$^{2}_{\infty}\rm [Tb(Tz\ast)_{3}]$, A Homoleptic 2‐Dimensional Framework from a Solvent Free Synthesis of Terbium Metal with 1H‐1,2,3‐Triazole

Single crystalline , (Tz*)^– = 1,2,3‐triazolate anion, C₂H₂N₃^–, was obtained by the reaction of terbium metal with the amine 1H‐1,2,3‐triazole. As no additional solvent was used, the formation of a homoleptic framework without additional co‐ligands is accessible. Furthermore molecular hydrogen is produced. is a 2‐dimensional framework with a (6,6) topology including (Tz*)^– double bridges. The structure can be deduced from a basic structure type as it adopts the AlCl₃ structure with the triazolate ligands establishing the package. (Tz*)^– thus function as μ‐η¹:η²/μ‐η²:η¹ linkers between trivalent terbium ions that have a C.N. of nine. The framework exhibits an exceptional thermal stability up to 380 °C considering the three neighbouring nitrogen atoms of the triazolate ligands. At this point the framework decomposes in one single exothermic step under release of N₂.     

$^{1}_{\infty}\rm [Ho_{2}Cl_{6}\{1,3-Ph(CN)_{2}\}_{3}]$ – Eine zu Doppelsträngen kondensierte Variante der PaCl5‐Struktur in einem Selten‐Erd‐Benzodinitril‐Koordinationspolymer

– A Variant of the PaCl₅ Structure Condensed to Double Strands in a Rare Earth Benzodinitrile Coordination Polymer Single crystalline transparent pink (1,3‐Ph(CN)₂ = 1,3‐benzodinitrile, C₆H₄(CN)₂) was obtained by the reaction of anhydrous holmium trichloride with a melt of 1,3‐benzodinitrile at 175 °C. The trichloride structure is broken up by the dinitrile ligands and re‐arranged to double strands of edge connected pentagonal bipyramids of chlorine and nitrogen atoms. The structure can be deduced from the PaCl₅ structure type by condensation of two PaCl₅ strands and exchange of two chlorine atoms with nitrile groups. The double strands exhibit ligand free cavities of 600–800 pm diameter.     

Ab initio molecular orbital study on the structures and energetics of CH3OH\documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document}(H2O)n and CH3SH\documentclass{article}\pagestyle{empty}\begin{document}$_{2}^{+}$\end{document}(H2O)n in the gas phase

The purpose of this study was to calculate the structures and energetics of CH₃OH$_{2}^{+}$(H₂O)_n and CH₃SH$_{2}^{+}$(H₂O)_n in the gas phase: we asked how the CH₃OH$_{2}^{+}$ and CH₃SH$_{2}^{+}$ moieties of CH₃OH$_{2}^{+}$(H₂O)_n and CH₃SH$_{2}^{+}$(H₂O)_n change with an increase in n and how can we reproduce the experimental values ΔH°_n−1,n. For this purpose, we carried out full geometry optimizations with MP2/6‐31+G(d,p) for CH₃OH$_{2}^{+}$(H₂O)_n (n=0,1,2,3,4,5) and CH₃SH$_{2}^{+}$(H₂O)_n (n=0,1,2,3,4). We also performed a vibrational analysis for all clusters in the optimized structures to confirm that all vibrational frequencies are real. All of the vibrational frequencies of these clusters are real, and they correspond to equilibrium structures. For CH₃OH$_{2}^{+}$(H₂O)_n, when n increases, (1) the C O bond length decreases, (2) the C H bond lengths do not change, (3) the O H bond lengths increase, (4) the OCH bond angles increase, (5) the COH bond angles decrease, (6) the charge on CH₃ becomes less positive, and (7) these predicted values, except for the O H bond lengths of CH₃OH$_{2}^{+}$(H₂O)_n, approach the corresponding values in CH₃OH. The C O bond length in CH₃OH$_{2}^{+}$(H₂O)₅ is shorter than that in CH₃OH$_{2}^{+}$ in the gas phase by 0.061 Å at the MP2/6‐31+G(d,p) level. Except for the S H bond lengths in CH₃SH$_{2}^{+}$(H₂O)_n, however, the structure of the CH₃SH$_{2}^{+}$ moiety does not change with an increase in n. © 2000 John Wiley & Sons, Inc. J Comput Chem 22: 125–131, 2001     

$^{1}_{\infty}\rm [M^{II}(Py)_{2}(H_{2}O)_{n}(ADC)_{2/2}]$ mit MII = Fe,Co, Ni (n = 2) und MII = Cu (n = 1): Vier neue Koordinationspolymere mit dem Acetylendicarboxylat‐Dianion (ADC2−) als verbrückendem Liganden

with M^II = Fe, Co, Ni (n = 2) and M^II = Cu (n = 1): Four New Coordination Polymers with Acetylenedicarboxylate (ADC^2?) as Bridging Ligand By slow diffusion of pyridine (Py) into an aqueous solution of a respective metal salt and acetylenedicarboxylic acid (H₂ADC) single crystals of new coordination polymers of composition (M = Fe, Co, Ni; C2/c, Z = 4) ( 1 – 3 ) and (P2₁2₁2₁, Z = 4) ( 4 ) were obtained. In compounds 1 – 3 octahedral M^IIO₄N₂ units are connected via acetylenedicarboxylate anions to form chain‐like polymers. In compound 4 square pyramidal Cu^IIO₃N₂ units are found, which are also connected to chains by acetylenedicarboxylates. Thermoanalytical investigations on 3 show an abrupt mass loss of approx. 40 % above 130 °C, which points to a release of both pyridine ligands (calc.: 43 %). Thereafter, the sample decomposes continuously, which is confirmed by XRPD measurements, as an amorphous residue is found. Magnetic susceptibility measurements of 1 – 3 display paramagnetic behaviour in the temperature range 2‐300 K. While μ_eff of 3 (d⁸ configuration) with orbital singlet ground state is nearly temperature‐independent, 1 (d⁶) and 2 (d⁷) exhibit complicated μ_eff?T behaviour on account of a ligand‐field ground state derived from the cubic states ⁵T₂ and ⁴T₁, respectively. On the basis of a tetragonal ligand‐field model excellent adaptations are obtained with reasonable ligand‐field parameters. Exchange interactions between the magnetic ions are detected in no case.     

Electrochemical Detection of ClO$\rm{ {_{3}^{-}}}$, BrO$\rm{ {_{3}^{-}}}$, and IO$\rm{ {_{3}^{-}}}$ at a Phosphomolybdic Acid Linked 3‐Aminopropyl‐Trimethoxysilane Modified Electrode

A composite film modified electrode containing a Keggin‐type heteropolyanion, H₃(PMo₁₂O₄₀)?H₂O, was fabricated with 3‐aminopropyltrimethoxysilane (APMS) attached on an electrochemically activated glassy carbon (GC) electrode through the formation of C? O? Si bond. PMo₁₂O was then complexed with APMS through the electrostatic interaction between the phosphate groups of PMo₁₂O and amine groups of APMS (PMo₁₂O ‐APMS). XPS and cyclic voltammetry were employed for characterization of the composite film. The PMo₁₂O ‐APMS modified electrode showed three reversible redox pairs with smaller peak‐separation and was stable in the larger pH range compared with that in a solution phase. The catalytic properties of the modified electrode for the reduction of ClO , BrO , and IO were studied and the modified electrode exhibited good electrocatalytic activities for the three anions. The experimental parameters, such as pH, temperature, and the applied potential were optimized. The detection limits were determined to be 7.0±0.35 μM, 4.0±0.17 μM, and 0.1±0.04 μM for ClO , BrO , and IO , respectively. The modified electrode was applied to natural water samples for the detection of ClO , BrO , and IO .     

Supramolecular Arrays of Cationic Complexes Containing Pyrazole Ligands and Tetrafluoroborate,Trifluoromethanesulfonate, or Nitrate as Counterions. Crystal Structure of Bis(3,5‐dimethyl‐4‐nitro‐1H‐pyrazole‐κN2)silver(1+) Nitrate ([Ag(HpzNO2)2](NO3))

The structures of [Pd(η³‐C₃H₅)(Hpz^R2)₂](BF₄) (Hpz^R2=Hpz^bp2=3,5‐bis(4‐butoxyphenyl)‐1H‐pyrazole, 1 ; Hpz^R2=Hpz^NO2=3,5‐dimethyl‐4‐nitro‐1H‐pyrazole=Hdmnpz, 2 ) and [Ag(Hpz^R2)₂](A) (Hpz^R2=Hpz^bp2, A= , 3 ; Hpz^R2=Hpz^NO2, A= , 4 ) were comparatively analyzed to determine the factors responsible for polymeric assemblies. In all cases, the H‐bonding interactions between the pyrazole moieties and the appropriate counterion and, in particular, the orientation of the NH groups of the pyrazole ligands are determinant of one‐dimensional polymeric arrays. In this context, the new compound [Ag(Hpz^NO2)₂](NO₃) ( 5 ) was synthesized and its structure analyzed by X‐ray diffraction (Fig. 4). The Hpz^NO2 serves as N‐monodentate ligand, which coordinates to the Ag^I center through its pyrazole N‐atom giving rise to an almost linear N Ag N geometry. The planar NO counterion bridges two adjacent Ag^I centers to form a one‐dimensional zigzag‐shaped chain which is also supported by the presence of N H⋅⋅⋅O bonds between the pyrazole NH group of adjacent cationic entities and the remaining O‐atom of the bridging NO (Fig. 5). The chains are further extended to a two‐dimensional layer‐like structure through additional Ag⋅⋅⋅O interactions involving the NO₂ substituents at the pyrazole ligands (Fig. 6).     

Palladium(II) and platinum(II) complexes of (1R,2R)‐(−)‐1,2‐diaminocyclohexane (DACH) with various carboxylato ligands and their cytotoxicity evaluation

Several palladium(II) and platinum(II) complexes analogous to oxaliplatin, bearing the enantiomerically pure (1R,2R)‐(?)‐1,2‐diaminocyclohexane (DACH) ligand, of the general formula {MX₂[(1R,2R)‐DACH]}, where M = Pd or Pt, X (COO)₂, CH₂(COO)₂, , , {1,1′‐C₅H₈(CH₂COO)₂}, [1,1′‐C₆H₁₀(CH₂COO)₂], [1,1′‐(COO)₂ferrocene], , , , MeCOO and Me₃CCOO, were synthesized. All the complexes prepared were characterized physicochemically and spectroscopically. Some selected complexes were screened in vitro against several tumor cell lines and the results were compared with reference standard drug, oxaliplatin. Copyright © 2009 John Wiley & Sons, Ltd.     

Iodostannate(II) mit kettenförmigen [SnI3]–‐Anionen – der Übergang von fünffach zu sechsfach koordinierten SnII‐Zentralatomen

Iodostannates(II) with Anionic [SnI₃]^– Chains – the Transition from Five to Six‐coordinated Sn^II The iodostannates (Me₄N) [SnI₃] ( 1 ), [Et₃N–(CH₂)₄–NEt₃] [SnI₃]₂ ( 2 ), [EtMe₂N–(CH₂)₂–NEtMe₂] [SnI₃]₂ ( 3 ), [Me₂HN–(CH₂)₂–NH–(CH₂)₂–NMe₂H] [SnI₃]₂ ( 4 ), [Et₃N–(CH₂)₆–NEt₃] [SnI₃]₂ ( 5 ) and [Pr₃N–(CH₂)₄–NPr₃]‐ [SnI₃]₂ · 2 DMF ( 6 ) with the same composition of the anionic [SnI₃]^– chains show differences in the coordination of the Sn^II central atoms. Whereas the Sn atoms in 1 and 2 are coordinated in an approximately regular octahedral fashion, in compounds 3 – 6 the continuous transition to coordination number five in (Pr₄N) [SnI₃] ( 7 ) or [Fe(dmf)₆] [SnI₃]₂ ( 8 ) can be observed. Together with the shortening of two or three Sn–I bonds, the bonds in trans position are elongated. Thus weak, long‐range Sn…I interactions complete the distorted octahedral environment of SnI₄ groups in 3 and 4 and SnI₃ groups in 5 and 6 . Obviously the shape, size and charge of the counterions and the related cation‐anion interactions are responsible for the variants in structure and distortion.     

Fe(CN)$\rm{ {_{6}^{4-}}}$‐Doped‐Glutaraldehyde‐Cross‐Linked Poly‐L‐Lysine Film Electrode. Part 1: Electrochemical Characterization and Its Electrocatalytic Activity Towards Oxidation of Ascorbic Acid

The present work describes preparation, characterization, and electrocatalytic behavior of a hexacyanoferrate‐doped‐glutaraldehyde‐cross‐linked poly‐L ‐lysine (PLL‐GA‐Fe(CN) film modified glassy carbon electrode. The modified electrode has been successfully prepared by electrostatically binding negatively charged Fe(CN) mediator into cross‐linked poly‐L ‐lysine cationic film. The dependence of the peak current of the modified electrode in pure supporting electrolyte (pH 6.8 phosphate buffer solution; PBS) shows that the charge transport in the film is fast and relatively unimpeded at lower scan rates. Cyclic voltammetry and rotating disk electrode (RDE) techniques are used to investigate the electrocatalytic activity of modified electrode towards oxidation of ascorbic acid. The rate constant (k), of catalytic reaction between electrogenerated Fe(CN) ions and ascorbic acid, obtained from RDE analysis was found to be 5.53×10⁵ cm³ mol^?1 s^?1. Finally, the PLL‐GA‐Fe(CN) film electrodes are successfully used for the individual estimation of ascorbic acid in the concentration range of physiological interest.     

Incorporating glycidyl methacrylate into block copolymers using poly(methacrylate‐ran‐styrene) macroinitiators synthesized by nitroxide‐mediated polymerization

Methyl methacrylate/styrene (MMA/S), ethyl methacrylate/styrene (EMA/S) and butyl methacrylate/styrene (BMA/S) feeds (>90 mol % methacrylate) were copolymerized in 50 wt % p‐xylene at 90 °C with 10 mol % of additional SG1‐free nitroxide mediator relative to unimolecular initiator (BlocBuilder^®) to yield methacrylate rich copolymers with polydispersities _w/ _n = 1.23–1.46. k_pK values (k_p = propagation rate constant, K = equilibrium constant) for MMA/S copolymerizations were comparable with previous literature, whereas EMA/S and BMA/S copolymerizations were characterized by slightly higher k_pK's. Chain extensions with styrene at 110 °C initiated by the methacrylate‐rich macroinitiators (number average molecular weight _n = 12.9–33.5 kg mol^?1) resulted in slightly broader molecular weight distributions with _w/ _n = 1.24–1.86 and were often bimodal. Chain extensions with glycidyl methacrylate/styrene/methacrylate (GMA/S/XMA where XMA = MMA, EMA or BMA) mixtures at 90 °C using the same macroinitiators resulted frequently in bimodal molecular weight distributions with many inactive macroinitiators and higher _w/ _n = 2.01–2.48. P(XMA/S) macroinitiators ( _n = 4.9–8.9 kg mol^?1), polymerized to low conversion and purified to remove “dead” chains, initiated chain extensions with GMA/MMA/S and GMA/EMA/S giving products with _w/ _n ～ 1.5 and much fewer unreacted macroinitiators (<5%), whereas the GMA/BMA/S chain extension was characterized by slightly more unreacted macroinitiators (～20%). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2574–2588, 2009     

Structure and Bonding of the Hexameric Platinum(II) Dichloride,Pt6Cl12 (β‐PtCl2)

The crystal structure of Pt₆Cl₁₂ (β‐PtCl₂) was redetermined ( a_h = 13.126Å, c_h = 8.666Å, Z = 3; a_rh = 8.110Å, α = 108.04°; 367 hkl, R = 0.032). As has been shown earlier, the structure is in principle a hierarchical variant of the cubic structure type of tungsten (bcc), which atoms are replaced by the hexameric Pt₆Cl₁₂ molecules. Due to the 60° rotation of the cuboctahedral clusters about one of the trigonal axes, the symmetry is reduced from to ( ). The molecule Pt₆Cl₁₂ shows the (trigonally elongated) structure of the classic M₆X₁₂ cluster compounds with (distorted) square‐planar PtCl₄ fragments, however without metal‐metal bonds. The Pt atoms are shifted outside the Cl₁₂ cuboctahedron by Δ = +0.046Å ( (Pt—Cl) = 2.315Å; (Pt—Pt) = 3.339Å). The scalar relativistic DFT calculations results in the full symmetry for the optimized structure of the isolated molecule with d(Pt—Cl) = 2.381Å, d(Pt—Pt) = 3.468Å and Δ = +0.072Å. The electron distribution of the Pt‐Pt antibonding HOMO exhibits an outwards‐directed asymmetry perpendicular to the PtCl₄ fragments, that plays the decisive role for the cluster packing in the crystal. A comparative study of the Electron Localization Function with the hypothetical trans‐(Nb₂Zr₄)Cl₁₂ molecule shows the distinct differences between Pt₆Cl₁₂ and clusters with metal‐metal bonding. Due to the characteristic electronic structure, the crystal structure of Pt₆Cl₁₂ in space group is an optimal one, which results from comparison with rhombohedral Zr₆I₁₂ and a cubic bcc arrangement.     

Lanthanide(III) Complexes of 2‐[4,7,10‐Tris(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecan‐1‐yl]acetic Acid (H7DOA3P): Multinuclear‐NMR and Kinetic Studies

The protonation constants of 2‐[4,7,10‐tris(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecan‐1‐yl]acetic acid (H₇DOA3P) and of the complexes [Ln(DOA3P)]^4? (Ln=Ce, Pr, Sm, Eu, and Yb) have been determined by multinuclear NMR spectroscopy in the range pD 2–13.8, without control of ionic strength. Seven out of eleven protonation steps were detected (pK =13.66, 12.11, 7.19, 6.15, 5.77, 2.99, and 1.99), and the values found compare well with the ones recently determined by potentiometry for H₇DOA3P, and for other related ligands. The overall basicity of H₇DOA3P is higher than that of H₄DOTA and trans‐H₆DO2A2P but lower than that of H₈DOTP. Based on multinuclear‐NMR spectroscopy, the protonation sequence for H₇DOA3P was also tentatively assigned. Three protonation constants (pK_MHL, pK_MH2L, and pK_MH3L) were determined for the lanthanide complexes, and the values found are relatively high, although lower than the protonation constants of the related ligand (pK , pK , and pK ), indicating that the coordinated phosphonate groups in these complexes are protonated. The acid‐assisted dissociation of [Ln(DOA3P)]^4? (Ln=Ce, Eu), in the region c_H+=0.05–3.00 mol dm^?3 and at different temperatures (25–60°), indicated that they have slightly the same kinetic inertness, being the [Eu(H₂O)₉]³⁺ aqua ion the final product for europium. The rates of complex formation for [Ln(DOA3P)]^4? (Ln=Ce, Eu) were studied by UV/VIS spectroscopy in the pH range 5.6–6.8. The reaction intermediate [Eu(DOA3P)]* as ‘out‐of‐cage’ complex contains four H₂O molecules, while the final product, [Eu(DOA3P)]^4?, does not contain any H₂O molecule, as proved by steady‐state/time‐resolved luminescence spectroscopy.     

Structural Characterization of Some Coinage Metal(I) Thiosulfate Complexes, $\rm M^{1}_{a}M\rm ^{2}_{b}(X_{c}) (S_{2}O_{3})_{d}(\cdot eS)$ (M1 = Group 1 Cation,X = Univalent Anion,M2 = CuI,AgI, S = Solvent)

Building on previous single crystal X‐ray structure determinations for the group 1 salts of complex thiosulfate/univalent coinage metal anions previously defined for (NH₄)₉AgCl₂(S₂O₃)₄, NaAgS₂O₃·H₂O and Na₄[Cu(NH₃)₄][Cu(S₂O₃)₂]·NH₃, a wide variety of similar salts, of the form , M¹ = group 1 metal cation, M² = univalent coinage metal cation (Cu, Ag), (X = univalent anion), most previously known, but some not, have been isolated and subjected to similar determinations. These have defined further members of the isotypic, tetragonal series, for M¹ = NH₄, M² = Cu, Ag, X = NO₃, Cl, Br, I, together with the K/Cu/NO₃ complex, all containing the complex anion [M²(SSO₃)₄]^7? with M² in an environment of symmetry, Cu, Ag‐S typically ca. 2.37, 2.58Å, with quasi‐tetrahedral S‐M‐S angular environments. Further salts of the form , n = 1‐3, have also been defined: For n = 3, M² = Cu, M¹/x = K/2.25 or 1 5/6, NH₄/6, (and also for the (NH₄)₄Na/4H₂O·MeOH adduct) the arrays take the form with distorted trigonal planar CuS₃ coordination environments, Cu‐S distances being typically 2.21Å, S‐Cu‐S ranging between 105.31(4)–129.77(4)°; the silver counterparts take the form for M¹ = K, NH₄. For n = 2, adducts have only been defined for M² = Ag, the anions of the M¹ = Na, K adducts being dimeric and polymeric respectively: Na₆[(O₃SS)₂Ag(μ‐SSO₃)₂Ag(SSO₃)]·3H₂O, K₃[Ag(μ‐SSO₃)₂]_(∞|∞)·H₂O; a polymeric copper(I) counterpart of the latter is found in Na₅Cu(NO₃)₂(S₂O₃)₂ ≡ 2NaNO₃·Na₃[Cu(μ‐SSO₃)₂]_(∞|∞). For n = 1, NaAgS₂O₃, the an‐ and mono‐ hydrates, exhibit a two‐dimensional polymeric complex anion in both forms but with different contributing motifs. (NH₄)₁₃Ag₃(S₂O₃)₈·2H₂O takes the form (NH₄)₁₃[{(O₃SS)₃Ag(μ‐SSO₃)}₂Ag], a linearly coordinated central silver atom linking a pair of peripheral [Ag(SSO₃)₄]^7? entities. In Na₆[(O₃SS)Ag(μ‐SSO₃)₂Ag(SSO₃)]·3H₂O, the binuclear anions present as Ag₂S₄ sheets, the associated oxygen atoms being disposed to one side, thus sandwiching layers of sodium ions; the remarkable complex Na₅[Ag₃(S₂O₃)₄]_(∞|∞)·H₂O is a variant, in which one sodium atom is transformed into silver, linking the binuclear species into a one‐dimensional polymer. In (NH₄)₈[Cu₂(S₂O₃)₅]·2H₂O a binuclear anion of the form [(O₃SS)₂Cu(μ‐S.SO₃)Cu(SSO₃)₂]^8? is found; the complex (NH₄)₁₁Cu(S₂O₃)₆ is 2(NH₄)₂(S₂O₃)·(NH₄)₇[Cu(SSO₃)₄]. A novel new hydrate of sodium thiosulfate is described, 4Na₄S₂O₃·5H₂O, largely describable as sheets of the salt, shrouded in water molecules to either side, together with a redetermination of the structure of 3K₂S₂O₃·H₂O.     

Electrochemiluminescent Determination of Chlorphenamine Maleate Based on Ru(bpy)$\rm{ {_{3}^{2+}}}$ Immobilized in a Nano‐Titania/Nafion Membrane

The immobilization of tris(2,2'‐bipyridyl)ruthenium(II) [Ru(bpy) ] in a TiO₂/Nafion nanocomposites membrane modified glassy carbon electrode (GCE) was achieved via both an ion‐exchange process and hydrophobic interactions .The surface‐confined Ru(bpy) shows good electrochemical and photochemical activities. The Ru(bpy) underwent reversible surface process and reacted with chlorphenamine maleate (CPM) to produce electrochemiluminescence. The modified electrode was used for the ECL determination of CPM. It showed good linearity in the concentration range from 2×10^?8 g/mL to 1×10^?6 g/mL (R=0.9995) with a detection 6×10^?9 g/mL (S/N=3). The relative standard derivation (n=11) was 2%. This method is developed for the determination of CPM with simplicity and high sensitivity.     

Disupersilylsilanide M(SiHR*2)2 der Zinkgruppenmetalle (M = Zn,Cd, Hg; R* = SitBu3): Synthesen,Charakterisierung und Strukturen

Disupersilylsilanides M(SiHR^*₂)₂ of Metals of the Zinc Group (M = Zn, Cd, Hg; R* = Si t Bu₃): Syntheses, Characterization, and Structures Bis(disupersilyl)silylmetals M(SiHR )₂ (R* = Supersilyl = SitBu₃) with M = Zn, Cd, Hg are obtained in tetrahydrofuran/benzene/pentane by the reaction of NaSiHR with ZnCl₂, CdI₂, HgCl₂ in the molar ratio 2 : 1. The compounds form colorless, in organic media soluble, not hydrolysis‐ and air‐sensitive crystals, the stabilities of which for thermolysis or photolysis decrease in the row Zn > Hg > Cd compound. According to X‐ray structure analyses, the compounds M(SiHR )₂ are monomeric with a – to date not observed – non‐linear framework –M– (angle SiMSi for M(SiHR )₂ with M = Zn/Cd/Hg 170.7/174.2/174.4°).     

Combining Modular Ligation and Supramolecular Self‐Assembly for the Construction of Star‐Shaped Macromolecules

A well‐defined random copolymer of styrene (S) and chloromethylstyrene (CMS) featuring lateral chlorine moieties with an alkyne terminal group is prepared (P(S‐co‐CMS), = 5500 Da, PDI = 1.13). The chloromethyl groups are converted into Hamilton wedge (HW) entities (P(S‐co‐HWS), = 6200 Da, PDI = 1.13). The P(S‐co‐HWS) polymer is subsequently ligated with tetrakis(4‐azidophenyl)methane to give HW‐functional star‐shaped macromolecules (P(S‐co‐HWS))₄, = 25 100 Da, PDI = 1.08). Supramolecular star‐shaped copolymers are then prepared via self‐assembly between the HW‐functionalized four‐arm star‐shaped macromolecules ( P(S‐co‐HW )) ₄ and cyanuric acid (CA) end‐functionalized PS (PS–CA, = 3700 Da, PDI = 1.04), CA end‐functionalized poly(methyl methacrylate) (PMMA–CA, = 8500 Da, PDI = 1.13) and CA end‐functionalized polyethylene glycol (PEG–CA, = 1700 Da, PDI = 1.05). The self‐assembly is monitored by ¹H NMR spectroscopy and light scattering analyses.     

Stable γ-distonic oxonium ions: R\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm O}\limits^ + $\end{document}HCHR′ĊH2CHR″ and their characteristic reaction

The γ-distonic radical ions R$ \mathop {\rm O}\limits^ + $CHR′CH₂?HR″ and their molecular ion counterparts R$ \mathop {\rm O}\limits^{{\rm + } \cdot } $CHR′CH₂CH₂R″ have been studied by isotopic labelling and collision-induced dissociation, applying a potential to the collision cell in order to separate activated from spontaneous decompositions. The stability of CH₃$ \mathop {\rm O}\limits^ + $HCH(CH₃)CH₂?HCH₃, C₂H₅$ \mathop {\rm O}\limits^ + $HCH(CH₃)CH₂?HCH₃, CH₃$ \mathop {\rm O}\limits^ + $HCH(CH₃)CH₂?H₂, CH₃$ \mathop {\rm O}\limits^ + $HCH₂CH₂?HCH₃ and C₂H₅$ \mathop {\rm O}\limits^ + $HCH₂CH₂?HCH₃, has been demonstrated and their characteristic decomposition, alcohol loss, identified. For all these γ-distonic ions, the 1,4-H abstraction leading to their molecular ion counterpart exhibits a primary isotope effect.     

Zur Reaktivität der Ferriophosphaalkene [(η5‐C5Me5)(CO)2FeP=C(NR)R2] (NR = NMe2, NC5H10, R2 = Ph,tBu) gegenüber Protonsäuren,Alkylierungsmitteln und [{(Z)‐Cycloocten}Cr(CO)5]

Transition Metal‐substituted Phosphaalkenes. 42 Reactivity of the Ferriophosphaalkenes [(η⁵‐C₅Me₅)(CO)₂FeP=C(NR )R²] (NR = NMe₂, NC₅H₁₀, R² = Ph, t Bu) towards Protic Acids, Alkylation Reagents, and [{( Z )‐Cyclooctene}Cr(CO)₅] The reaction of equimolar amounts of [(η⁵‐C₅Me₅)(CO)₂FeP=C(NR )R²] ( 2 a : NR = NMe₂, R² = Ph; 2 b : NMe₂. tBu; 2 c : NC₅H₁₀, Ph) and etherial HBF₄ gave rise to the formation of [(η⁵‐C₅Me₅)(CO)₂FeP(H)C(NR )R²] (BF₄) ( 3 a – c ) which were isolated as light red powders. Compounds 2 a – c were converted into [(η⁵‐C₅Me₅)(CO)₂FeP(Me)C(NR )R²] (SO₃CF₃) ( 4 a – c ) by treatment with methyl trifluoromethane sulfonate. In addition 2 a and Me₃SiCH₂OSO₂CF₃ afforded light red [(η⁵‐C₅Me₅)(CO)₂FeP(CH₂SiMe₃)C(NMe₂)Ph](SO₃CF₃) ( 5 ). The black complex [(η⁵‐C₅Me₅)(CO)₂FeP{Cr(CO)₅}C(NMe₂)Ph] ( 6 ) resulted from the combination of 2 a with [{(Z)‐cyclooctene}Cr(CO)₅]. The novel products were characterized by elemental analyses and spectra (IR, ¹H‐, ¹³C‐ und ³¹P‐NMR).     

Direct Cyclodextrin‐Mediated Ring Opening Polymerization of ϵ‐Caprolactone in the Presence of Yttrium Trisphenolate Catalyst

Unmodified β‐cyclodextrin has been directly used to initiate ring‐opening polymerization of ϵ‐caprolactone in the presence of yttrium trisphenolate. Well‐defined cyclodextrin (CD)‐centered star‐shaped poly(ϵ‐caprolactone)s have been successfully synthesized containing definite average numbers of arms (N_arm = 4–6) and narrow polydispersity indexes (below 1.10). The number‐average molecular weight ( ) and average molecular weight per arm ( ) are controlled by the feeding molar ratio of monomer to initiator. The prepared star‐PCL with of 2.7 × 10³ is in fully amorphous and that with of 13.3 × 10³ is crystallized. In addition, the obtained poly(e‐caprolactone) (PCL) stars with various molecular weights have different solubilities in methanol and tetrahydrofuran, which can be applied for further modifications.     

On the Interchange Ability of the N‐donor Position in the Rare Earth Coordination Polymers $^{1}_{\infty}\rm [Ln(Btz)_{3}(L)]$, L = BtzH,Ph(NH2)2, NH3, and Pyridine

Benzotriazolates of the rare earth elements form chain like coordination polymers of the formula . An additional neutral ligand L saturates the coordination spheres of the trivalent lanthanide ions and, depending on the reaction conditions, can be a varying donor (L = BtzH, Ph(NH₂)₂, NH₃ and Py). Reactions in the BtzH (1H‐benzotriazole) melt result in coordination of benzotriazole and its thermal decomposition products as L. We have now investigated if the site occupied by L can be exchanged with other N donor ligands. Pyridine can substitute BtzH, Ph(NH₂)₂ and NH₃ under solvothermal conditions giving the coordination polymer even for the biggest Ln^III cation lanthanum without changing the overall strand structure. Chains proof to be the chemically favoured and stable structure fragment with the L position being the chemically variable site.