterized by elemental analysis, IR and NMR spectroscopy, and X‐ray diffraction analyses, which revealed that complexes 1 and 3 are mononuclear structures, complex 1 can further form a one‐dimensional (1D) helical chain, and complex 3 can further form a 22‐membered macrocycle through the intermolecular C–H·N hydrogen bond; complex 2 is a 1D infinite chain linked by intermolecular N→Sn and S→Sn bonding interactions; complex 4 is a typical ladder structure. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 00:1–8, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21046     

Novel organotin (IV) complexes derived from 4,4′‐oxybisbenzoic acid: synthesis,structure, in vitro cytostatic activity and binding interaction with BSA

Six novel organotin (IV) complexes, [(Me₃Sn)₂(H₂O)₂L] ( 1 ), [(R₃Sn)₂L]_n (R = Me 2 , R = n‐Bu 3 ), [(Ph₃Sn)₂L] ( 4 ), [Me₂SnL]_n ( 5 ), [(Me₂Sn)₂L(μ₃‐O)]_n ( 6 ) have been designed and synthesized by the reactions of 4,4′‐oxybisbenzoic acid (H₂L) and triorganotin (IV) chloride or oxide. All the complexes have been characterized by elemental analysis, FT‐IR, NMR, ESI‐Mass, PXRD and X‐ray crystallography. The single crystal diffraction reveals that complexes 1 and 4 represent dinuclear tin monomers. Complexes 2 and 3 display 2D network structure and 2D corrugated framework respectively, which both contain tetranuclear 36‐membered macrocycles. Furthermore, 2D structures are linked into a 3D supramolecular structures through intermolecular C‐H ··· π interactions. Complex 5 shows 1D infinite helical chain and further constructs 3D ladder supramolecular architecture through additional Sn ··· O and C‐H ··· O intermolecular interactions. Complex 6 displays 1D infinite polymeric chain containing 28‐membered macrocyclic ring. Preliminarily in vitro cytostatic activity studies on cervical carcinoma cell lines (HeLa) and hepatocellular carcinoma cell lines (HepG‐2) by MTT assay for some complexes reveal that complexes 3 and 4 exhibit high cytostatic activity. Further, complexes 3 and 4 were selected to investigate interactions of bovine serum albumin (BSA) by fluorescence quenching spectra and synchronous fluorescence spectra, which indicates that the complexes could quench the intrinsic fluorescence of BSA in a static quenching process.     

LSn(OCH2CH2)2NR (L = lone pair,W(CO)5; R = Me,t‐Bu). The Molecular Structures of 5‐Aza‐2,8‐dioxa‐1‐stannabicyclo[3.3.0]1.5octanes and Their Tungstenpentacarbonyl Complexes

Single crystal X‐ray diffraction analyses of LSn(OCH₂CH₂)₂NR [ 1 , R = Me, L = lone pair; 2 , R = Me, L = W(CO)₅; 3 , R = t‐Bu, L = W(CO)₅] reveal these compounds to be dimeric and cis‐configurated. The dimerization is realized by intramolecular O→Sn interactions to give four‐membered Sn₂O₂‐rings. In addition, there are intramolecular N→Sn interactions ranging in between 2.356(5) ( 2 ) and 2.549(4) Å ( 3 ).     

Die ersten Röntgenstrukturen kationischer Diorganylzinn(IV)‐Dichelate [R2Sn(L–L)2]2⊕ mit zweizähnigen Phosphanoxid‐Liganden: Di(methansulfonyl)amid als nichtkoordinierendes Gegenion

Polysulfonylamines. CXI. The First X‐Ray Structures of Cationic Diorganyltin(IV) Dichelates [R₂Sn(L–L)₂]^2⊕ Involving Bidentate Phosphine Oxide Ligands: Di(methanesulfonyl)amide as a Non‐Coordinating Counter‐Ion The reaction of Me₂Sn(A)₂, where A^⊖ = (MeSO₂)₂N^⊖, with DPPOE = ethane‐1,2‐diylbis(diphenylphosphine oxide) or CDPPOET = cis‐ethene‐1,2‐diylbis(diphenylphosphine oxide) yields the ionic dichelates [Me₂Sn(dppoe)₂]^2⊕ · 2 A^⊖ ( 1 ; monoclinic, space group P2₁/c) and [Me₂Sn(cdppoet)₂]^2⊕ · 2 A^⊖ ( 2 ; monoclinic, P2₁/n). A solvated variety of 2 , [Me₂Sn(cdppoet)₂]^2⊕ · 2 A^⊖ · Et₂O · 0.15 MeCN ( 4 ; triclinic, P 1), was serendipitously obtained by thermal degradation of the new compound [Me₂Sn(A)(μ‐OH)]₂ · 2 CDPPOET in an MeCN/Et₂O medium. The crystals of 1 , 2 and 4 consist of discrete formula units (one independent unit for 1 and 2 , two independent units for 4 ); in the structure of 4 , the solvent molecules are located in lattice cavities. All the tin atoms lie on crystallographic inversion centres and display moderately distorted octahedral C₂O₄ coordinations with short Sn–O bonds in the range 218–223 pm. Within the formula units, the anions are connected to the P–CH donor groups of the chelating ligands by C–H…O/N interactions, some of which are remarkably short (e.g. in 1 : H…O 220 pm, C–H…O 170°; H…N 242 pm, C–H…N 153°).     

Syntheses,Crystal Structures,and Properties of Metal(II) Coordination Polymers based on Flexible Ligand 1,3‐Bis(4‐phenoxy)benzenedicarboxylic Acid and Bis(benzimidazole)

Three new coordination polymers, [Zn(PBDC)(bbbm)_0.5]_n ( 1 ), [Co(PBDC)(bbbm)]_n ( 2 ), and [Cd(PBDC)(bbbm)]_n ( 3 ) were prepared via hydrothermal reactions of different metal(II) nitrates with flexible 1,3‐bis(4‐phenoxy)benzenedicarboxylic acid (H₂L) and 1,1‐(1,4‐butanediyl)bis(benzimidazole) ligand. All these complexes were fully characterized by elemental analysis, FT‐IR, thermogravimetric analysis (TGA), powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Structure analyses revealed that complex 1 has a 2D→2D twofold interpenetrating framework simplified by a 4‐connected sql net with point symbol (4⁴.6²), whereas complexes 2 and 3 are isostructural and exhibit a 2D→2D twofold interpenetrating framework rationalized as a three‐connected hcb net with point symbol (6³). Complexes 1 – 3 further expand to 3D supramolecular structures through non‐covalent C–H ··· O interactions. Additionally, the luminescent and magnetic properties of some of these complexes were studied. Complex 3 presents ideal photoluminescent behavior, whereas complex 2 shows antiferromagnetic coupling between the central Co^II ions, suggesting its latent application in magnetic material.     

Syntheses,Crystal Structures,and Properties of Lead(II), ­Zinc(II), and Manganese(II) Complexes Constructed from 2, 3, 5, 6‐Tetraiodo‐1, 4‐benzenedicarboxylic Acid

Three new coordination compounds, [Pb(HBDC‐I₄)₂(DMF)₄]( 1 ) and [M(BDC‐I₄)(MeOH)₂(DMF)₂]_n (M = Zn^II for 2 and Mn^II for ( 3 ) (H₂BDC‐I₄ = 2, 3, 5, 6‐tetraiodo‐1, 4‐benzenedicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric (TG) analysis, and X‐ray single crystal structure analysis. Single‐crystal X‐ray diffraction reveals that 1 crystallizes in the monoclinic space group C2/c and has a discrete mononuclear structure, which is further assembled to form a two‐dimensional (2D) layer through intermolecular O–H ··· O and C–H ··· O hydrogen bonding interactions. The isostructural compounds 2 and 3 crystallize in the space group P2₁/c and have similar one‐dimensional (1D) chain structures that are extended into three‐dimensional (3D) supramolecular networks by interchain C–H ··· π interactions. The Pb^II and Zn^II complexes 1 and 2 display similar emissions at 472 nm in the solid state, which essentially are intraligand transitions.     

Synthesis,Structures, and Properties of Two Novel Supramolecular Architectures Constructed from [2,3‐f]Pyrazino[1,10]phenanthroline‐2,3‐dicarboxylic Acid

Two new compounds, [Ag(Hppdb)]_n ( 1 ) and {[Ag₂(Hppdb)₂(bpe)] · 5.5H₂O}_n( 2 ) [H₂ppdb = [2,3‐f]pyrazino[1,10]phenanthroline‐2,3‐dicarboxylic acid, bpe = trans‐1,2‐bis(4‐pyridyl)ethylene], were synthesized and characterized. In 1 , Hppdb^– ions link Ag^I cations to form an infinite 1D [–Ag–(Hppdb)–Ag–]_n chain, furthermore, the dimensionality is extended to 2D layers through synergistic π–π stacking, hydrogen‐bonding and weak Ag ··· O interactions. Correspondingly, the dimeric [(Ag)(Hppdb)]₂ subunits in 2 are connected by bpe ligands to generate a loop‐link‐shaped 1D chain motif, which is further joined through a R₂²(18)C–H ··· O hydrogen‐bonding ring to afford interesting diagonal/diagonal inclined catenation 2D + 2D → 3D supramolecular architectures. In addition, solid‐state properties such as photoluminescence and thermal stability of the two compounds were studied.     

N → Sn coordination in the complexes of tin halides with pyridine: A comparison between Sn(II) and Sn(IV)

The experimentally well‐known complexation of tin(II) and tin(IV) halides with pyridine (py) leads to structures showing N → Sn coordination. In the present work, the complexes SnX_n·mpy (where X = F, Cl, Br, I; n = 2, 4; m = 1, 2) possessing this kind of coordination were studied using a computational quantum chemical approach. Various aspects in the theoretical picture of these complexes were examined to find similarities and differences in their N → Sn coordination. The aspects included, among others, the physical nature of intermolecular interactions, and their role in establishing the structure and energetic stabilization of the complexes. In this context, the effect of tin valency was inspected in great detail. As proven by several theoretical methods, a largely ionic character with a certain covalent component can be attributed to the studied N → Sn coordination, irrespective of tin valency. All complexes are destabilized by py‐py and three‐body interactions, but the Sn(II) complexes experience it to a greater extent. Marked differences are observed in the structural behavior of N → Sn and SnX_n during complex formation. This affects the energetics of complexation and, in consequence, the penta‐coordinated Sn(IV) center shows a higher propensity to expand its coordination number, compared with the tri‐coordinated Sn(II) center. The present study supplements the experimental characterization of SnX_n·mpy and, in general, it sheds light on the coordination of heteroaromatic nitrogen to tin. The survey of the Cambridge Structural Database revealed that such coordination occurred in a number of crystal structures.     

Formation,Structural Characterization,and Calculated NMR Chemical Shifts of Selenium‐Nitrogen Compounds from SeCl4 and ArNHLi (Ar = supermesityl,mesityl)

Supermesityl selenium diimide [Se{N(C₆H₂^tBu₃‐2, 4, 6)}₂; Se{N(mes*)}₂] can be prepared in a good yield from the reaction of SeCl₄ and (mes*)NHLi. The molecule adopts an unprecedented anti, anti‐conformation, as deduced by DFT calculations at PBE0/TZVP level of theory and supported by ⁷⁷Se NMR spectroscopy and a crystal structure determination. An analogous reaction involving (C₆H₂Me₃‐2, 4, 6)NHLi [(mes)NHLi] unexpectedly lead to the reduction of selenium and afforded the selenium diamide Se{NH(mes)}₂ that was characterized by X‐ray crystallography and ⁷⁷Se NMR spectroscopy. The Se‐N bonds of 1.847(3) and 1.852(3) Å show normal single bond lengths. The <NSeN bond angle of 109.9(1)° also indicates a tetrahedral AX₂E₂ bonding arrangement around selenium. Two N‐H···N hydrogen bonds link the Se{NH(mes)}₂ molecule with two discrete (mes)NH₂ molecules. In the solid state selenium diamide adopts the anti‐conformation, whereas in solution the presence of both syn‐ and anti‐isomers could be observed. PBE0/TZVP calculations of the shielding tensors of 28 different types of selenium‐containing molecules, for which the ⁷⁷Se chemical shifts are unambiguously known, were carried out to assist the spectral assignment of Se{N(mes*)}₂ and Se{NH(mes)}₂.     

Destruktive Komplexierung des dimeren Diorganylzinn(IV)‐hydroxids [Me2Sn(A)(μ‐OH)]2 (HA = Benzol‐1,2‐disulfonsäureimid): Bildung und Strukturen der Einkernkomplexe [Me2Sn(A)2(OPPh3)2] und [Me2Sn(phen)2]2⊕ · 2 A⊖ · MeCN

Polysulfonylamines. CXVI. Destructive Complexation of the Dimeric Diorganyltin(IV) Hydroxide [Me₂Sn(A)(μ‐OH)]₂ (HA = Benzene‐1,2‐disulfonimide): Formation and Structures of the Mononuclear Complexes [Me₂Sn(A)₂(OPPh₃)₂] and [Me₂Sn(phen)₂]^2⊕ · 2 A^⊖ · MeCN Destructive complexation of the dimeric hydroxide [Me₂Sn(A)(μ‐OH)]₂, where A^⊖ is deprotonated benzene‐1,2‐disulfonimide, with two equivalents of triphenylphosphine oxide or 1,10‐phenanthroline in hot MeCN produced, along with Me₂SnO and water, the novel coordination compounds [Me₂Sn(A)₂(OPPh₃)₂] ( 3 , triclinic, space group P 1) and [Me₂Sn(phen)₂]^2⊕ · 2 A^⊖ · MeCN ( 4 , monoclinic, P2₁/c). In the uncharged all‐trans octahedral complex 3 , the heteroligands are unidentally O‐bonded to the tin atom, which resides on a crystallographic centre of inversion [Sn–O(S) 227.4(2), Sn–O(P) 219.6(2) pm, cis‐angles in the range 87–93°; anionic ligand partially disordered over two equally populated sites for N, two S and non‐coordinating O atoms]. The cation occurring in the crystal of 4 has a severely distorted cis‐octahedral C₂N₄ coordination geometry around tin and represents the first authenticated example of a dicationic tin(IV) dichelate [R₂Sn(L–L′)₂]^2⊕ to adopt a cis‐structure [C–Sn–C 108.44(11)°]. The five‐membered chelate rings are nearly planar, with similar bite angles of the bidentate ligands, but unsymmetric Sn–N bond lengths, each of the longer bonds being trans to a methyl group [ring 1: N–Sn–N 71.24(7)°, Sn–N 226.81(19) and 237.5(2) pm; ring 2: 71.63(7)°, 228.0(2) and 232.20(19) pm]. In both structures, the bicyclic and effectively C_S symmetric A^⊖ ions have their five‐membered rings distorted into an envelope conformation, with N atoms displaced by 28–43 pm from the corresponding C₆S₂ mean plane.     

Syntheses,Structures, and Luminescent Properties of d10 Coordination Polymers with 2‐(4‐Carboxyphenyl)‐imidazo[4, 5‐f]‐1, 10‐phenanthroline and 1, 3‐Benzenedicarboxylate Derivatives

Four Zn^II/Cd^II coordination polymers (CPs) based on 2‐(4‐carboxy‐phenyl)imidazo[4, 5‐f]‐1, 10‐phenanthroline (HNCP) and different derivatives of 5‐R‐1, 3‐benzenedicarboxylate (5‐R‐1, 3‐BDC) (R = NO₂, H, OH), [Zn(HNCP)(5‐NO₂‐1, 3‐BDC)]_n ( 1 ), [Cd(HNCP)(5‐NO₂‐1, 3‐BDC)]_n ( 2 ), [Zn(HNCP)(1, 3‐BDC)(H₂O)₂]_n ( 3 ), and {[Zn(HNCP)(5‐OH‐1, 3‐BDC)(H₂O) · H₂O}_n ( 4 ) were synthesized under hydrothermal conditions. Compounds 1 – 4 were determined by elemental analyses, IR spectroscopy, and single‐crystal and powder X‐ray diffraction. Compounds 1 and 2 are isomorphous, presenting a 4‐connected uninodal (4, 4)‐sql 2D framework with threefold interpenetration, which are further extended into the three‐dimensional (3D) supramolecular architecture through π ··· π stacking interactions between the aryl rings of 5‐NO₂‐1, 3‐BDC. Compared to compound 1 , 3 is obtained by using different reaction temperatures and metal‐ligand ratios, generating a 3D framework with –ABAB– fashion via π ··· π stacking interactions. Compound 4 is a 1D chain, which is further extended into a 3D supramolecular net by hydrogen bonds and π ··· π stacking interactions. The thermogravimetric and fluorescence properties of 1 – 4 were also explored.     

Intra‐ and intermolecular Se...X (X = Se,O) interactions in selenium‐containing heterocycles: 3‐benzoylimino‐5‐(morpholin‐4‐yl)‐1,2,4‐diselenazole

In the selenium‐containing heterocyclic title compound {systematic name: N‐[5‐(morpholin‐4‐yl)‐3H‐1,2,4‐diselenazol‐3‐ylidene]benzamide}, C₁₃H₁₃N₃O₂Se₂, the five‐membered 1,2,4‐diselenazole ring and the amide group form a planar unit, but the phenyl ring plane is twisted by 22.12 (19)° relative to this plane. The five consecutive N—C bond lengths are all of similar lengths [1.316 (6)–1.358 (6) Å], indicating substantial delocalization along these bonds. The Se...O distance of 2.302 (3) Å, combined with a longer than usual amide C=O bond of 2.252 (5) Å, suggest a significant interaction between the amide O atom and its adjacent Se atom. An analysis of related structures containing an Se—Se...X unit (X = Se, S, O) shows a strong correlation between the Se—Se bond length and the strength of the Se...X interaction. When X = O, the strength of the Se...O interaction also correlates with the carbonyl C=O bond length. Weak intermolecular Se...Se, Se...O, C—H...O, C—H...π and π–π interactions each serve to link the molecules into ribbons or chains, with the C—H...O motif being a double helix, while the combination of all interactions generates the overall three‐dimensional supramolecular framework.     

The synthesis,NMR (1H, 13C, 119Sn) and IR spectral studies of some di‐ and tri‐organotin(IV) sulfonates: X‐ray crystal structure of [(n‐C4H9)2Sn(OSO2C6H4CH3‐4)2·2H2O]

A number of alkyltin(IV) paratoluenesulfonates, R_nSn(OSO₂C₆H₄CH₃‐4)_4?n (n = 2, 3; R = C₂H₅, n‐C₃H₇, n‐C₄H₉), have been prepared and IR spectra and solution NMR (¹H, ¹³C, ¹¹⁹Sn) are reported for these compounds, including (n‐C₄H₉)₂Sn(OSO₂X)₂ (X = CH₃ and CF₃), the NMR spectra of which have not been reported previously. From the chemical shift δ(¹¹⁹Sn) and the coupling constants ¹J(¹³C, ¹¹⁹Sn) and ²J(¹H, ¹¹⁹Sn), the coordination of the tin atom and the geometry of its coordination sphere in solutions of these compounds is suggested. IR spectra of the compounds are very similar to that observed for the paratoluenesulfonate anion in its sodium salt. The studies indicate that diorganotin(IV) paratoluenesulfonates, and the previously reported compounds (n‐C₄H₉)₂Sn(OSO₂X)₂ (X = CH₃ and CF₃), contain bridging SO₃X groups that yield polymeric structures with hexacoordination around tin and contain non‐linear C? Sn? C bonds. In triorganotin(IV) sulfonates, pentacoordination for tin with a planar SnC₃ skeleton and bidentate bridging paratoluenesulfonate anionic groups are suggested by IR and NMR spectral studies. The X‐ray structure shows [(n‐C₄H₉)₂Sn(OSO₂C₆H₄CH₃‐4)₂·2H₂O] to be monomeric containing six‐coordinate tin and crystallizes from methanol–chloroform in monoclinic space group C2/c. The Sn? O (paratoluenesulfonate) bond distance (2.26(2) Å) is indicative of a relatively high degree of ionic character in the metal–anion bonds. Copyright © 2003 John Wiley & Sons, Ltd.     

Intermolecular Se···I Interactions Identified in Cu11(μ9‐Se)(μ3‐I)3[Se2P(OEt)2]6 Form a One Dimensional Polymeric Chain

The undecanuclear copper cluster Cu₁₁(μ9‐Se)(μ₃‐I)₃[Se₂P(OEt)₂]₆ 1 , has been isolated along with Cu₈(μ₈‐Se)[Se₂P(OEt)₂]₆ 2 , from the reaction of NH₄Se₂P(OEt)₂, Cu(CH₃CN)₄PF₆, and Bu₄NI in a molar ratio of 3:2:2 in diethyl ether. The molecular formulation of 1 was confirmed by elemental analysis, positive FAB mass spectrometry, multinuclear NMR (¹H, ³¹P, and ⁷⁷Se), and X‐ray diffraction. In cluster 1 eleven copper atoms adopt the geometry of a 3,3,4,4,4‐pentacapped trigonal prism with a selenium atom in the center. The coordination geometry for the central, nonacoordinated selenium atom is tricapped trigonal prismatic. In addition, the central core Cu₁₁Se is further stabilized by three iodides and six dsep ligands. Besides, weak inter‐molecular Se···I interactions (3.949–3.972 Å) are uncovered and form a one dimensional polymeric chain.     

Two New Zinc(II) Coordination Polymers Based on 1, 6‐Bis(2‐methyl‐imidazole‐1‐yl)‐hexane Ligand: Synthesis,Structures, and Properties

Two coordination polymers based on 1, 6‐bis(2‐methyl‐imidazole‐1‐yl)‐hexane (bimh), namely {[Zn₃(BTC)₂(bimh)] · (bimh)}_n ( 1 ) and {[Zn(IPA)(bimh)] · (CH₃CH₂OH)_0.5}_n ( 2 ) (H₃BTC = trimesic acid, H₂IPA = isophthalic acid), were synthesized through hydrothermal reactions. In compound 1 , the zinc(II) ions are bridged by BTC^3– ligands to form an undulating infinite two‐dimensional (2D) polymeric network. The 3D networks of 1 show a twofold interpenetrating net. In compound 2 , zinc(II) ions are bridged by IPA^2– ligands to form one‐dimensional (1D) helical structures. The 2D structures of 2 are further assembled into 3D networks through aromatic π–π stacking interactions. Both compounds exhibit strong photoluminescence at room temperature and may be good candidates for potential luminescence materials.     

Synthesis,Spectroscopic, and X‐Ray Diffraction Studies of cis‐Dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl3 H‐pyrazol‐3‐onato) Tin(IV)

Reaction between an aqueous ethanol solution of tin(II) chloride and that of 4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐one in the presence of O₂ gave the compound cis‐dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐onato) tin(IV) [(C₂₆H₂₆N₄O₄)SnCl₂]. The compound has a six‐coordinated Sn^IV centre in a distorted octahedral configuration with two chloro ligands in cis position. The tin atom is also at a pseudo two‐fold axis of inversion for both the ligand anions and the two cis‐chloro ligands. The orange compound crystallizes in the triclinic space group P 1 with unit cell dimensions, a = 8.741(3) Å, b = 12.325(7) Å, c = 13.922(7) Å; α = 71.59(4), β = 79.39(3), γ = 75.18(4); Z = 2 and D_x = 1.575 g cm^–3. The important bond distances in the chelate ring are Sn–O [2.041 to 2.103 Å], Sn–Cl [2.347 to 2.351 Å], C–O [1.261 to 1.289 Å] and C–C [1.401 Å] the bond angles are O–Sn–O 82.6 to 87.7° and Cl–Sn–Cl 97.59°. The UV, IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectral data of the compound are reported and discussed.     

Synthesis,structural characterization and cytotoxic activity of diorganotin(IV) complexes of N‐(5‐halosalicylidene)tryptophane

Four new diorganotin(IV) complexes of N‐(5‐halosalicylidene)tryptophane, R₂Sn[5‐X‐2‐OC₆H₃CH?NCH(CH₂Ind)COO] [Ind = 3‐indolyl; R, X = Et, Cl ( 1 ); Et, Br( 2 ); n‐Bu, Cl ( 3 ); n‐Bu, Br ( 4 )], were synthesized and characterized by elemental analysis, IR and NMR (¹H, ¹³C and ¹¹⁹Sn) spectra. The crystal structures of complexes 1 – 3 were determined by X‐ray single crystal diffraction and showed that the tin atoms are in a distorted trigonal bipyramidal geometry and form five‐ and six‐membered chelate rings with the tridentate ligand. Intermolecular weak interactions in 1–3 link molecules, respectively, into a two‐dimensional array, a one‐dimensional infinite chain and a one‐dimensional double‐chain supramolecular structure. Bioassay results of the compounds indicated that the dibutyltin complexes 3 and 4 have potent in vitro cytotoxic activity against two human tumor cell lines, CoLo205 and Bcap37, while the diethyltin complexes 1 and 2 display weak cytotoxic activity. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis,Characterization, and Crystal Structure of Three Coordination Polymers from 5‐(Pyridin‐2‐ylmethyl)aminoisophthalic Acid

Three new complexes: [M(L)(H₂O)] [M = Zn ( 1 ), Co ( 2 ), Ni ( 3 ); H₂L = 5‐(pyridin‐2‐ylmethyl)aminoisophthalic acid] were synthesized under hydrothermal conditions at 180 °C and were characterized by elemental analysis, FT‐IR spectroscopy, single‐crystal X‐ray diffraction, and thermogravimetric analysis (TGA). The results of X‐ray diffraction analysis reveal that complexes 1 – 3 are isostructural and crystallize in the monoclinic system with space group P2₁/c. Each of the complexes displays a (3,3′)‐connected two‐dimensional (2D) wave‐like network with (4,8²) topology, within which five‐membered uncoplanar N,N‐chelated metallacycles are shaped. Delicate N–H ··· O and O–H ··· O hydrogen bonding interactions exist in complexes 1 – 3 . Adjacent 2D layers are linked by intermolecular interactions, resulting in the construction of extended metal‐organic frameworks (MOFs) in complexes 1 and 2 .     

Octahedral Tin(IV) Complexes of the Chalcogen‐Centered Ligands [EC(PPh2S)2]2– (E = S,Se)

The metathetical reactions between SnBr₄ and Li₂[E'C(PPh₂E)₂] in toluene produce the homoleptic tin(IV) complexes Sn[E′C(PPh₂E)₂]₂ [E = E′ = S ( 1b ); E = S, E′ = Se ( 1c )], which were isolated as red crystals and structurally characterized by X‐ray crystallography. The metrical parameters of these octahedral complexes are compared with those of the all‐selenium analog Sn[E′C(PPh₂E)₂]₂ (E = E′ = Se, 1a ), which was prepared previously by a different route.     

Self‐Assembly,Spectroscopic and Electrochemical Studies of Nickel(II)‐4,8‐Diazaundecanediamide Complex

The self‐assembly of NiCl₂·6H₂O with a diaminodiamide ligand 4,8‐diazaundecanediamide (L‐2,3,2) gave a [Ni(C₉H₂₀N₄O₂)(Cl)(H₂O)] Cl·2H₂O ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction analysis. Structural data for 1 indicate that the Ni(II) is coordinated to two tertiary N atoms, two O atoms, one water and one chloride in a distorted octahedral geometry. Crystal data for 1: orthorhombic, space group P 21nb, a = 9.5796(3) Å, b = 12.3463(4) Å, c = 14.6305(5) Å, Z = 4. Through NH···Cl–Ni (H···Cl 2.42 Å, N···Cl 3.24 Å, NH···Cl 158°) and OH···Cl–Ni contacts (H···Cl 2.36 Å, O···Cl 3.08 Å, OH···Cl 143°), each cationic moiety [Ni(C₉H₂₀N₄O₂) (Cl)(H₂O)]⁺ in 1 is linked to neighboring ones, producing a charged hydrogen‐bonded 1D chainlike structure. Thermogrametric analysis of compound 1 is consistent with the crystallographic observations. The electronic absorption spectrum of Ni(L‐2,3,2)²⁺ in aqueous solution shows four absorption bands, which are assigned to the ³A_2g → ³T_2g, ³T_2g → ¹Eg, ³T_2g → ³T_1g, and ³A_2g → ³T_1g transitions of triplet‐ground state, distorted octahedral nickel(II) complex. The cyclic volammetric measurement shows that Ni²⁺ is more easily reduced than Ni(L‐2,3,2)²⁺ in aqueous solution.