Synthesis,structure and property of diorganotin N‐[(3‐methoxy‐2‐oxyphenyl)methylene]tyrosinates

Five new diorganotin N‐[(3‐methoxy‐2‐oxyphenyl)methylene] tyrosinates, R₂Sn[2‐O‐3‐MeOC₆H₃CH=NCH (CH₂C₆H₄OH‐4)COO] (R = Me, 1 ; Et, 2 ; Bu, 3 ; Cy, 4 ; Ph, 5 ), have been synthesized and characterized by elemental analysis, IR, NMR (¹H, ¹³C and ¹¹⁹Sn) spectra, and the X‐ray single crystal diffraction. In non‐coordinated solvent, complexes 1 – 5 have penta‐coordinated tin atom. In the solid state, 1 – 3 are centrosymmetric dimmers in which each tin atom is seven‐coordinated in a distorted pentagonal bipyramid, and 4 displays discrete molecular structure with distorted trigonal bipyramidal geometry, and the tin atom of 5 is hexa‐coordinated and possess the distorted octahedral geometry with a coordinational methanol molecule. The intermolecular O‐H???O hydrogen bonds in 1 – 4 link molecules into the different one‐dimensional supramolecular chain with R₂² (30) or R₂² (20) macrocycles, and the molecules of 5 are joined into a two‐dimensional supramolecular network containing R₄⁴ (24) and R₄⁴ (28) two macrocycles. Bioassay results against human tumour cell HeLa indicated that 3 ‐ 5 belonged to the efficient cytostatic agents and the activity decreased in the order 4 > 3 > 5 > 2 > 1. The fluorescence determinations show the complexes may be explored for potential luminescent materials.     

Sandwich Double‐Decker Lanthanide(III) “Intracavity” Complexes Based on Clamshell‐Type Phthalocyanine Ligands: Synthesis,Spectral, Electrochemical,and Spectroelectrochemical Investigations

Phthalocyanine compounds of novel type based on a bridged bis‐ligand, denoted “intracavity” complexes, have been prepared. Complexation of clamshell ligand 1,1′‐[benzene‐1,2‐diylbis(methanediyloxy)]bis[9(10),16(17),23(24)‐tri‐tert‐butylphthalocyanine] (^clam,tBuPc₂H₄, 1 ) with lanthanide(III) salts [Ln(acac)₃] ? n H₂O (Ln=Eu, Dy, Lu; acetylacetonate) led to formation of double‐deckers ^clam,tBuPc₂Ln ( 2 a – c ). Formation of high molecular weight oligophthalocyanine complexes was demonstrated as well. The presence of an intramolecular covalent bridge affecting the relative arrangement of macrocycles was shown to result in specific physicochemical properties. A combination of UV/Vis/NIR and NMR spectroscopy, MALDI‐TOF mass‐spectrometry, cyclic voltammetry, and spectroelectrochemistry provided unambiguous characterization of the freshly prepared bis‐phthalocyanines, and also revealed intrinsic peculiarities in the structure–property relationship, which were supported by theoretical calculations. Unexpected NMR activity of the paramagnetic dysprosium complex 2 b in the neutral π‐radical form was observed and examined as well.     

A Dicationic Organoplatinum(II) Complex Containing a Bridging 2,5‐Bis‐(4‐ethynylphenyl)‐[1,3,4]oxadiazole Ligand Behaves as a Phosphorescent Gelator for Organic Solvents

A dicationic platinum(II) terpyridyl complex, [(tBu₃tpy)Pt(OXD)Pt(tBu₃tpy)](PF₆)₂ (tBu₃tpy=4,4′,4“‐tri‐tert‐butyl‐2,2′:6′,2”‐terpyridyl, OXD=2,5‐bis(4‐ethynylphenyl)[1,3,4]oxadiazole) formed phosphorescent organogels in acetonitrile or in a mixture of acetonitrile and alcohol. The structure and properties of these emissive gels were analyzed by polarizing optical and confocal laser scanning microscopy, and by variable‐temperature ¹H NMR, UV/Vis, and emission spectroscopy. Dry gels were studied by scanning electron microscopy, powder X‐ray diffraction (PXRD), and small‐angle X‐ray scattering (SAXS). SEM images of the dry gel revealed a network of interwoven nanofibers (diameter 12–60 nm, length>5 μm). Intermolecular π–π interactions between the [(tBu₃tpy)PtC≡C] moieties could be deduced from the variable ¹H NMR spectra. The PXRD and SAXS data showed that the assembly of the gelator could be represented by a rectangular 2D lattice of 68 Å × 14 Å. The ability of the complex to gelate a number of organic solvents is most likely due to intermolecular π–π interactions between the [(tBu₃tpy)PtC≡C] moieties.     

Lithiated Stannasilanes – Building Blocks for Monocyclic Si–Sn Rings

Dilithiated di(stannyl)oligosilanes (^tBu₂Sn(Li)– (SiMe₂)_n–Sn(Li)^tBu₂; 4 , n = 2; 5 , n = 3) were synthesized by the reaction of lithium diisopropylamide (LDA) with the α,ω‐hydrido tin substituted oligosilanes (^tBu₂Sn(H)– (SiMe₂)_n–Sn(H)^tBu₂; 1 , n = 2; 2 , n = 3). Surprisingly, the reaction of 1 and 3 (^tBu₂Sn(H)–(SiMe₂)₄–Sn(H)^tBu₂) with LDA resulted not in the formation of the lithiated compound, but what one can find is the formation of the 5,5‐ditert.butyl‐octamethyl‐1,2,3,4‐tetrasila‐5‐stannacyclopentane ( 8 ) (n = 4) in addition to the expected product 4 (n = 4) and the 3,3,6,6‐tetratert.butyl‐octamethyl‐1,2,4,5‐tetrasila‐3,6‐distannacyclohexane ( 7 ) (n = 3). Reactions of 4 and 5 with dimethyl and diphenyldichlorosilanes yielding monocyclic Si–Sn derivatives ( 9 – 11 ) are also discussed. The solid‐state structures of 7 and 11 were determined by X‐ray crystallography.     

Synthesis and solid‐state structures of t‐Bu3Ga–EPh3 Lewis acid–base adducts

Three Lewis acid–base adducts t‐Bu₃Ga–EPh₃ (E = P 1 , As 2 , Sb 3 ) were synthesized by reactions of Ph₃E and t‐Bu₃Ga and characterized by heteronuclear NMR (¹H, ¹³C (³¹P)) and IR spectroscopy, elemental analysis and single crystal X‐ray diffraction. Their structural parameters are discussed and compared to similar t‐Bu₃Ga adducts. The strength of the donor‐acceptor interactions within 1 – 3 was investigated in solution by temperature‐dependent ¹H NMR spectroscopy and by quantum chemical calculations.     

Synthesis,characterization, and molecular modeling studies of novel polyurethanes based on 2,2′‐[ethane‐1,2‐diylbis(nitrilomethylylidene)]diphenol and 2,2′‐[hexane‐1,6‐diylbis(nitrilomethylylidene)] diphenol hard segments

Novel polyurethanes (PUs) based on 2,2′‐[ethane‐1,2‐diylbis(nitrilomethylylidene)]diphenol and 2,2′‐[hexane‐1,6‐diylbis(nitrilomethylylidene)]diphenol as hard segments containing four aromatic diisocyanates (4,4′‐diphenylmethane diisocyanate, toluene 2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) have been prepared. Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, ¹H NMR and ¹³C NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis have been used to determine the structural characterization and thermal properties of the segmented PUs. All the PUs contain domains of both semicrystalline and amorphous structures, as indicated by X‐ray diffraction. The acoustic properties have been calculated with the group contribution method. Molecular dynamics simulations have been performed on all the PUs to estimate the cohesive energy density and solubility parameter values, which compare well with the values calculated with the group contribution method. Furthermore, the simulation protocols have been applied to the PUs to produce X‐ray diffraction plots to determine the phase morphology of the PUs. The surface properties of the PUs have been estimated from the simulation protocols. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6032–6046, 2006     

Unprecedented isolation of a dinuclear tin (II) complex stabilized by pyridine‐2,6‐dimethanol: structure,DFT and in vitro screening of cytotoxic properties

In this work, we report a novel dinuclear Sn (II) complex, [Sn₂(Hpdm)₂(H₂O)₆] 2H₂O 2Cl ( 1 ) (H₂pdm = pyridine‐2,6‐dimethanol), which has been crystallized out and characterized by elemental analysis, FTIR, ¹H and ¹³C NMR, single crystal X‐ray studies and Density Functional Theory (DFT) analysis. X‐ray structure of 1 has confirmed it to be a dinuclear alkoxo‐bridged Sn (II) species where each metal adopts a seven coordinate distorted pentagonal bipyramidal (pbp) geometry. This is the first hepta‐coordinated Sn (II) complex ever isolated apart from already reported stannylenes. Spin density plots from DFT support the +2 oxidation state of each tin metal. Hirshfeld surface analysis reveals the presence of various H‐bonding interactions in the molecule and molecular docking results along with DFT confirm higher binding affinity of the present complex towards DNA. Moreover, the complex exhibits promising anticancer activities against HeLa and A549 cancer cell lines.     

Synthesis and Cytotoxic Evaluation of Potential Bis‐Intercalators: Tetramethylenebis(oxy)‐ and Hexamethylenebis(oxy)‐Linked Assemblies Consisting of Flavone,Xanthone, Anthraquinone,and Dibenzofuran

In a search for potential inhibitors of solid‐tumor growth, certain alkanediylbis(oxy)‐linked assemblies were synthesized and evaluated for their cytotoxicity as bis‐intercalators. Symmetrical assemblies 1b – 12b were synthesized from their respective Aryl‐OH and either dibromobutane or dibromohexane, while unsymmetrical ones 13 – 15 were prepared from Aryl¹‐OH and either Aryl²‐O‐(CH₂)₄Br or Aryl²‐O‐(CH₂)₆Br. These bis‐intercalators were inactive against the growth of leukemia cells. However, some of them were active against the growth of certain solid tumors such as HOP‐62, HOP‐92 (non‐small‐cell lung cancer), SF‐265, SNB‐75, U251 (CNS cancer), A498 (renal cancer), and HS578T (breast cancer). Among them, [hexane‐1,6‐diylbis(oxy)bis(4,1‐phenylene)]bis[4H‐1‐benzopyran] ( 6b ) was especially active against the growth of all CNS cancer cell lines and also the growth of A498, HOP‐62, and HOP‐92 with GI₅₀ values of 17.0, 20.0, and 21.8 μM , respectively.     

Cluster Fusion: Face‐Fused Nine‐Atom Deltahedral Clusters in [Sn14Ni(CO)]4−

The title anion was synthesized by heating dimethylformamide (DMF) solution of the known Ni‐centered and Ni(CO)‐capped tin clusters [Ni@Sn₉Ni(CO)]^3?. The new anion represents the first example of face‐fused nine‐atom molecular clusters. The two clusters are identical elongated tricapped trigonal prisms of nido‐[Sn₈Ni(CO)]^6? with nickel at one of the capping positions. They are fused along a triangular face adjacent to a trigonal prismatic base and made of two Sn and one Ni atoms. The new anion is structurally characterized by single‐crystal X‐ray diffraction in the compound (K[222‐crypt])₄[Sn₁₄Ni(CO)]?DMF. Its presence in solution is corroborated by electrospray mass spectrometry.     

Koordinativ ungesättigte Dirutheniumkomplexe: Synthese und Kristallstrukturen von [Ru2(CO)n(μ‐H)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] (n = 4; 5) und [Ru2(CO)4(μ‐CH2)(μ‐H)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)]

Coordinatively Unsaturated Diruthenium Complexes: Synthesis and X‐ray Crystal Structures of [Ru₂(CO)_n(μ‐H)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] (n = 4; 5) and [Ru₂(CO)₄(μ‐CH₂)(μ‐H)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] The reaction of [Ru₂(μ‐CO)(CO)₅(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)] ( 2 ) with dppm yields the dinuclear species [Ru₂(μ‐CO)(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 3 ) (dppm = Ph₂PCH₂PPh₂). Under thermal or photolytic conditions 3 loses very easily one carbonyl ligand and affords the corresponding electronically and coordinatively unsaturated complex [Ru₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 4 ). 4 is also obtainable by an one‐pot synthesis from [Ru₃(CO)₁₂], an excess of ^tBu₂PH and stoichiometric amounts of dppm via the formation of [Ru₂(CO)₄(μ‐H)(μ‐P^tBu₂)(^tBu₂PH)₂] ( 1 ). 4 exhibits a Ru–Ru double bond which could be confirmed by addition of methylene to the dimetallacyclopropane [Ru₂(CO)₄(μ‐CH₂)(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 5 ). The molecular structures of 3 , 4 and 5 were determined by X‐ray crystal structure analyses.     

Heteropentanuclear Oxalato‐Bridged nd–4f (n=4, 5) Metal Complexes with NO Ligand: Synthesis,Crystal Structures,Aqueous Stability and Antiproliferative Activity

A series of heteropentanuclear oxalate‐bridged Ru(NO)‐Ln (4d–4f) metal complexes of the general formula (nBu₄N)₅[Ln{RuCl₃(μ‐ox)(NO)}₄], where Ln=Y ( 2 ), Gd ( 3 ), Tb ( 4 ), Dy ( 5 ) and ox=oxalate anion, were obtained by treatment of (nBu₄N)₂[RuCl₃(ox)(NO)] ( 1 ) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1 , 2 , and 5 were in addition analyzed by X‐ray crystallography, 1 by Ru K‐edge XAS and 1 and 2 by ¹³C NMR spectroscopy. X‐ray diffraction showed that in 2 and 5 four complex anions [RuCl₃(ox)(NO)]^2? are coordinated to Y^III and Dy^III, respectively, with formation of [Ln{RuCl₃(μ‐ox)(NO)}₄]^5? (Ln=Y, Dy). While Y^III is eight‐coordinate in 2 , Dy^III is nine‐coordinate in 5 , with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu₄N⁺ ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium‐lanthanide complexes 2 – 5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC‐5) and compared with those obtained for the previously reported Os(NO)‐Ln (5d–4f) analogues (nBu₄N)₅[Ln{OsCl₃(ox)(NO)}₄] (Ln=Y ( 6 ), Gd ( 7 ), Tb ( 8 ), Dy ( 9 )). Complexes 2 – 5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d–4f metal complexes 6 – 9 in terms of IC₅₀ values. The highest antiproliferative activity with IC₅₀ values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP‐MS data, indicating five‐ to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells.     

Isolation and Characterization,Including by X‐ray Crystallography,of Contact and Solvent‐Separated Ion Pairs of Silenyl Lithium Species

Reaction of bromoacylsilane 1 (pink solution) with tBu₂MeSiLi (3.5 equiv) in a 4:1 hexane:THF solvent mixture at −78 °C to room temperature yields the solvent separated ion pair (SSIP) of silenyl lithium E‐[(tBuMe₂Si)(tBu₂MeSi)C=Si(SiMetBu₂)]⁻ [Li⋅4THF]⁺ 2 a (green–blue solution). Removal of the solvent and addition of benzene converts 2 a into the corresponding contact ion pair (CIP) 2 b (violet–red solution) with two THF molecules bonded to the lithium atom. The 2 a ⇌ 2 b interconversion is reversible upon THF⇌ benzene solvent change. Both 2 a and 2 b were characterized by X‐ray crystallography, NMR and UV/Vis spectroscopy, and theoretical calculations. The degree of dissociation of the Si−Li bond has a large effect on the visible spectrum (and thus color) and on the silenylic ²⁹Si NMR chemical shift, but a small effect on the molecular structure. This is the first report of the X‐ray molecular structure of both the SSIP and the CIP of any R₂E=E′RM species (E=C, Si; E′=C, Si; M=metal).     

Isolation and Characterization,Including by X‐ray Crystallography,of Contact and Solvent‐Separated Ion Pairs of Silenyl Lithium Species

Reaction of bromoacylsilane 1 (pink solution) with tBu₂MeSiLi (3.5 equiv) in a 4:1 hexane:THF solvent mixture at ?78 °C to room temperature yields the solvent separated ion pair (SSIP) of silenyl lithium E‐[(tBuMe₂Si)(tBu₂MeSi)C=Si(SiMetBu₂)]^? [Li?4THF]⁺ 2 a (green–blue solution). Removal of the solvent and addition of benzene converts 2 a into the corresponding contact ion pair (CIP) 2 b (violet–red solution) with two THF molecules bonded to the lithium atom. The 2 a ? 2 b interconversion is reversible upon THF? benzene solvent change. Both 2 a and 2 b were characterized by X‐ray crystallography, NMR and UV/Vis spectroscopy, and theoretical calculations. The degree of dissociation of the Si?Li bond has a large effect on the visible spectrum (and thus color) and on the silenylic ²⁹Si NMR chemical shift, but a small effect on the molecular structure. This is the first report of the X‐ray molecular structure of both the SSIP and the CIP of any R₂E=E′RM species (E=C, Si; E′=C, Si; M=metal).     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalysen der Tetrahalogeno‐bis‐Pyridin‐Osmium(III)‐Komplexe cis‐(n‐Bu4N)[OsCl4Py2] und trans‐(n‐Bu4N)[OsX4Py2], X = Cl,Br

Synthesis, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Tetrahalogeno‐bis‐Pyridine‐Osmium(III) Complexes cis ‐( n ‐Bu₄N)[OsCl₄Py₂] and trans ‐( n ‐Bu₄N)[OsX₄Py₂], X = Cl, Br By reaction of (n‐Bu₄N)₂[OsX₆], X = Cl, Br, with pyridine and (n‐Bu₄N)[BH₄] tetrahalogeno‐bis‐pyridine‐osmium(III) complexes are formed and purified by chromatography. X‐ray structure determinations on single crystals have been performed of cis‐(n‐Bu₄N)[OsCl₄Py₂] ( 1 ) (triclinic, space group P1, a = 9.4047(9), b = 10.8424(18), c = 17.007(2) Å, α = 71.833(2), β = 81.249(10), γ = 67.209(12)°, Z = 2), trans‐(n‐Bu₄N)[OsCl₄Py₂] ( 2 ) (orthorhombic, space group P2₁2₁2₁, a = 8.7709(12), b = 20.551(4), c = 17.174(4) Å, Z = 4) and trans‐(n‐Bu₄N)[OsBr₄Py₂] ( 3 ) (triclinic, space group P1, a = 9.132(3), b = 12.053(3), c = 15.398(2) Å, α = 95.551(18), β = 94.12(2), γ = 106.529(19)°, Z = 2). Based on the molecular parameters of the X‐ray structure determinations and assuming C₂ point symmetry for the anion of 1 and D_2h point symmetry for the anions of 2 and 3 the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants of 1 are in the Cl–Os–Cl axis f_d(OsCl) = 1.58, in the asymmetrically coordinated N′–Os–Cl ^· axes f_d(OsCl ^· ) = 1.45, f_d(OsN′) = 2.48, of 2 f_d(OsCl) = 1.62, f_d(OsN) = 2.42 and of 3 f_d(OsBr) = 1.39 and f_d(OsN) = 2.34 mdyn/Å.     

The First Molybdenum Oxo‐iodide Cluster – [Mo4OI12]2–

Reaction of Mo(CO)₆ with Bu₄NI and I₂ in diglyme yielded a new butterfly Mo^III cluster [Mo₄OI₁₂]^2–. The structure of tetraphenylphosphonium salt was determined by X‐ray single crystal diffraction. Ph₄P⁺ and Bu₄N⁺ salts were further characterized by elemental analysis, mass spectrometry, energy‐dispersive X‐ray (EDX), IR, Raman, and UV/Vis spectroscopy and CVA studies. The cluster anion has a butterfly array of molybdenum atoms and can be represented as [Mo₄(μ₄‐O)(μ₃‐I)₂(μ₂‐I₄)I₆]^2–.     

Organo‐ and Hydrogelators Based on Luminescent Monocationic Terpyridyl Platinum(II) Complexes with Biphenylacetylide Ligands

A series of phosphorescent terpyridyl platinum(II) complexes with ancillary biphenylacetylide ligands, namely, [(R₃tpy)PtC≡C(biphenyl)]X (R=tBu, H, or Et₂N; tpy=2,2′;6′,2′′‐terpyridyl; X is an anion) were synthesized and structurally characterized by various spectroscopic techniques and X‐ray diffraction methods. Despite a lack of long alkyl chain(s) or hydrogen‐bonding motif(s), complexes [(tpy)PtC≡C(biphenyl)]Cl and [(tBu₃tpy)PtC≡C(biphenyl)]X (X=Cl, ClO₄, PF₆, or BF₄) were found to gelate water and organic solvents, respectively. The self‐aggregation of these complexes in solutions and the resulting gels were investigated with variable‐temperature (VT) ¹H NMR spectroscopy, polarized optical microscopy, and absorption/emission spectroscopy. SEM micrographs on dry gels revealed entangled nanofibers with diameters of 20–40 nm and lengths of tens of micrometers. Powder X‐ray diffraction (PXRD) study revealed various degrees of crystallinity of these fibrillar nanostructures. The substituents on both the terpyridyl and acetylide ligands and counterion of these complexes play a profound but concerted role in tuning the intermolecular metal???metal and/or π–π interactions, and hence the gelation properties.     

Synthesis,structure and cytotoxic activity of binuclear phenyltin(IV) complexes with N,N′‐bis(2‐hydroxybenzyl)‐1,2‐ethanebis(dithiocarbamate) ligand

Two new dinuclear phenyltin(IV) complexes derived from N,N′‐bis(2‐hydroxybenzyl)‐1,2‐ethanebis(dithiocarbamate) ligand, [2‐HOC₆H₄CH₂N(CS₂SnPh₃)CH₂]₂ ( 1 ) and [2‐HOC₆H₄CH₂N(CS₂SnClPh₂)CH₂]₂ ( 2 ) have been synthesized and characterized by elemental analysis, IR and NMR (¹H, ¹³C and ¹¹⁹Sn) spectra. The crystal structures of complexes 1 and 2 were determined by X‐ray single crystal diffraction and show that the dithiocarbamate ligand is coordinated to the tin atom in the anisobidentate manner and the tin atom is five‐coordinated. The coordination geometry of tin atom is best described as an intermediate between trigonal bipyramidal and square pyramidal with τ‐values of 0.63 and 0.53, respectively. Intermolecular hydrogen bonds (O H···S and O H···Cl) in 1 and 2 connect neighboring molecules into a one‐dimensional supramolecular chain with the centrosymmetric cyclic motifs. Complex 1 has potent in vitro cytotoxic activity against two human tumor cell lines, CoLo205 and Bcap37, while complex 2 displays weak cytotoxic activity. Copyright © 2011 John Wiley & Sons, Ltd.     

Offenkettige und cyclische As‐funktionalisierte Stannylarsine: Darstellung,Reaktionen und Struktur

Open‐Chain and Cyclic As‐functionalized Stannylarsines: Synthesis, Reactions, and Structure ^tBu₃SnAsH₂ ( 1 ) reacts with MeLi to form the lithium compound ^tBu₃SnAsHLi which reacts with ^tBu₂SnCl₂ to give the AsH‐functionalized bis(arsino)stannane ^tBu₂Sn(AsHSn^tBu₃)₂ ( 2 ). Metallation of diarsadistannetane (^tBu₂SnAsH)₂ ( 3 ) with two equivalents of ^tBuLi yields the dilithio compound (^tBu₂SnAsLi)₂ which reacts with Me₃SiCl or Me₃SnCl to give the corresponding As,As′‐bis‐substituted diarsadistannetanes (^tBu₂SnAsSiMe₃)₂ ( 4 ) and (^tBu₂SnAsSnMe₃)₂ ( 5 ), respectively. The novel compounds are characterized by NMR (¹H, ¹¹⁹Sn) and mass spectroscopy, ring compounds 4 and 5 further by X‐ray structure analysis. In the solid state both ring compounds contain molecules with planar tin‐arsenic rings and two trans‐configurated Me₃Si‐ or Me₃Sn‐ring substituents (space group P2₁/n (No. 14), Z = 2).     

Polylactones, 56. ABA Triblock Copolymers Derived from ε‐Caprolactone or L‐Lactide and a Central Polysiloxane Block

A commercial oligosiloxane having two γ‐hydroxypropyl endgroups and a number‐average molecular weight (M̄_n) around 1 000 Da was condensed with Bu₂Sn(OMe)₂ yielding tin‐containing macrocycles but no polymers. These macrocycles reacted with γ‐thiobutyrolactone by insertion of one thiolactone per Sn—O bond. When ε‐caprolactone was added a ring‐expansion polymerization was initiated, so that the M̄_n could be controlled via the monomer/initiator (M/I) ratio. Triblock copolymers with free OH endgroups were obtained by removal of the Bu₂Sn group from the cyclic polymers with 1,2‐dimercaptoethane or methanol. Analogous cyclic and linear triblockcopolymers were prepared from L ‐lactide.     

Koordinativ ungesättigte Dirutheniumkomplexe: Synthese und Kristallstrukturen von [Ru2(CO)3L(μ‐η1 : η2‐C≡CPh)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] (L = CO,PnBu3)

Coordinatively Unsaturated Diruthenium Complexes: Synthesis and X‐ray Crystal Structures of [Ru₂(CO)₃L(μ‐η¹ : η²‐C≡CPh)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] (L = CO, PⁿBu₃) [Ru₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 1 ) reacts with several phosphines (L) in refluxing toluene under substitution of one carbonyl ligand and yields the compounds [Ru₂(CO)₃L(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] (L = PⁿBu₃, 2 a ; L = PCy₂H, 2 b ; L = dppm‐P, 2 c ; dppm = Ph₂PCH₂PPh₂). The reactivity of 1 as well as the activated complexes 2 a – c towards phenylethyne was studied. Thus 1 , 2 a and 2 b , respectively, react with PhC≡CH in refluxing toluene with elimination of dihydrogen to the acetylide‐bridged complexes [Ru₂(CO)₄(μ‐η¹ : η²‐C≡CPh)(μ‐P^tBu₂)(μ‐dppm)] ( 3 ) and [Ru₂(CO)₃L(μ‐η¹ : η²‐C≡CPh)(μ‐P^tBu₂)(μ‐dppm)] ( 4 a and 4 b ). The molecular structures of 3 and 4 a were determined by crystal structure analyses.