Preparation and Radical Oligomerization of anFe(II) Complex without Loss of Spin-Crossover Properties

Summary.  11-(4H-1,2,4-Triazol-4-yl)-undecylmethacrylate (1), a new ligand for Fe(II) spin-crossover (SCO) complexes containing a polymerizable group, was synthesized and characterized. The complex [Fe·1 ₃](BF₄)₂ (2) was obtained by reaction of 1 with Fe(BF₄)₂·6H₂O (molar ratio 1/Fe(II) = 3/1) in THF. Complex 2 showed a gradual spin-crossover between 80 and 230 K. The methacrylate units in the ligands of complex 2 could be oligomerized radically in solution (initiator: azoisobutyronitrile) without loss of the spin-crossover behaviour. Received May 30, 2000. Accepted December 10, 2000     

Thiolate-Bridged Diiron(III) Complex with Spin-Crossover Behaviour

The reaction of the ligand HL · (HCl)₂ (HL = 2,6-di(aminomethyl)-4-tert-butyl-thiophenol) with MCl₂ in methanol in the presence of sodium methanolate and air affords the dinuclear complexes [L₃M₂][ClO₄]₃ (M = Fe: 2 , Co: 3 ) in 85% and 68% yield, respectively. Both complexes were characterized by infrared spectroscopy, magnetic susceptibility measurements, and ¹H NMR spectroscopy. By temperature-variable ⁵⁷Fe Mössbauer spectroscopy diamagnetic 2 is shown to exhibit a gradual spin transition between the species [L₃(low-spin-Fe)₂]³⁺ ((ls,ls)- 2 ) and [L₃(high-spin-Fe)₂]³⁺ ((hs,hs)- 2 ). At room temperature the relative concentrations of both species are nearly equal. Well resolved quadrupole doublets at all temperatures for both (ls,ls)- 2 (γ in the range 0.22(1)–0.28(1) mm s^–1) and (hs,hs)- 2 (γ in the range 0.48(1)–0.53(2) mm s^–1) are indicative of a spin conversion time longer than the half-life of the I = ³/₂ state of ⁵⁷Fe. Cyclic voltammetry and square wave voltammetry of 2 in CH₃CN solution reveal four quasi-reversible one-electron transfer processes. The first two processes were assigned to metal-centered reductions of (hs,hs)- 2 and (ls,ls)- 2 , respectively, to yield the mixed-valent species [L₃Fe^IIFe^III]³⁺.     

Electrochemistry and Spin-Crossover Behavior of Fluorinated Terpyridine-Based Co(II) and Fe(II) Complexes

Due to their ability to form stable molecular complexes that have tailor-made properties, terpyridine ligands are of great interest in chemistry and material science. In this regard, we prepared two terpyridine ligands with two different fluorinated phenyl rings on the backbone. The corresponding Co^II and Fe^II complexes were synthesized and characterized by single-crystal X-ray structural analysis, electrochemistry and temperature-dependent SQUID magnetometry. Single crystal X-ray diffraction analyses at 100 K of these complexes revealed Co−N and Fe−N bond lengths that are typical of low spin Co^II and Fe^II centers. The metal centers are coordinated in an octahedral fashion and the fluorinated phenyl rings on the backbone are twisted out of the plane of the terpyridine unit. The complexes were investigated with cyclic voltammetry and UV/Vis-NIR spectroelectrochemistry. All complexes show a reversible oxidation and several reduction processes. Temperature dependent SQUID magnetometry revealed a gradual thermal SCO behavior in two of the complexes, while EPR spectroscopy provided further insights on the electronic structure of the metal complexes, as well as site of reduction.     

Synthesis,Structure and Magnetic Properties of a Novel Nickel(II) Radical Heterospin Complex with Salicylaldoxime

A novel heterospin complex containing both Ni^II and nitroxide radical ligands: [Ni(salox)₂(NIT4Py)₂] ( 1 ) (salox = salicylaldoxime, NIT4Py = 2‐(4′‐pyridyl)‐4,4,5,5‐ tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) has been synthesized and structurally characterized. The structure consists of neutral Ni(salox)₂(NIT4Py)₂ moieties bridged by intermolecular hydrogen bonds, forming a one‐dimensional chain structure. Magnetic measurements show intramolecular antiferromagnetic interactions between NIT4Py and Ni²⁺ ion.     

Spin-Crossover Iron(II) Compounds with Pendent Tetraphenylethylene Group

Two iron(II) compounds with the general formula of [Fe(phen-TPE)₂(NCX)₂] ⋅ Y (phen-TPE=3-(tetraphenylethylene)-1,10-phenanthroline; X=S and Y=2DMF for 1 ⋅ 2DMF ; X=Se and Y=DMF for 2 ⋅ DMF ) were synthesized and characterized by single-crystal X-ray crystallography and magnetic measurements. Both compounds exhibited thermal-induced complete one-step spin-crossover (SCO) behavior with the critical transition temperatures of 210 K and 260 K for 1 ⋅ 2DMF and 2 ⋅ DMF , respectively. The SCO behavior of these two isomorphic compounds depended significantly on robust intermolecular π⋅⋅⋅π interactions, NCX⁻ groups and solvent molecules.     

Toward an Iron(II) Spin-Crossover Grafted Phosphazene Polymer

Two new cyclotriphosphazene ligands with pendant 2,2':6',2″-terpyridine (Terpy) moieties, namely, (pentaphenoxy){4-[2,6-bis(2-pyridyl)]pyridoxy}cyclotriphosphazene (L(1)), (pentaphenoxy){4-[2,6-terpyridin-4-yl]phenoxy}cyclotriphosphazene (L(2)), and their respective polymeric analogues, L(1P) and L(2P), were synthesized. These ligands were used to form iron(II) complexes with an Fe(II)Terpy(2) core. Variable-temperature resonance Raman, UV-visible, and M?ssbauer spectroscopies with magnetic measurements aided by density functional theory calculations were used to understand the physical characteristics of the complexes. By a comparison of measurements, the polymers were shown to behave in the same way as the cyclotriphosphazene analogues. The results showed that spin crossover (SCO) can be induced to start at high temperatures by extending the spacer length of the ligand to that in L(2) and L(2P); this combination provides a route to forming a malleable SCO material.     

Organosulfonate-Modulated Spin-Crossover Behavior in Three Halogen-Functionalized Cobalt(II) Complexes

We present here the syntheses, crystal structures, and spin crossover (SCO) properties of a series of halogen-functionalized cobalt(II) complexes, [Co(Brphtpy)₂](OTf)₂ ⋅ DMF ⋅ 2H₂O ( 1 ), [Co(Brphtpy)₂](HBS)₂ ⋅ H₂O ( 2 ), [Co(Brphtpy)₂](MQ)₂ ⋅ 2MeCN ⋅ 3H₂O ( 3 ) ( Brphtpy =4′–(4-Bromophenyl)–2,2′:6′,2′′-terpyridine; OTf⁻=trifluoromethanesulfonate; HBS⁻=hydroxybenzenesulfonate dihydrate; MQ⁻=methyl orange). Variable-temperature single-crystal X-ray analyses revealed mononuclear compounds of 1 – 3 consisted of [Co(Brphtpy)₂]²⁺ SCO active units and organosulfonate anions and no structural phase transformation happened in measured high-low temperature. The packing structures of these complexes were tuned by varying organosulfonates. However, no notable supramolecular interactions can be found, in turn leading to gradual, incomplete, and non-hysteretic SCO behaviors. Interestingly, the SCO behaviors of these three complexes were significantly modified after the removal of lattice solvents. Combined structural and magnetic investigations revealed the non-cooperative supramolecular packing structures, guest internal pressure, and the small structural distortions of the SCO units should be responsible for the worse SCO properties of 1 – 3 . The foregoing results show that to achieve high-performance Co²⁺ SCO, both the weak interactions, internal pressure, and structural distortion should be considered during the design and construction of SCO complexes.     

四苯乙烯基铂炔化合物的合成及发光性能

以4,4’-二溴二苯甲酮为原料,经缩合反应、Sonogashira偶联等反应合成了化合物3。以三联吡啶与四氯铂酸钾等为原料合成了化合物5,化合物5与化合物3通过Cu(I)催化的脱氯化氢反应得到目标化合物6,产率48%,其结构经¹H NMR,¹³C NMR和HR-MS（ESI）表征。吸收光谱和荧光光谱研究结果表明：化合物3在四氢呋喃/水体系中具有明显的AIE现象;而化合物6在二甲基亚砜/二氯甲烷体系中,随着二氯甲烷含量的增加荧光先增强后淬灭。      

Elucidating the Structural Chemistry of a Hysteretic Iron(II) Spin-Crossover Compound From its Copper(II) and Zinc(II) Congeners

Annealing [FeL₂][BF₄]₂ ⋅ 2 H₂O (L=2,6-bis-[5-methyl-1H-pyrazol-3-yl]pyridine) affords an anhydrous material, which undergoes a spin transition at T_1/2=205 K with a 65 K thermal hysteresis loop. This occurs through a sequence of phase changes, which were monitored by powder diffraction in an earlier study. [CuL₂][BF₄]₂ ⋅ 2 H₂O and [ZnL₂][BF₄]₂ ⋅ 2 H₂O are not perfectly isostructural but, unlike the iron compound, they undergo single-crystal-to-single-crystal dehydration upon annealing. All the annealed compounds initially adopt the same tetragonal phase but undergo a phase change near room temperature upon re-cooling. The low-temperature phase of [CuL₂][BF₄]₂ involves ordering of its Jahn–Teller distortion, to a monoclinic lattice with three unique cation sites. The zinc compound adopts a different, triclinic low-temperature phase with significant twisting of its coordination sphere, which unexpectedly becomes more pronounced as the crystal is cooled. Synchrotron powder diffraction data confirm that the structural changes in the anhydrous zinc complex are reproduced in the high-spin iron compound, before the onset of spin-crossover. This will contribute to the wide hysteresis in the spin transition of the iron complex. EPR spectra of copper-doped [Fe_0.97Cu_0.03L₂][BF₄]₂ imply its low-spin phase contains two distinct cation environments in a 2:1 ratio.     

含双二苯基膦乙烷镍配合物的合成与性质

在氯访中通过取代反应制备了含双二苯基膦乙烷（ｄｐｐｅ）的镍配合物［Ｎｉ（ｄｐｐｅ）Ｃｌ_２］,并通过元素分析、热分析、红外光谱、核磁、电导测定、光电子能谱及Ｘ－射线单晶分析表征了配合物的结构和性质,晶体属于单斜品系,空间群为ｐ２_１／ｃ。晶胞参数如下：ａ＝１１．４２９（２）,ｂ＝１３．３４６（２）,ｃ二１５．９５３（７）Ａ;β＝９９．１３（３）°,Ｖ＝２４０２．５Ａ~３, Ｚ＝４, Ｆ（０００）＝１０８８, Ｄ_（ｃａｌｃ）＝１４６０９· ｃｍ~（－３）, ｐ＝１１．７８２ｃｍ~（－１）, Ｒ＝０．０４４７０, Ｒｗ＝０．０５３５２。分析结果表明,配合物中双二苯基膦乙烷属双齿配体,氯离子是单齿配体．     

A Mononuclear Iron(II) Spin-Crossover Molecule Decorated by Photochromic Azobenzene Group

Aiming at constructing photoresponsive spin crossover (SCO) behavior, herein we designed a new ligand Abtz (Abtz = (E)-N-(4-((E)-phenyldiazenyl)phenyl)-1-(thiazol-4-yl)methanimine) which was decorated by a photochromic azobenzene group. Based on this photochromic ligand, a mononuclear Fe(II) SCO molecule [Fe(Abtz)₃](BF₄)₂·(EAC)₂ (1, EAC = ethyl acetate) was successfully synthesized and showed a complete one-step SCO behavior. Under continuous UV light and blue-light exposure, the cis–trans photoisomerization of both ligand Abtz and compound 1 in the liquid phase was confirmed through UV–Vis spectra. Moreover, the ¹H-NMR spectra of Abtz reveal a trans–cis conversion ratio of 37%. Although the UV–Vis spectra reveal the photochromic behavior for 1 in the solution phase, the SCO behavior in the liquid state is absent according to the variable-temperature Evans method, suggesting the possible decomposition. Moreover, in the solid state, the cis–trans photoisomerization of both Abtz and 1 was not observed, due to the steric hindrance.     

Preparation,Crystal Structure and Properties of a Pentametallic 3-Ferrocenyl-2-crotonic acid-Bridged Copper(II) Complex

IntroductionDimericcopper(II)carboxylatescontainingavarietyofoxygenandnitrogen donorligandshavebeenextensivelyinvestigatedandtheirpreparations ,magneticandspectralpropertieshavebeenreviewed .1 5Differentkindsofcopper(II)carboxylateadductshavebeensynthesizedandalsodinuclearcopper(II)complexeshavebeenearlystud iedasusefulmodelstoestablishmagneto structuralcorre lationsforspinexchangebetweenmetalions .Inparticu lar,theoccurrenceofdicopperionsattheactivesiteofthevariousformsoftheoxygencarrierpro…     

Dimerization and Oligomerization of Ethylene Catalyzed by a Palladium(II) Complex with Imine‐phosphine Ligand

The palladium‐iminophosphine complex [Pd(P‐N)(CH₃)Cl] (P‐N = o‐diphenyl‐phosphino‐N‐benzaldimine) has been found to be a catalyst for dimerization and trimerization of ethylene. Some mechanistic insight concerning this oligomerization is discussed.     

钌(II)多吡啶配合物的合成、荧光性质及与脱氧核糖核酸DNA的 作用机制研究

设计合成含多个配位中心的多吡啶配体ODCIP (3,4-二氯基苯并咪唑并[4,5-f][1,10]邻菲咯啉)及其钌(II)多吡啶配合物[Ru(bpy)2ODCIP]2＋. 运用元素分析、红外光谱、核磁谱和质谱对配体及配合物进行结构表征. 利用紫外吸收光谱、荧光光谱和粘度法研究了[Ru(bpy)2ODCIP]2＋与DNA(脱氧核糖核酸)的作用机制、与Co2＋配位后与DNA的作用机制及其荧光变化情况. 结果表明[Ru(bpy)2ODCIP]2＋与DNA通过部分插入模式作用, [Ru(bpy)2ODCIP]2＋与Co2＋配位形成的双核配合物[Ru(bpy)2(ODCIP)Co]4＋也能与DNA插入结合. 进一步利用稳态荧光发射光谱、荧光淬灭实验等方法研究了单核配合物[Ru(bpy)2ODCIP]2＋和双核配合物[Ru(bpy)2(ODCIP)Co]4＋的荧光性质.     

Ethylene Oligomerization Catalyzed by Nickel（Ⅱ） Diimine Complexes

Ethylene oligomerization has been investigated by using catalyst systems composed of nickel(II) diimine complexes (diimine = N, N′‐o‐phenylene bis (salicylideneaminato), N, N′‐o‐phenylenebisbenzal, N, N′‐ethylenebisbenzal) and ethylaluminoxane (EAO). The main products in toluene and at 110–200 °C were olefins with low carbon numbers (C₄—C₁₀). Effects of reaction temperature, Al/Ni molar ratio and reaction period on both the catalytic activity and product distribution were explored. The activity of 1.84 × 10⁵ g of oligomer/(mol_NI · h), with 87.4% of selectivity to C₄—C₁₀ olefins, was attained at 200 °C in the reaction when a catalyst composed of NiCl₂ (PhCH = o‐NC₆H₄N = CHPh) and EAO was used.     

Ethylene Oligomerization Catalyzed by Nickel(II) Diimine Complexes

ＩｎｔｒｏｄｕｃｔｉｏｎＬｏｗ ｃａｒｂｏｎｌｉｎｅａｒα ｏｌｅｆｉｎｓａｒｅｕｓｅｄｐｒｉｍａｒｉｌｙａｓｃｏ ｍｏｎｏｍｅｒｓｆｏｒｔｈｅｐｒｏｄｕｃｔｉｏｎｏｆｌｉｎｅａｒｌｏｗｄｅｎｓｉｔｙｐｏｌｙｅｔｈｙｌｅｎｅ (ＬＬＤＰＥ) ,ｐｌａｓｔｉｃｉｚｅｒｓａｎｄｓｙｎｔｈｅｔｉｃｌｕｂｒｉ ｃａｎｔｓ .Ｉｎｒｅｃｅｎｔｙｅａｒｓ ,ｍｕｃｈａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎａｔｔｒａｃｔｅｄｔｏｔｈｅｆｉｅｌｄｏｆｃａｔａｌｙｔｉｃｂｅｈａｖｉｏｒｏｆｌａｔｅｔｒａｎｓｉｔｉｏｎｍｅｔａｌｃｏｍ…     

铜(II)-锰(II)四核配合物的合成、晶体结构和磁性

(中国地质大学地质实验室, 北京100083) 报道了一个草酰胺桥连的四核Cu(II)Mn(II)配合物[Mn(CuL)3][Mn(H2O)6][N(CN)2]2(ClO4)2 4H2O (L为1,4,8,11-四氮杂环十四烷-2,3-二酮) (C34H74Cl2Cu3Mn2N18O24, Mr = 1490.51)的合成、晶体结构和磁性。配合物属于单斜晶系, 空间群为C2/c, 晶胞参数如下:a = 22.295(5), b = 12.852(3), c = 20.109(4) , = 90.47(3), V = 5762(2) 3, Dc = 1.718 g/m3, Z = 4, F(000) = 3068, m = 1.701mm-1, R = 0.0915, wR = 0.1810 (based on F2)。3个中性Cu(II)大环配合物通过6个氧原子与Mn(II)配位, MnO键长范围为2.190(6)~2.208(5) 拧Mn(CuL)3]2+通过高氯酸根离子连接起来形成一个二维层。高氯酸根的氧原子与CuII键长范围为2.902~2.996 , 为弱相互作用。[Mn(H2O)6]2+, N(CN)2-和H2O位于层间, 并通过氢键连成三维网络结构。磁性研究表明CuII-MnII离子间通过草酰胺传递反铁磁相互作用, 用基于各向同性的Hamiltonian算符 = 2JMnCuMn(Cu1 + Cu2 + Cu3)进行磁性拟合得到磁耦合常数JCuMn =-17 cm-1。     

Structural and Physical Properties of New Conducting Cation Radical Salts with Te-Based Counteranions, Tetraiodotellurate(II) and Hexaiododitellurate(II)

This article reports preparation, structure, and conducting property of several cation radical salts of organic donors tetramethyltetrathiafulvalene (TMTTF), ethylenedithiotetrathiafulvalene (EDT-TTF), bis(ethylenedithio)tetrathiafulvalene (ET), bis(ethylenedithio)tetraselenafulvalene (BETS) and hexamethylenetetraselenafulvalene (HMTSF) with two novel planar Te-based dianions, TeI₄²⁻ and Te₂I₆²⁻. (ET)₅Te₂I₆ 1 and (BETS)₅Te₂I₆ 2 are isostructural. In these Te₂I₆²⁻ salts, intermolecular short I···I contacts form a supramolecular corrugated anion sheet. Donor arrangement is similar to the θ-type. With lowering temperature, the resistivity of 1 shows a gradual increase followed by a sharp upturn at 110 K. 2 is metallic down to 120 K and shows a gradual increase of the resistivity followed by a clear transition to an insulating state around 60 K. Crystal structure of (ET)₄TeI₄ 3 is based on the “herring bone” arrangement of ET molecules similar to the α-type. 3 shows a semiconductive behavior around room temperature followed by a transition to an insulating state at 210 K. (EDT-TTF)₄TeI₄ 4, a semiconductor, exhibits a unique two-dimensional arrangement of dimerized EDT-TTF molecules.