Sn-N Bond Lengths Research Articles

New supramolecular architectures of 4′-(4-quinolinyl)-2,2′:6′,2″-terpyridine based on tin complexes: Design, structural variations and thermal properties

The reactions of 4′-(4-quinolinyl)-2,2′:6′,2″-terpyridine (qtpy) with SnMe2Cl2 and SnMe2(NCS)2 have been investigated. The reaction of SnMe2Cl2 with qtpy resulted in the formation of the new complex [SnMe2Cl(qtpy)]+[SnMe2Cl3]− (1) while the reaction of SnMe2(NCS)2 with qtpy affords the complex [SnMe2(NCS)2(qtpy)] (2). The resulting products have been characterized using elemental analysis, IR and multinuclear NMR (1H, 13C, 119Sn) spectroscopy. The new complex [SnCl2(qtpy)] (3) was characterized by X-ray crystallography from an acetone/n-hexane solution of 1 which reveals that 1 dissociates in solution. The new complex 2[SnMe2(NCS)2(qtpy)]·CH2Cl2·H2O (2.CH2Cl2·H2O) was characterized by X-ray crystallography from a dichloromethane/n-hexane solution of 2. Interestingly, the crystal structure of 3 reveals that the Sn(II) center is penta-coordinated as a slightly distorted square pyramid, as suggested by the index of the trigonality (τ) parameter. However, Sn(IV) is hepta-coordinated in 2.CH2Cl2·H2O which adopts a pentagonal bipyramidal geometry. The intermolecular hydrogen bond interactions and π…π stacking interactions establish to form the supramolecular assembly. The Hirshfeld surfaces analysis confirms that H…H and π…π interactions play major roles to stabilize the crystal architectures. The crystal structure of 2.CH2Cl2·H2O reveals the formation of porous material containing voids which have been occupied by the solvents. The volume of voids is 370 and 17 Å3, occupied by dichloromethane and water, respectively. Analysis of Sn-N bond lengths of complex 2.CH2Cl2·H2O shows that Sn-N bond lengths are greater than 2.39 Å for active organotin(IV) complexes, suggesting it as a good candidate for anti‐tumor activity. The thermal properties of the complexes indicate that 1 is stable up to 120 °C while 2 decomposes at 147 °C.

Tin(II) Phthalocyaninate and Tin(IV) bis-Phthaloc Yaninate: A Quantum Chemical Study

The structural parameters of tin(II) phthalocyaninate PcSn and tin(IV) bis-phthalocyaninate Pc2Sn as well as of their cations are determined by B3LYP/SDD and PBE0/SDD quantum chemical methods. The PcSn molecule is characterized by C4v symmetry, and SnN bond lengths are 2.307/2.299 A (B3LYP/PBE0). The Sn nucleus is by 1.11 A (B3LYP, PBE0, single crystal X-ray diffraction analysis) higher than the plane of four neighboring nitrogen nuclei. The “hindered” configuration (D4d symmetry) with a high (27–30 kcal/mole) internal rotation barrier corresponds to the Pc2Sn energy minimum. The calculated equilibrium lengths of eight equivalent SnN bonds of 2.366/2.347 (B3LYP/PBE0) are similar to the average SnN bond length of 2.347 A (single crystal X-ray diffraction). Vertical and adiabatic ionization potentials are calculated: Iv 6.40/6.48 eV, IA 6.38/6.45 eV for PcSn and Iv 5.63/5.66 eV, IA 5.60/5.63 eV for Pc2Sn.

Tin(IV) porphyrin complexes. Crystal structures of meso-tetraphenyl-porphyrinatotin(IV) diacetate, bis(dichloro-acetate), bis(trifluoroacetate) and diformate, and structural correlations for tin(IV) porphyrin complexes with O-bound anionic ligands

Structures of four tetraphenylporphyrinatotin(IV) bis(carboxylato) complexes [Sn(tpp)(OCOR)2] have been determined by single crystal X-ray diffraction. All complexes have typical octahedral geometry. The average Sn-N bond lengths for R = CH3, CHC12, CF3, and H are 2.091 A, 2.084 A, 2.082 A, and 2.086 A, respectively. The Sn-0 bond lengths are 2.096 A, 2.091 A, 2.109 A, and 2.090 A respectively. These bond lengths and those of all other reported Sn(tpp) complexes of O-bound anionic ligands are compared. There is an inverse correlation between the Sn-N and Sn-O bond lengths, indicating that stronger electron donation by the axial anionic ligand results in an expansion of the porphyrin core. Correlation of the Sn-O bond lengths with the pKa of the conjugate acids of the axial ligands shows that the stronger the acid, the longer the Sn-0 bonds, indicating that the bonding is dominated by electrostatic effects.

In vitro cytotoxic evaluation of novel dichlorodiorgano[N-(2-pyridylmethylene)arylamine]tin(IV) derivatives in human tumor cell lines

The present report overviews the studies on diorganotin(IV) complexes of N-(2-pyridylmethylene)arylamine, R(2)SnCl(2).L (R = Me (1), Et (2), Bu (3) or Ph (4)) as cytotoxic agents. This family of complexes was designed to include highly electron-donating N;Nchelating ligand to afford octahedral R(2)SnCl(2).L complexes of relatively high hydrolytic stability, with the aim to retain ligand binding throughout the biological activity for achieving controlled processes and allowing mechanistic evaluation. It is observed that the high cytotoxic activity is dependent on the Sn-R groups and Sn-N bond lengths, and which is related to the cytotoxic potential. Complex (2) was found to exhibit stronger cytotoxic activity in vitro particularly for A498 (renal cancer), IGROV (ovarian cancer), MCF-7 (breast cancer), and WIDR (colon cancer) of human tumour cell lines and the results are far superior to standard reference drugs e.g., doxorubicin, cisplatin, 5-fluorouracil, methotrexate, etoposide including paclitaxel. The important insights gained with the diorganotin(IV) compounds in regards to their cytotoxic activity are discussed.

Inhibition of Cell Proliferation and Antitumor Activity of a Novel Organotin Compound

Organotin compounds showed more antineoplastic effect against P388 leukemia in mice than any other class of compounds. However, they have not received as much attention as the platinum compounds. The present compound, Et2SnCl2.L [L = N-(2-pyridylmethylene)-4-toluidine] (OTC), showed an Sn-N bond length of 2.46 A which, because it is bigger than 2.39 A, is expected to achieve better formation of tin-DNA complexes. We previously reported on the synthesis and biological activity of this compound and on its ability to cause a delay in cell proliferation and sister chromatid exchanges in mouse bone marrow cells. In this study, we carried out further investigations on the antiproliferative and antitumor activity of OTC in relation to the cellular glutathione (GSH) level, which plays an important role in the cellular defense mechanism. OTC induced significant delay in the cell cycle in mouse bone marrow cells and, when the GSH level was low, the extent of the delay was reduced. The antitumor activity was determined in accordance with the US National Cancer Institute (NCI) standard protocol for primary screening in Dalton's lymphoma (DL) that was maintained by serial intraperitoneal transplantation. The T/C (treated/control) value was 146% when organotin was treated after transplantation; this improved significantly when buthionine sulfoximine (BSO), a GSH-depleting agent, was added 24 hours before the tin treatment. Our data suggest that the present tin compound has antiproliferative ability and can increase the survival of mice bearing DL. The endogenous GSH level influences the effect of the tin compound.

Synthesis and Structure of Tris(trialkylstannyl)‐ and Tris(dialkylhalostannyl)amines; Stabilization of the Sn3N Skeleton by Intramolecular Sn–X–Sn Bridges

AbstractTris(triorganylstannyl)amines (R2R'Sn)3N (1, 2) with substituents R = R' = Me, Bu or R = Me and R' = iPr, tBu are obtained by metathesis from R2R'SnX and NaNH2 in liquid ammonia or by transamination of R3SnNMe2 with NH3. Tris(diorga‐nylhalostannyl)amines (R2XSn)3N (3) are synthesized by stannazane cleavage of (Me3Sn)3N (1) with R2SnX2. Information from multinuclear magnetic resonance spectra ascertain the planarity of the Sn3N skeleton of type 2 and 3, as well as the relationship between the coupling constants 1J(119Sn15N) and 2J(119Sn117Sn) and the Sn–N bond length as determined by the X‐ray structure analysis of 1, 3b and 3r. Compound 3b shows an almost undistorted D3h symmetry with a planar Br3Sn3N skeleton and SnN bond lengths of 1.99 Å, which beside those of 3a are the shortest found so far. According to MNDO approximate and ab initio calculations π interactions between the lone electron pair at the N atom and empty orbitals at the Sn atoms can be excluded. Therefore, the tristan‐nylamines discussed here have a trigonal planar nitrogen center with its lone electron pair in a p‐type orbital. Further characteristic features of the molecular structures of typ 3 compounds are the intramolecular Sn–X–Sn bridges (X = Cl, Br, I) found in the solid state as well as in solution. The molecular geometries of the tristannylamines are supported by MS fragmentation patterns as well as by infrared and Raman spectra.

Synthesis and spectroscopic studies of thienyl triorganotin(IV) compounds. Crystal structures of [2-(4,4-dimethyl-2-oxazolinyl)-3-thienyl]dimethyltin N, N-dimethyldithiocarbamate and [2-(4,4-dimethyl-2-oxazolinyl)-3-thienyl]diphenyltin chloride

Two series of stannylated thiophenes of formula ( Z-C 4H 2SnR 2X ( Z = 3-(2-pyridyl) and 2-(4,4-dimethyl-2-oxazolinyl); R = Me, nBu, Ph, p-tolyl and cHex; X = Cl, Br, I, OH, SC(S)NMe 2, and 8-quinolinolyl) have been prepared and their structures established by 119 m Sn Mössbauer and NMR ( 13C and 119Sn) spectral analyses. A pronounced C, N-chelate bonding mode is inferred for the 3-(2-pyridyl)-2-thienyl ligand in the first series, the tin atoms thus being essentially five-coordinate with trans-C 3SnNX trigonal bipyramidal geometries. Crystal structure determinations on two products in the second series, namely [2-(4,4-dimethyl-2-oxazolinyl)-3-thienyl]dimethyltin N, N-dimethyldithiocarbamate ( 1) and [2-(4, 4-dimethyl-2-oxazolinyl)-3-thienyl]diphenyltin chloride ( 2), confirmed the spectroscopic indications of pentacoordinate trigonal bipyramidal tin environments and revealed that the oxazolinyl nitrogen is the intramolecularly coordinated donor atom in each case and is located in an apical position with respect to the C 3Sn trigonal girdle; the Sn-N bond length in 2 (2.580(8); 2.525(7) Å) is relatively shorter than in 1 (2.720(3) Å). The apical angle for 1 (162.12(7)°) shows the molecule to be more distorted than 2 (168.4(2) and 169.9(2)°).

Synthese und Struktur von Bis(trimethylstannyl)‐ und Bis(dimethylhalogenstannyl)aminen: zur Rolle des Stickstoff‐Elektronenpaares

Synthesis and Structure of Bis(trimethylstannyl) and Bis(dimethylhalostannyl) Amines: The Role of the Nitrogen Lone PairMonoaminostannanes RNH— SnMe3 (1) with substituents R = tBu, Mes, 2,6‐iPr2C6H3 are obtained by transmetallation from Me3SnX and RNH—Li, the distannylamines RN(SnMe3)2 (2) by transamination of Et2N —SnMe3 with RNH2, and bis(dimethylhalostannyl)amines R—N(SnMe2X)2 (8) by stannazane cleavage of 2 with Me2SnX2 or by SnC cleavage with BX3 (8n, o). Me2Sn(NtBuH)2, prepared from tBuNHLi and Me2SnBr2, decomposes with tBuNH2 elimination into the diazadistannetidine 4 already below room temperature. Information from multinuclear NMR spectra of type 2, 4, and 8 compounds ascertain the proposed relation between the value of the geminal coupling constant 2J(119Sn117Sn) of distannazanes and the Sn—N—Sn bond angle as determined by the X‐ray structure analysis of 2c and of (8a)2 as well as the participation of the electron pair at the nitrogen atom in bonding. 2c has C2 symmetry, contains a planar nitrogen atom with SnN bond lengths of 2.044 Å and an Sn—N—Sn bond angle of 125.0°. The aryl group stands perpendicular to the Sn2N plane. These data exclude any π interaction between the N atom and the substituents. 2c, therefore, represents an example of a tertiary amine with the lone electron pair at the nitrogen atom in a p‐type orbital. The supposed distannylamine (ClMe2Sn)2NMe (8a) is actually a dimer, whose unexpected structure contains a diazadistannetidine unit bearing two Me2SnCl2 groups at its nitrogen atoms in cis‐configuration. This arrangement allows the formation of weak intramolecular SnCl bonds.

Cyclische diazastannylene: XXII. Zur umsetzung eines bis(amino)stannylens mit organylphosphanen, -methylen-phosphoranen, -phosphaniminen, -oxiden und -sulfiden

1,3-Di-t-butyl-2,2-dimethyl-1,3,2,4λ 2-diazasilastannetidin (I) was allowed to react with the phosphanes PEt 3 and PPh 3 as well as with Me 3PCH 2, Ph 3PCH 2, Ph 3PNH, Me 3PO and Et 3PS. While the phosphor ylides and the phosphane oxide interact with I to yield crystalline acid-base adducts, no stable adducts can be isolated with the phosphanes and the phosphane sulfide. The adduct of Ph 3PCH 2 and I crystallizes with one benzene molecule per formula unit in the monoclinic space group P2 1/ c ( a 1188.2(8), b 1438.4(2), c 2169.4(5) pm, β 106.5(4)°). I and Ph 3PCH 2 are linked together by a SnC bond of 240.3(10) pm. The electron transfer from the ylide-carbon to the tin atom can be evaluated from the PC bond length of 174.3(11) pm. The phosphaneimine reacts with I by displacement of the tin atom in I by hydrogen atoms yielding N, N ′-di-t-butyl- Si, Si-dimethylsilazanean and Sn(NPPh 3) 4, and oxidation at the tin atom. 3 molecules of benzene are crystallizing together with one formula unit of Sn(NPPh 3) 4 (monoclinic; C2/ c; a 2470.0(4), b 1643.6(6), c 2382.7(4) pm, β 128.1(3)°). The tin atom is the centre of a tetrahedron of nitrogen atoms, the mean SnN-bond length (197.5 pm) being the shortest so far reported.

The crystal and molecular structure of SnBr[N(SiMe3)2

The crystal structure of SnBr[N(SiMe3)2]3 has been determined from three-dimensional X-ray diffraction data collected by counter methods. This compound crystallizes in the rhombohedral space groupR3c witha=11.970(3) A, α=99.06(3)°, andZ=2forD c> =1.37 g cm−3. The finalR value was 0.027 based on 608 independent observed reflections. The molecule lies on a crystallographic three-fold axis which contains the Sn and Br atoms. The bromine atom is covalently coordinated to the tin atom at a Sn-Br separation of 2.519(2) A. The three nitrogen atoms complete the bonding to tin with an Sn-N bond length of 2.056(7) A.