Synthesis and structure of a new macrotricyclic ligand that encapsulates lithium and transition metal ions

A new macrotricyclic ligand, L3 with an N4S2 donor set that encapsulates lithium and transition metal ions has been synthesized from the tetraazamacrocycle cyclam.     

4,5-diazafluorene-based overcrowded alkene: a new ligand for transition metal complexes

[structure: see text] A new ligand system, where a 4,5-diazafluorene-type chelate and a methoxybenzoxanthene unit are coupled by a double bond has been synthesized and fully characterized including X-ray structure. The synthesis and UV-vis spectra of Ru(II), Os(II), and Re(I) complexes with the above-mentioned ligand are also shown.     

Co-ordination behaviour of a novel bisthiourea tripodal ligand: structural, spectroscopic and electrochemical properties of a series of transition metal complexes

The synthesis of a thiourea substituted derivative of tris(pyridyl-2-methyl)amine (TPA) is reported. Two of the three pyridine rings are substituted in the 6-position with benzoylthiourea groups. These thiourea groups undergo intramolecular hydrogen bonding to form six-membered rings which leaves one N-H group available to form hydrogen bonds with other molecules. This reports details how the complexation of this new ligand with transition metal ions yields complexes with differing geometries. Seven co-ordinate Mn(II) and Cd(II), six co-ordinate Ni(II) and five co-ordinate Co(II), Cu(II) and Zn(II) complexes have been isolated.     

The effect of small ions on transition metal complex configurations. Synthesis,crystal structures and properties of two new copper(II) complexes containing a tripodal ligand

The monomeric Cu^II complex, [Cu(TLA)C₂O₄].₂O (1), and dimeric Cu^II complex, [Cu₂(TLA)₂(C₄O₄)](ClO₄)₂ (1), where TLA=[tris(6-methyl-2-pyridyl)methyl]amine, have been synthesized and characterized. Both complexes have been obtained as single crystals and their structures were determined by X-ray diffraction analysis. The configuration of (1) is pseudo-octahedral owing to the fact that one of the Cu-N_pyridyl bonds is much longer than the others. Two molecules of (1) link via hydrogen bonding to the oxalic oxygen in the unit cell. The copper complex (2) dimer is obtained, using the squarate ion as a bridging ligand, from a monomer copper complex, [Cu(TLA)N₃].₄ClO₄ (3). By comparison of the configurations of (1), (2) with that of (3), the copper center is coordinated with TLA first, and then with secondary ligands, such as the azido group, squaric acid, or oxalate ion. The configurations of the transition metal complexes are affected by the smaller ions, as is further discussed below. The variable temperature magnetic susceptibilities of (2) have been studied, and the exchange integral is J=–2.5474cm^-, g=2.061, indicating the existence of a weaker anti-ferromagnetic interaction between the two copper ions in compound (2). The spectral behavior of the title complexes in solution has been studied by u.v.–vis. and i.r. techniques, and the results are discussed.     

A new bis(imidazolyl)(alkylthiolate) tripodal ligand and the spontaneous formation of a disulfide-linked,hydroxo-bridged dinuclear zinc complex

The new sterically encumbered, tripodal N2S(alkylthiolate) ligand, LIm2SH, has been synthesized and used to prepare [(LIm2S)ZnCH3], which upon protonolysis under acidic conditions leads to the synthesis of a novel dinucleating ligand and a zinc dimer with an unusual structure.     

A new class of transition metal pincer ligand: tantalum complexes that feature a [CCC] X3-donor array derived from a terphenyl ligand

A new class of [CCC] X(3)-donor pincer ligand for transition metals has been constructed via cyclometalation of a 2,6-di-p-tolylphenyl ([Ar(Tol(2))]) derivative. Specifically, addition of PMe(3) to [Ar(Tol(2))]TaMe(3)Cl induces elimination of methane and formation of the pincer complex, [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)MeCl (Tol' = C(6)H(3)Me), which may also be obtained by treatment of Ta(PMe(3))(2)Me(3)Cl(2) with [Ar(Tol(2))]Li. Solutions of [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)MeCl undergo ligand redistribution with the formation of [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)Me(2)and [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)Cl(2), which may also be synthesized by the reactions of [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)MeCl with MeMgBr and ZnCl(2), respectively. Reduction of [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)Cl(2) with KC(8) in benzene gives the benzene complex [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)(η(6)-C(6)H(6)) that is better described as a 1,4-cyclohexadienediyl derivative. Deuterium labeling employing Ta(PMe(3))(2)(CD(3))(3)Cl(2) demonstrates that the pincer ligand is created by a pair of Ar-H/Ta-Me sigma-bond metathesis transformations, rather than by a mechanism that involves α-H abstraction by a tantalum methyl ligand.     

三爪结构萘乙酰胺衍生物与过渡金属离子的螯合荧光增强

合成了具有三爪结构的化合物三-(1-萘乙酰胺乙基)胺(1),它对具有荧光猝灭能力的过渡金属离子具有荧光增强的效应。比较不同的过渡金属离子存在时上述化合物溶液的荧光光谱和吸收光谱变化,可以发现：在利用荧光光谱进行检测时必须注意过程中引起荧光增强和猝灭的机制,这将对考察配体与金属离子间配位能力大小作出正确估计有着重要的帮助。     

Synthesis of a first-row transition metal parent amido complex and carbon monoxide insertion into the amide N-H bond

The parent amido iron complex (dmpe)2Fe(H)(NH2) (dmpe = 1,2-bis(dimethylphosphino)ethane), the first such first-row transition metal complex, has been synthesized and characterized spectroscopically and crystallographically. This complex has been found to insert carbon monoxide into the amide N-H bond (rather than the M-N bond) to give trans-(dmpe)2Fe(H)(NHCHO). The mechanism of this transformation has been studied and is believed to occur through an unusual mechanism in which CO behaves as an apparent electrophile.     

Study of metal complexes of a tripodal hydroxypyridinone ligand by electrospray tandem mass spectrometry

The tripodal ligand N,N,N-tris[(1,hydroxy-2-pyridinon-6-yl)amide]propylamine was synthesized. It is composed of an anchor (nitrogen atom), a functional group (hydroxamate), and also a spacer of variable length defined by the number of methylene groups linking the anchor and the functional group. The characterization of this ligand in the presence of several divalent metal cations (Fe(II), Mn(II), Co(II) and Cu(II)), performed by electrospray ionization mass spectrometry (ESI-MS and ESI-MS/MS), allowed elucidation of oxidation states and also of different fragmentation patterns. The importance of the spacer length was studied in the case of the iron binary complex by comparing this ligand with another with a shorter spacer. In this way the stabilizing conditions, in which hydrogen bonds are implicated, were clarified.     

A novel dimeric zinc(II) complex with a tripodal peptide ligand: a structure stabilized by ligand sharing

The crystal structure of a novel dimeric zinc(II) complex, [ZnL(H₂O)]₂(ClO₄)₂·4H₂O (L?=?N-(bis(2-pyridyl)methyl)-2-pyridinecarboxamide), has been determined by X-ray diffraction. In this complex each planar N_py–N_amido–N_py moiety of the ligand coordinates to one zinc ion and the pendant pyridine of one [ZnL] unit completes the coordination sphere of a [ZnL] neighbor. Units of the complex are connected in a two-dimensional network by intermolecular hydrogen bonds. The thermodynamic properties of the ligand with bivalent metal ions Co(II), Ni(II), Cu(II) and Zn(II) were studied by potentiometric titration and the order of the stability constants is in agreement with the Irving–Williams series. The dimeric complex is stabilized through ligand sharing, as confirmed by the crystal structure and thermodynamic properties.     

Formation of a 1-azaallenylidene ligand by reaction of an amido complex with tetracyanoethylene

Amido complexes of Mo(II) allyl carbonyl fragments containing monodentate amido ligands, prepared by reaction of suitable chloro precursors with potassium amides, react (for the N(H)(p-tolyl) derivative) with tetracyanoethylene to give a 1-azaallenylidene complex.     

Ligand substitution in a transition metal complex: a new type of photocatalytic reaction in a semiconductor

We show that a semiconductor can serve as a photocatalyst for the ligand substitution reaction in coordination compounds of chromium(III). The mechanism of the process includes stages of generation of an electron-hole pair upon action of light quanta with energy equal to (or greater than) the width of the forbidden gap in the semiconductor, capture of the electron from the conduction band by the chromium(III) complex, fast ligand substitution in the chromium(II) complex formed by a solvent molecule, and oxidation of the chromium(II) complex by the hole from the valence band. The reaction of aquation of the complex ions [CrCl₂(H₂O)₄]⁺ proceeds when using the semiconductors (CdS, GaAs), whose conduction band is located in the more negative potential region compared with the standard oxidation-reduction potential of the Cr(III)/Cr(II) pair. We show that the reaction rate is slowed down when electron acceptors (oxygen) and hole acceptors (ethanol) are introduced, which confirms the proposed mechanism.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 1, pp. 89–92, January–February, 1990.     

Synthesis and characterization of a new tetradentate ligand for Cu(II) metal ions

The synthesis and characterization of a tailor-made ligand 1 is described. Self-assembly of 1 on a GaAs surface was studied by FT-IR spectroscopy. The IR spectrum of the thin film points to the conclusion that the monolayer adsorbs to the surface via both carboxylates of the malonic acid derivative. The distinction between the possible binding modes is discussed.     

Novel linear transition metal clusters of a heptadentate bis-beta-diketone ligand

The synthesis and the structure of the new potentially heptadentate ligand 1,3-bis-(3-oxo-3-(2-hydroxyphenyl)-propionyl)-2-methoxybenzene (H5L) is described. The reaction in pyridine or DMF of this ligand with various M(AcO)2 salts (M = NiII, CoII, MnII) leads to very different products depending on the metal. Thus, the dinuclear complexes [M2(H3L)2(py)4] (M = NiII, 1; CoII, 2) or the linear zigzag tetranuclear clusters [Mn4(H2L)2(AcO)2(py)5] (3) and [Mn4(H2L)2(AcO)2(dmf)4] (4) have been synthesized and characterized crystallographically. Slow oxidation of complex 3 leads to the formation of the novel mixed-valence linear complex [Mn3(HL)2(py)6] (5), displaying an unprecedented asymmetric MnIIIMnIIIMnII topology. The coordination geometry of complexes 1 to 5 has been analyzed and discussed by means of continuous shape measures. Magnetic measurements of 3 and 5 demonstrate that the metals within these complexes weakly interact magnetically with coupling constants of J1 = -1.13 cm-1 and J2 = -0.43 cm-1 (S = 0) for complex 3 and J1 = -5.4 cm-1 and J2 = -0.4 cm-1 (S = 5/2) for complex 5 (using the H = -Sigma2JijSiSj convention). These results are consistent with X-band EPR measurements on these compounds.     

Application of transition metal complex formation in gas chromatography,part II

Summary This part of this review discusses the applications of adsorbents containing transition metals in gas chromatography, and the methods permitting the calculation of the stability constants of weak complexes between transition metals and organic compounds from gas chromatographic data.     

Application of transition metal complex formation in gas chromatography,part I

Summary Part I of this review paper discusses applications of superselective liquid phases containing transition metal salts or complexes in gas chromatography.     

Synthesis,crystal structure and properties of a new lanthanide‐transition metal carbonyl cluster

A new type heterobimetallic complex containing lanthanide and transition metal carbonyl cluster (Ln? M carbonyl cluster), Sm₂{OOCCCo₃(CO)₉}₂{OOCCF₃}₄{(CO)₉Co₃CCOOH}₄, has been synthesized by reaction of (CO)₉Co₃CCOOH with Sm(OOCCF₃)₃(H₂O)₂, and structurally characterized by single‐crystal X‐ray diffraction. Application of the complex as a catalyst precursor for hydrogenation of carbon monoxide (Fischer–Tropsch reaction) was explored, and the thermogravimetric behavior and magnetic properties of the compound were examined as well. Copyright © 2008 John Wiley & Sons, Ltd.     

过渡金属配合物与铀酰-有机框架复合:两例新型铀/铜异金属配合物的合成、晶体结构及其性能研究

在水热条件下,将铜金属配合物插入到铀酰有机框架化合物中,合成了两例新型铀/铜异金属杂化配合物[Cu(bipy)(UO2)(bdc)2·H2 O]n(1),{[Cu(phen)(UO2)(bdc)(bc)(H2O)]·H2O}n(2)(bipy=2,2′-联吡啶,bdc=对苯二甲酸,phen=1,10-邻菲罗琳,bc=苯...     

Acetylenedithiolate: alkyne complex formation renders it a dithiolate chelate ligand

The isostructural complexes [{Tp'W(CO)(2)(eta(2)-C(2)S(2))}(2)M] (M = Ni, Pd, Pt) show that the eta(2)-C,C'-alkyne complexes of acetylenedithiolate at [Tp'W(CO)(2)](+) can generally act as dithiolate chelate ligands, leading to dithiolene type complexes.