Mono- and di-nuclear complexes of the ligands 3,4-di(2-pyridyl)-1,2,5-oxadiazole and 3,4-di(2-pyridyl)-1,2,5-thiadiazole; new bridges allowing unusually strong metal–metal interactions

Richardson, Christopher; Steel, Peter J.; D’Alessandro, Deanna M.; Junk, Peter Courtney; Keene, F. Richard

doi:10.1039/b202954e

Cited by 59 publications

(30 citation statements)

References 40 publications

(46 reference statements)

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“…The only example of a dipyridyl-1,2,5-thiadiazole found in the literature was in the already cited paper [50]. The authors obtained 3,4-di(2-pyridyl)-1,2,5-thiadiazole by the reaction of 1,2-di(2-pyridyl)ethylene with S 3 N 3 Cl 3 : The coordination chemistry of dipyridylthiadiazoles has not so far been investigated as actively as the analogous chemistry of oxadiazoles.…”

Section: Triazoles Oxadiazoles and Thiadiazolesmentioning

confidence: 97%

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Synthesis of Azoles with Two Pyridine Substituents at Carbon Atoms and Their Use in Coordination Chemistry. (Review)

Вацадзе

Nuriev

Зык

2005

Chem Heterocycl Compd

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Published data on the synthesis of azoles containing two pyridine substituents are analyzed in relation to the type of central five-membered ring. The applications of such molecules as ligands in coordination chemistry are discussed.The design of coordination polymers having unique structures and valuable functional characteristics is one of the most rapidly developing regions of modern chemistry and materials science [1,2]. Most of the employed exo-dentate ligands belong to the bipyridine class with the general formula Py-X-Py, where X is a conjugated disubstituted fragment. The parent of such ligands is 4,4'-bipyridine (X is absent), which has been widely used for a long time in the construction of coordination polymers [3]. The most widely used bridges X include double and triple carbon-carbon bonds, azo and imino groups, and benzene, pyridine, triazine, and tetrazine rings or combinations of these fragments [4].One modern trend in the synthesis of coordination polymers is to use ligands of the Py-X-Py type, where X is a meta-or ortho-substituted azole. The interest in such compounds is due, first, to their electronic characteristics and, second, to the ability of the pyridine nitrogen atom of the azole ring to coordinate with the metal ion. This fact significantly extends the possibilities of the ligands in coordination, enhancing the practical characteristics of the complexes. At the moment the coordination characteristics of a small group of dipyridylazoles have been studied. It is important to emphasize that at this time there has been no systematic treatment of data on the design and synthesis of such compounds. In view of the foregoing it seemed to us important and timely to clarify some of the problems that arise in the synthesis of dipyridylazoles for the systems that are finding use in coordination chemistry.It should be noted that in this paper we restrict ourselves to examination of the synthesis and coordination characteristics of azoles containing not less than one nitrogen atom of the pyridine type. Consequently, we do not consider five-membered donating heterocycles with one heteroatom. The second restriction is the fact that we decided to examine only azoles substituted by pyridine groups at carbon atoms, and the range of compounds studied does not therefore include tetrazoles.The review is divided up according to the types of central five-membered heterocycles. In each section the synthetic aspects and questions concerning the use of specific ligands in coordination chemistry are examined. _______ * Dedicated to Academician Nikolai Serafimovich Zefirov in honor of his seventieth birthday. __________________________________________________________________________________________

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Section: Triazoles Oxadiazoles and Thiadiazolesmentioning

confidence: 97%

“…The synthesis of this compound, which is at present the only known oxadiazole with pyridine substituents, was published in 2002 [50]. The production of this compound was based on the well known cyclocondensation of 1,2-dioximes:…”

Section: Triazoles Oxadiazoles and Thiadiazolesmentioning

confidence: 99%

Synthesis of Azoles with Two Pyridine Substituents at Carbon Atoms and Their Use in Coordination Chemistry. (Review)

Вацадзе

Nuriev

Зык

2005

Chem Heterocycl Compd

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“…Keywords: 1,2,4-Oxadiazole; Palladium; Silver; N Ligands [11,12]. Within this context, we noted that 1,2,4-oxadiazoles have been curiously ignored as subcomponents within ligands, be they monodentate, chelating or bridging.…”

Section: Introductionmentioning

confidence: 99%

“…It forms a mononuclear complex (3) with palladium(II) chloride, which is shown by X-ray crystallography to contain the ligand chelated through the two N4 nitrogens. The X-ray structure of the complex (5) with silver(I) nitrate shows a one-dimensional coordination polymer in which the ligand acts in a bridging mode, again with coordination through the N4 nitrogen atoms.Keywords: 1,2,4-Oxadiazole; Palladium; Silver; N Ligands [11,12]. Within this context, we noted that 1,2,4-oxadiazoles have been curiously ignored as subcomponents within ligands, be they monodentate, chelating or bridging.…”

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confidence: 99%

“…In particular, we have focused on the design of ligands incorporating less commonly studied heterocyclic ring systems, such as tetrazoles [2],1,2-benzisoxazoles [3], furoxans [4], benzotriazoles [5,6], 1,4,2,5-dioxadiazines [7], thiazolo [5,4-d]thiazoles [8], 1,2,3-thia(and selena)diazoles [9], pyridazines [10], 1,2,5-oxadiazoles and 1,2,5-thiadiazoles [11,12]. Within this context, we noted that 1,2,4-oxadiazoles have been curiously ignored as subcomponents within ligands, be they monodentate, chelating or bridging.…”

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The first metal complexes of 3,3′-bi-1,2,4-oxadiazole: A curiously ignored ligand

Richardson

Steel

2007

Inorganic Chemistry Communications

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The crystal structure of 3,3'-bi-1,2,4-oxadiazole (1) reveals a planar centrosymmetric structure for this molecule in the solid state. It forms a mononuclear complex (3) with palladium(II) chloride, which is shown by X-ray crystallography to contain the ligand chelated through the two N4 nitrogens. The X-ray structure of the complex (5) with silver(I) nitrate shows a one-dimensional coordination polymer in which the ligand acts in a bridging mode, again with coordination through the N4 nitrogen atoms.Keywords: 1,2,4-Oxadiazole; Palladium; Silver; N Ligands [11,12]. Within this context, we noted that 1,2,4-oxadiazoles have been curiously ignored as subcomponents within ligands, be they monodentate, chelating or bridging. Indeed, a search of the Cambridge Crystallographic Database revealed that only three papers reported metal complexes of ligands containing a 1,2,4-oxadiazole subunit [13][14][15].In continuation of our interest in the chemistry of biheterocycles [16], we realised that of the three isomeric bi-1,2,4-oxadiazoles, the 3,3'-isomer (1) represents a particularly interesting potential ligand. This compound has been known for over forty years [17] and could potentially chelate to a single metal in any of three modes (Fig. 1, (a)-(c)) and, furthermore, offers the possibility of bridging two metals in either of two ways ( Fig.1, (d)-(e)). Curiously however, it has never been used as a ligand in coordination or metallosupramolecular chemistry. We therefore set out to explore the use of this compound as a ligand and herein describe the synthesis and X-ray crystal structures of the free ligand, a mononuclear palladium(II) complex and a one-dimensional silver(I) coordination polymer.[ Fig. 1 here] 3,3'-Bi-1,2,4-oxadiazole (1) was prepared in 76% yield by a double cyclisation of oxamidoxime (Scheme 1), based on a literature procedure [18]. In order to confirm unambiguously its structure and to examine the conformation of the ligand in the solid state we determined the X-ray crystal structure of 1 [19]. It crystallises in the orthorhombic space group Cmca with a mere quarter of the molecule in the asymmetric unit; the whole molecule lies on a crystallographic mirror plane and also resides upon a crystallographic centre of inversion (Fig. 2). As such the molecule is perfectly planar and centrosymmetric, a situation that we have previously proposed to be favoured for symmetrical biheterocycles for the 3 reason that this eliminates any dipole moment and facilitates maximal π-π stacking of the molecules in the solid state [20].[Scheme 1 and Fig. 2 here] We next proceeded to explore the coordination chemistry of 1 by preparing a mononuclear complex. We chose palladium(II) as the metal, based on a long standing affection for this well-behaved, square-planar metal synthon [21]. Our first attempt to prepare a palladium complex of 1 involved reaction with PdCl 2 in 2M HCl solution. This reaction furnished crystals of a product that we were able to identify as the ring-opened hydrolysis derivative 2 (Scheme 1), o...

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Palladium‐catalyzed Heck coupling of 2‐vinylpyridine with aryl chlorides

Hua

2008

Applied Organom Chemis

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Mono- and di-nuclear complexes of the ligands 3,4-di(2-pyridyl)-1,2,5-oxadiazole and 3,4-di(2-pyridyl)-1,2,5-thiadiazole; new bridges allowing unusually strong metal–metal interactions

Cited by 59 publications

References 40 publications

Synthesis of Azoles with Two Pyridine Substituents at Carbon Atoms and Their Use in Coordination Chemistry. (Review)

Synthesis of Azoles with Two Pyridine Substituents at Carbon Atoms and Their Use in Coordination Chemistry. (Review)

The first metal complexes of 3,3′-bi-1,2,4-oxadiazole: A curiously ignored ligand

Palladium‐catalyzed Heck coupling of 2‐vinylpyridine with aryl chlorides

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