Aluminum Complexes Stabilized by Piperazidine‐Bridged Bis(phenolate) Ligands: Syntheses,Structures, and Application in the Ring‐Opening Polymerization of ε‐Caprolactone

The synthesis and characterization of aluminum alkoxide and alkyl complexes stabilized by piperazidine‐bridged bis(phenolate) ligands are described. Treatment of ligand precursors H₂[ONNO]¹ {H₂[ONNO]¹=1,4‐bis(2‐hydroxy‐3‐tert‐butyl‐5‐methylbenzyl)piperazidine} and H₂[ONNO]² {H₂[ONNO]²=1,4‐bis(2‐hydroxy‐3,5‐di‐tert‐butylbenzyl)piperazidine} with AlEt₂(OCH₂Ph) and AlEt₂(OPr‐i), which were generated in situ by the reactions of AlEt₃ with equivalent of the corresponding alcohols, in a 1:1 molar ratio in THF gave the corresponding aluminum alkoxide complexes [ONNO]¹Al(OCH₂Ph) ( 1 ) and [ONNO]²Al(OPr‐i) ( 2 ), respectively. The reaction of H₂[ONNO]¹ with AlEt₂(OCH₂Ph) in a 1:2 molar ratio in THF afforded a mixture of monometallic aluminum ethyl complex [ONNO]¹AlEt ( 3 ) and complex 1 , which can be isolated by stepwise crystallization. Similarly, H₂[ONNO]² reacted with AlEt₂(OPr‐i) in a 1:2 molar ratio in THF to give a mixture of aluminum ethyl complex [ONNO]²AlEt ( 4 ) and complex 2 . Complexes 1 and 2 were also available via treatment of complexes 3 and 4 with 1 equiv. of benzyl alcohol and isopropyl alcohol, respectively. All of these complexes were fully characterized including X‐ray structural determination. It was found that complexes 1 to 4 can initiate the ring‐opening polymerization of ε‐caprolactone, and complexes 1 and 2 showed higher catalytic activity in comparison with complexes 3 and 4 .     

Dielectric anomaly and giant deuteration effect in a H-bond trimeric co-crystal [4, 4'-Bipyridine]2[1,4-dihydroxybenzene]

Co-crystal [4,4?-bipyridine]₂[1,4-dihydroxybenzene] (1) was prepared by evaporating methanol solution of 4,4?-bipyridine with 1,4-dihydroxybenzene at 4°C. 1 shows a fascinating dielectric anomaly with a maximum at ~210 K, which is independent on ac frequency. However, the absence of thermal anomaly and structural phase transition is related to the dielectric anomaly. The co-crystal [4,4?-bipyridine]₂[1,4-dihydroxybenzene-d₂] (2) was further obtained via H⁺/D⁺ exchange in 1 and the deuteration gives rise to the maximum shifting to 254 K in the dielectric spectrum of 2. The dielectric anomaly corresponds to disorder-to-order transformation of H⁺/D⁺ in the O–H/D···N H-bond in 1 and 2.     

Phosphites and Hexafluoroacetone-Hexafluoroacetylacetones: a Comparison

Abstract

Selected acyclic and cyclic phosphites (RO)₂PX (1-5) were reacted with activated ketones (CF₃)₂CO (6) and Z-CF₃C(O)CH=C(OH)CF₃ (7a) / E-CF₃C(O)CH=C(OSiMe₃)CF₃ (7b) in order to study the influence of R and X on the product formation. A new type of insertion, a 1,4 group shift and cyclo-addition reactions yielding five membered rings and bicyclic fused systems were observed. In most cases phosphonates and their λ⁵[sgrave]⁵ P derivatives were obtained. The ketones in question can be considered versatile reactants in phosphorus chemistry.     

Synthesis and Reactions of Some New Benzo[a]phenothiazine‐3,4‐dione Derivatives

The reaction of 2,3‐dihydro‐2,3‐epoxy‐1,4‐naphthoquinone ( 4 ) with substituted anilines furnished the corresponding benzo[fused]heterocyclic derivatives 5 , 6 , 6a , 6b , 7 , 8 . Furthermore, treatment of benzo[a]phenothiazine derivative 7 with halo compounds, namely, ethyl bromoacetate, phenacyl bromide, dibromoethane, or chloroacetone afforded ether derivatives 11 , 12 , 13 , 14 , respectively. Moreover, the reaction of 11 with o‐substituted aniline gave the corresponding benzo[a]phenothiazin‐5‐one derivatives 15 , 16 , 17 and benzo[d][1,3]oxazin‐4‐one 18 , respectively. Finally, the chromenone derivative 19 was synthesized via the reaction of ester derivative 11 with salicyaldhyde in refluxing pyridine. The newly synthesized compounds were characterized by spectroscopic measurements (IR, ¹H NMR, ¹³C NMR, and mass spectra).     

用扩展的Istomin-Palm模型估算双向延伸化合物R1-Y-R2生成焓

Istomin和Palm曾提出用模型Δ_fH⁰(RX)=h[R]+h[X]+φ[R]φ[X](式中h[R]和h[X]分别为烷基R 和取代基X对单取代烷烃生成焓Δ_fH⁰(RX)的贡献, φ[R]φ[X]则表示R与X之间的相互作用对Δ_fH⁰(RX)的贡献)来表示单取代烷烃生成焓Δ_fH⁰(RX). 对于双向延伸化合物R1-Y-R2, 其取代基Y位于分子链的中间, 与两个烷基(R1和R2)相连. 此类化合物分子内取代基与烷基之间的相互作用, 较单取代烷烃的相比更为复杂. 因此, Istomin-Palm模型在R1-Y-R2体系中应用必须进行修正. 本文把取代基Y、烷基R1和R2三者之间的相互作用对R1-Y-R2类化合物生成焓Δ_fH⁰(R1-Y-R2)的贡献分为三部分: R1Y与R2之间的相互作用(φ[R2]φ[R1Y]), YR2与R1之间的相互作用(φ[R1]φ[YR2]), 以及两烷基R1与R2之间的相互作用(ψ[R1]ψ[R2]). 用以上三项替换φ[R]φ[X], 扩展Istomin-Palm模型, 建立一个新的经验模型Δ_fH⁰(R1-Y-R2)=h[R1]+h[R2]+h[Y]+φ[R1]φ[YR2]+φ[R2]φ[R1Y]+ψ[R1]ψ[R2], 来表示Δ_fH⁰(R1-Y-R2)(式中h[R1]、h[R2]和h[Y]分别为烷基R1、R2和取代基Y对Δ_fH⁰(R1-Y-R2)的贡献, 后三项则表示烷基R1、R2和取代基Y两两之间相互作用对Δ_fH⁰(R1-Y-R2)的贡献). 进而, 采用本研究组最近报道的相互作用势指数IPI(X)(Wu, Y. X.; Cao, C. Z.; Yuan, H. Chin. J. Chem. Phys. 2012,25 (2), 153.)表示取代基Y对烷基的固有作用(φ[Y]), 从而建立两个定量估算生成焓的通用模型. 其中, 一个用于估算硫醚、仲胺、醚和酮类化合物生成焓, 另一个用于估算酯类化合物生成焓. 这两个模型均得到良好的结果, 与采用G3和G3MP2方法相比具有同样的精度, 还可以避免大量繁琐的计算.     

CHLOROSULPHONATION OF 2-ANILINO-1,4-NAPHTHOQUINONE AND SYNTHESIS OF NEWER SULPHONYL DERIVATIVES

Synthesis of 2-anilino-1,4-napthoquinone-3-sulphonyl chloride (2) was achieved from the reaction of the title compound with chlorosulphonic acid. The interesting derivative 2 was used as a building block for synthesis of the sulphonyl derivatives 3–24. All these sulphonyl derivatives were characterized by the physical and spectral data (IR, Mass, ¹H- and ¹³C NMR spectra).     

Synthesis of Lewis a and Lewis X Pentasaccharides Based on N-Trichloroethoxycarbonyl Protection 1

Abstract

Thexyldimethylsilyl 4,6-O-benzylidene-2-deoxy-2-trichloroethoxycarbonylamino-β-D- glucopyranoside (4), having the 3-hydroxy group unprotected, is a versatile starting material for the synthesis of glucosamine containing oligosaccharides. Thus, reaction with galactosyl donor 5 or fucosyl donor 6 afforded the desired β(1-3)- and α(1-3)-linked disaccharides 7 and 8, respectively, in high yields. Reductive opening of the benzylidene moieties in 7 and 8 gave access to the 4-hydroxy groups in 9 and 10. Ensuing fucosylation of 9 or galactosylation of 10 led to Lewis A (Le^a) and Lewis X (Le^x) trisaccharide building blocks 13 and 14, respectively. Their transformation into glycosyl donors 19 and 20 and subsequent reaction with 3b-O-unprotected lactose derivative 23 as acceptor furnished the Le^a? and Le^x pentasaccharide precursors 24 and 25. Exchange of the N-trichloroethoxycarbonyl group for an N-acetyl group and removal of the O-benzyl and O-acetyl protective groups afforded the desired Le^a? and Le^x? pentasaccharides 1 and 2.

     

Insight into the Reaction of a Dinuclear Phosphinidene Complex with Nitriles

The phosphinidene complex [Cp*P{W(CO)₅}₂] ( 1 ; Cp*=C₅Me₅) reacted with malononitrile to give the 1,2‐dihydro‐1,3,2‐diazaphosphinine derivative 2 . The reaction of 1 with 1,4‐benzodinitrile gave [1,4‐{{W(CO)₅}₂P‐N=C(Cp*)}₂(C₆H₄)] ( 3 ), the first example of a cumulene‐like aminophosphinidene complex. The reaction of 1 with aniline gave the aminophosphinidene complex [(Ph)N(H)P{W(CO)₅}₂] ( 4 ). To compare the reactivity of benzonitrile and aniline with 1 , the phosphinidene complex 1 was reacted with three different isomers of aminobenzonitrile (2‐, 3‐, and 4‐aminobenzonitrile). These reactions gave an insight into the reaction pathway of 1 with benzonitrile derivatives. Compounds 5 , 6 a , 6 b , and 7 , which are derivatives of 1,2‐dihydro‐1,3,2‐diazaphosphinine or benzo‐2H‐1,2‐azaphospholes, were, as well as all other products, characterized by mass spectrometry, NMR and IR spectroscopy, and X‐ray structure analysis.     

Pyrimidinthiones (Part I): Utility of 2-Thioxopyrimidin-6-(1H)ones as Ring Transformer in the Synthesis of Fused Bi- and Tri-Cyclic Heterocyclic Compounds and Their Potential Biological Activities

The pyrimidinethiones have wide biological and pharmaceutical activities, that have attracted considerable interest in recent years especially as antiviral inhibiting production of hepatitis B virus (HBV), and in vitro insulin-mimetic. Activity of the complexes of pyrimidinone derivatives evaluated from 50% inhibitory concentration promoted us to study the transformation of the 2-thioxopyrimidin-6(1H) ones to fused bi- and tri-cyclic heterocyclic compounds having the pyrimidine moieties and screening their biological activity.

The reactivity of 2-mercapto-4-aryl-5-cyanopyrimidin-6(1H)ones (1) towards alkylation by different mono and bifunctional halo-organic compounds has been investigated to give S-monoalkylated products 2, 7 and 9; S- and N-dialkylated products 3, 13 and 14. Treatment of 1 and/or 2 with hydrazine hydrate as a nitrogen nucleophile have been investigated to give 4, treatment of 4 with CS₂ and sodium nitrite in the presence of acetic acid (0°C) produced 1,2,4-triazolopyrimidin-5(1H)one derivatives (5)and tetrazolo[1,5-a]pyrimidin-5(1H)ones (6), respectively. Also cyclization of 7 and 9 gave [1,3]thiazolo[3,2-a]pyrimidin-5(1H)one and [1,3]thiazolo[3,2-a]pyrimidin-3,5-dione derivatives 8 and 10 respectively, treatment of 10 with aromatic aldehyde produces 11 which reacted with guanidine HCl to give pyrimido[4,5-d]thiazolo[3,2-a]pyrimidin-6(1H)one derivative 12. Reaction of 14 with o-phenylenediamine was investigated and gave [1,4]quinoxalino[2,3-b][1,3]thiazolo[3,2-a]pyrimidin-9(1H)one derivative 15.     

Research on nitrogen containing heterocyclic compounds. XIX: Synthesis of 8H-imidazo[2,1-c]-s-triazolo[4,3-a]-[1,4]benzodiazepine and its 1-derivatives

Reaction of 2-nitrobenzyl iodide with 1H-imidazole, in the presence of potassium tert-butoxide and 18-crown-6, gave 1-(2-nitrobenzyl)-1H-imidazole. Trichloroacetylation of this compound furnished trichloroacet-ylimidazole 8 , which on treatment with sodium ethoxide was transformed into the corresponding ethoxycarbonyl derivative 9 . Catalytic reduction of the nitro group to the amino group yielded 10 , which was then cyclized to 10,11-dihydro-11-oxo-5H-imidazo[2,1-c][1,4]benzodiazepine 11. Treatment of this lactam with di-4-morpholinylphosphinic chloride followed by reaction of the intermediate 12 with formylhydrazine gave the title compound or its 1-derivatives when acetylhydrazine or isonicotinoylhydrazine were used instead of formylhydrazine.     

Utilization of 2-substituted 3, 1-benzoxazin-4-ones in synthesis of some quinazoline annulated derivatives

Abstract

In this study, a new series of quinazoline and their annulated derivatives have been synthesized. A number of quiazolinone derivatives substituted at position-3 were prepared from 3, 1-benzoxazinone by the treatment of 3,1-benzoxazinone with different nitrogen nucleophiles such as, hydrazine hydrate, phenylhydrazine, ethanolamine, and cyano acetohydrazide afforded the quinazolinone derivatives 7–11. The reaction of hydrazide derivative 5 with aromatic aldehydes gave the Schiff’s bases derivative 16a–c. Some of the synthesized compounds were tested against the breast cancer cell line (MCF-7). The structures of all the newly synthesized compounds were established based on IR, ¹H, ¹³C NMR, mass spectral data, and elemental analyses.     

Sulfur ylides. 11. Selected chemical transformations of 1-methylthio-3,4-dihydropyrido[2,1-a]isoindole-2,6-dione

The reaction of 1-methylthio-3,4-dihydropyrido[2,1-a]isoindole-2,6-dione (2) with NaBH₄ led to reduction of the keto group to the hydroxy group. The reaction with the use of LiAlH₄ resulted in complete reduction of the carboximide group, reduction of the keto group to the hydroxy function, and reduction of the double bond accompanied by desulfurization. The reaction of indolizidinedione 2 with Zn afforded a reductive desulfurization product. The reactions of 2 with hydrazine hydrate, hydroxylamine, and formamide proceeded according to a mechanism typical of the keto group to give hydrazone, oxime, and the formyl derivative, respectively. Oxidation of the thiomethyl group of the starting compound with Bu^tOOH gave rise to sulfone or sulfoxide depending on the amount of the oxidizing agent used.     

Simons electrochemical fluorination of substituted homopiperazines(hexahydro-1,4-diazepines) and piperazines

Simons electrochemical fluorination (ECF) of 1,4-dimethyl-1,4-homopiperazine, methyl 4-ethylhomopiperazin-1-ylacetate and 1,4-bis(methoxycarbonylmethyl)-1,4-homopiperazine was studied. For comparison, ECF of three piperazines with a N-(methoxycarbonylmethyl) group(s) was also studied. ECF of 1,4-dimethyl-1,4-homopiperazine gave a low yield of corresponding perfluoro(1,4-dimethyl-1,4-homopiperazine) together with perfluoro(2,6-diaza-2,6-dimethylheptane) as the major product. Corresponding perfluoro(homopiperazines) with mono- and/or di-(fluorocarbonyldifluoromethyl) groups [CF₂C(O)F] at the 1- and/or 4-position were formed in low yields from methyl 4-ethylhomopiperazin-1-ylacetate and 1,4-bis(methoxycarbonylmethyl)-1,4-homopiperazine, respectively. These new seven-membered perfluoro(1,4-dialkyl-1,4-homopiperazines) were accompanied by the formation of mono- and/or di-basic linear perfluoroacid fluorides resulting from the CC bond scission at the 2- and 3-positions of the ring. From mono- and/or di-N-(methoxycarbonylmethyl)-substituted piperazines, corresponding perfluoropeperazines having the acid fluoride group(s) were formed in low yields.     

The ‘Azirine/Oxazolone Approach’ to the Synthesis of Aib‐Pro Endothiopeptides

The reaction of methyl N‐(2,2‐dimethyl‐2H‐azirin‐3‐yl)‐L ‐prolinate ( 2a ) with thiobenzoic acid at room temperature gave the endothiopeptide Bz‐AibΨ[CS]‐Pro‐OMe ( 7 ) in high yield. In an analogous manner, (benzyloxy)carbonyl (Z)‐protected proline was transformed into the thioacid, which was reacted with 2a to give the endothiotripeptide Z‐Pro‐AibΨ[CS]‐Pro‐OMe ( 12 ). The corresponding thioacid of 7 was prepared in situ via saponification, formation of a mixed anhydride, and treatment with H₂S. A second reaction with 2a led to the endodithiotetrapeptide 9 , but extensive epimerization at Pro² was observed. Similarly, saponification of 12 and coupling with either 2a or H‐Phe‐OMe and 2‐(1H‐benzotriazol‐1‐yl)‐1,1,3,3‐tetramethyluronium tetrafluoroborate/1‐hydroxy‐1H‐benzotriazole (TBTU/HOBt) gave the corresponding endothiopeptides as mixtures of two epimers. The synthesis of the pure diastereoisomer BzΨ[CS]‐Aib‐Pro‐AibΨ[CS]‐N(Me)Ph ( 21 ) was achieved via isomerization of 7 to BzΨ[CS]‐Aib‐Pro‐OMe ( 16 ), transformation into the corresponding thioacid, and reaction with N,2,2‐trimethyl‐N‐phenyl‐2H‐azirin‐3‐amine ( 1a ). The structures of 12 and 21 were established by X‐ray crystallography.     

Synthesis and characterization of modular polyphosphonate homopolymers and copolymers

Linear polyphosphonates with the generic formula –[P(Ph)(X)OR′O]_n– (X = S or Se) have been synthesized by polycondensations of P(Ph)(NEt₂)₂ and a diol (HOR′OH = 1,4-cyclohexanedimethanol, 1,4-benzenedimethanol, tetraethylene glycol, or 1,12-dodecanediol) followed by reaction with a chalcogen. Random copolymers have been synthesized by polycondensations of P(Ph)(NEt₂)₂ and mixture of two of the diols in a 2:1:1 mol ratio followed by reaction with a chalcogen. Block copolymers with the generic formula –[P(Ph)(X)OR′O]_{(x + 2)} –[P(Ph)(X)OR′O]_{(x + 3)}– (X = S or Se) have been synthesized by the polycondensations of Et₂N[P(Ph)(X)OR′O]_{(x + 2)}P(Ph)NEt₂ oligomers with HOR′O[P(Ph)(X)OR′O]_{(x + 3)}H oligomers followed by reaction with a chalcogen. The Et₂N[P(Ph)(X)OR′O]_{(x + 2)}P(Ph)NEt₂ oligomers are prepared by the reaction of an excess of P(Ph)(NEt₂)₂ with a diol while the HOR′O[P(Ph)(X)OR′O]_{(x + 3)}H oligomers are prepared by the reaction of P(Ph)(NEt₂)₂ with an excess of the diol. In each case the excess, x is the same and determines the average block sizes. All of the polymers were characterized using ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopy, TGA, DSC, and SEC. ³¹P{¹H} NMR spectroscopy demonstrates that the random and block copolymers have the expected arrangements of monomers and, in the case of block copolymers, verifies the block sizes. All polymers are thermally stable up to ~300°C, and the arrangements of monomers in the copolymers (block vs. random) affect their degradation temperatures and T_g profiles. The polymers have weight average MWs of up to 3.8 × 10⁴ Da.     

Ionic thermo‐responsive copolymer with multi LCST values: easy and fast LCST‐change through anion exchange

An ionic thermo‐responsive copolymer with multiple lower critical solution temperatures (multi‐LCSTs) has been developed, and the multi‐LCSTs were easily changeable according to the various counter anion types. The multi‐LCST values were achieved by introducing an ionic segment with an imidazolium moiety within the p‐NIPAAm polymer chain to produce poly(NIPAAm‐co‐BVIm) copolymers, [p‐NIBIm]⁺[Br]^?, and changing the counter anion type to produce [p‐NIBIm]⁺[X]^? (X = Cl, AcO, HCO₃, BF₄, CF₃SO₃, PF₆, SbF₆). The as‐prepared temperature‐responsive copolymers were physicochemically characterized via proton nuclear magnetic resonance spectroscopy (¹H‐NMR), Fourier‐transform infrared, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. Their various LCST values, micelle sizes, and surface charges were determined using an Ultraviolet‐visible spectrophotometer and a Zeta (ξ) sizer, which were fitted with temperature and stirring control. The copolymers showed a broad LCST spectrum between 39°C and 52°C. The Zeta (ξ) potential values at a pH = 7 decreased from about +9.7 for [p‐NIBIm]⁺[X]^? (X = Cl ≈ Br) to about +2.0 mV for [p‐NIBIm]⁺[X]^? (X = PF₆ ≈ SbF₆). The micelle size (or volume) of the copolymers with different anionic species gradually increased from 181.2 nm (or 2.49 × 10^?17 cm^?3) for [p‐NIBIm]⁺[Br]^? to 229.2 nm (or 5.04 × 10^?17 cm^?3) for [p‐NIBIm]⁺[CF₃SO₃]^?, showing a clear effect of the anion on the micelle size (or volume) at a constant temperature, such as body temperature. The fact that the most important physicochemical properties for the thermo‐responsive copolymers, such as the LCST value, micelle size (or volume), and surface charge, could be easily controlled only through the anion exchange suggests these are highly applicable as ionic thermo‐responsive copolymers in a drug (or gene, protein) delivery system. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and Stereochemical Studies of Derivatives of 1,4-Dimethyl-2-phosphabicyclo[2.2.1]heptane

Abstract

1,4-Dimethyl-2-phenyl-2-phosphabicyclo[2.2.1]heptane 2-oxide 1 was prepared by the reaction of 2,5-dimethyl-1,5-hexadiene with PhPCl₂-AlCl₃: stereo-assignments of the exo and endo isomers were established by ¹³C NMR spectroscopy (using lanthanide shift reagents) and by x-ray crystal structures. The isomers of 1 were separately reduced (phenylsilane) to give the phosphine derivative; in turn the phosphines were thermally equilibrated at 190°C to give a predominance (70%) of the exo-phenyl isomer.     

Radical cations of 1,4-dialkoxybenzenes and alkyl 1,4-dialkoxybenzenes generated through one-electron oxidation by perfluorodiacyl peroxides

Radical cations of 1,4-dialkoxybenzenes 1 and 2 and alkyl 1,4-dialkoxybenzenes 3–9 generated in oxidation of the parent donors by perfluorodi[1-(2-fluorosulfonyl)ethoxy]propionyl peroxide 10 at −40°C and pentafluorobenzoyl peroxide 11 at 15°C were observed by ESR. Radical cation 6^+˙, generated in other oxidation systems, i.e., Ce(SO₄)₂/THF, NH₄/OAc and (NH₄)₂S₂O₈/HOAc, has also been investigated. Based on ESR observation and products analysis, an electron-transfer mechanism of the oxidation reaction is proposed and the influencing factors on hyperfine splitting constants of the radical cations are discussed.     

Transition metal salts of quinoline: synthesis,structure and magnetic behavior of (QuinH)2[MX4]·2H2O [Quin = quinoline; M = Mn,Co, Cu,Zn], (QuinH)2[MnBr2(H2O)2](Br)2 and (QuinH)[Cu(Quin)Br3]

Abstract

A family of compounds of general formula (QuinH)₂MX₄·2H₂O has been prepared and characterized [Quin?=?quinoline; M, X?=?Co,Cl (1); M, X?=?Co,Br (2); M, X?=?Zn,Br (3); M, X?=?Mn,Cl (4)]. The complexes crystallize in the monoclinic space group C2/c as well-isolated layers containing the MX₄^?2 anions and water molecules, separated by the quinolinium cations. The bromide analogue of 4, compound 5 (QuinH)₂[MnBr₂(H₂O)₂](Br)₂, also crystallizes in the C2/c space group, but comprises a co-crystal of manganese bromide dihydrate and quinolinium bromide. The temperature dependent magnetic properties of the complexes are described, along with the tetrachlorocuprate analogue (7). All compounds show weak antiferromagnetic interactions (J/k_B?～?0.06–1.4 K) and good one- or two-dimensional isolation. In addition, the crystal structure of the mixed quinoline/quinolinium complex (QuinH)[Cu(Quin)Br₃] (triclinic, P-1) is reported.     

Reaction of the Pincer‐type Ligand {2, 6‐[P(O)(OEt)2]2‐4‐tert‐Bu‐C6H2}— with [Ph3C]+[PF6]—. Unprecedented Rearrangement and Carbon‐Carbon Bond Formation

The reaction of the organolithium derivative {2, 6‐[P(O)(OEt)₂]₂‐4‐tert‐Bu‐C₆H₂}Li ( 1 ‐Li) with [Ph₃C]⁺[PF₆]^— gave the substituted biphenyl derivative 4‐[(C₆H₅)₂CH]‐4′‐[tert‐Bu]‐2′, 6′‐[P(O)(OEt)₂]₂‐1, 1′‐biphenyl ( 5 ) which was characterized by ¹H, ¹³C and ³¹P NMR spectroscopy and single crystal X‐ray analysis. Ab initio MO‐calculations reveal the intramolecular O···C distances in 5 of 2.952(4) and 2.988(5)Å being shorter than the sum of the van der Waals radii of oxygen and carbon to be the result of crystal packing effects. Also reported are the synthesis and structure of the bromine‐substituted derivative {2, 6‐[P(O)(OEt)₂]₂‐4‐tert‐Bu]C₆H₂}Br ( 9 ) and the structure of the protonated ligand 5‐tert‐Bu‐1, 3‐[P(O)(OEt)₂]₂C₆H₃ ( 1 ‐H). The structures of 1 ‐H, 5 , and 9 are compared with those of related metal‐substituted derivatives.