Comparative study on polyimides from isomeric 3,3′‐, 3,4′‐, and 4,4′‐linked bis(thioether anhydride)s

Three isomeric bis(thioether anhydride) monomers, 4,4′‐bis(2,3‐dicarboxyphenylthio) diphenyl ketone dianhydride (3,3′‐PTPKDA), 4,4′‐bis(3,4‐dicarboxyphenylthio) diphenyl ketone dianhydride (4,4′‐PTPKDA), and 4‐(2,3‐dicarboxyphenylthio)‐4′‐(3,4‐dicarboxyphenylthio) diphenyl ketone dianhydride (3,4′‐PTPKDA), were prepared through multistep reactions. Their structures were determined via Fourier transform infrared, NMR, and elemental analysis. Three series of polyimides (PIs) were prepared from the obtained isomeric dianhydrides and aromatic diamines in N‐methyl‐2‐pyrrolidone (NMP) via the conventional two‐step method. The PIs showed excellent solubility in common organic solvents such as chloroform, N,N‐dimethylacetamide, and NMP. Their glass‐transition temperatures decreased according to the order of PIs on the basis of 3,3′‐PTPKDA, 3,4′‐PTPKDA, and 4,4′‐PTPKDA. The 5% weight loss temperatures (T_5%) of all PIs in nitrogen were observed at 504–519 °C. The rheological properties of isomeric PI resins based on 3,3′‐PTPKDA/4,4′‐oxydianiline/phthalic anhydride showed lower complex viscosity and better melt stability compared with the corresponding isomers from 4,4′‐ and 3,4′‐PTPKDA. In addition, the PI films based on three isomeric dianhydrides and 2,2′‐bis(trifluoromethyl)benzidine had a low moisture absorption of 0.27–0.35%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A one‐dimensional zinc(II) coordination polymer incorporating [1,1′‐biphenyl]‐4,4′‐dicarboxylate and N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide ligands

In the title compound, catena‐poly[[[N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide]chloridozinc(II)]‐μ‐[1,1′‐biphenyl]‐4,4′‐dicarboxylato‐[[N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide]chloridozinc(II)]‐μ‐[N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide]], [Zn₂(C₁₄H₈O₄)Cl₂(C₂₆H₂₂N₄O₂)₃]_n, the Zn^II centre is four‐coordinate and approximately tetrahedral, bonding to one carboxylate O atom from a bidentate bridging dianionic [1,1′‐biphenyl]‐4,4′‐dicarboxylate ligand, to two pyridine N atoms from two N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide ligands and to one chloride ligand. The pyridyl ligands exhibit bidentate bridging and monodentate terminal coordination modes. The bidentate bridging pyridyl ligand and the bridging [1,1′‐biphenyl]‐4,4′‐dicarboxylate ligand both lie on special positions, with inversion centres at the mid‐points of their central C—C bonds. These bridging groups link the Zn^II centres into a one‐dimensional tape structure that propagates along the crystallographic b direction. The tapes are interlinked into a two‐dimensional layer in the ab plane through N—H...O hydrogen bonds between the monodentate ligands. In addition, the thermal stability and solid‐state photoluminescence properties of the title compound are reported.     

Synthesis and characterization of fluorinated poly(amide imide)s derived from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and aromatic diamines

A series of fluorinated poly(amide imide)s were prepared from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and various aromatic diamines [3,3′,5,5′‐tetramethyl‐4,4′‐diaminediphenylmethane, α,α‐bis(4‐amino‐3,5‐dimethyl phenyl)‐3′‐trifluoromethylphenylmethane, 1,4‐bis(4′‐amino‐2′‐trifluoromethylphenoxy)benzene, 4‐(3′‐trifluoromethylphenyl)‐2,6‐bis(3′‐aminophenyl)pyridine, and 1,1‐bis(4′‐aminophenyl)‐1‐(3′‐trifluoromethylphenyl)‐2,2,2‐trifluoroethane]. The fluorinated poly(amide imide)s, prepared by a one‐step polycondensation procedure, had good solubility both in strong aprotic solvents, such as N‐methyl‐2‐pyrrolidinone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and cyclopentanone, and in common organic solvents, such as tetrahydrofuran and m‐cresol. Strong and flexible polymer films with tensile strengths of 84–99 MPa and ultimate elongation values of 6–9% were prepared by the casting of polymer solutions onto glass substrates, followed by thermal baking. The poly(amide imide) films exhibited high thermal stability, with glass‐transition temperatures of 257–266 °C and initial thermal decomposition temperatures of greater than 540 °C. The polymer films also had good dielectric properties, with dielectric constants of 3.26–3.52 and dissipation factors of 3.0–7.7 × 10^?3, and acceptable electrical insulating properties. The balance of excellent solubility and thermal stability associated with good mechanical and electrical properties made the poly(amide imide)s potential candidates for practical applications in the microelectronics industry and other related fields. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1831–1840, 2003     

Substituted 2,2′‐Bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl Complexes of Zinc

The condensation reaction of 2,2′‐diamino‐4,4′‐dimethyl‐6,6'‐dibromo‐1,1′‐biphenyl with 2‐hydroxybenzaldehyde as well as 5‐methoxy‐, 4‐methoxy‐, and 3‐methoxy‐2‐hydroxybenzaldehyde yields 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyl ( 1a ) as well as the 5‐, 4‐, and 3‐methoxy‐substituted derivatives 1b , 1c , and 1d , respectively. Deprotonation of substituted 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls with diethylzinc yields the corresponding substituted zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls ( 2 ) or zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyls ( 3 ). Recrystallization from a mixture of CH₂Cl₂ and methanol can lead to the formation of methanol adducts. The methanol ligands can either bind as Lewis base to the central zinc atom or as Lewis acid via a weak O–H ··· O hydrogen bridge to a phenoxide moiety. Methanol‐free complexes precipitate as dimers with central Zn₂O₂ rings.     

Reaction of 2‐Imino‐2H‐chromene‐3‐carboxamide with Phosphorus Isothiocyanates: First Synthesis of Novel Chromeno[2,3‐d]pyrimidinyl and Bis(chromeno[2,3‐d]pyrimidinyl)phosphines and Chromeno[2′,3′:4,5]pyrimido[2,1‐d][1,3,5,2]triazaphosphinine

Novel chromeno[2,3‐d]pyrimidinyl and bis(chromeno[2,3‐d]pyrimidinyl)phosphines and chromeno[2′,3′:4,5]pyrimido[2,1‐d][1,3,5,2]triazaphosphinine were obtained in a simple one‐pot procedure via treatment of 2‐imino‐2H‐chromene‐3‐carboxamide with phenyl phosphorus isothiocyanates. Possible reaction mechanisms were proposed. The structures of the obtained products were confirmed by elemental analyses and spectral tools.     

Silylhydrazine und dimere N,N′‐Dilithium‐N,N′‐bis(silyl)hydrazide – Synthesen,Reaktionen, Isomerisierungen

Silylhydrazines and Dimeric N,N′‐Dilithium‐N,N′‐bis(silyl)hydrazides – Syntheses, Reactions, Isomerisations Di‐tert.‐butylchlorosilane reacts with dilithiated hydrazine in a molar ratio to give the N,N′‐bis(silyl)hydrazine, [(Me₃C)₂SiHNH]₂, ( 5 ). Isomeric tris(silyl)hydrazines, N‐difluorophenylsilyl‐N′,N′‐bis(dimethylphenylsilyl)hydrazine ( 7 ) and N‐difluorophenylsilyl‐N,N′‐bis(dimethylphenylsilyl)hydrazine ( 8 ) are formed in the reaction of N‐lithium‐N′‐N′‐bis(dimethylphenylsilyl)hydrazide and F₃SiPh. Isomeric bis(silyl)hydrazines, (Me₃C)₂SiFNHNHSiMe₂Ph ( 9 ) and (Me₃C)₂‐ SiF(PhMe₂Si)N–NH₂ ( 10 ) are the result of the reaction of di‐tert.‐butylfluorosilylhydrazine and ClSiMe₂Ph in the presence of Et₃N. Quantum chemical calculations for model compounds demonstrate the dyotropic course of the rearrangement. The monolithium derivative of 5 forms a N‐lithium‐N′,N′‐bis(silyl)hydrazide ( 11 ). The dilithium salts of 5 ( 13 ) and of the bis(tert.‐butyldiphenylsilyl)hydrazine ( 12 ) crystallize as dimers with formation of a central Li₄N₄ unit. The formation of 12 from 11 occurs via a N′ → N‐silyl group migration. Results of crystal structure analyses are reported.     

Alcohol‐Induced C−N Bond Cleavage of Cyclometalated N‐Heterocyclic Carbene Ligands with a Methylene‐Linked Pendant Imidazolium Ring

Reaction of the pentamethylcyclopentadienyl rhodium iodide dimer [Cp*RhI₂]₂ with 1,1′‐diphenyl‐3,3′‐methylenediimidazolium diiodide in non‐alcohol solvents, in the presence of base, led to the formation of bis‐carbene complex [Cp*Rh(bis‐NHC)I]I (bis‐NHC=1,1′‐diphenyl‐4,4′‐methylenediimidazoline‐5,5′‐diylidene). In contrast, when employing alcohols as the solvent in the same reaction, cleavage of a methylene C?N bond is observed, affording ether‐functionalized (cyclometalated) carbene ligands coordinated to the metal center and the concomitant formation of complexes with a coordinated imidazole ligand. Studies employing other 1,1′‐diimidazolium salts indicate that the cyclometalation step is a prerequisite for the activation/scission of the C?N bond and, based on additional experimental data, a S_N2 mechanism for the reaction is tentatively proposed.     

Synthesis and Crystal Structure of 4,4′‐(Methylenediimino)bis‐1,2,5‐Oxadiazole‐3‐carboxylic Acid and Carboxamide

4,4′‐(Methylenediimino)bis‐1,2,5‐oxadiazole‐3‐carboxylic acid and 4,4′‐(methylenediimino)bis‐1,2,5‐oxadiazole‐3‐carboxamide have been synthesized by the acid‐catalyzed condensation of 4‐amino‐1,2,5‐oxadiazole‐3‐carboxylic acid and 4‐amino‐1,2,5‐oxadiazole‐3‐carboxamide with formaldehyde. The crystal and molecular structures of the compounds have been determined by X‐ray crystallography. 4,4′‐(Methylenediimino)bis‐1,2,5‐oxadiazole‐3‐carboxylic acid crystallizes in space group C2/c, and its measured density is 1.800 g/mL, significantly above the calculated value of 1.68 g/mL. 4,4′‐(Methylenediimino)bis‐1,2,5‐oxadiazole‐3‐carboxamide crystallizes in space group P2₁/c, and its measured density is 1.623 g/mL, in close agreement with the calculated value of 1.64 g/mL. The structure of the starting amide 4‐amino‐1,2,5‐oxadiazole‐3‐carboxamide has also been determined. These data, combined with literature data, suggest that ortho‐aminocarboxylic acids have unusually high densities, but the reasons for this are unclear.     

Functionalized 3,3′,5,5′‐Tetraaryl‐1,1′‐Biphenyls: Novel Platforms for Molecular Receptors

This paper describes the development of novel aromatic platforms for supramolecular construction. By the Suzuki cross‐coupling protocol, a variety of functionalized m‐terphenyl derivatives were prepared (Schemes 1–4). Macrolactamization of bis(ammonium salt) (S,S)‐ 6 with bis(acyl halide) 7 afforded the macrocyclic receptor (S,S)‐ 2 (Scheme 1), which was shown by ¹H‐NMR titration studies to form ‘nesting' complexes of moderate stability (K_a between 130 and 290 M ^?1, 300 K) with octyl glucosides 13 – 15 (Fig. 2) in the noncompetitive solvent CDCl₃. Suzuki cross‐coupling starting from 3,3′,5,5′‐tetrabromo‐1,1′‐biphenyl provided access to a novel series of extended aromatic platforms (Scheme 5) for cleft‐type (Fig. 1) and macrotricyclic receptors such as (S,S,S,S)‐ 1 . Although mass‐spectral evidence for the formation of (S,S,S,S)‐ 1 by macrolactamization between the two functionalized 3,3′,5,5′‐tetraaryl‐1,1′‐biphenyl derivatives (S,S)‐ 33 and 36 was obtained, the ¹H‐ and ¹³C‐NMR spectra of purified material remained rather inconclusive with respect to both purity and constitution. The versatile access to the novel, differentially functionalized 3,3′,5,5′‐tetrabromo‐1,1′‐biphenyl platforms should ensure their wide use in future supramolecular construction.     

2,2‐Bis(methoxy‐NNO‐azoxy)ethyl Derivatives of 4,8‐Dihydro‐bis‐furazano[3,4‐b:3′4′‐e]pyrazine: The Synthesis and X‐ray Investigation

The first synthesis of 4,8‐dihydro‐bis‐furazano[3,4‐b:3′4′‐e]pyrazine bearing 2,2‐bis(methoxy‐NNO‐azoxy)ethyl groups has been developed. These compounds are obtained by aza‐Michael reaction of 1,1‐bis(methoxy‐NNO‐azoxy)ethene or its equivalents, such as 2,2‐bis(methoxy‐NNO‐azoxy)ethanol derivatives, with 4,8‐dihydro‐bis‐furazano[3,4‐b:3′4′‐e]pyrazine.     

Synthesis,Modification, and Anticonvulsant Activity of 3′‐R1‐Spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′(7′H)‐diones Derivatives

Previously unknown 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazoline]‐2,2′‐(7′H)‐diones and their N‐substituted analogues were obtained via reaction of 6‐R¹‐3‐(2‐aminophenyl)‐1,2,4‐triazin‐5‐ones with isatin and its substituted derivatives. It was shown that alkylation of 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′‐(7′H)‐diones by N‐R³‐chloroacetamides or chloroacetonitrile in the presence of а base proceeds by N‐1 atom of isatin fragment. The spectral properties (¹H and ¹³C NMR spectra) of synthesized compounds were studied, and features of spectral patterns were discussed. The high‐effective anticonvulsant and radical scavenging agents among 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′(7′H)‐diones and their N‐substituted derivatives were detected. It was shown that compounds 2.2 , 2.8 , and 3.1 exceed or compete the activity of the most widely used in modern neurology drug—lamotrigine on the pentylenetetrazole‐induced seizures model. The aforementioned fact may be considered as a reason for further profound study of synthesized compounds using other pathology models.     

Syntheses of multicyclic poly(ether sulfone)s from 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane and 4,4′‐bis(4‐chlorophenyl) sulfones

5,5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane (TTSBI) was polycondensed with 4,4′‐dichlorodiphenyl sulfone (DCDPS) or with 4,4′‐bis(4‐chlorophenyl sulfonyl) biphenyl (BCSBP) in DMSO. Concentration and feed ratio were optimized to avoid gelation and to obtain a maximum yield of multicyclic polyethers free of functional groups. Regardless of these reaction conditions, only low fractions of perfect multicycles were obtained from DCDPS apparently due to steric hindrance of ring closure. Under the same conditions high fractions of perfect multicycles were achieved with the longer and more flexible DCSBP. The reaction products were characterized by MALDI‐TOF mass spectrometry, ¹H‐NMR spectroscopy viscosity, and DSC measurements. Relatively low glass transition temperatures (T_gs ≈ 160–175 °C) were found. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3732–3739, 2008     

Synthesis of 3‐substituted pyrido[4′,3′:4,5]thieno[2,3‐d]pyrimidines and related fused thiazolo derivatives

Convenient syntheses of 3‐substituted ethyl 4‐oxo‐2‐thioxo‐1,2,3,4,5,6,7,8‐octahydropyrid[4′,3′:4,5]thieno[2,3‐d]pyrimidine‐7‐carboxylates 3a, b, 6, 11–13 , ethyl 3‐methyl‐5‐oxo‐2,3,6,9‐tetrahydro‐5 H‐pyrido[4′,3′:4,5]thieno[2,3‐d][1,3]thiazolo[3,2‐a]pyrimidine‐8‐7H‐carboxylate ( 4 ), and ethyl 2‐methyl‐5‐oxo‐2,3,6,9‐tetrahydro‐5H‐pyrido[4′,3′:4,5]thieno[2, 3‐d][1,3]thiazolo[3,2‐a]pyrimidine‐8[7H]carboxylate ( 8 ) from diethyl 2‐isothiocyanato‐4,5,6,7‐tetrahythieno[2,3‐c]pyridine‐3,6‐dicarboxylate ( 1 ) are reported. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:201–207, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10131     

Di‐μ‐iodo‐bis{[1,1′‐methyl­enebis(3,5‐dimethyl‐1H‐pyrazole‐κN2)]copper(I)}

In the title compound, [Cu₂I₂(C₁₁H₁₆N₄)₂], each of the two crystallographically equivalent Cu atoms is tetrahedrally coordinated by two N atoms from one 1,1′‐methyl­ene­bis(3,5‐di­methyl‐1H‐pyrazole) ligand and two bridging iodide anions. The mol­ecule has a crystallographic center of symmetry located at the mid‐point of the Cu·Cu line. One H atom of the CH₂ group of the 1,1′‐methyl­ene­bis(3,5‐di­methyl‐1H‐pyrazole) ligand interacts with an iodide ion in an adjacent mol­ecule to afford pairwise intermolecular C—H·I contacts, thereby forming chains of mol­ecules running along the [101] direction.     

The amplified circularly polarized luminescence emission response of chiral 1,1′‐binaphthol‐based polymers via Zn(II)‐coordination fluorescence enhancement

Two kinds of chiral 1,1′‐binaphthol (BINOL)‐based polymer enantiomers were designed and synthesized by the polymerization of 5,5′‐((2,2′‐bis (octyloxy)‐[1,1′‐binaphthalene]‐3,3′‐diyl)bis(ethyne‐2,1‐diyl))bis(2‐hydroxybenzaldehyde) ( M1 ) with alkyl diamine ( M2 ) via nucleophilic addition–elimination reaction. The resulting chiral polymers can exhibit mirror image cotton effects either in the absence or in the presence of Zn²⁺ ion. Almost no fluorescence or circularly polarized luminescence (CPL) emission could be observed for two chiral BINOL‐based polymer enantiomers in the absence of Zn²⁺. Interestingly, the chiral polymers can show strong fluorescence and CPL response signals upon the addition of Zn²⁺, which can be attributed to Zn²⁺‐coordination fluorescence enhancement effect. This work can develop a new strategy on the design of the novel CPL materials via metal‐coordination reaction. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1282–1288     

Efficient asymmetric addition of diethylzinc to aldehydes using C2‐novel chiral pyridine β‐amino alcohols as chiral ligands

A series of novel C₂‐symmetric chiral pyridine β‐amino alcohol ligands have been synthesized from 2,6‐pyridine dicarboxaldehyde, m‐phthalaldehyde and chiral β‐amino alcohols through a two‐step reaction. All their structures were characterized by ¹H NMR, ¹³C NMR and IR. Their enantioselective induction behaviors were examined under different conditions such as the structure of the ligands, reaction temperature, solvent, reaction time and catalytic amount. The results show that the corresponding chiral secondary alcohols can be obtained with high yields and moderate to good enantiomeric excess. The best result, up to 89% ee, was obtained when the ligand 3c (2S,2′R)‐2,2′‐((pyridine‐2,6‐diylbis(methylene))bisazanediyl))bis(4‐methyl‐1,1‐diphenylpentan‐1‐ol) was used in toluene at room temperature. The ligand 3g (2S,2′R)‐2,2′‐((1,3‐phenylenebis(methylene))bis(azanediyl))bis(4‐methyl‐1,1‐diphenylpentan‐1‐ol) was prepared in which the pyridine ring was replaced by the benzene ring compared to 3c in order to illustrate the unique role of the N atom in the pyridine ring in the inductive reaction. The results indicate that the coordination of the N atom of the pyridine ring is essential in the asymmetric induction reaction. Copyright © 2014 John Wiley & Sons, Ltd.     

Maximum Compaction of Ionic Organic Explosives: Bis(hydroxylammonium) 5,5′‐Dinitromethyl‐3,3′‐bis(1,2,4‐oxadiazolate) and its Derivatives

Within this contribution on bis(oxadiazoles) we report on bis‐hydroxylammonium 5,5′‐dinitro‐methyl‐3,3′‐bis(1,2,4‐oxadiazolate), which (to the best of our knowledge) shows the highest density (2.00 g cm^?3 at 92 K, 1.95 g cm^?3 at RT) ever reported for an ionic CHNO explosive. Also the corresponding bis(ammonium) salt shows an outstanding density of 1.95 g cm^?3 (173 K). The reaction of the 3,3′‐bis(1,2,4‐oxadiazolyl)‐5,5′‐bis(2,2′‐dinitro)‐diacetic acid diethyl ester with different nitrogen‐rich bases, such as ammonia, hydrazine, hydroxylamine, and triaminoguanidine causes decarboxylation followed by the formation of the corresponding salts (cation/anion stoichiometry 2:1). The reactions are performed at ambient temperature in H₂O/MeOH mixtures and furnish qualitatively pure products showing characteristics of typical secondary explosives. The obtained compounds were characterized by multinuclear NMR spectroscopy, IR and Raman spectroscopy, as well as mass spectrometry. Single‐crystal X‐ray diffraction studies were performed and the structures of all compounds were determined at low temperatures. The thermal stability was measured by differential scanning calorimetry (DSC). The sensitivities were explored by using the BAM drophammer and friction test. The heats of formation were calculated by the atomization method based on CBS‐4M enthalpies. With these values and the X‐ray densities, several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code.     

Kristallstrukturen und spektroskopische Eigenschaften von 2λ3‐Phospha‐1, 3‐dionaten und 1, 3‐Dionaten des Calciums ‐ ein Vergleich am Beispiel der 1, 3‐Diphenyl‐ und 1, 3‐Di(tert‐butyl)‐Derivate

Crystal Structures and Spectroscopic Properties of 2λ³‐Phospha‐1, 3‐dionates and 1, 3‐Dionates of Calcium ‐ Comparative Studies on the 1, 3‐Diphenyl and 1, 3‐Di(tert‐butyl) Derivatives A hydrogen‐metal exchange between dibenzoylphosphane and calcium carbide in tetrahydrofuran (THF) followed by addition of the ligand 1, 3, 5‐trimethyl‐1, 3, 5‐triazinane (TMTA) furnishes the binuclear complex bis[(tmta‐N, N′, N″)calcium bis(dibenzoylphosphanide)] ( 1a ) co‐crystallizing with benzene. Similarly, reaction of bis(2, 2‐dimethylpropionyl)phosphane with bis(thf‐O)calcium bis[bis(trimethylsilyl)amide] in 1, 2‐dimethoxyethane (DME) gives bis(dme‐O, O′)calcium bis[bis(2, 2‐dimethylpropionyl)phosphanide] ( 1b ) in high yield. The carbon analogues 1, 3‐diphenylpropane‐1, 3‐dione (dibenzoylmethane) or 2, 2, 6, 6‐tetramethylheptane‐3, 5‐dione (dipivaloylmethane) and bis(thf‐O)calcium bis[tris(trimethylsilylmethyl)zincate] in DME afford bis(dme‐O, O′)calcium bis(dibenzoylmethanide) ( 2a ) and the binuclear complex (μ‐dme‐O, O′)bis[(dme‐O, O′)calcium bis(dipivaloylmethanide)] ( 2b ), respectively. Dialkylzinc formed during the metalation reaction shows no reactivity towards the 1, 3‐dionates 2a and 2b . Finally, from the reaction of the unsymmetrically substituted ligand 2‐(methoxycarbonyl)cyclopentanone and bis(thf‐O)calcium bis[bis(trimethylsilyl)amide] in toluene, the trinuclear complex 3 is obtained, co‐crystallizing with THF. The β‐ketoester anion bridges solely via the cyclopentanone unit.     

Synthesis,crystal structure and magnetic properties of (acetato‐κ2O,O′)bis(5,5′‐dimethyl‐2,2′‐bipyridine‐κ2N,N′)nickel(II) perchlorate monohydrate

The title hydrated ionic complex, [Ni(CH₃COO)(C₁₂H₁₂N₂)₂]ClO₄·H₂O or [Ni(ac)(5,5′‐dmbpy)₂]ClO₄·H₂O (where 5,5′‐dmbpy is 5,5′‐dimethyl‐2,2′‐bipyridine and ac is acetate), (1), was isolated as violet crystals from the aqueous ethanolic nickel acetate–5,5′‐dmbpy–KClO₄ system. Within the complex cation, the Ni^II atom is hexacoordinated by two chelating 5,5′‐dmbpy ligands and one chelating ac ligand. The mean Ni—N and Ni—O bond lengths are 2.0628 (17) and 2.1341 (15) Å, respectively. The water solvent molecule is disordered over two partially occupied positions and links two complex cations and two perchlorate anions into hydrogen‐bonded centrosymmetric dimers, which are further connected by π–π interactions. The magnetic properties of (1) at low temperatures are governed by the action of single‐ion anisotropy, D, which arises from the reduced local symmetry of the cis‐NiO₂N₄ chromophore. The fitting of the variable‐temperature magnetic data (2–300 K) gives g_iso = 2.134 and D/hc = 3.13 cm⁻¹.     

Axially Dissymmetric Chiral (R)‐N,W‐Bis(2‐hydroxy‐3,5‐ditert‐butyl‐arylmethyl)‐1, 1′‐binaphthalene‐2,2′‐diamine as Chiral Ligands in the Reaction of Diethylzinc to Aldehydes†

Chiral ligand (A)‐N,N′‐Bis(2‐hydroxy‐3,5‐di‐tert‐butyl‐arylmethyl)‐1,1′‐binaphthalene‐2,2′‐diamine derived from the reduction of Schiff base (R)‐2,2′‐bis (3,5‐di‐tert‐butyl‐2‐hydroxybenzylideneamino)‐1, 1′‐binaphthyl with LiAlH₄, is fairly effective in the asymmetric addition reaction of diethylzinc to aldehydes by which good yields (46%‐94%) of the corresponding sec‐alcohols can be obtained in moderate ee (51%‐79%) with R configuration for a variety of aldehydes.