Synthesis and Properties of Mixed Ligand Complexes of Diorganotin(IV): Part(VII) – Synthesis and Characterisation of Some Antibacterial Dibenzoylmethane Diorganotin(IV)‐O‐alkyl Trithiophosphates

A series of some new mixed ligand complexes have been synthesized with an objective for evaluation as antimicrobials. Reactions of diorganotin(IV) dichloride with dibenzoyl methane and O‐alkyl trithiophosphates in a 1:1:1 molar ratio in refluxing benzene yield products of the type [PhCOCHCOPh]R₂Sn‐[SSH(S)POR'] [where R = Me, Bu, Ph; R' = Me, Et, Prⁱ, Buⁱ, Ph]. The newly synthesized complexes are light yellow colored crystalline solids, non‐volatile, soluble in common organic solvents, monomeric in nature and highly sensitive towards atmospheric moisture. These complexes are characterized by elemental analysis, IR and multinuclear NMR (¹H, ³¹P and ¹¹⁹Sn) spectral studies. Spectral studies of these complexes indicate that dibenzoyl methane and O‐alkyl trithiophosphate moieties are bidentate and the central tin atom is hexacoordinated in nature. A few of these compounds were tested for their antibacterial activity using standard drugs.     

Synthesis,spectral and antimicrobial studies of diorganotin(IV)3(2′‐hydroxyphenyl)‐5‐(4‐substituted phenyl) pyrazolinates

Diorganotin(IV) dipyrazolinates of the type R₂Sn(C₁₅H₁₂N₂OX)₂ [where C₁₅H₁₂N₂OX = 3(2′‐Hydroxyphenyl)‐5(4‐X‐phenyl)pyrazoline {where X = H ( a ); CH₃ ( b ); OCH₃ ( c ); Cl ( d ) and R = Me, Prⁿ and Ph}] have been synthesized by the reaction of R₂SnCl₂ with sodium salt of pyrazolines in 1:2 molar ratio, in anhydrous benzene. These newly synthesized derivatives have been characterized by elemental analysis (C, H, N, Cl and Sn), molecular weight measurement as well as spectral [IR and multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn)] studies. The bidentate behaviour of the pyrazoline ligands was confirmed by IR, ¹H and ¹³C NMR spectral data. A distorted trans‐octahedral structure around tin(IV) atom for R₂Sn(C₁₅H₁₂N₂OX)₂ has been suggested. The free pyrazoline and diorganotin(IV) dipyrazolinates have also been screened for their antibacterial and antifungal activities. Some diorganotin(IV) dipyrazolinates exhibit higher antibacterial and antifungal effect than free ligand and some of the antibiotics. Copyright © 2006 John Wiley & Sons, Ltd.     

Crystallographic report: Bis(3‐methyl‐2‐cyclopenten‐1‐one)dichloro‐oxovanadium(IV)

The crystal structure of the oxovanadium(IV) complex (CH₃C₅H₅O)₂VOCl₂ was determined. The molecule has trigonal bipyramidal geometry, with oxygen atoms of cyclopentenones in axial positions and oxygen and two chlorine atoms in equatorial positions. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesen und Strukturen der Lithiumtitanate(III) und ‐(IV), (py)2Li[(py)2Ti(OPh)4] und (py)2Li[(py)Ti(OPh)5]

Syntheses and Structures of the Lithiumtitanates(III)/(IV) (py)₂Li[(py)₂Ti(OPh)₄] and (py)₂Li[(py)Ti(OPh)₅] The new lithiumtitanates (py)₂Li[(py)₂Ti(OPh)₄] ( 1 ) and (py)₂Li[(py)Ti(OPh)₅] ( 2 ) have been obtained from the reaction of titaniumtrichloride (respectively titaniumtetrachloride 2 ) with LiOPh in the presence of the base pyridine (py). The crystal structures of both compounds show that the titanium atoms are in the centres of distorted octahedral coordination figures. In compound 1 , four oxygen and two nitrogen atoms (in cis orientation) are bonded to titanium, whereas in 2 , five oxygen and one nitrogen atom form the coordination polyeder around titanium. In both compounds, the lithium atoms are attached through phenolate bridges to the octahedra. The titanate (py)₂Li[(py)₂Ti(OPh)₄] ( 1 ) has a single absorption band in the visible region of the UV‐spectrum showing a shoulder shifted to the bathochromic region, due to the Jahn‐Teller‐effect for d¹‐systems.     

Titanium (IV) complexes of some tetra‐dentate symmetrical bis‐Schiff bases of 1,6‐hexanediamine: Synthesis,characterization, and in silico prediction of potential inhibitor against coronavirus (SARS‐CoV‐2)

Symmetrical bis‐Schiff bases (LH ₂) have been synthesized by the condensation of 1,6‐hexanediamine (hn) and carbonyl or dicarbonyl. One of the synthesized Schiff bases has been subjected to the molecular docking for the prediction of their potentiality against coronavirus (SARS‐CoV‐2). Molecular docking revealed that tested Schiff base possessed high binding affinity with the receptor protein of SARS CoV‐2 compared with hydroxychloroquine (HCQ). The ADMET analysis showed that ligand is non‐carcinogenic and less toxic than standard HCQ. Schiff bases acting as dibasic tetra‐dentate ligands formed titanium (IV) complexes of the type [TiL(H₂O)₂Cl₂] or [TiL(H₂O)₂]Cl₂ being coordinated through ONNO donor atoms. Ligands and complexes were characterized by the elemental analysis and physicochemical and spectroscopic data including FTIR, ¹H NMR, mass spectra, UV‐Visible spectra, molar conductance, and magnetic measurement. Optimized structures obtained from quantum chemical calculations supported the formation of complexes. Antibacterial, antifungal, and anti‐oxidant activity assessments have been studied for synthesized ligands and complexes.     

Synthesis and Cytotoxicity of 2‐(2′‐Pyridyl)benzimidazole Complexes of Palladium(II) and Platinum(II)

Compounds of type [MX₂(Hpben)] [M = Pd (X = Cl), Pt (X = Cl, I); Hpben = 2‐(2′‐pyridyl)benzimidazole] were prepared and characterized, and the structures of the Pt derivatives were determined by X‐ray crystallography. The crystals of [PtI₂(Hpben)] consist of discrete units in which the Pt atom is coordinated to two iodine atoms and to pyridine and imidazole N atoms in a distorted square planar arrangement. The structure of the chloro derivative is similar, except that the [PtCl₂(Hpben)] monomers are hydrogen‐bonded in zig‐zag chains. In assays of the interactions of the Pd and Pt chloro compounds with DNA, and of their in vitro cytotoxic activity against human cervical carcinoma cells (HeLa‐229), human ovarian carcinoma cells (A2780) and a cisplatin‐resistant mutant A2780 line (A2780cis), the only activity observed was modest cytotoxicity of the Pd derivative for A2780.     

Electrochemical and Spectroscopic Behaviour of Bis(2‐mercaptopyridine‐N‐oxide)oxovanadium(IV)

The complex [VO(MPO)₂] (MPO = deprotonated 2‐mercaptopyridine N‐oxide) was synthesized and characterized by IR spectroscopy. Its electrochemical behaviour was investigated by cyclic voltammetry in different organic solvents. The V^IV/V^V and V^IV/V^III couples could be identified. The nature of the electroactive species is strongly dependent on the solvent. The results are discussed in terms of a reaction mechanism describing the characteristics of the electron transfer processes and the involved chemical reactions, and the stability of the complex in each solvent was also determined. The electronic spectra of the investigated solutions gave additional support to the proposed mechanisms.     

Neue Halogenochalkogen(IV)‐Säuren: [H3O(Benzo‐18‐Krone‐6)]2[Te2Br10] und [H5O2(Dibenzo‐24‐Krone‐8)]2[Te2Br10]

Novel Halogenochalcogeno(IV) Acids: [H₃O(Benzo‐18‐Crown‐6)]₂[Te₂Br₁₀] and [H₅O₂(Dibenzo‐24‐Crown‐8)]₂[Te₂Br₁₀] Systematic studies on halogenochalcogeno(IV) acids containing tellurium and bromine led to the new crystalline phases [H₃O(Benzo‐18‐Crown‐6)]₂[Te₂Br₁₀] ( 1 ) and [H₅O₂(Dibenzo‐24‐Crown‐8)]₂[Te₂Br₁₀] ( 2 ). The [Te₂Br₁₀]^2‐ anions consists of two edge‐sharing distorted TeBr₆ octahedra, the oxonium cations are stabilized by crownether. ( 1 ) crystallizes in the monoclinic space group P2₁/n with a = 14.520(5) Å, b = 22.259(6) Å, c = 16.053(5) Å, β = 97.76(3)° and Z = 4, whereas ( 2 ) crystallizes in the triclinic space group with a = 11.005(4) Å, b = 12.103(5) Å, c = 14.951(6) Å, α = 71.61(3)°, β = 69.17(3)°, γ = 68.40(3)° and Z = 1.     

Tin(IV) complexes of 2‐benzoylpyridine N(4)‐phenyl‐thiosemicarbazone: spectral characterization,structural studies and antifungal activity

Three tin(IV) complexes of 2‐benzoylpyridine N(4)‐phenylthiosemicarbazone (H2Bz4Ph) were prepared: [Sn(L)Cl₃] (1), [BuSn(L)Cl₂] (2) and [(Bu)₂Sn(L)Cl] (3), in which L stands for the anionic ligand formed upon complexation with deprotonation and release of HCl. The complexes were characterized by a number of spectroscopic techniques. The crystal structures of H2Bz4Ph and complex 3 were determined. The antifungal activity of the ligand and its tin(IV) complexes was tested against Candida albicans. The thiosemicarbazone proved to be more active than the tin(IV) complexes. Copyright © 2003 John Wiley & Sons, Ltd.     

Crystallographic report: Diisopropylammonium [3‐(2‐thienyl)‐2‐sulfanylpropenoato]triphenylstannate

The title compound comprises trigonal bipyramidal SnPh₃(tspa) anions and ⁱPr₂NH₂ cations linked into centrosymmetric dimers by N? H·O hydrogen bonds. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and Structure of New Trimethylplatinum(IV) Iodide Complexes of 2,2′‐Bipyridine Ligands

The synthesis and structural characterization of four new trimethylplatinum(IV) iodide complexes of 2,2′‐bipyridine ligands {[PtMe₃(4,4′‐Clbipy)I] ( 1 ), [PtMe₃(4,4′‐Brbipy)I] ( 2 ), [PtMe₃(4,4′‐CNbipy)I] ( 3 ) and [PtMe₃(4,4′‐NO₂bipy)I] ( 4 )} are reported. The ¹H NMR spectra of the complexes reveal the presence of two chemically distinct methyl groups in the complexes. X‐ray crystal structures of complexes 1 – 4 show that the platinum metal center in each of the complexes form distorted octahedral structure being surrounded by methyl groups, bipyridine ligand, and iodine atom. Furthermore, the crystal packing study shows that self‐assembly of the complexes are governed by weak hydrogen bonding and other non‐covalent interactions such as π ··· π, halogen ··· π and C–H ··· π interactions. Complex 1 exhibits infinite one‐dimensional zigzag chain structure and other three complexes form infinite ladder type structures.     

Synthesis,structural characterization and antimicrobial activity of mixed aryl–alkyl diorganotin(IV) compounds with quinoline‐2‐carboxylate (L−): {RR′SnLCl}n and RR′SnL2

A series of unsymmetrical diorganotin derivatives of quinoline‐2‐carboxylic acid (LH), namely polymeric {MePhSnClL}_n (1) and {EtPhSnClL}_n (2), and mononuclear MePhSnL₂ (3) and EtPhSnL₂ (4), was synthesized by the reaction of LH with the MePhSnCl₂, EtPhSnCl₂, MePhSnO, and EtPhSnO precursors, respectively. The compounds were characterized by elemental analysis and infrared spectroscopy, as well as by ¹ H, ¹³ C and ¹¹⁹Sn NMR. The molecular structures of representative compounds 2 and 4 were determined by single‐crystal X‐ray crystallography. This study showed that polymeric 2 adopts a distorted octahedral geometry as the carboxylate ligand N,O chelates an Sn atom and at the same time bridges a neighbouring Sn atom via the second O atom, with the remaining sites being occupied by the Cl and two C atoms; the O atoms are trans to each other. The result of the μ₂‐bridging mode of L^? is the formation of a supramolecular helical chain. Compound 4 adopts a skew‐trapezoidal bipyramidal geometry with the organo groups lying over the plane of the two N,O‐chelating carboxylate ligands and being directed over the weaker Sn―N bonds. The in vitro antimicrobial activities of 1–4 against a Gram‐positive bacteria strain (Bacillus subtilis), a Gram‐negative bacteria strain (Escherichia coli) and against Candida albicans were studied and compared with the antimicrobial activities of Ph₂SnL₂ and Me₂SnL₂, and with the antimicrobial standards gentamicin, tetracycline, ampicillin and penicillin. All organotin compounds displayed remarkable antibacterial activities that were comparable to those of the standard drugs, in particular against B. subtilis, where the activity was correlated with the number of Cl substituents. Copyright © 2012 John Wiley & Sons, Ltd.     

HoClTe2O5: Ein tellurdioxidreiches Holmium(III)‐Chlorid‐Oxotellurat(IV)

HoClTe₂O₅: A Telluriumdioxide‐rich Holmium(III) Chloride Oxotellurate(IV) While attempting to synthesize anionically derivatized holmium oxotellurates by reacting holmium chloride (HoCl₃) with tellurium oxide (TeO₃; molar ratio 1 : 3, 800°C 10 d) in evacuated silica ampoules, transparent, greenish yellow and coarse single crystals of holmium(III) chloride oxotellurate(IV) HoClTe₂O₅ (triclinic, P1; a = 762.07(6), b = 796.79(6), c = 1010.36(8) pm, α = 100.987(4), ß = 99.358(4), γ = 91.719(4)°; Z = 4) were obtained. The crystal structure contains eightfold coordinated (Ho1)³⁺ (only surrounded by oxygen atoms) and sevenfold coordinated (Ho2)³⁺ cations (surrounded by one chloride and six oxide anions). Each sort of holmium polyhedra convenes independently to chains along [100] by edge‐sharing which again combine alternately via O6 and O9 to form ²{[Ho₂O₁₀(Cl1)]^15—} layers parallel (001). Each of the four crystallographically different Te⁴⁺ cations are surrounded by three close oxygen atoms (d(Te—O) = 188 — 195 pm) and always one more situated further away. The stereochemical activity of the non‐bonding electron pairs (“lone pairs”) leads to ψ¹‐trigonal bipyramidal coordination figures. The ψ¹‐tetrahedral [TeO₃]^2— basic units form discrete [Te₂O₅]^2— doubles with ecliptic conformation which are arranged in a fish‐bone pattern parallel to (001) on both sides of the ²{[Ho₂O₁₀Cl]^15—} layers. The coherence of the ²{[Ho₂(Cl1)Te₄O₁₀]⁺} layers is exclusively maintained via Cl2—Te1 contacts with an extraordinary long distance of 335 pm. As (Cl1)^— belongs to the coordination sphere of (Ho2)³⁺ and (Cl2)^— is only surrounded by Te⁴⁺, the compound should be correctly named holmium(III) chloride oxochlorotellurate(IV) Ho₂Cl[Te₄O₁₀Cl] (Z = 2).     

Einkristalle des Cer(IV)–Oxotellurats(IV) CeTe2O6

Single Crystals of the Cerium(IV) Oxotellurate(IV) CeTe₂O₆ Orange‐red, coffin‐shaped single crystals of CeTe₂O₆ (monoclinic, P2₁/n; a = 703.71(5), b = 1106.32(8), c = 735.24(5) pm, β = 108.066(6)°; Z = 4) were obtained by the reaction of admixtures of cerium dioxide and tellurium dioxide (CeO₂, TeO₂; molar ratio 1 : 2) in the presence of fluxing CsCl (750 °C, 4 d) in evacuated silica tubes. The crystal structure contains eightfold coordinated Ce⁴⁺ cations, which are surrounded by irregular trigonal dodecahedra of oxygen atoms. The interconnection of these [CeO₈] polyhedra occurs via two edges (O2–O2′ and O3–O3′) with equatorial orientation relative to each other forming zigzag chains {[CeO_4/1O_4/2]^8–} which run parallel to [100] and arrange as a hexagonal packing of rods. Both crystallographically different Te⁴⁺ cations exhibit trigonal non‐planar coordination figures (ψ¹ tetrahedra) with three oxygen atoms each as a result of the stereochemical activity of the non‐binding electron pairs (“lone pairs”). They also are responsible for the necessary cross‐linkage of the anionic {[CeO₆]^8–} chains. The isotypical relationship with Ce(SeO₃)₂ therefore justifies the formulation Ce(TeO₃)₂ for CeTe₂O₆.     

Synthesis of Aib‐ and Phe(2Me)‐Containing Cyclopentapeptides

Some recently described pentapeptides containing the α,α‐disubstituted α‐amino acids Aib and Phe(2Me) have been cyclized in DMF solution using diphenyl phosphorazidate (DPPA), O‐(1H‐benzotriazol‐1‐yl)‐N,N,N′,N′‐tetamethyluronium tetrafluoroborate/1‐hydroxybenzotriazole (TBTU/HOBt), and diethyl phosphorocyanidate (DEPC), respectively, to give the corresponding cyclopentapeptides in fair‐to‐good yields. In the case of peptides with L ‐amino acids, and (R)‐ and (S)‐Phe(2Me), the yields differed significantly in favor of the L /(R) combination. The conformations in the crystals of cyclo(Gly‐Aib‐(R,S)‐Phe(2Me)‐Aib‐Gly) and cyclo(Gly‐(R)‐Phe(2Me)‐Pro‐Aib‐Gly) have been determined by X‐ray crystallography, leading to quite different results. In the latter case, the conformation in solution has been elucidated by NMR studies.     

A Tin(IV) Porphyrin with Two Axial Organometallic NCN‐Pincer Platinum Units

A tin(IV) porphyrin was combined with two axial NCN‐pincer platinum(II) fragments by utilizing the oxophilicity of the apical positions on the tin atom and the acidic nature of the NCN‐pincer platinum derived benzoic acid. The solid‐state structure determined by X‐ray crystallography revealed some close contacts between the pincer complexes and the meso‐p‐tolyl subsitutents of the porphyrin. It was shown by ¹H NMR spectroscopy that these close contacts were not present in solution and that this compound can potentially act as a novel building block for supramolecular architectures.     

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.