Dihalomethanes as Bent Bifunctional XB/XB‐Donating Building Blocks for Construction of Metal‐involving Halogen Bonded Hexagons

The dihalomethanes CH₂X₂ (X=Cl, Br, I) were co‐crystallized with the isocyanide complexes trans‐[MX^M₂(CNC₆H₄‐4‐X^C)₂] (M=Pd, Pt; X^M=Br, I; X^C=F, Cl, Br) to give an extended series comprising 15 X‐ray structures of isostructural adducts featuring 1D metal‐involving hexagon‐like arrays. In these structures, CH₂X₂ behave as bent bifunctional XB/XB‐donating building blocks, whereas trans‐[MX^M₂(CNC₆H₄‐4‐X^C)₂] act as a linear XB/XB acceptors. Results of DFT calculations indicate that all XCH₂–X???X^M–M contacts are typical noncovalent interactions with estimated strengths in the range of 1.3–3.2 kcal mol^?1. A CCDC search reveals that hexagon‐like arrays are rather common but previously overlooked structural motives for adducts of trans‐bis(halide) complexes and halomethanes.     

Two succinic acid derivatives of 2‐ethyl‐6‐methylpyridin‐3‐ol

Crystals of bis(2‐ethyl‐3‐hydroxy‐6‐methylpyridinium) succinate–succinic acid (1/1), C₈H₁₂NO⁺·0.5C₄H₄O₄²⁻·0.5C₄H₆O₄, (I), and 2‐ethyl‐3‐hydroxy‐6‐methylpyridinium hydrogen succinate, C₈H₁₂NO⁺·C₄H₅O₄⁻, (II), were obtained by reaction of 2‐ethyl‐6‐methylpyridin‐3‐ol with succinic acid. The succinate anion and succinic acid molecule in (I) are located about centres of inversion. Intermolecular O—H...O, N—H...O and C—H...O hydrogen bonds are responsible for the formation of a three‐dimensional network in the crystal structure of (I) and a two‐dimensional network in the crystal structure of (II). Both structures are additionally stabilized by π–π interactions between symmetry‐related pyridine rings, forming a rod‐like cationic arrangement for (I) and cationic dimers for (II).     

Three‐dimensional networks in 5‐methylimidazolium 3‐carboxy‐4‐hydroxybenzenesulfonate and bis(5‐methylimidazolium) 3‐carboxylato‐4‐hydroxybenzenesulfonate

The two title proton‐transfer compounds, 5‐methylimidazolium 3‐carboxy‐4‐hydroxybenzenesulfonate, C₄H₇N₂⁺·C₇H₅O₆S⁻, (I), and bis(5‐methylimidazolium) 3‐carboxylato‐4‐hydroxybenzenesulfonate, 2C₄H₇N₂⁺·C₇H₅O₆S²⁻, (II), are each organized into a three‐dimensional network by a combination of X—H...O (X = O, N or C) hydrogen bonds, and π–π and C—H...π interactions.     

Synthesis and Characterization of donor‐functionalized ansa‐Cyclopentadienyl‐Indenyl and ansa‐Indenyl‐Indenyl Complexes of Yttrium,Samarium, Thulium,and Lutetium

The stepwise reaction of Me₂SiCl₂ with K[C₅H₃ ^tBuMe‐3] or Li[C₉H₇] and then with K[C₉H₆CH₂CH₂‐ NMe₂‐1] followed by double deprotonation with NaH or LiBu, yields the two dimethylsilicon bridged cyclopentadienyl‐indenyl and indenyl‐indenyl donor‐functionalized ligand systems K₂[(C₅H₂ ^tBu‐3‐Me‐5)SiMe₂(1‐C₉H₅CH₂CH₂NMe₂‐3)] ( 1 ), and Li₂[(1‐C₉H₆)SiMe₂(1‐C₉H₅CH₂CH₂NMe₂‐3)] ( 2 ), respectively. Treatment of 1 with YCl₃(THF)₃, SmCl₃(THF)_1.77, TmI₃(DME)₃, and LuCl₃(THF)₃ gives the mixed ansa‐metallocenes [(C₅H₂ ^tBu‐3‐Me‐5)SiMe₂(1‐C₉H₅CH₂CH₂NMe₂‐3)]LnX (X = Cl, Ln = Y ( 3 ), Sm ( 4 ), Lu ( 5 ); X = I, Ln = Tm ( 6 )), respectively. The reaction of 2 with LuCl₃(THF)₃ yields [(1‐C₉H₆)SiMe₂(1‐C₉H₅CH₂CH₂NMe₂‐3)]LuCl ( 7 ). Compound 4 reacts with LiMe to give the corresponding alkyl derivative [(C₅H₂ ^tBu‐3‐Me‐5)SiMe₂(1‐C₉H₅CH₂CH₂NMe₂‐3)]Sm(CH₃) ( 8 ). The new complexes were characterized by elemental analyses, MS spectrometry, and NMR spectroscopy. The molecular structures of 5 and 6 were determined by single crystal X‐ray diffraction.     

Thermotropic Liquid Crystals Based on Extended 2,5‐Disubstituted‐1,3,4‐Oxadiazoles: Structure–Property Relationships,Variable‐Temperature Powder X‐ray Diffraction,and Small‐Angle X‐ray Scattering Studies

A class of extended 2,5‐disubstituted‐1,3,4‐oxadiazoles R¹‐C₆H₄‐{OC₂N₂}‐C₆H₄‐R² (R¹=R²=C₁₀H₂₁O 1 a , p‐C₁₀H₂₁O‐C₆H₄‐C?C 3 a , p‐CH₃O‐C₆H₄‐C?C 3 b ; R¹=C₁₀H₂₁O, R²=CH₃O 1 b , (CH₃)₂N 1 c ; F 1 d ; R¹=C₁₀H₂₁O‐C₆H₄‐C?C, R²=C₁₀H₂₁O 2 a , CH₃O 2 b , (CH₃)₂N 2 c , F 2 d ) were prepared, and their liquid‐crystalline properties were examined. In CH₂Cl₂ solution, these compounds displayed a room‐temperature emission with λ_max at 340–471 nm and quantum yields of 0.73–0.97. Compounds 1 d , 2 a – 2 d , and 3 a exhibited various thermotropic mesophases (monotropic, enantiotropic nematic/smectic), which were examined by polarized‐light optical microscopy and differential scanning calorimetry. Structure determination by a direct‐space approach using simulated annealing or parallel tempering of the powder X‐ray diffraction data revealed distinctive crystal‐packing arrangements for mesogenic molecules 2 b and 3 a , leading to different nematic mesophase behavior, with 2 b being monotropic and 3 a enantiotropic in the narrow temperature range of 200–210 °C. The structural transitions associated with these crystalline solids and their mesophases were studied by variable‐temperature X‐ray diffractometry. Nondestructive phase transitions (crystal‐to‐crystal, crystal‐to‐mesophase, mesophase‐to‐liquid) were observed in the diffractograms of 1 b, 1 d , 2 b, 2 d , and 3 a measured at 25–200 °C. Powder X‐ray diffraction and small‐angle X‐ray scattering data revealed that the structure of the annealed solid residue 2 b reverted to its original crystal/molecular packing when the isotropic liquid was cooled to room temperature. Structure–property relationships within these mesomorphic solids are discussed in the context of their molecular structures and intermolecular interactions.     

Hydrogen bonding in two benzene‐1,2‐diaminium pyridine‐2‐carboxylate salts and a cocrystal of benzene‐1,2‐diamine and benzoic acid

The isostructural salts benzene‐1,2‐diaminium bis(pyridine‐2‐carboxylate), 0.5C₆H₁₀N₂²⁺·C₆H₄NO₂^?, (1), and 4,5‐dimethylbenzene‐1,2‐diaminium bis(pyridine‐2‐carboxylate), 0.5C₈H₁₄N₂²⁺·C₆H₄NO₂^?, (2), and the 1:2 benzene‐1,2‐diamine–benzoic acid cocrystal, 0.5C₆H₈N₂·C₇H₆O₂, (3), are reported. All of the compounds exhibit extensive N—H…O hydrogen bonding that results in interconnected rings. O—H…N hydrogen bonding is observed in (3). Additional π–π and C—H…π interactions are found in each compound. Hirshfeld and fingerprint plot analyses reveal the primary intermolecular interactions and density functional theory was used to calculate their strengths. Salt formation by (1) and (2), and cocrystallization by (3) are rationalized by examining pK_a differences. The R₂²(9) hydrogen‐bonding motif is common to each of these structures.     

Kinetics of C6H5 radical reactions with 2‐methylpropane, 2,3‐dimethylbutane and 2,3,4‐trimethylpentane

The absolute bimolecular rate constants for the reactions of C₆H₅ with 2‐methylpropane, 2,3‐dimethylbutane and 2,3,4‐trimethylpentane have been measured by cavity ringdown spectrometry at temperatures between 290 and 500 K. For 2‐methylpropane, additional measurements were performed with the pulsed laser photolysis/mass spectrometry, extending the temperature range to 972 K. The reactions were found to be dominated by the abstraction of a tertiary C H bond from the molecular reactant, resulting in the production of a tertiary alkyl radical: C₆H₅ + CH(CH₃)₃ → C₆H₆ + t‐C₄H₉ (1) (1) C₆H₅ + (CH₃)₂CHCH(CH₃)₂ → C₆H₆ + t‐C₆H₁₃ (2) (2) C₆H₅ + (CH₃)₂CHCH(CH₃)CH(CH₃)₂ → C₆H₆ + t‐C₈H₁₇ (3) (3) with the following rate constants given in units of cm³ mol⁻¹ s⁻¹: k₁ = 10^{(11.45 ± 0.18)} e^{−(1512 ± 44)/T} k₂ = 10^{(11.72 ± 0.15)} e^{−(1007 ± 124)/T} k₃ = 10^{(11.83 ± 0.13)} e^{−(428 ± 108)/T} © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 645–653, 1999     

Hydrogen‐bonding patterns in 3‐alkyl‐3‐hydroxyindolin‐2‐ones

The molecules of racemic 3‐benzoylmethyl‐3‐hydroxyindolin‐2‐one, C₁₆H₁₃NO₃, (I), are linked by a combination of N—H...O and O—H...O hydrogen bonds into a chain of centrosymmetric edge‐fused R₂²(10) and R₄⁴(12) rings. Five monosubstituted analogues of (I), namely racemic 3‐hydroxy‐3‐[(4‐methylbenzoyl)methyl]indolin‐2‐one, C₁₇H₁₅NO₃, (II), racemic 3‐[(4‐fluorobenzoyl)methyl]‐3‐hydroxyindolin‐2‐one, C₁₆H₁₂FNO₃, (III), racemic 3‐[(4‐chlorobenzoyl)methyl]‐3‐hydroxyindolin‐2‐one, C₁₆H₁₂ClNO₃, (IV), racemic 3‐[(4‐bromobenzoyl)methyl]‐3‐hydroxyindolin‐2‐one, C₁₆H₁₂BrNO₃, (V), and racemic 3‐hydroxy‐3‐[(4‐nitrobenzoyl)methyl]indolin‐2‐one, C₁₆H₁₂N₂O₅, (VI), are isomorphous in space group P. In each of compounds (II)–(VI), a combination of N—H...O and O—H...O hydrogen bonds generates a chain of centrosymmetric edge‐fused R₂²(8) and R₂²(10) rings, and these chains are linked into sheets by an aromatic π–π stacking interaction. No two of the structures of (II)–(VI) exhibit the same combination of weak hydrogen bonds of C—H...O and C—H...π(arene) types. The molecules of racemic 3‐hydroxy‐3‐(2‐thienylcarbonylmethyl)indolin‐2‐one, C₁₄H₁₁NO₃S, (VII), form hydrogen‐bonded chains very similar to those in (II)–(VI), but here the sheet formation depends upon a weak π–π stacking interaction between thienyl rings. Comparisons are drawn between the crystal structures of compounds (I)–(VII) and those of some recently reported analogues having no aromatic group in the side chain.     

Transition‐Metal Complexes Based on the 1,3,5‐Triethynyl Benzene Linking Unit

The synthesis of a unique series of heteromultinuclear transition metal compounds is reported. Complexes 1‐I‐3‐Br‐5‐(FcC≡C)‐C₆H₃ ( 4 ), 1‐Br‐3‐(bpy‐C≡C)‐5‐(FcC≡C)‐C₆H₃ ( 6 ), 1,3‐(bpy‐C≡C)₂‐5‐(FcC≡C)‐C₆H₃ ( 7 ), 1‐(XC≡C)‐3‐(bpy‐C≡C)‐5‐(FcC≡C)‐C₆H₃ ( 8 , X = SiMe₃; 9 , X = H), 1‐(HC≡C)‐3‐[(CO)₃ClRe(bpy‐C≡C)]‐5‐(FcC≡C)‐C₆H₃ ( 11 ), 1‐[(Ph₃P)AuC≡C]‐3‐[(CO)₃ClRe(bpy‐C≡C)]‐5‐(FcC≡C)‐C₆H₃ ( 13 ), 1‐[(Ph₃P)AuC≡C]‐3‐(bpy‐C≡C)‐5‐(FcC≡C)‐C₆H₃ ( 14 ), [1‐[(Ph₃PAuC≡C]‐3‐[{[Ti](C≡CSiMe₃)₂}Cu(bpy‐C≡C)]‐5‐(FcC≡C)‐C₆H₃]PF₆ ( 16 ), and [1,3‐[(tBu₂bpy)₂Ru(bpy‐C≡C)]₂‐5‐(FcC≡C)‐C₆H₃](PF₆)₄ ( 18 ) (Fc = (η⁵‐C₅H₄)(η⁵‐C₅H₅)Fe, bpy = 2,2′‐bipyridiyl‐5‐yl, [Ti] = (η⁵‐C₅H₄SiMe₃)₂Ti) were prepared by using consecutive synthesis methodologies including metathesis, desilylation, dehydrohalogenation, and carbon–carbon cross‐coupling reactions. In these complexes the corresponding metal atoms are connected by carbon‐rich bridging units comprising 1,3‐diethynyl‐, 1,3,5‐triethynylbenzene and bipyridyl units. They were characterized by elemental analysis, IR and NMR spectroscopy, and partly by ESI‐TOF mass spectrometry., The structures of 4 and 11 in the solid state are reported. Both molecules are characterized by the central benzene core bridging the individual transition metal complex fragments. The corresponding acetylide entities are, as typical, found in a linear arrangement with representative M–C, C–C_C≡C and C≡C bond lengths.     

Encapsulation of Triphenylene Derivatives in the Hexanuclear Arene Ruthenium Metallo‐Prismatic Cage [Ru6(p‐PriC6H4Me)6(tpt)2(dhbq)3]6+ (tpt = 2,4,6‐tri(pyridin‐4‐yl)‐1,3,5‐triazine,dhbq = 2,5‐dihydroxy‐1,4‐benzoquinonato)

A large cationic triangular metallo‐prism, [Ru₆(p‐PrⁱC₆H₄Me)₆(tpt)₂(dhbq)₃]⁶⁺ ( 1 )⁶⁺, incorporating p‐cymene ruthenium building blocks, bridged by 2,5‐dihydroxy‐1,4‐benzoquinonato (dhbq) ligands, and connected by two 2,4,6‐tri(pyridin‐4‐yl)‐1,3,5‐triazine (tpt) subunits, allows the permanent encapsulation of the triphenylene derivatives hexahydroxytriphenylene, C₁₈H₆(OH)₆ and hexamethoxytriphenylene, C₁₈H₆(OMe)₆. These two cationic carceplex systems [C₁₈H₆(OH)₆⊂ 1 ]⁶⁺ and [C₁₈H₆(OMe)₆⊂ 1 ]⁶⁺ have been isolated as their triflate salts. The molecular structure of these systems has been established by one‐dimensional ¹H ROESY NMR experiments as well as by the single‐crystal structure analysis of [C₁₈H₆(OMe)₆⊂ 1 ][O₃SCF₃]₆.     

Hydrogen‐bonded sheet structures in neutral,anionic and hydrated 6‐amino‐2‐(morpholin‐4‐yl)‐5‐nitrosopyrimidines

In each of 6‐amino‐3‐methyl‐2‐(morpholin‐4‐yl)‐5‐nitrosopyrimidin‐4(3H)‐one, C₉H₁₃N₅O₃, (I), morpholin‐4‐ium 4‐amino‐2‐(morpholin‐4‐yl)‐5‐nitroso‐6‐oxo‐1,6‐dihydropyrimidin‐1‐ide, C₄H₁₀NO⁺·C₈H₁₀N₅O₃⁻, (II), and 6‐amino‐2‐(morpholin‐4‐yl)‐5‐nitrosopyrimidin‐4(3H)‐one hemihydrate, C₈H₁₁N₅O₃·0.5H₂O, (III), the bond distances within the pyrimidine components are consistent with significant electronic polarization, which is most marked in (II) and least marked in (I). Despite the high level of substitution, the pyrimidine rings are all effectively planar, and in each of the pyrimidine components, there are intramolecular N—H...O hydrogen bonds. In each compound, the organic components are linked by multiple N—H...O hydrogen bonds to form sheets of widely differing construction, and in compound (III) adjacent sheets are linked by the water molecules, so forming a three‐dimensional hydrogen‐bonded framework. This study also contains the first direct geometric comparison between the electronic polarization in a neutral aminonitrosopyrimidine and that in its ring‐deprotonated conjugate anion in a metal‐free environment.     

3‐Cyano‐6‐hydroxy‐4‐methyl‐2‐pyridone: two new pseudopolymorphs and two cocrystals with products of an in situ nucleophilic aromatic substitution

Four crystal structures of 3‐cyano‐6‐hydroxy‐4‐methyl‐2‐pyridone (CMP), viz. the dimethyl sulfoxide monosolvate, C₇H₆N₂O₂·C₂H₆OS, (1), the N,N‐dimethylacetamide monosolvate, C₇H₆N₂O₂·C₄H₉NO, (2), a cocrystal with 2‐amino‐4‐dimethylamino‐6‐methylpyrimidine (as the salt 2‐amino‐4‐dimethylamino‐6‐methylpyrimidin‐1‐ium 5‐cyano‐4‐methyl‐6‐oxo‐1,6‐dihydropyridin‐2‐olate), C₇H₁₃N₄⁺·C₇H₅N₂O₂⁻, (3), and a cocrystal with N,N‐dimethylacetamide and 4,6‐diamino‐2‐dimethylamino‐1,3,5‐triazine [as the solvated salt 2,6‐diamino‐4‐dimethylamino‐1,3,5‐triazin‐1‐ium 5‐cyano‐4‐methyl‐6‐oxo‐1,6‐dihydropyridin‐2‐olate–N,N‐dimethylacetamide (1/1)], C₅H₁₁N₆⁺·C₇H₅N₂O₂⁻·C₄H₉NO, (4), are reported. Solvates (1) and (2) both contain the hydroxy group in a para position with respect to the cyano group of CMP, acting as a hydrogen‐bond donor and leading to rather similar packing motifs. In cocrystals (3) and (4), hydrolysis of the solvent molecules occurs and an in situ nucleophilic aromatic substitution of a Cl atom with a dimethylamino group has taken place. Within all four structures, an R₂²(8) N—H...O hydrogen‐bonding pattern is observed, connecting the CMP molecules, but the pattern differs depending on which O atom participates in the motif, either the ortho or para O atom with respect to the cyano group. Solvents and coformers are attached to these arrangements via single‐point O—H...O interactions in (1) and (2) or by additional R₄⁴(16) hydrogen‐bonding patterns in (3) and (4). Since the in situ nucleophilic aromatic substitution of the coformers occurs, the possible Watson–Crick C–G base‐pair‐like arrangement is inhibited, yet the cyano group of the CMP molecules participates in hydrogen bonds with their coformers, influencing the crystal packing to form chains.     

Two two‐dimensional hydrogen‐bonded coordination networks: bis(3‐carboxybenzoato‐κO)bis(4‐methyl‐1H‐imidazole‐κN3)copper(II) and bis(3‐methylbenzoato‐κN)bis(4‐methyl‐1H‐imidazole‐κN3)copper(II) monohydrate

The title two‐dimensional hydrogen‐bonded coordination compounds, [Cu(C₈H₅O₄)₂(C₄H₆N₂)₂], (I), and [Cu(C₈H₇O₂)₂(C₄H₆N₂)₂]·H₂O, (II), have been synthesized and structurally characterized. The molecule of complex (I) lies across an inversion centre, and the Cu²⁺ ion is coordinated by two N atoms from two 4‐methyl‐1H‐imidazole (4‐MeIM) molecules and two O atoms from two 3‐carboxybenzoate (HBDC⁻) anions in a square‐planar geometry. Adjacent molecules are linked through intermolecular N—H...O and O—H...O hydrogen bonds into a two‐dimensional sheet with (4,4) topology. In the asymmetric part of the unit cell of (II) there are two symmetry‐independent molecules, in which each Cu²⁺ ion is also coordinated by two N atoms from two 4‐MeIM molecules and two O atoms from two 3‐methylbenzoate (3‐MeBC⁻) anions in a square‐planar coordination. Two neutral complex molecules are held together via N—H...O(carboxylate) hydrogen bonds to generate a dimeric pair, which is further linked via discrete water molecules into a two‐dimensional network with the Schläfli symbol (4³)₂(4⁶,6⁶,8³). In both compounds, as well as the strong intermolecular hydrogen bonds, π–π interactions also stabilize the crystal stacking.     

Preparation of new 2‐amino‐ and 2,3‐diamino‐pyridine trifluoroacetyl enamine derivatives and their application to the synthesis of trifluoromethyl‐containing 3H‐pyrido[2,3‐b][1,4] diazepinols

The synthesis of a novel series of the intermediates N²(N³)‐[1‐alkyl(aryl/heteroaryl)‐3‐oxo‐4,4,4‐trifluoroalk‐1‐en‐1‐yl]‐2‐aminopyridines [F₃CC(O)CH?CR¹(2? NH?C₅H₃N)] and 2,3‐diaminopyridines [F₃CC(O)CH?CR¹(2‐NH₂‐3‐NH? C₅H₃N)], where R¹ = H, Me, C₆H₅, 4‐FC₆H₄, 4‐CIC₆H₄, 4‐BrC₆H₄, 4‐CH₃C₆H₄, 4‐OCH₃C₆H₄, 4,4′‐biphenyl, 1‐naphthyl, 2‐thienyl, 2‐furyl, is reported. The corresponding series of 2‐aryl(heteroaryl)‐4‐trifluoromethyl‐3H‐pyrido[2,3‐b][1,4]diazepin‐4‐ols obtained from intramolecular cyclization reaction of the respective trifluoroacetyl enamines or from the direct cyclocondensation reaction of 4‐methoxy‐1,1,1‐trifluoroalk‐3‐en‐2‐ones with 2,3‐diaminopyridine, under mild conditions, is also reported.     

Experimental and Theoretical Studies on Arene‐Bridged Metal–Metal‐Bonded Dimolybdenum Complexes

The bis(hydride) dimolybdenum complex, [Mo₂(H)₂{HC(N‐2,6‐iPr₂C₆H₃)₂}₂(thf)₂], 2 , which possesses a quadruply bonded Mo₂^II core, undergoes light‐induced (365 nm) reductive elimination of H₂ and arene coordination in benzene and toluene solutions, with formation of the Mo^I₂ complexes [Mo₂{HC(N‐2,6‐iPr₂C₆H₃)₂}₂(arene)], 3?C₆H₆ and 3?C₆H₅Me , respectively. The analogous C₆H₅OMe, p‐C₆H₄Me₂, C₆H₅F, and p‐C₆H₄F₂ derivatives have also been prepared by thermal or photochemical methods, which nevertheless employ different Mo₂ complex precursors. X‐ray crystallography and solution NMR studies demonstrate that the molecule of the arene bridges the molybdenum atoms of the Mo^I₂ core, coordinating to each in an η² fashion. In solution, the arene rotates fast on the NMR timescale around the Mo₂‐arene axis. For the substituted aromatic hydrocarbons, the NMR data are consistent with the existence of a major rotamer in which the metal atoms are coordinated to the more electron‐rich C?C bonds.     

2, 4‐Dimethylpenta‐1, 3‐dien‐ und 2, 4‐Dimethylpentadienyl‐Komplexe des Rhodiums und Iridiums

2, 4‐Dimethylpenta‐1, 3‐diene and 2, 4‐Dimethylpentadienyl Complexes of Rhodium and Iridium The complexes [(η⁴‐C₇H₁₂)RhCl]₂ ( 1 ) (C₇H₁₂ = 2, 4‐dimethylpenta‐1, 3‐diene) and [(η⁴‐C₇H₁₂)₂IrCl] ( 2 ) were obtained by interaction of C₇H₁₂ with [(η²‐C₂H₄)₂RhCl]₂ and [(η²‐cyclooctene)₂IrCl]₂, respectively. The reaction of 1 or 2 with CpTl (Cp = η⁵‐C₅H₅) yields the compounds [CpM(η⁴‐C₇H₁₂)] ( 3a : M = Rh; 3b : M = Ir). The hydride abstraction at the pentadiene ligand of 3a , b with Ph₃CBF₄ proceeds differently depending on the solvent. In acetone or THF the “half‐open” metallocenium complexes [CpM(η⁵‐C₇H₁₁)]BF₄ ( 4a : M = Rh; 4b : M = Ir) are obtained exclusively. In dichloromethane mixtures are produced which additionally contain the species [(η⁵‐C₇H₁₁)M(η⁵‐C₅H₄CPh₃)]BF₄ ( 5a : M = Rh; 5b : M = Ir) formed by electrophilic substitution at the Cp ring, as well as the η³‐2, 4‐dimethylpentenyl compound [(η³‐C₇H₁₃)Rh{η⁵‐C₅H₃(CPh₃)₂}]BF₄ ( 6 ). By interaction of 2, 4‐dimethylpentadienyl potassium with 1 or 2 the complexes [(η⁴‐C₇H₁₂)M(η⁵‐C₇H₁₁)] ( 7a : M = Rh; 7b : M = Ir) are generated which show dynamic behaviour in solution; however, attempts to synthesize the “open” metallocenium cations [(η⁵‐C₇H₁₁)₂M]⁺ by hydride abstraction from 7a , b failed. The new compounds were characterized by elemental analysis and spectroscopically, 4b and 5a also by X‐ray structure analysis.     

Conformations and resulting hydrogen‐bonded networks of hydrogen {phosphono[(pyridin‐1‐ium‐3‐yl)amino]methyl}phosphonate and related 2‐chloro and 6‐chloro derivatives

In the crystal structures of the conformational isomers hydrogen {phosphono[(pyridin‐1‐ium‐3‐yl)amino]methyl}phosphonate monohydrate (pro‐E), C₆H₁₀N₂O₆P₂·H₂O, (Ia), and hydrogen {phosphono[(pyridin‐1‐ium‐3‐yl)amino]methyl}phosphonate (pro‐Z), C₆H₁₀N₂O₆P₂, (Ib), the related hydrogen {[(2‐chloropyridin‐1‐ium‐3‐yl)amino](phosphono)methyl}phosphonate (pro‐E), C₆H₉ClN₂O₆P₂, (II), and the salt bis(6‐chloropyridin‐3‐aminium) [hydrogen bis({[2‐chloropyridin‐1‐ium‐3‐yl(0.5+)]amino}methylenediphosphonate)] (pro‐Z), 2C₅H₆ClN₂⁺·C₁₂H₁₆Cl₂N₄O₁₂P₄²⁻, (III), chain–chain interactions involving phosphono (–PO₃H₂) and phosphonate (–PO₃H⁻) groups are dominant in determining the crystal packing. The crystals of (Ia) and (III) comprise similar ribbons, which are held together by N—H...O interactions, by water‐ or cation‐mediated contacts, and by π–π interactions between the aromatic rings of adjacent zwitterions in (Ia), and those of the cations and anions in (III). The crystals of (Ib) and (II) have a layered architecture: the former exhibits highly corrugated monolayers perpendicular to the [100] direction, while in the latter, flat bilayers parallel to the (001) plane are formed. In both (Ib) and (II), the interlayer contacts are realised through N—H...O hydrogen bonds and weak C—H...O interactions involving aromatic C atoms.     

Highly active copolymerization of ethylene with 10‐undecen‐1‐ol using phenoxy‐based zirconium/methylaluminoxane catalysts

Activated with methylaluminoxane (MAO), phenoxy‐based zirconium complexes bis[(3‐^tBu‐C₆H₃‐2‐O)‐CH?NC₆H₅]ZrCl₂, bis[(3,5‐di‐^tBu‐C₆H₂‐2‐O)‐PhC?NC₆H₅] ZrCl₂, and bis[(3,5‐di‐^tBu‐C₆H₂‐2‐O)‐PhC?N(2‐F‐C₆H₄)]ZrCl₂ for the first time have been used for the copolymerization of ethylene with 10‐undecen‐1‐ol. In comparison with the conventional metallocene, the phenoxy‐based zirconium complexes exhibit much higher catalytic activities [>10⁷ g of polymer (mol of catalyst)^?1 h^?1]. The incorporation of 10‐undecen‐1‐ol into the copolymers and the properties of the copolymers are strongly affected by the catalyst structure. Among the three catalysts, complex c is the most favorable for preparing higher molecular weight functionalized polyethylene containing a higher content of hydroxyl groups. Studies on the polymerization conditions indicate that the incorporated commoner content in the copolymers mainly depends on the comonomer concentration in the feed. The catalytic activity is slightly affected by the Al_(MAO)/Zr molar ratio but decreases greatly with an increase in the polymerization temperature. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5944–5952, 2005     

Regioselective ortho‐Metallation of 2‐Diphenylphosphanylpyridine and (2‐(2‐Diphenylphosphanyl)phenyl)‐1‐3‐dioxalane with Methyltetrakis(trimethylphosphane)cobalt(I)

Co(CH₃)(PMe₃)₄ forms 100 % regioselectively with (2‐(2‐diphenylphosphanyl)phenyl)‐1,3‐dioxalane and 2‐diphenylphosphanyl‐pyridine, by elimination of methane, the four‐membered metallacycles Co{(C₃O₂HC₆H₃)P(C₆H₅)₂}(PMe₃)₃ ( 1 ) and Co{(CNC₄H₃)P(C₆H₅)₂}(PMe₃)₃ ( 4 ). The regioselectivity is independent of the steric requirement of the ortho substituent in the 2‐diphenylphosphanylaryl‐ligands. Oxidative addition with iodomethane transforms 1 and 4 into octahedral, diamagnetic low‐spin d⁶ complexes Co(CH₃)I‐{(C₃O₂HC₆H₃)P(C₆H₅)₂}(PMe₃)₂ ( 2 ) and Co(CH₃)I‐{(CNC₄H₃)P(C₆H₅)₂}(PMe₃)₂ ( 5 ). Under an atmosphere of carbon monoxide, insertion into the Co‐C bond results in ring expansion by forming the new assembled phosphanylbenzoyl complexes Co{(C₄O₃HC₆H₃)‐P(C₆H₅)₂}CO(PMe₃)₂ ( 3 ) and Co{(OCNC₄H₃)P(C₆H₅)₂}CO(PMe₃)₂ ( 6 ). The three different types of cobaltacycles are supported by X‐ray diffraction of 1 , 3 , 5 and 6 .     

New hydrophobic L‐amino acid salts: maleates of L‐leucine,L‐isoleucine and L‐norvaline

Crystals of maleates of three amino acids with hydrophobic side chains [L‐leucenium hydrogen maleate, C₆H₁₄NO₂⁺·C₄H₃O₄⁻, (I), L‐isoleucenium hydrogen maleate hemihydrate, C₆H₁₄NO₂⁺·C₄H₃O₄⁻·0.5H₂O, (II), and L‐norvalinium hydrogen maleate–L‐norvaline (1/1), C₅H₁₁NO₂⁺·C₄H₃O₄⁻·C₅H₁₂NO₂, (III)], were obtained. The new structures contain C₂²(12) chains, or variants thereof, that are a common feature in the crystal structures of amino acid maleates. The L‐leucenium salt is remarkable due to a large number of symmetrically non‐equivalent units (Z′ = 3). The L‐isoleucenium salt is a hydrate despite the fact that L‐isoleucine is a nonpolar hydrophobic amino acid (previously known amino acid maleates formed hydrates only with lysine and histidine, which are polar and hydrophilic). The L‐norvalinium salt provides the first example where the dimeric cation L‐Nva...L‐NvaH⁺ was observed. All three compounds have layered noncentrosymmetric structures. Preliminary tests have shown the presence of the second harmonic generation (SGH) effect for all three compounds.