Dibutyltin(IV) complexes of the 5-[(E)-2-(Aryl)-1-diazenyl]-2-hydroxybenzoic acid ligand: an investigation of structures by X-ray diffraction, solution and solid state tin NMR, electrospray ionisation MS and assessment of in vitro cytotoxicity

A series of dibutylbis{5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoato}tin(IV) complexes, Bu₂Sn(LH)₂, have been prepared and characterized by ¹H, ¹³C, ¹¹⁹Sn NMR and ESI mass spectrometry in solution. The structures of the complexes Bu₂Sn(L¹H)₂ (1), Bu₂Sn(L³H)₂ (3), Bu₂Sn(L⁴H)₂ (4), and Bu₂Sn(L⁶H)₂ (6) (L = 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoate: aryl = phenyl (L¹H), 3-methylphenyl (L³H), 4-methylphenyl (L⁴H) and 4-bromophenyl (L⁶H)) were determined by X-ray crystallography and ¹¹⁷Sn CP-MAS NMR spectroscopy in the solid state. In general, the complexes were found to adopt a skew-trapezoidal bipyramidal arrangement around the tin atom. In addition, there are weak bridging intermolecular Sn?O contacts in complexes 1 and 3, but not in 4 and 6, where one of the hydroxy oxygen atoms from a neighboring molecule coordinates weakly with the Sn atom, thereby completing a seventh coordination site in the extended Sn coordination sphere. The Sn?O distance is 3.080(2) and 3.439(2) Å in 1 and 3, respectively, which are significantly shorter than the sum of the van der Waals radii of the Sn and O atoms (∼3.8 Å). In 1, this Sn?O interaction links the molecules into polymeric chains. In 3, these interactions link pairs of molecules into head-to-head dimeric units. The in vitro cytotoxicity of compound 2 indicates better results than cisplatin and etoposide against seven well characterized human tumor cell lines.     

Self-assembly of diorganotin(IV) 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetates: An investigation of structures by X-ray diffraction, solution and solid-state tin NMR, and electrospray ionization MS

The diorganotin(IV) compounds, [Me₂SnL²(OH₂)]₂ (1), [ⁿBu₂SnL²(OH₂)]₂ (2), [ⁿBu₂SnL¹]₃ · 0.5C₃H₆O (3), [ⁿBu₂SnL³]₃ · 0.5C₆H₆ (4) and [Ph₂SnL³]_n · 0.5C₆H₆ (5) (L = carboxylic acid residue, i.e., 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetate), were synthesized by treating the appropriate diorganotin(IV) dichloride with the potassium salt of the ligand in anhydrous methanol.The reaction of Ph₂SnL² (L = 2-{[(E)-1-(2-oxyphenyl)ethylidene]amino}acetate) with 1,10-phenanthroline (Phen) yielded a 1:1 adduct of composition, [Ph₂SnL²(Phen)] (6).The crystal structures of 1-6 were determined.The crystal of 1 is composed of centrosymmetric dimers of the basic Me₂SnL²(OH₂) moiety, where the two Sn-centres are linked by two asymmetric Sn-O?Sn bridges involving the carboxylic acid O atom of the ligand and a long Sn?O distance of 3.174(2) Å.The dimers are further linked into columns by hydrogen bonds.The coordination geometry about the Sn atom is a distorted pentagonal bipyramid with the two methyl groups in axial positions.The structure of 2 is similar.The same Sn atom coordination geometry is observed in compound 3, which is a cyclic trinuclear[ⁿBu₂SnL¹]₃ compound. Each Sn atom is coordinated by the phenoxide O atom, one carboxylate O atom and the imino N atom from one ligand and both the exo- and endo-carboxylate O atoms (mean Sn-O(exo): 2.35 Å; Sn-O(endo): 2.96 Å) from an adjacent ligand to form the equatorial plane, while the two butyl groups occupy axial positions. Compound 4 was found to crystallize in two polymorphic forms. The Sn-complex in both forms has a trinuclear [ⁿBu₂SnL³]₃ structural motif similar to that found in 3. In compound 5, distorted trigonal bipyramidal Ph₂SnL³ units are linked into polymeric cis-bridged chains by a weak Sn?O interaction (3.491(2) Å) involving the exocyclic O atom of the tridentate ligand of a neighboring Sn-complex unit. This interaction completes a highly distorted octahedron about the Sn atom, where the weakly coordinated exocyclic O atom and one phenyl group are trans to one another. In contrast, a monomeric distorted pentagonal bipyramidal geometry is found for adduct 6 where the Sn-phenyl groups occupy the axial positions. The solution and solid-state structures are compared by using ¹¹⁹Sn NMR chemical shift data. Compounds 1-6 were also studied using ESI-MS and their positive- and negative-ions mass fragmentation patterns are discussed.     

Diphenyltin(IV) complexes of the 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olates: Synthesis and multinuclear NMR, Sn Mössbauer, electrospray ionization MS, X-ray characterization and assessment of in vitro cytotoxicity

A series of cis-bis{5-[(E)-2-(aryl)-1-diazenyl]quinolinolato}diphenyltin(IV) complexes have been synthesized and characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analysis. The structures of a ligand L⁶H (i.e., 5-[(E)-2-(4-ethoxyphenyl)-1-diazenyl]quinolin-8-ol) and three diphenyltin(IV) complexes, viz., Ph₂Sn(L¹)₂ · (CH₃)₂CO (1), Ph₂Sn(L⁴)₂ (4) and Ph₂Sn(L⁵)₂ (5) (L = 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-ol: aryl = phenyl - (L¹H); 4′-methylphenyl - (L⁴H) and 4′-bromophenyl - (L⁵H)) were determined by single crystal X-ray diffraction. In general, the complexes were found to adopt a distorted cis-octahedral arrangement around the tin atom. These complexes retain their solid-state structure in non-coordinating solvent as evidenced by ¹¹⁹Sn NMR spectroscopic results. The in vitro cytotoxicity of 1 is reported and compared with Ph₂Sn(Ox)₂ (Ox = deprotonated quinolin-8-ol) against seven well characterized human tumor cell lines.     

Dibenzyltin(IV) complexes of the 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olates: Synthesis and an investigation of structures by X-ray diffraction, solution and solid-state tin NMR, Sn Mössbauer and electrospray ionization MS

A series of cis-bis{5-[(E)-2-(aryl)-1-diazenyl]quinolinolato}dibenzyltin(IV) complexes have been synthesized by reacting sodium salts of 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-ol (LH) and dibenzyltin dichloride. These complexes have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS in solution and by IR and ^119mSn Mössbauer, ¹¹⁷Sn CP-MAS NMR spectroscopy in solid state. In addition, the structures of three of the dibenzyltin(IV) complexes, viz., Bz₂Sn(L²)₂ (2), Bz₂Sn(L³)₂ (3), and Bz₂Sn(L⁵)₂ (5) (L = 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-ol: aryl = 4′-methylphenyl- (L²H), 4′-methoxylphenyl- (L³H) and 4′-bromophenyl- (L⁵H)) were determined by single-crystal X-ray diffraction. In general, the complexes were found to adopt a distorted cis-octahedral arrangement around the tin atom in both solution and solid state.     

Re-visiting of 5-[(E)-2-(aryl)-1-diazenyl]-quinolin-8-ol with tweaking of Sn-Ph groups: Synthesis, spectroscopic characterization and X-ray crystallography

Reactions of sodium 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olates (LH, where the aryl group is an R-substituted phenyl ring such that for L¹H: R = H; L²H: R = 2′-CH₃; L³H: R = 3′-CH₃; L⁴H: R = 4′-CH₃; L⁵H: R = 4′-OCH₃ and L⁶H: R = 4′-OC₂H₅) with Ph₃SnCl in a 1:1 molar ratio yielded complexes of composition Ph₃SnL. The complexes have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of Ph₃SnL¹ · 0.5C₆H₆ (1), Ph₃SnL² (2), Ph₃SnL⁵ · C₆H₆ (5) and Ph₃SnL⁶ · 0.5C₆H₆ (6) were determined. The results of the X-ray studies indicated that the benzene solvated compounds 1, 5 and 6 are distorted square pyramid, with one of the phenyl C atoms in the apex while the ligand arrangement around central Sn atom in 2 is distorted trigonal-bipyramidal, with a phenyl C and the oxinato N atoms in axial positions.     

Synthesis and characterization of bis[dicarboxylatotetraorganodistannoxane] units involving 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids: An investigation of structures by X-ray diffraction, NMR, electrospray ionisation MS and assessment of in vitro cytotoxicity

Reactions of 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids (LHH′, where the aryl group is an R-substituted phenyl ring such that for L¹HH′: R = H; L²HH′: R = 2′-CH₃; L³HH′: R = 3′-CH₃; L⁴HH′: R = 4′-CH₃; L⁵HH′: R = 4′-Cl; L⁶HH′: R = 4′-Br) with ⁿBu₂SnO in a 1:1 molar ratio yielded complexes of composition {[ⁿBu₂Sn(LH)]₂O}₂. The complexes have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of {[ⁿBu₂Sn(L¹H)]₂O}₂ (1), {[ⁿBu₂Sn(L⁴H)]₂O}₂ (4), {[ⁿBu₂Sn(L⁵H)]₂O}₂ (5) and {[ⁿBu₂Sn(L⁶H)]₂O}₂ (6) were determined. The compounds are centrosymmetric tetranuclear bis(dicarboxylatotetrabutyldistannoxane) complexes containing a planar Sn₄O₂ core in which two μ₃-oxo O-atoms connect an Sn₂O₂ ring to two exocyclic Sn-atoms. The four carboxylate ligands display two different modes of coordination where both modes involve bridging of two structurally distinct Sn-atoms. The solution structures were confirmed by ¹¹⁹Sn NMR spectroscopy by observing two tin resonances in compounds 1, and 4-6. The observed difference between the two tin resonances was about 3 ppm while the differences in ¹³C resonances were even smaller. Compounds {[ⁿBu₂Sn(L²H)]₂O}₂ (2) and {[ⁿBu₂Sn(L³H)]₂O}₂ (3) undergo a very complex exchange processes in deuteriochloroform solution. The in vitro cytotoxic activity of compounds 1 and 4 against WIDR, M19 MEL, A498, IGROV, H226, MCF7 and EVSA-T human tumour cell lines is reported.     

Synthesis, characterization and crystal structures of polymeric and dimeric triphenyltin(IV) complexes of 4-[((E)-1-{2-hydroxy-5-[(E)-2-(2-carboxyphenyl)-1-diazenyl]phenyl}methylidene)amino]aryls

The triphenyltin(IV) complexes of 4-[((E)-1-{2-hydroxy-5-[(E)-2-(2-carboxyphenyl)-1-diazenyl]phenyl}methylidene)amino]aryls (aryls = 4-CH₃, 4-Br, 4-Cl, 4-OCH₃) have been synthesized and characterized by ¹H-, ¹³C-, ¹¹⁹Sn-NMR, ESI mass spectrometry, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analysis. The crystal structures of a representative carboxylate ligand (aryl = 4-CH₃) and three Sn complexes, viz., polymeric (Ph₃Sn[O₂CC₆H₄{NN(C₆H₃-4-OH(C(H)NC₆H₄X-4))}-o])_n (X = Me (1) and Br (2)) and dimeric (Ph₃Sn[O₂CC₆H₄{NN(C₆H₃-4-OH(C(H)NC₆H₄X-4))}-o])₂ (X = OMe (4)) complexes are reported. The coordination environment in each complex is trigonal bipyramidal trans-Ph₃SnO₂. A single zwitterionic carboxylate ligand bridges adjacent Sn atoms via the carboxylate and phenoxide O atoms.     

Dinuclear copper(II) perchlorate complexes with 6-(benzylamino)purine derivatives: Synthesis,X-ray structure,magnetism and antiradical activity

The reactions of Cu(ClO₄)₂·6H₂O with 6-(benzylamino)purine derivatives in a stoichiometric 1:2 metal-to-ligand ratio led to the formation of penta-coordinated dinuclear complexes of the formula [Cu₂(μ-L^1–8)₄(ClO₄)₂](ClO₄)₂·nsolv, where L¹ = 6-(2-fluorobenzylamino)purine (complex 1), L² = 6-(3-fluorobenzylamino)purine (2), L³ = 6-(4-fluorobenzylamino)purine (3), L⁴ = 6-(2-chlorobenzylamino)purine (4), L⁵ = 6-(3-chlorobenzylamino)purine (5), L⁶ = 6-(4-chlorobenzylamino)purine (6), L⁷ = 6-(3-methoxybenzylamino)purine (7) and L⁸ = 6-(4-methoxybenzylamino)purine (8); n = 0–4 and solv = H₂O, EtOH or MeOH. All the complexes have been fully characterized by elemental analysis, FTIR, UV–Vis and EPR spectroscopy, and by magnetic and conductivity measurements. Variable temperature (80–300 K) magnetic susceptibility data of 1–8 showed the presence of a strong antiferromagnetic exchange interaction between two Cu(II) (S = 1/2) atoms with J ranging from −150.0(1) to −160.3(2) cm⁻¹. The compound 6·4EtOH·H₂O was structurally characterized by single crystal X-ray analysis. The Cu?Cu separation has been found to be 2.9092(8) Å. The antiradical activity of the prepared compounds was tested by in vitro SOD-mimic assay with IC₅₀ in the range 8.67–41.45 μM. The results of an in vivo antidiabetic activity assay were inconclusive and the glycaemia in pre-treated animals did not differ significantly from the positive control.     

Di-n-octyltin(IV) complexes with 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acid: Syntheses and assessment of solid state structures by Sn Mössbauer and X-ray diffraction and further insight into the solution structures using electrospray ionization MS, Sn NMR and variable temperature NMR spectroscopy

Reactions of 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids (LHH′, where the aryl group is an R-substituted phenyl ring such that for L¹HH′: X = H; L²HH′: X=2′-OCH₃; L³HH′: X = 3′-CH₃; L⁴HH′: X = 4′-CH₃; L⁵HH′:X = 4′-Cl) with ⁿOct₂SnO in 2:1 and 1:1 molar ratios have been investigated. Two types of complexes, ⁿOct₂Sn(LH)₂ and {[ⁿOct₂Sn(LH)]₂O}₂, were isolated and they have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of ⁿOct₂Sn(L¹H)₂ (1), {[ⁿOct₂Sn(L²H)]₂O}₂ (3) and {[ⁿOct₂Sn(L³H)]₂O}₂(4) were determined. The mononuclear complex 1 was found to adopt a skew-trapezoidal bipyramidal arrangement around the tin atom while 3 and 4 are centrosymmetric tetranuclear bis(dicarboxylatotetrabutyldistannoxane) complexes containing a planar Sn₄O₂ core in which two μ₃-oxo O-atoms connect an Sn₂O₂ ring to two exocyclic Sn-atoms. The solution structures were confirmed by ¹¹⁹Sn NMR spectroscopy by observing one tin resonance in compound 1 and two tin resonances in {[ⁿOct₂Sn(L⁵H)]₂O}₂ (5). {[ⁿOct₂Sn(L²H)]₂O}₂ (3) and {[ⁿOct₂Sn(L³H)]₂O}₂ (4) undergo very complex exchange processes in deuteriochloroform solution, which has been confirmed by variable temperature ¹H NMR spectroscopy. The cleavage of the most labile bond in the molecule was studied by ESI mass spectrometry.     

Dimolybdenum complexes containing anions of N,N′-bis(pyrimidine-2-yl)formamidine and N-(2-pyrimidinyl)formamide

The reactions of Mo₂(O₂CCH₃)₄ with different equivalents of N,N′-bis(pyrimidine-2-yl)formamidine (HL1) and N-(2-pyrimidinyl)formamide (HL2) afforded dimolybdenum complexes of the types Mo₂(O₂CCH₃)(L1)₂(L2) (1) trans-Mo₂(L1)₂(L2)₂ (2) cis-Mo₂(L1)₂(L2)₂ (3) and Mo₂(L2)₄ (4). Their UV–Vis and NMR spectra have been recorded and their structures determined by X-ray crystallography. Complexes 2 and 3 establish the first pair of trans and cis forms of dimolybdenum complexes containing formamidinate ligands. The L1 ligands in 1–3 are bridged to the metal centers through two central amine nitrogen atoms, while the L2 ligands in 1–4 are bridged to the metal centers via one pyrimidyl nitrogen atom and the amine nitrogen atom. The Mo–Mo distances of complexes 1 [2.0951(17) Å], 2 [2.103(1) Å] and 3 [2.1017(3) Å], which contain both Mo?N and Mo?O axial interactions, are slightly longer than those of complex 4 [2.0826(12)–2.0866(10) Å] which has only Mo?O interactions.     

A “sodium trap” based on benzo-15-crown-5 with an exocyclic N-(thiophosphoryl)thiourea moiety

For N-(thio)phosphorylthioureas of the common formula RC(S)NHP(X)(OiPr)₂HL^I (R = N-(4′-aminobenzo-15-crown-5), X = S), HL^II (R = N-(4′-aminobenzo-15-crown-5), X = O), HL^III (R = PhNH, X = S), HL^IV (R = PhNH, X = O), and (N,N′-bis-[C(S)NHP(S)(OiPr)₂]₂-1,10-diaza-18-crown-6) H₂L^V, salts LiL^I,III,IV, NaL^I–IV, KL^I–IVM₂L^V (M = Li⁺, Na⁺, K⁺), Ba(L^I,III,IV)₂, and BaL^V have been synthesized and investigated. Compounds NaL^I,II quantitatively drop out as a deposit in ethanol medium, allowing the separation of Na⁺ and K⁺ cations. This effect is not displayed for the other compounds. The crystal structures of HL^III and the solvate of the composition [K(Me₂CO)L^III] have been investigated by X-ray crystallography.     

Experimental and theoretical study of N-(2-hydroxyethyl)morpholine betaine

N-(2-hydroxyethyl)morpholine betaine (HEMB) has been characterized by a single crystal X-ray analysis, FTIR spectroscopy and DFT calculations. The crystals are monoclinic, space group P2₁/c with a=10.273(2), b=9.360(2), c=9.447(2) Å and β=104.72(3)Å. Two molecules of HEMB form a centrosymmetric dimer (X2) connected by a pair of hydrogen bonds between the CH₂CH₂OH and COO⁻ groups, with the O?O distance of 2.672(2) Å. The morpholine ring adopts a chair conformation with the CH₂CH₂OH group in the axial and the CH₂COO⁻ group in the equatorial position. The structures of the dimer, B2, and two monomers, B1a and B1b, have been optimized by the B3LYP approach using the 6-31G(d,p) basis set. The computed structure of B2, agrees well with the experimental X2. From two stable monomeric conformers the more favored is B1a, with the intramolecular hydrogen bond with the O-H?O distance of 2.566 Å. The effects of hydrogen bonding and electrostatic interactions on the conformation of the molecules investigated have been discussed. The FTIR spectrum shows a broad absorption in the 3300-2600 cm⁻¹ region, typical of moderate O-H?O hydrogen bonds.     

Structure of N,C,N-chelated organotin(IV) fluorides

The set of starting tri-, di- and monoorganotin(IV) halides containing N,C,N-chelating ligand (L^NCN = {1,3-[(CH₃)₂NCH₂]₂C₆H₃}⁻) has been prepared (1-5) and two compounds structurally characterized ([L^NCNPh₂Sn]⁺I₃⁻ (1c), L^NCNSnBr₃ (5)) in the solid state. These compounds were reacted with KF with 18-crown-6, NH₄F or L^CNnBu₂SnF to give derivatives containing fluorine atom(s). Triorganotin(IV) fluorides L^NCNMe₂SnF (2a) and L^NCNnBu₂SnF (3a) revealed monomeric structural arrangement with covalent Sn-F bond both in the coordinating and non-coordinating solvents, except the behaviour of 3a that was ionized in the methanol solution at low temperature. The products of fluorination of L^NCNSnPhCl₂ (4) and 5 were described by NMR in solution as the ionic hypervalent fluorostannates or the oligomeric species reacting with chloroform, methanol or moisture to zwitterionic monomeric stannate L^NCN(H)⁺SnF₄⁻ (5c), which was confirmed by XRD analysis in the solid state.     

The structures of (phenylato)(N-2-thiophenecarboxamido-meso-tetraphenylporphyrinato)mercury(II) and bisphenylmercury(II) complex of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,20-tetraphenylporphyrin

The reaction of PhHgOAc with N-NHCO-2-C₄H₃S-Htpp (5) and N-p-HNSO2C6H4^tBu-Htpp (4) gave a mercury (II) complex of (phenylato) (N-2-thiophenecarboxamido-meso-tetra phenylporphyrinato)mercury(II) 1.5 methylene chloride solvate [HgPh(N-NHCO-2-C₄H₃S-tpp) · CH₂Cl₂ · 0.5C₆H₁₄;  6 · CH₂Cl₂ · 0.5C₆H₁₄] and a bismercury complex of bisphenylmercury(II) complex of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,20-tetraphenylporphyrin, [(HgPh)2(N-p-NSO₂C₆H₄^tBu-tpp); 7], respectively. The crystal structures of 6 · CH₂Cl₂ · 0.5C₆H₁₄ and 7 were determined. The coordination sphere around Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and Hg(2) in 7 is a sitting-atop derivative with a seesaw geometry, whereas for the Hg(1) in 7, it is a linear coordination geometry. Both Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and Hg(2) in 7 acquire 4-coordination with four strong bonds [Hg(1)–N(1) = 2.586(3) Å, Hg(1)–N(2) = 2.118(3) Å, Hg(1)–N(3) = 2.625(3) Å, and Hg(1)–C(50) = 2.049(4) Å for 6 · CH₂Cl₂ · 0.5C₆H₁₄; Hg(2)–N(1) = 2.566(6) Å, Hg(2)–N(2) = 2.155(6) Å, Hg(2)–N() = 2.583(6) Å, and Hg(2)–C(61) = 2.064(7) Å for 7]. The plane of the three pyrrole nitrogen atoms [i.e., N(1)–N(3)] strongly bonded to Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and to Hg(2) in 7 is adopted as a reference plane 3N. For the Hg²⁺ complex in 6 · CH₂Cl₂ · 0.5C₆H₁₄, the pyrrole nitrogen bonded to the 2-thiophenecarboxamido ligand lies in a plane with a dihedral angle of 33.4° with respect to the 3N plane, but for the bismercury(II) complex in 7, the corresponding dihedral angle for the pyrrole nitrogen bonded to the NSO₂C₆H₄^tBu group is found to be 42.9°. In the former complex, Hg(1)²⁺ and N(5) are located on different sides at 1.47 and −1.29 Å from its 3N plane, and in the latter one, Hg(2)²⁺ and N(5) are also located on different sides at −1.49 and 1.36 Å form its 3N plane. The Hg(1)?Hg(2) distance in 7 is 3.622(6) Å. Hence, no metallophilic Hg(II)?Hg(II) interaction may be anticipated. NOE difference spectroscopy, HMQC and HMBC were employed to unambiguous assignment for the ¹H and ¹³C NMR resonances of 6 · CH₂Cl₂ ·  0.5C₆H₁₄ in CD₂Cl₂ and 7 in CDCl₃ at 20 °C. The ¹⁹⁹Hg chemical shift δ for a 0.05 M solution of 7 in CDCl₃ solution is observed at −1074 ppm for Hg(2) nucleus with a coordination number of four and at −1191 ppm for Hg(1) nucleus with a coordination number of two. The former resonance is consistent with that chemical shift for a 0.01 M solution of 6 in CD₂Cl₂ having observed at −1108 ppm for Hg(1) nucleus with a coordination number of four.     

Synthesis, structural characterization and electrochemistry of C,N-chelated organotin(IV) dicarboxylates with ferrocenyl substituents

A set of C,N-chelated organotin(IV) ferrocenecarboxylates, [L^CN(n-Bu)Sn(O₂CFc)₂] (1), [(L^CN)₂Sn(O₂CFc)₂] (2), [L^CN(n-Bu)Sn(O₂CCH₂Fc)₂] (3), [L^CN(n-Bu)Sn(O₂CCH₂CH₂Fc)₂] (4), [L^CN(n-Bu)Sn(O₂CCHCHFc)₂] (5), [L^CN(n-Bu)Sn(O₂CfcPPh₂)₂] (6), [(L^CN)₂Sn(O₂CfcPPh₂)₂] (7), and [L^CN(n-Bu)₂Sn(O₂CFc)] (8) (L^CN = 2-(N,N-dimethylaminomethyl)phenyl, Fc = ferrocenyl and fc = ferrocene-1,1′-diyl) has been synthesized by metathesis of the respective organotin(IV) halides and carboxylate potassium salts and characterized by multinuclear NMR and IR spectroscopy. The spectral data indicated that the tin atoms in diorganotin(IV) dicarboxylates bearing one C,N-chelating ligand (1 and 3-6) are seven-coordinated with a distorted pentagonal bipyramidal environment around the tin constituted by the n-butyl group, the chelating L^CN ligand and bidentate carboxylate. Compounds 2 and 7 possessing two chelating L^CN ligands comprise octahedrally coordinated tin atoms and monodentate carboxylate donors, whereas compound 8 assumes a distorted trigonal bipyramidal geometry around tin with the carboxylate binding in unidentate fashion. The solid state structures determined for 1⋅C₆D₆ and 2 by single-crystal X-ray diffraction analysis are in agreement with spectroscopic data. Compounds 1, 3-5, and 8 were further studied by electrochemical methods. Whereas the oxidations of ferrocene units in bis(carboxylate) 2 and monocarboxylate 8 proceed in single steps, compound 1 undergoes two closely spaced one-electron redox waves due to two independently oxidized ferrocenyl groups. The spaced analogues of 2, compounds 3-5, again display only single waves corresponding to two-electron exchanged.     

Preparation and cis-to-trans transformation study of square-planar [Pt(Ln)2Cl2] complexes bearing cytokinins derived from 6-benzylaminopurine (Ln) by view of NMR spectroscopy and X-ray crystallography

Mononuclear, square-planar platinum(II) complexes involving derivatives of aromatic cytokinins as the ligands, and having the general formula cis-[Pt(L_n)₂Cl₂] (1–3) and trans-[Pt(L_n)₂Cl₂] (4–6), where n = 1–3, L₁ = 2-chloro-6-(benzylamino)-9-isopropylpurine, L₂ = 2-chloro-6-[(4-methoxybenzyl)amino]-9-isopropylpurine and L₃ = 2-chloro-6-[(2-methoxybenzyl)-amino]-9-isopropylpurine, have been synthesized and characterized by elemental analysis, MALDI-TOF mass, FT IR, ¹H, ¹³C, ¹⁵N and ¹⁹⁵Pt NMR spectral measurements. Dynamic cis-to-trans isomerization process of complex 1 in N,N′-dimethylformamide (DMF) has been investigated by means of multinuclear NMR spectroscopy. The solid-state structures of 1, 4 · (DMF)₂, and 5 have been determined by single crystal X-ray analysis. X-ray structures revealed that the heterocyclic ligands are coordinated to platinum via nitrogen atom N(7) in all the complexes studied. In vitro cytotoxicity of the prepared complexes against MCF7, G361, K562, and HOS has been evaluated. Owing to low solubility of the complexes in water, the cytotoxicity has been only tested up to 5 μM concentration. Unfortunately, all complexes have been found to be non-cytotoxic in the accessible concentration range.     

Synthesis and characterization of tri(o-fluorobenzyl)tin esters of heteroaromatic carboxylic acid and crystal structures of tri(o-fluorobenzyl)tin esters of 4-pyridinecarboxylic acid and 3-pyridinecarboxylic acid

Reaction of tri(o-fluorobenzyl)tin chloride with sodium of heteroaromatic carboxylic acid in 1:1 stoichiometry yielded complexes of the type (2-F-Bz)₃SnOOCR (R=2-furanyl, 2-furanvingl, 2-thiophenyl, 2-pyridinyl, 3-pyridinyl, 4-pyridinyl, 3-indolyl, 3-indolmethyl and 3-indolpropyl), respectively. These complexes have been characterized by elemental analyses, IR and ¹H NMR spectroscopy. The crystal structures of tri(o-fluorobenzyl)tin esters of 4-pyridinecarboxylic acid (5) and 3-pyridinecarboxylic acid (6) were determined by single crystal X-ray diffraction. In the crystals of compounds 5 and 6, the tin atoms are rendered five-coordinate in a trigonal bipyramidal structure by coordinating with pyridine N atom of carboxylate group. The resulting structure is a one-dimensional linear polymer containing Sn-O bond lengths of 2.161(4), 2.202(9) Å and Sn-N bond lengths of 2.518(5), 2.454(10) Å.     

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.     

Five-membered ring chelate complexes of Ni(II), Pd(II) and Pt(II) derived of di-(2-pyridyl)-N-ethylimine

Cis-diaquobis{di-(2-pyridyl)-N-ethylimine}nickel(II) chloride (2) was obtained from the reaction of di-(2-pyridyl)-N-ethylimine (1) and [NiCl₂dppe] [dppe = cis-1,2-bis(diphenylphosphino)ethylene] in a 2:1 ratio in hot acetonitrile. Cis-dichloro{di-(2-pyridyl)-N-ethylimine}palladium(II) (3) and cis-dichloro{di-(2-pyridyl)-N-ethylimine}platinum(II) (4) complexes were obtained from the reaction of MCl₂ (M = Pd, Pt) and (1) in equimolar ratio in hot acetonitrile. Compounds 1–4 were characterized by IR spectroscopy, elemental analysis, and mass spectrometry; the complexes 3 and 4 were characterized in solution by NMR. In addition, solid state structures of compounds 1–4 were determined using single crystal X-ray diffraction analyses. X-ray diffraction data of the complexes 3 and 4 showed a distorted square planar local geometry at palladium and platinum atoms with the chlorine atoms in a cis-coordination; in 2 a local octahedral geometry at nickel atom was observed. Complexes 3 and 4 are arranged as dimers with a M?M distance of 3.4567(4) Å (M = Pd) and 3.4221(4) Å (M = Pt), respectively; 2 consists of units linked by intermolecular hydrogen bonding.