An economical synthesis of dibenzocyclamnickel(II) and a metal-free macrocycle with tetramethyl substituents

The cationic dibenzocyclamnickel(II) complex, [Ni(Me₄Bzo₂[14]aneN₄)]²⁺, was obtained in good yield by Fe/HCl reduction of the corresponding tetraazaannulene complex [Ni(Me₄taa)], (1) {Me₄Bzo₂[14]aneN₄ = 5,7,12,14-tetramethyldibenzo[b,i]-1,4,8,11-tetraazacyclotetradecane; Me₄taa = 5,7,12,14-tetramethyldibenzo[b,i]-1,4,8,11-tetraazaannulene(2-)}. The orange–red product was isolated as the chloride (2) and perchlorate (3) salts. Analogous reduction with Zn/HCl yielded a diprotonated silky-white product [Ni(Me₄Bzo₂[14]aneN₄-H₂)][ZnCl₄]₂, (4). In the dry state, complex (4) is stable only under an HCl atmosphere and readily dissociates to give a solution of (2) when dissolved in polar solvents. Complexes (2) and (3), upon treatment with an excess of aqueous NaCN, undergo facile demetallation yielding the metal free macrocycle Me₄Bzo₂[14]aneN₄, (5). These compounds were characterized using a combination of i.r., u.v.–vis., ¹H-n.m.r., mass spectroscopy and voltammetry techniques. Unlike the parent tetraazaannulene complex (1), the reduced macrocycle complex, [Ni(Me₄Bzo₂[14]aneN₄)]²⁺ exhibits mild catalytic activity towards electro-reduction of CO₂ in MeCN solution.     

Synthesis,Spectral, and 3D Molecular Modeling of Tin(II) and Organotin(IV) Complexes of Biologically Active Schiff Bases Having Nitrogen and Sulfur Donor Ligands

Reaction of tin(II) chloride and dimethyltin dichloride with Schiff bases derived from S-benzyldithiocarbazate leads to the formation of a new series of tin(II) and organotin(IV) complexes of general formula SnCl ₂ .L and Me ₂ SnCl ₂ .L (where L = Schiff bases are derived from the condensation of S-benzyldithiocarbazate with heterocyclic aldehydes). An attempt has been made to prove the structures of the resulting complexes on the basis of elemental analysis, conductance measurements, molecular weight determinations, infrared, and multinuclear magnetic resonance ( ¹ H, ¹³ C, and ¹¹⁹ Sn NMR) spectral studies. A few representative ligands and their tin complexes have also been screened for their antibacterial and antifungal activities and found to be quite active in this respect.     

Synthesis,kinetics, and mechanism for adduct formation of tetraaza Schiff base cobalt(II) complexes with diorganotin(IV)dichlorides in dimethylformamide solvent

The kinetics and mechanism of the adduct formation of diorganotin(IV)dichlorides with Co(II) tetraaza Schiff base complexes, such as [Co(ampen)] {[N,N′‐ethylenebis‐(o‐amino‐α‐phenylbenzylideneiminato)cobalt(II)]}, [Co(campen)] {[N,N′‐ethylenebis‐(5‐chloro‐o‐amino‐α‐phenylbenzylideneiminato)cobalt(II)]}, and [Co(amaen)] {[N,N′‐ethylenebis‐(o‐amino‐α‐methylbenzylideneiminato)cobalt(II)]}, were studied spectrophotometrically. The kinetic parameters and the rate constant values show the following acceptor tendency trend for the diorganotin(IV)dichlorides: Ph₂SnCl₂> Me₂SnCl₂> Bu₂SnCl₂. Adducts have been separately synthesized and fully characterized by ¹¹⁹SnNMR, IR, UV–vis spectra, and elemental microanalysis (C,H,N) methods. The trend of the rate constants for the adduct formation of the cobalt complexes with a given tin acceptor decreases as follow: Co(amaen) > Co(ampen) > Co(campen). The linear plots of k_obs vs. the molar concentration of the diorganotin(IV)dichlorides, the high span of the second‐order rate constant k₂ values, and the large negative values of AS^≠ suggest an associative (A) mechanism for the acceptor–donor adduct formation. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 499–507, 2010     

Reactions of silylated Schiff bases with organotitanium(IV) and organotin(IV) chlorides

The interactions of silylated dibasic quadridentate Schiff bases derived fromo-hydroxyacetophenone and ethylenediamine and orthophenylenediamine with (π-C₅H₅)TiCl₃, (π-C₅H₅)(MeO)TiCl₂, (MeO)₂TiCl₂, Me₂SnCl₂ and MeSnCl₃ yield a new series of organotitanium(IV) and tin(IV) compounds. The reactivity of (π- C₅H₅)Ti(L₁)Cl and MeSn(L₁)Cl, towards MeSH, Me₂NSiMe₃, SiMe₃N₃ and Me₃SiC = CPh are also described. The structures for the compounds isolated are proposed on the basis of elemental analyses, molecular weights, IR and¹H nmr spectroscopic studies.     

Benzoylation of macrocyclic jäger type Ni(II) complexes and an efficient demetalation of γ,γ′-dibenzoylated products

The reaction of [Bzo₂Me₄[14]hexaenato(2?)N₄]Ni(II) and [Bzo₂Me₂Ph₂[14]hexaenato(2?)N₄]Ni(II) with benzoyl chloride leading to mono- and disubstituted derivatives is reported. The condition of the reliable demetalation of γ,γ′-dibenzoylated complexes by means of gaseous HCl are described. The Cu(II) complexes are synthesized from free ligands. All new compounds are characterized by elemental analysis, IR, ¹H NMR and MS data.     

Bis(4‐aminopyridinium) hexachloridostannate(IV) and bis(p‐toluidinium) hexachloridostannate(IV)

The crystal structures of the two organic–inorganic hybrids bis(4‐aminopyridinium) hexachloridostannate(IV), (C₅H₇N₂)₂[SnCl₆], and bis(p‐toluidinium) hexachloridostannate(IV), (C₇H₁₀N)₂[SnCl₆], differ in the way their cations pack in the layered structures. The Sn atom in the 4‐aminopyridinium compound lies on an inversion centre.     

Organotin(IV) carboxylates of cyclopropane carboxylic acid and 3‐cyclohexylpropanoic acid: synthesis,characterization and biological activity. The crystal structure of bis(cyclopropanecarboxylato) tetramethyldistannoxane

A series of tri‐ and di‐organotin(IV) derivatives of the types R₃SnL, R₂SnL₂ and [(R₂SnL)₂O]₂ have been synthesized by the reaction of tri‐ and di‐organotin(IV) chloride(s) with sodium cyclopropane carboxylate and sodium 3‐cyclohexylpropanoate. Based on spectroscopic evidence (IR and NMR), all the triorganotin carboxylates were found to be penta‐coordinated in the solid state (except the tricyclohexyltin derivative, which was found to be four‐coordinated) and four‐coordinated in the solution state. Attempted reaction of Me₂SnCl₂ with sodium cyclopropane carboxylate in 1:2 stoichiometry afforded a bis(dicarboxylato tetraorganodistannoxane) complex, {[Me₂Sn(cyclo‐CH₂)₂CHCOO]₂O}₂. The X‐ray diffraction of this ‘dimethyltin(IV) complex’ shows that the compound possesses a tetranuclear aggregate with one bridging bidentate and other free organic ester type monodentate carboxylate groups in which each Sn atom has a five‐coordinated geometry. These complexes were also screened for their antifungal activities. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of pseudohalogen groups on the optical properties and the structures of diorganotin coordination compounds based on the flexible ligand 1,2,3,4‐tetra‐(4‐pyridyl)‐butane

To investigate the effect of pseudo‐halogen groups on the structure and optical properties of diorganotin(IV) coordination compounds the reaction of dimethyltin diisothiocyanate and dimethyltin dichloride with 1,2,3,4‐tetra‐ (4‐pyridyl)‐butane (TPB) were studied. The results of spectroscopic data and structural analyses of prepared compounds showed that the reaction of Me₂SnCl₂ with TPB ligand leads to the formation of a 2D organotin(IV) coordination polymer, while the replacement of chloride ions with thiocyanate ions as pseudohalogen groups in the structure of Me₂SnCl₂ results in the development of a salt with an anion complex and a dimeric stannoxane as a side product. The results showed that the use of pseudo‐halogen groups instead of halogen groups in the structure of diorganotin(IV) dihalogen compounds could be as a suitable factor in the control of the structure of diorganotin(IV) coordination compounds. The investigation of optical properties of prepared compounds demonstrated that the use of pseudo‐halogen groups in the structure of diorganotin(IV) coordination compounds have an influence on their photoluminescence behavior.     

Donor property of cobalt(II) Schiff base complexes toward triphenyltin(IV)‐chloride: A kinetic study

In this study, some cobalt(II)tetraaza Schiff base complexes were used as donors in coordinating to triphenyltin(IV)chloride as acceptors; the kinetics and mechanism of the adduct formation were studied spectrophotometrically. Co(II)tetraaza Schiff base complexes used were [Co(amaen)][N,N′‐ethylene‐bis‐(o‐amino‐α‐methylbenzylideneiminato)cobalt(II)] ( 1 ), [Co(appn)] [N,N′‐1,2‐propylene‐bis‐(o‐amino‐α‐phenylbenzylideneiminato)cobalt(II)] ( 2 ), [Co(ampen)] [N,N′‐ethylene‐bis‐(o‐amino‐α‐phenylbenzylideneiminato)cobalt‐(II)] ( 3 ), [Co(cappn)][N,N′‐1,2‐proylene‐bis‐(5‐chloro‐o‐amino‐α‐phenylbenzylideneiminato)cobalt(II)] ( 4 ), and [Co(campen)] [N,N′‐ethylene‐bis‐(5‐chloro‐o‐amino‐α‐phenylbenzylid‐eneiminato)cobalt(II)] ( 5 ). The reactivity trend of the complexes in interaction with triphenyltin(IV)chloride was Co(amaen) > Co(appn) > Co(ampen) > Co(cappn) > Co(campen). The linear plots of k_obs versus the molar concentration of the triphenyltin(IV)chloride, a high span of the second‐order rate constant k₂ values, and large negative values of ΔS^≠ and low ΔH^≠ values suggest an associative (A) mechanism for the acceptor–donor adduct formation. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 635–640, 2012     

Synthesis of sitting‐atop type adducts of diphenyl and dimethyltin(IV) dihalides with meso‐tetraarylporphyrins

Some molecular adducts of dimethyltin(IV) dichloride, diphenyltin(IV) dichloride and diphenyltin(IV) dibromide with para‐substituted meso‐tetraphenylporphyrin have been prepared. This adducts with general formula [(Me₂SnCl₂)₂H₂T(4‐X)PP], [(Ph₂SnCl₂)₂H₂T(4‐X)PP], and [(Ph₂SnBr₂)₂H₂T(4‐X)PP]; {X= CH₃O, CH₃, H, and Cl} have been synthesized and characterized by means of ¹H NMR, UV‐Vis, and elemental microanalysis methods.     

Syntheses,characterizations, and crystal structures of organotin(IV) chloride complexes with 4,4′‐bipyridine

The organotin(IV) chlorides R_nSnCl_4−n (n = 3, R = Ph, PhCH₂, n−Bu; and n =2, R = n−Bu, Ph, PhCH₂) react with 4,4′‐bipyridine (4′4‐bpy) to give [(Ph₃SnCl)₂(4,4′‐bpy)_1.5(C₆H₆)_0.5] ( 1 ), [(PhCH₂)₃‐ SnCl]₂ (4,4′‐bpy) ( 2 ), [(n−Bu)₃SnCl]₂(4,4′‐bpy) ( 3 ), [(n−Bu)₂SnCl₂(4,4′‐bpy)] ( 4 ), [Ph₂SnCl₂(4,4′‐bpy)] ( 5 ), and [(PhCH₂)₂SnCl₂(4,4′‐bpy)] ( 6 ). The new complexes have been characterized by elemental analyses, IR, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopy. The structures of ( 1 ), ( 2 ), ( 4 ), and ( 6 ) have been determined by X‐ray crystallography. Crystal structures of ( 1 ) and ( 2 ) show that the coordination number of tin is five. In complex ( 1 ), two different molecules exist: one is a binuclear molecule bridged by 4,4′‐bpy and another is a mononuclear one, only one N of 4,4′‐bpy coordinate to tin. Complex ( 2 ) contains an infinite 1‐D polymeric binuclear chain by weak Sn…Cl intermolecular interactions with neighboring molecules. In the complexes ( 4 ) and ( 6 ), the tin is six‐coordinate, and the 4,4′‐bpy moieties bridge adjacent dialkyltin(IV)dichloride molecules to form a linear chain. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:338–346, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20016     

Synthesis,spectroscopic characterization (IR, 1H, 13C and 119Sn NMR,electrospray mass spectrometry) and toxicity of new organotin(IV) complexes with N,N′,O‐ and N,N′,S‐scorpionate ligands

New organotin(IV) derivatives containing the anionic ligands bis(3,5‐dimethylpyrazol‐1‐yl)dithioacetate [LCS₂]⁻ and bis(3,5‐dimethylpyrazol‐1‐yl)acetate [LCO₂]⁻ have been synthesized from reaction between (CH₃)₂SnCl₂ and lithium salts of the ligands. Mononuclear complexes of the type {[LCX₂](CH₃)₂SnCl} (X = S or O) have been obtained and fully characterized by elemental analyses and FT‐IR in the solid state and by NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry in solution. The acute toxicity of new organotin(IV) derivatives on rat was studied, comparing their effect with those of dimethyltin chloride (CH₃)₂SnCl₂. The comparison of LD₅₀ of organotin(IV) complexes and (CH₃)₂SnCl₂ administered intraperitoneally, as a single dose, evaluated in vivo on rats, showed that toxicity decreases as follows: (CH₃)₂SnCl₂ > LCO₂ > LCS₂. The effect of these organotin(IV) complexes on DNA was evaluated in vitro and in vivo on rats treated with different doses of these compounds (1/20 LD₅₀ and 1/100 LD₅₀). The lymphocyte DNA status was assessed by the comet assay, a rapid and sensitive single‐cell electrophoresis technique, used to detect primary DNA damage in individual cells. After 36 h from the start of treatment the two new organotin(IV) derivatives induced a significant rise in comet assay parameters, indicating an increasing presence of damaged DNA. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and characterization of tin(IV)/organotin(IV) complexes with 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone [HBPCT]: X-ray crystal structure of [SnCl3(BPCT)]

Four new tin(IV)/organotin(IV) complexes, [SnCl₃(BPCT)] (2), [MeSnCl₂(BPCT)] (3), [Me₂SnCl(BPCT)] (4), and [Ph₂SnCl(BPCT)] (5), have been synthesized by the direct reaction of 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone [HBPCT, (1)] and stannic chloride/organotin(IV) chloride(s) in absolute methanol under purified nitrogen. HBPCT and its tin(IV)/organotin(IV) complexes (2–5) were characterized by CHN analyses, molar conductivity, UV-Vis, FT-IR, and ¹H NMR spectral studies. In all the complexes, tin(IV) was coordinated via pyridine-N, azomethine-N, and thiolato-S from 1. The molecular structure of 2 has been determined by X-ray single-crystal diffraction analysis. Complex 2 is a monomer and the central tin(IV) is six-coordinate in a distorted octahedral geometry. The crystal system of 2 is monoclinic with space group P121/n1 and the unit cell dimensions are a?=?8.3564(3)?Å, b?=?23.1321(8)?Å, c?=?11.9984(4)?Å.     

Organotin(IV) complexes with various donor ligands and their cytotoxicity against tumour cell lines. Part(I): R2SnCl2 with Schiff bases; unusual CN bond cleavage of the bases and X‐ray structures of the ionic products formed

Several Schiff bases derived from salicylaldehyde and aminopyridines were found to coordinate with Me₂SnCl₂ in 1:1 or 1:2 (tin:base) molar ratio in diethylether, depending on the nature of the Schiff base used, to form complexes of the general formula Me₂SnCl₂·L or Me₂SnCl₂·2L respectively. These Schiff bases coordinate with Ph₂SnCl₂ in a similar manner, but if the reaction is carried out in chloroform or if the product formed in ether is dissolved in chloroform then colourless to pale yellow crystals precipitated. The latter were analysed and found to be due to the ionic compounds [H₂NpyN–H⁺]₂ [Ph₂SnCl₄]^2? which were formed as a result of an unusual cleavage of the C?N bond of the Schiff bases. The Schiff bases, their Me₂SnCl₂ complexes and the ionic compounds were analyzed physicochemically and spectroscopically. The crystal structures of two of the ionic compounds showed that the cation [H₂NpyN–H⁺] binds with the anion [Ph₂SnCl₄]^2? via hydrogen bonds. The Schiff bases, their Me₂SnCl₂ complexes and the ionic compounds were screened against the three tumour cell lines, L₉₂₉, K₅₆₂ and HeLa, and the results were compared with those of the anticancer drugs, cisplatin, carboplatin and oxaliplatin. Copyright © 2003 John Wiley & Sons, Ltd.     

Schiff base supported mononuclear organotin(IV) complexes: Syntheses,structures and fluorescence cell imaging

Three mononuclear organotin(IV) complexes supported by Schiff bases have been synthesized. The complexes [(C₆H₅)₂Sn(L)] ( 1 ), [(t‐Bu)₂Sn(L)] ( 2 ) and [(t‐Bu)₂Sn(L')] ( 3 ) (L, L' = deprotonated Schiff bases) were obtained in good yield by the reaction of Schiff bases H ₂ L or H ₂ L′ with corresponding diorganotin dichlorides respectively. All newly synthesized complexes were characterized by means of FT‐IR spectroscopy, elemental analysis and multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR spectroscopy. In addition, single crystal X‐ray diffraction analyses were employed to establish the solid state molecular structures of these complexes. The structures of 1 – 3 reveal that all complexes are mononuclear with a five‐coordinated tin(IV) centre in it. The absorption and emission properties of all complexes have been investigated. Moreover, cytotoxicity and fluorescence cell imaging studies of theses complexes have been performed.     

Nickel(II) salophen-type complexes characterization and their thermodynamic studies with diorganotin(IV) dichlorides in chloroform

A u.v.–vis spectrophotometric study of the adduct formation of the nickel(II) Schiff base complexes,([NiL]) where L = [3-methoxysalophen, N,N′-bis(3-methoxysalicylidene)-1,2-phenylenediimine] (1), [4-methoxysalophen, N,N′-bis(4-methoxysalicylidene)-1,2-phenylenediimine] (2), [5-methoxysalophen, N,N′-bis(5-methoxysalicylidene)-1,2-phenylenediimine] (3) and [Salophen, [N,N′-bis(salicylaldehydo)-1,2-phenylenediimine] (4) as donors with R₂SnCl₂ (R = methyl, phenyl and n-butyl) as acceptors have been investigated in chloroform, as solvent. Adducts have been characterized by ¹H, ¹³C and ¹¹⁹Sn NMR, IR and electronic spectroscopy and CHN elemental microanalysis. The formation constants and the thermodynamic free energies were measured using u.v.–vis spectrophotometry titration for 1:1 adduct formation at various temperatures (T = 278 to 308 K). The trend of the adduct formation of the nickel Schiff base complexes with a given tin acceptor decreases as follows:

Synthetic, structural, and antimicrobial studies of organotin(IV) complexes of semicarbazone, thiosemicarbazone derived from 4-hydroxy-3-methoxybenzaldehyde

Reaction of dibutyltin dichloride, dimethyltin dichloride, and tributyltin chloride with ligands derived from thiosemicarbazone and semicarbazone leads to the formation of a new series of organotin(IV) complexes of general formula R₂SnCl₂·L and R₃SnCl·L (where L ligands derived from the condensation of thiosemicarbazide and semicarbazide with 4-hydroxy-3-methoxybenzaldehyde). The authenticity of these ligands and their metal complexes have been established on the basis of elemental analysis, conductance measurements, molecular weight determinations, infrared, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR, and UV spectral studies. These studies showed that the ligands coordinate to the metal atom in a bidentate. An octahedral structure is proposed for the organotin(IV) complexes. The ligands and its metal complexes are screened for their antimicrobial activities against some Gram-positive and Gram-negative bacteria, and fungus. The studies demonstrated that metalation can increase the antimicrobial activity rather than the free ligands.     

Synthesis and characterization of diorganotin(IV) complexes of Schiff bases with ONO‐type donors and crystal structure of [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐ethoxysalicylideneiminato]diphenyltin(IV)

A series of neutral complexes, namely, [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐hydroxysalicylideneiminato]‐ diphenyltin(IV) ( Ia ), [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐methoxysalicylideneiminato]diphenyltin(IV) ( IIa ) and [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐ethoxysalicylideneiminato]diphenyltin(IV) ( IIIa ) were prepared by the reaction of diphenyltin dichloride on the corresponding Schiff bases. The Schiff bases were the reaction products of 2‐hydroxy‐4‐nitroaniline and appropriate salicylaldehydes. All the compounds were characterized by elemental analysis, ¹H‐NMR, ¹³C‐NMR, IR and mass spectroscopy. Compound IIIa was also characterized by single crystal X‐ray diffraction and shows a C₂NO₂ coordination geometry nearly half‐way between a trigonal bipyramidal and square pyramidal arrangement. In the solid state, π? π interactions exist between the aniline fragments of neighbouring molecules. Copyright © 2007 John Wiley & Sons, Ltd.     

Transition metal schiff base chelates as ligands for phenyltin(IV) chlorides

Summary Binuclear complexes of phenyltin(IV) chlorides with transition metal chelates of tetradentate Schiff bases derived from acetylacetone, benzoylacetone oro-hydroxyacetophenone and ethylenediamine or propylenediamine, of the general formula Ph_nSnCl₄-nML (where n = 1 or 2, M = Ni¹¹ or Cu¹¹ and L^2–= the Schiff base dianion), have been synthesised and characterized through elemental analysis, conductance and i.r. spectroscopic data. The coordination of metal chelates to tin involves two triply bonded oxygen atoms giving rise to an octahedral environment around Sn^IV. The molar conductance of the complexes in nitrobenzene shows the presence of the uncoordinated ML and phenyltin(IV) chloride moieties in solution.Author to whom all correspondence should be directed.     

Diorganotin(IV) Complexes of Some Schiff Bases With a Potential Biological Activity

Diorganotin dichloride compounds, Rl₂SnCl₂ (R=Me, nBu, Ph) react with Schiff bases (L), derived from substituted and non-substituted 2- or 3-aminopyridine with 2-hydroxy-, 2-methoxy- or 2-hydroxy-3-methoxy-benzaldehyde in a 1 : 1 molar ratio, to give complexes of general formula R₂SnCl₂·L. It is suggested that the Schiff bases coordinate with tin in bidentate fashion to give hexacoordinate tin species. Almost all the complexes prepared show some 1 : 1 molar conductivity in ethanol and DMF, indicating on R₂Sn(L)Cl⁺ Cl⁻ ionic structure type. The complexes were screened against seven species of bacteria.