Coordination of benzene to a sodium cation

The complexes Na(Et₂O)(dpp-BIAN)AlEt₂ (5) and Na(η⁶-C₆H₆)(dpp-BIAN)AlEt₂ (6) were synthesized by reactions of the disodium salts of dpp-BIAN (dpp-BIAN is 1,2-bis[(2,6-di-isopropylphenyl)imino]acenaphthene) with 1 equiv. of Et₂AlCl in diethyl ether and benzene, respectively. The structures of both complexes were established by X-ray diffraction. In molecules 5 and 6, diethylaluminum is chelated by the dianionic dpp-BIAN ligand. The sodium cations in molecules 5 and 6 are located above the plane of the diimine fragments and coordinate the Et₂O or benzene molecule, respectively. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1702–1707, September, 2007.     

Unexpected Coordination Behaviour of a Polypyrrole Ligand

The first coordination compounds of a hexapyrrin reveal an unexpected binding mode of longer open‐chain oligopyrroles to transition metal ions as observed by the X‐ray structural analysis of a Pd^II derivative.     

Coordination chemistry of a chelating amidoximato ligand

A potentially general strategy for accessing the rarely encountered coordination of amidoximates through both oximato O and amido N atoms was developed. The new amidoxime (Z)-R(1)C(=NOH)NR(2)H (R(1) = mesityl, R(2) = 2-[[dimethylamino]methyl]phenyl), H(2)L, was prepared by reaction of equimolar amounts of the appropriate nitrile oxide and primary amine. Treatment of H(2)L with 1 equiv of AlMe(3) produced the dimeric species (MeAlL)(2) (1) possessing the formally dianionic ligand L(2)(-) bound to the aluminum via the oximato oxygen and the amido and amino nitrogens. The oximato oxygen atoms serve to link the two monomeric organoaluminum units together. Reaction of (ON)Cr(N(i)Pr(2))(3) with H(2)L provided the diamagnetic complex (ON)Cr(N(i)Pr(2))(eta(3)-L) (2). Interaction of 2 with excess methanol led, in particular, to the oxidative loss of NO and yielded the paramagnetic dimer [Cr(LH)(OMe)(mu-OMe)](2) (3) containing the eta(3)-bound amidoximato ligand protonated at its oximato nitrogen. In addition to spectroscopic characterizations of the new substances, single-crystal X-ray structures of H(2)L, 1.(4)/(3)C(6)H(6), and 3.MeOH were obtained.     

Self-assembly of a Novel One-dimensional Zigzag Coordination Polymer

Abstract

Reaction of anhydrous NiBr₂ with pyrazine and disodium terephthalate in the presence of water results in the formation of a one-dimensional (1D) coordination polymer [Ni(pyrazine)₂(H₂O)₄] · (terephthalate) 1 which demonstrates a linear zigzag coordination pattern running along the crystallographic c-axis. The title compound crystallizes in the monoclinic space group C2/c with a = 16.833(2), b = 9.173(1), c = 11.107(1) Å, β = 119.373(2)°, and D_c = 1.667 for Z = 4. Final refinement based upon 4345 observed reflections led to a final R value of 0.052 for the polymeric product. The included terephthalate anion participates in eight O—H…O hydrogen bonds to coordinated water molecules.     

Synthesis and Coordination Ability of a Donor-Stabilised Bis-Phosphinidene

Chelating phosphines have long been a mainstay as efficient directing ligands in transition-metal catalysis. Low-valent derivatives, namely chelating phosphinidenes, are to date unknown, and could lead to chelating complexes containing more than one metal centre due to the intrisic capacity of phosphinidenes to bind two metal fragments at one P-centre. Here we describe the synthesis of the first such chelating bis-phosphinidene ligand, XantP₂ ( 2 ), generated by the reduction of a diphosphino xanthene derivative, Xant(PH₂)₂ ( 1 ) with ^iPrNHC (^iPrNHC=[:C{N(iPr)C(H)}₂]). Initial studies have shown that this novel chelating ligand can act as a bidentate ligand towards element dihalides (i.e. FeCl₂, ZnI₂, GeCl₂, SnBr₂), forming cationic complexes with the tetryl elements. In contrast, XantP₂ demonstrates an ability to bind multiple metal centres in the reaction with CuCl, leading to a cationic Cu₃P₃ ring complex, with Cu centres bridged by phosphinidene arms. Density Functional Theory calculations show that 2 indeed holds 4 lone pairs of electrons, shedding further light on the coordination capacity for this novel ligand class through observation of directionality and hybridisation of these electron pairs.     

Coordination Numbers of Central Atoms in Coordination Compounds

A sample of structurally characterized 10000 complexes (X-ray diffraction data) was carefully selected from available databases for analysis of coordination numbers (CNs) of their central atoms (complexing agents). The coordination numbers of various chemical elements are tabulated for their different oxidation numbers (ONs). Variations in CN with the ordinal number of an element in the Periodic Table were followed. A general distribution of the sample complexes over the CNs of the central atom, as well as their distributions for particular ONs, is displayed. References to particular coordination compounds are given for extreme and very uncommon CNs of a central atom with different ONs. A general pattern of the observed variations in the CN of chemical elements can be useful for predicting the properties of complexes, constructing their stability models, designing compounds with rich and unique properties, and developing retrieval and graphic tools for chemical databases.     

Self-Assembly and Antitumor Activity of a Polyoxovanadate-Based Coordination Nanocage

A new supramolecular nanocage, VMOP- 31 , based on polyoxovanadate as the molecular building block, has been designed and synthesized under solvothermal conditions. The structure of VMOP- 31 was determined by single-crystal and powder X-ray diffraction, FTIR spectroscopy, UV/Vis spectrophotometry, and thermogravimetric analysis. The nanocage exhibits octahedral geometry and is constructed of six {V₅O₉Cl(COO)₄} at the vertices and eight TATB (H₃TATB=4,4′,4′′-(s-triazine-2,4,6-triyl)tribenzoic acid) ligands on the faces. Impressively, VMOP- 31 exhibited high efficiency in the inhibition of cell growth of solid tumors, such as human liver cancer cells SMMC-7721, and superior results in the treatment of liver tumors in mice compared with classic cisplatin. Detailed studies revealed that the potential mechanism of cell death induced by VMOP- 31 involves cell cycle arrests, DNA damage, and subsequent apoptosis. Moreover, VMOP- 31 exhibited negligible side effects in the mice compared with cisplatin. To the best of our knowledge, VMOP- 31 is the first supramolecular nanocage applied to hepatic tumors both in vitro and in vivo.     

一个锰的二维配位聚合物的合成及其性质

本文用2-咪唑乙酸(Hiaa),2,2′-联吡啶,氢氧化钠和六水合高氯酸锰在水和乙醇中反应合成了1个二维配位化合物{[Mn(iaa)(2,2′-bipyridine)(H₂O)](ClO₄)}_n (1)。单晶结构表明化合物1是1个新颖的二维双核锰配位聚合物,锰离子的配位构型为扭曲的八面体。每一个锰离子与3个配体配位,而每个配体与3个锰离子桥连。磁性研究表明1中Mn(Ⅱ)离子间存在弱的反     

Coordination capabilities of a novel organic polychlorotriphenylmethyl monosulfonate radical

The treatment of alpha-H-p-H-PTM (PTM = polychlorotriphenylmethane) with oleum 65% followed by deprotonation and oxidation leads to the isolation of a novel pure organic radical PTMSO3H x 3 H2O x 0.5 hexane (2). The X-ray diffraction of 2 reveals a layered structure with disordered H2O molecules between facing sulfonic acid groups. We have explored the coordination abilities of the sulfonate derivative using different metals. The treatment of 2 with mild bases yields the sulfonate radical PTMSO3Na x H2O (3). On the other hand, the new compound [Cu(py)2(H2O)4](PTMSO3)2 x 2 H2O x 2 EtOH (4) has been crystallized using Cu(II) as the metallic counterion in the presence of pyridine. The structure reveals a solvent-separated ion-pair-type compound, with no direct coordination of the metal ion with the sulfonate group, and the formation of organic layers between layers of transition metal complexes. This situation has been overcome by favoring the stabilization of the sulfonate group over the Cu(II) center by changing the pyridine ligand to cyclam. This has led to compound [Cu(cyclam)](PTMSO3)2 x 6 EtOH (5a), in which the sulfonate group acts as a monodentate axial ligand for the Cu(II) center. We have observed a single-to-single crystal rearrangement from 5a to [Cu(cyclam)](PTMSO3)2 (5b) because of the loss of the solvent of crystallization, without significant modification of the metal coordination environment. All species have been structurally and magnetically characterized, and the magnetic coupling between the organic radicals and the metal paramagnetic centers is discussed.     

Arene Selectivity by a Flexible Coordination Polymer Host

The coordination polymers [Ag₄(O₂CCF₃)₄(phen)₃] ? phen ? arene ( 1? phen ? arene) (phen=phenazine; arene=toluene, p‐xylene or benzene) have been synthesised from the solution phase in a series of arene solvents and crystallographically characterised. By contrast, analogous syntheses from o‐xylene and m‐xylene as the solvent yield the solvent‐free coordination polymer [Ag₄(O₂CCF₃)₄(phen)₂] ( 2 ). Toluene, p‐xylene and benzene have been successfully used in mixed‐arene syntheses to template the formation of coordination polymers 1? phen ? arene, which incorporate o‐ or m‐xylene. The selectivity of 1? phen ? arene for the arene guests was determined, through pairwise competition experiments, to be p‐xylene>toluene≈benzene>o‐xylene>m‐xylene. The largest selectivity coefficient was determined as 14.2 for p‐xylene:m‐xylene and the smallest was 1.0 for toluene:benzene.     

Temperature-controlled Hydrothermal Synthesis of Copper(I or II) Coordination Polymers via a Variety of Copper Coordination Modes

Two 1D coordination polymers Cu₂^I(C₆N₃H₄)₂(1) and Cu^II(C₆N₃H₄)₂·H₂O(2) based on benzotriazole(Bta) were hydrothermally synthesized by controlling the crystallization temperature. Single-crystal X-ray diffraction (XRD) analyses reveal that compound 1 is a 1D tubular structure constructed from two types of 1D chains {-Cu-N=N-N-}_n, where the Cu(I) ions adopt linear, triangular, and tetrahedral coordination modes to connect two types of Bta ligands via π-π interaction inside the tubular-like chain. For compound 2, the Cu(II) ions assume a quadrilateral coordination mode linking to the Bta ligands to give 1D straight chains, which stacks through π-π interactions to construct a 2D layer structure. Further characterizations including elemental analyses, infrared IR spectra, thermogravimetric(TG) analyses and luminescence properties have been done.     

配位聚合物

配位聚合物是通过过渡金属和有机配体的自组装而形成的 ,它结合了复合高分子和配位化合物两者的特点 ,表现出其独特的性质 ,在非线性光学材料、磁性材料、超导材料及催化等诸多方面都有极好的应用前景。本文根据有机配体种类的不同 ,将配位聚合物分为五大类 ,以便于对它们进行研究。1.含氮杂环类配体的配位聚合物 ;2.含CN有机配体的配位聚合物 ;3.含氧有机配体的配位聚合物 ;4.通过两种配体与一种金属组装成的配位聚合物 ;5.两种以上的金属与相应的配体组装而成的配位聚合物。     

Overcoming Statistical Complexity: Selective Coordination of Three Different Metal Ions to a Ligand with Three Different Coordination Sites

In general, it is difficult to selectively introduce different metal ions at specific positions of a cluster‐like structure. This is mainly due to statistical problems as well as the reversibility of the formation of coordination bonds. To overcome this statistical problem, we used a carefully designed ligand, H₆L, which can accommodate three different kinds of metal ions in three types of coordination sites. The complex [LNiZn₂La]³⁺, which contains three different metals, was quantitatively obtained by a stepwise procedure, but different products were obtained when the metal ions were added in a different order. However, equilibration studies indicated that this complex was almost solely formed among 54 (=3×3×₃H₂) possible products upon heating; the formation efficiency (ca. 100 %) was significantly higher than the statistical probability (2.47 %). Such carefully designed ligands should be useful for the synthesis multimetallic systems, which are of interest because of the interplay between the different metals.     

Recombination of Coordination Bonds of a Mononuclear Precursor into a 3D d‐d′ Heterometallic Coordination Polymer with Double Helices

Abstract. Based on a mononuclear precursor [Mn(Hstp)₂(4,4′‐Hbpy)₂] ( 1 ), a hetero‐metallic complex, [Mn₂Ni(stp)₂(4,4′‐bpy)(H₂O)₄] ( 2 ) [stp = 2‐sulfoterephthalate, 4,4′‐bpy = 4,4′‐bpyridine] was synthesized by solvothermal reaction. Single‐crystal X‐ray diffraction analysis reveals that the Mn^II ion of the precursor 1 is hexacoordinate by four oxygen atoms from two Hstp^2– anions and two nitrogen atoms from two protonated 4, 4′‐Hbpy, and hydrogen bonding plays a significant role in constructing 3D supramolecular structure. While complex 2 features a self‐weaving framework from 1D straight chains and 2D wavy networks with double helical chains. Magnetic behavior of complex 2 was analyzed in connection with its crystal structure, which exhibits the weak antiferromagnetic interactions between the Mn^II and Ni^II ions.     

利用热分析质谱联用技术(TA-MS)分析比较配合物及双配合物的热分解行为——介绍一个综合性研究型化学实验

应用热分析．质谱联用技术考察了反式-[Co（en）2Cl2]Cl、K3[Fe（C2O4）3]·3H2O配合物以及相应的双配合物——反式-[Co（en）2Cl2]3[Fe（C2O4）3]·4．5H2O的程序升温热分解行为。通过对样品的热失重分析、逸出气体的质谱分析以及固相产物的物相分析,了解其热分解过程机理,比较了在受热过程中反式-[Co（en）2Cl2]Cl、K3[Fe（C2O4）3]·3H2O配合物和双配合物的过渡金属离子与配体之间以及配体与配体之间的相互作用的变化。     

Anion Control in the Self-Assembly of a Cage Coordination Complex

An anion is encapsulated in the center of the new cage compound [Ni₆(atu)₈X]X₃ (X=Cl—for the structure see picture—or Br; Hatu=amidinothiourea). A combination of Lewis acid–base and hydrogen-bonding interactions cause the square-planar [Ni(Hatu)₂]²⁺ units, after deprotonation, to assemble to form this compound. A remarkable feature is the anion dependence of the cage formation; nitrate, acetate, and perchlorate are unsuitable as templates.