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°).     

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.     

Lamellar Copper(I) Thiocyanate‐Based Coordination Polymers containing the Alkali Cation ligating Thiacrown Ether 1,10‐Dithia‐18‐crown‐6

The lamellar coordination polymer [(CuSCN)₂(μ‐1,10DT18C6)] (1,10DT18C6 = 1,10‐dithia‐18‐crown‐6), in which staircase‐like CuSCN double chains are bridged by thiacrown ether ligands, may be prepared in two triclinic modifications 1 a and 1 b by reaction of CuSCN with 1,10DT18C6 in respectively benzonitrile or water. Performing the reaction in acetonitrile in the presence of an equimolar quantity of KSCN leads, in contrast, to formation of the K⁺ ligating 2‐dimensional thiocyanatocuprate(I) net [{Cu₂(SCN)₃}^–] of 2 , half of whose Cu(I) atoms are connected by 1,10DT18C6 macrocycles. The potassium cations in [{K(CH₃CN)}{Cu₂(SCN)₃(μ‐1,10DT18C6)}] ( 2 ) are coordinated by all six potential donor atoms of a single thiacrown ether in addition to a thiocyanate S and an acetonitrile N atom. Under similar conditions, reaction of CuI, NaSCN and 1,10DT18C6 affords [{Na(CH₃CN)₂}{Cu₄I₄(SCN)(μ‐1,10DT18C6)}] ( 3 ), which contains distorted Cu₄I₄ cubes as characteristic molecular building units. These are bridged by thiocyanate and thiacrown ether ligands into corrugated Na⁺ ligating sheets. In the presence of divalent Ba²⁺ cations, charge compensation requirements lead to formation of discrete [Cu(SCN)₃(1,10DT18C6‐κS)]^2– anions in [Ba{Cu(SCN)₃(1,10DT18C6‐κS)}] ( 4 ).     

Darstellung,Schwingungsspektrum und Kristallstruktur von (n‐Bu4N)2[(W6Cl)F] · 2 CH2Cl2 und 19F‐NMR‐spektroskopischer Nachweis der gemischten Clusteranionen [(W6Cl)FCl]2–, n = 1–6

Synthesis, Vibrational Spectra, and Crystal Structure of ( n ‐Bu₄N)₂[(W₆Cl )F ] · 2 CH₂Cl₂ and ¹⁹F NMR Spectroscopic Evidence of the Mixed Cluster Anions [(W₆Cl )F Cl ]^2–, n = 1–6 The reaction of (n‐Bu₄N)₂[(W₆Cl)Cl] with CF₃COOH in dichloromethane gives intermediately a mixture of the cluster anions [(W₆Cl)(CF₃COO)Cl]^2–, n = 1–6. By treatment with NH₄F the outer sphere coordinated trifluoracetato ligands are easily substituted and the components of the series [(W₆Cl)FCl], n = 1–6 are formed and characterized by their distinct ¹⁹F NMR chemical shifts. An X‐ray structure determination has been performed on a single crystal of (n‐Bu₄N)₂[(W₆Cl)F] · 2 CH₂Cl₂ (orthorhombic, space group Pbca, a = 15.628(4), b = 17.656(3), c = 20.687(4) Å, Z = 4). The low temperatur IR (60 K) and Raman (20 K) spectra are assigned by normal coordinate analysis based on the molecular parameters of the X‐ray determination. The valence force constants are f_d(WW) = 1.89, f_d(WF) = 2.43 and f_d(WCl) = 0.93 mdyn/Å.     

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).     

Selektive Darstellung zweifach diorganophosphido-verbrückter Metallatetrahedrane [Re2(MPR3)2(μ-PR2)2(CO)6] mit Re2M2-Metallgerüst (M = Au,Ag)

Selective Preparation of Twofold Diorganophosphido-bridged Metallatetrahedranes [Re₂(MPR₃)₂(μ-PR₂)₂(CO)₆] with Re₂M₂ Metal Core (M = Au, Ag) The reaction of the in situ prepared salt Li[Re₂(AuPR)(μ-PR₂)(CO)₇Cl] (R = R′ = Cy ( 1 a ), R = Cy, R′ = Ph ( 1 b ), R = Ph, R′ = Cy ( 1 c ), R = Ph, R′ = Et ( 1 d ), R = Ph, R′ = Ph ( 1 e )) with one equivalent HPR in methanolic solution at room temperature yields the neutral cluster complexes [Re₂(AuPR)(μ-PR₂)(CO)₇(ax-HPR) (R = R′ = R″ = Cy ( 2 a ), Ph ( 2 b ), R = R′ = Cy, R″ = Et ( 2 c ), R = Cy, R′ = R″ = Ph ( 2 d ), R = Cy, R′ = Ph, R″ = Et ( 2 e ), R = R″ = Ph, R′ = Et ( 2 f ), R = Ph, R′ = Cy, R″ = Et (2 g)). Photochemically induced these complexes react in the presence of the organic base DBU in THF solution to give the doubly phosphido bridged anions Li[Re₂(AuPR)(μ-PR₂)(μ-PR)(CO)₆], which were characterized as salts PPh₄[Re₂(AuPR)(μ-PR₂)(μ-PR)(CO)₆] (R = R′ = R″ = Ph ( 3 a ), R = R′ = Ph, R″ = Cy ( 3 b ), R = Ph, R′ = Cy, R″ = Et ( 3 c ), R = R″ = Ph, R′ = Et ( 3 d )). These precursor complexes 3 then react with one equivalent of ClMPR (M = Au, Ag) to doubly phosphido bridged metallatetrahedranes [Re₂(MPR₃)₂(μ-PR₂)(μ-PR)(CO)₆] (M = Au, R = R′ = R″ = Ph ( 4 a ), M = Au, R′ = Et, R = R″ = Ph ( 4 b ), M = Au, R = R′ = Ph, R″ = Cy ( 4 c ), M = Au, R = Cy, R′ = Ph, R″ = Et ( 4 d ), M = Ag, R = R′ = R″ = Ph ( 4 e )). All isolated cluster complexes were characterized and identified by the following analytical methods: NMR- (¹H, ³¹P) and ν(CO) IR-spectroscopy and, additionally, complexes 2 b , 4 a and 4 e by X-ray structure analysis.     

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.     

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     

Preparation and Properties of the Hybrid Material n‐Propyl(3‐methylpyridinium)silsesquioxane Chloride. Application in Electrochemical Determination of Nitrite

The synthesis and properties of the ion exchange polymer 3‐n‐propyl(3‐methylpyridinium)silsesquioxane chloride (SiPy⁺Cl^?) are described. Based on the Langmuir model, the equilibrium constant at the solid‐solution interface for the reaction, SiPy⁺Cl^?+NO ?SiPy⁺NO , was calculated for nitrite adsorption. The value found, β=8.7×10³ L mol^?1, indicates good affinity of the anion for the solid phase. A carbon paste electrode of the material was tested for NO oxidation and a linear response, in the concentration range between 6.3 and 143.6 μmol L^?1, was obtained by amperometry. The analytical applicability of the proposed system was ascertained by the satisfactory results attained in its application to monitoring of nitrite in natural waters.     

CuYS2: Ein ternäres Kupfer(I)‐Yttrium(III)‐Sulfid mit Ketten {[Cu(S1)3/3(S2)1/1]3–} cis‐kantenverknüpfter [CuS4]7–‐Tetraeder

CuYS₂: A Ternary Copper(I) Yttrium(III) Sulfide with Chains {[Cu(S1)_3/3(S2)_1/1]^3–} of cis ‐Edge Connected [CuS₄]^7– Tetrahedra Pale yellow, lath‐shaped single crystals of the ternary copper(I) yttrium(III) sulfide CuYS₂ are obtained by the oxidation of equimolar mixtures of the metals (copper and yttrium) with sulfur in the molar ratio 1 : 1 : 2 within fourteen days at 900 °C in evacuated silica ampoules, while the presence of CsCl as fluxing agent promotes their growth. The crystal structure of CuYS₂ (orthorhombic, Pnma; a = 1345.3(1), b = 398.12(4), c = 629.08(6) pm, Z = 4) exhibits chains of cis‐edge linked [CuS₄]^7– tetrahedra with the composition {[Cu(S1)_3/3(S2)_1/1]^3–} running along [010] which are hexagonally bundled as closest rod packing. Charge equalization and three‐dimensional interconnection of these anionic chains occur via octahedrally coordinated Y³⁺ cations. These are forming together with the S^2– anions a network [Y(S1)_3/3(S2)_3/3]^– of vertex‐ and edge‐shared [YS₆]^9– octahedra with ramsdellite topology. The metall‐sulfur distances of the [CuS₄]^7– tetrahedra (230 (Cu–S2), 232 (Cu–S1), and 253 pm (Cu–S1′, 2 × )) cover a very broad interval, whilst these (Y–S: 267–280 pm) within the [YS₆]^9– octahedra range rather closely together.     

Neutral and Cationic Hexanuclear Rhenium Phosphine Clusters with μ3‐(Phosphido‐Chalcogenido), μ3‐(Arsenido‐Chalcogenido), and μ3‐(Imido or Oxo‐Chalcogenido) Hetero Ligand Shells

Reactions of dry THF/MeCN solutions of Ca[Re₆SCl(Cl^a)₆] with silylated derivatives E(SiMe₃)₂ (E = PhAs, PSiMe₃, HN, O, S) and addition of trialkylphosphine PPr₃ afford in high yields and at room temperature either the neutral clusters [Re₆SX(PPr₃)] ( 1 : X = As, 2 : X = P) or the ionic compounds [Re₆SX(PPr₃)]²⁺ · [Re₆S₆Cl₈]^2– ( 3 : X = NH, 4 : X = O, 5 : X = S). The compounds 1 – 5 were characterised by X‐ray crystal structure analysis. A di‐substitution reaction occurs on the {Re₆SCl}⁴⁺ cluster core, where the two inner μ₃‐chloro ligands Clⁱ are substituted by X (X = As, P, NH, O, S) and all six terminal chloro ligands Cl^a are exchanged by terminal PPr₃‐ligands.     

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.     

Iodostannate mit polymeren Anionen: (Me3PhN)4 [Sn3I10], [Me2HN–(CH2)2–NMe2H]2 [Sn3I10] und [Me2HN–(CH2)2–NMe2H][Sn3I8]

Iodostannates with Polymeric Anions: (Me₃PhN)₄ [Sn₃I₁₀], [Me₂HN–(CH₂)₂–NMe₂H]₂ [Sn₃I₁₀], and [Me₂HN–(CH₂)₂–NMe₂H] [Sn₃I₈] The polymeric iodostannate anions in (Me₃PhN)₄ [Sn₃I₁₀] ( 1 ) and [Me₂HN–(CH₂)₂–NMe₂H]₂ [Sn₃I₁₀] ( 2 ) consist of Sn₃I₁₂‐trioctahedra, which share four common iodine atoms with adjacent units to form infinite layers in 1 and polymeric chains in 2 . In the anion of [Me₂HN–(CH₂)₂–NMe₂H] [Sn₃I₈] ( 3 ) distorted SnI₆ octahedra sharing common edges and vertices form a two‐dimensional network. (Me₃PhN)₄ [Sn₃I₁₀] ( 1 ): Space group C2/c (No. 15), a = 2406.9(2), b = 968.26(7), c = 2651.7(2) pm, β = 111.775(9), V = 5738.9(8) · 10⁶ pm³; [Me₂HN–(CH₂)₂–NMe₂H]₂ [Sn₃I₁₀] ( 2 ): Space group P2₁/n (No. 14), a = 1187.2(1), b = 1554.4(1), c = 1188.9(1) pm, β = 116.620(8), V = 1961.4(3) · 10⁶ pm³; [Me₂HN–(CH₂)₂–NMe₂H] [Sn₃I₈] ( 3 ): Space group P2₁/c (No. 14), a = 1098.9(2), b = 803.93(7), c = 1571.5(2) pm, β = 102.96(1), V = 1352.9(2) · 10⁶ pm³.     

A Unified Interpretation of Kinetic Data on the Acid-Induced Cleavage and of Product-Analysis Data on Spontaneous Cleavage of the Mono-ol Cation μ-Hydroxo-bis[pentaamminecobalt(III)] ([(NH3)5CoOHCo(NH3)5]5+)

Recent work on the spontaneous (= acid-independent) cleavage of the mono-ol cation, i.e. in Cl^?/ClO and NO/ClO mixed-electrolyte media has established (by analysis of anion-competition experiments) the existence of reactive ion pairs of the mono-ol cation with Cl^? and NO. Their existence must be allowed for in the analysis of the rate data for the acid-induced cleavage (pH 0–1) of the mono-ol cation in these mixed-electrolyte media. Thus, previous data for acidic Cl^?/ClO media have been re-interpreted in this work, and new data for NO/ClO media have been analyzed in the same sense. This analysis removes an apparent discrepancy in the orders of magnitude of ion aggregate stability constants between the mono-ol and similar binuclear cations.     

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.     

Darstellung,Kristallstrukturen und Schwingungsspektren von [(Mo6X)Y]2–; Xi = Cl,Br; Ya = NO3, NO2

Synthesis, Crystal Structures, and Vibrational Spectra of [(Mo₆X)Y]^2–; Xⁱ = Cl, Br; Y^a = NO₃, NO₂ By treatment of [(Mo₆X)Y]^2–; Xⁱ = Y^a = Cl, Br with AgNO₃ or AgNO₂ by strictly exclusion of oxygene in acetone the hexanitrato and hexanitrito cluster anions [(Mo₆X)Y]^2–, Y^a = NO₂, NO₃ are formed. X-ray structure determinations of (Ph₄As)₂[(Mo₆Cl)(NO₃)] · 2 Me₂CO ( 1 ) (monoclinic, space group P2₁/n, a = 12.696(3), b = 21.526(1), c = 14.275(5) Å, β = 115.02(2)°, Z = 2), (n-Bu₄N)₂[(Mo₆Br)(NO₃)] · 2 CH₂Cl₂ ( 2 ) (monoclinic, space group P2₁/n, a = 14.390(5), b = 11.216(5), c = 21.179(5)Å, β = 96.475(5)°, Z = 2) and (Ph₄P)₂[(Mo₆Cl)(NO₂)] (3) (monoclinic, space group P2₁/n, a = 11.823(5), b = 13.415(5), c = 19.286(5) Å, β = 105.090(5)°, Z = 2) reveal the coordination of the ligands via O atoms with (Mo–O) bond lengths of 2.11–2.13 Å, and (MoON) angles of 122–131°. The vibrational spectra of the nitrato compounds show the typical innerligand vibrations ν_as(NO₂) (∼ 1500), ν_s(NO₂) (∼ 1270) and ν(NO) (∼ 980 cm^–1). The stretching vibrations ν(N=O) at 1460–1490 cm^–1 and ν(N–O) in the range of 950–1000 cm^–1 are characteristic for nitrito ligands coordinated via O atoms.     

Kinetics of the reaction O(3P) + SO2 + M → SO3 + M over the temperature range of 299°–440°K

Rate constants for the reaction O(³P) + SO₂ + M have been determined over the temperature range of 299°–440°K, using a flash photolysis–NO₂ chemiluminescence technique. For M?Ar, the Arrhenius expression was obtained. At room temperature k₂^Ar = (1.05 ± 0.21) × 10^?33 cm⁶/molec²·sec. In addition, the rate constants k₂ = (1.37 + 0.27) × 10^?33 cm⁶/molec²·sec, k₂ = (9.5 ± 3.0) ± 10^?33 cm⁶/molec²·sec, k₃ = (1.1 ± 0.2) ± 10^?31 cm⁶/molec²·sec, and k₃ = (2.6 ? 0.9) ± 10^?31 cm⁶/molec²·sec were obtained at room temperature where k₃^M is the rate constant for the reaction O + NO + M → NO₂ + M. The rate data are compared and discussed with literature values.     

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.     

Zur Reaktivität des Ferriophosphaalkens (Z)‐[Cp*(CO)2FeP=C(tBu)NMe2] gegenüber Propiolsäureestern HC≡C‐CO2R (R=Me,Et) und Acetylendicarbonsäureestern RO2C‐C≡C‐CO2R (R=Me,Et, tBu)

On the Reactivity of the Ferriophosphaalkene (Z)‐[Cp*(CO)₂Fe‐P=C(tBu)NMe₂] towards Propiolates HC≡C‐CO₂R (R=Me, Et) and Acetylene Dicarboxylates RO ₂C‐C≡C‐CO₂R (R=Me, Et, tBu) The reaction of equimolar amounts of (Z)‐[Cp*(CO)₂Fe‐P=C(tBu)NMe₂] 3 and methyl‐ and ethyl‐propiolate ( 2a, b ) or of 3 and dialkyl acetylene dicarboxylates 1a (R=Me), 1b (Et), 1c (tBu) afforded the five‐membered metallaheterocycles [Cp*(CO) =C(tBu)NMe₂] ( 4a, b ) and [Cp*(CO) =C(tBu)NMe₂] ( 5a—c ). The molecular structures of 4b and 5a were elucidated by single crystal X‐ray analyses. Moreover, the reactivity of 4b towards ethereal HBF₄ was investigated.     

Chiral recognition in molecular and macromolecular pairs of (S)‐ and (R)‐1‐cyano‐2‐methylpropyl‐4′‐ {[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐4‐ carboxylate enantiomers

(S)‐1‐Cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐ 4‐carboxylate [ (S)‐11 ] and (R)‐1‐cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐4‐carboxylate [( R)‐11 ] enantiomers, both greater than 99% enantiomeric excess, and their corresponding homopolymers, poly[ (S)‐11 ] and poly[ (R)‐11 ], with well‐defined molecular weights and narrow molecular weight distributions were synthesized and characterized. The mesomorphic behaviors of (S)‐11 and poly[ (S)‐11 ] are identical to those of (R)‐11 and poly[ (R)‐11 ], respectively. Both (S)‐11 and (R)‐11 exhibit enantiotropic S_A, S, and S_X (unidentified smectic) phases. The corresponding homopolymers exhibit S_A and S phases. The homopolymers with a degree of polymerization (DP) less than 6 also show a crystalline phase, whereas those with a DP greater than 10 exhibit a second S_X phase. Phase diagrams were investigated for four different pairs of enantiomers, (S)‐11 /( R)‐11 , (S)‐11 /poly[ (R)‐11 ], and poly[ (S)‐11 ]/poly[ (R)‐11 ], with similar and dissimilar molecular weights. In all cases, the structural units derived from the enantiomeric components are miscible and, therefore, isomorphic in the S_A and S phases over the entire range of enantiomeric composition. Chiral molecular recognition was observed in the S_A and S_X phases of the monomers but not in the S_A phase of the polymers. In addition, a very unusual chiral molecular recognition effect was detected in the S phase of the monomers below their crystallization temperature and in the S phase of the polymers below their glass‐transition temperature. In the S phase of the monomers above the melting temperature and of the polymers above the glass‐transition temperature, nonideal solution behavior was observed. However, in the S_A phase the monomer–polymer and polymer–polymer mixtures behave as an ideal solution. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3631–3655, 2000