Benzotriazole as a structural component in chelating and bridging heterocyclic ligands; ruthenium, palladium, copper and silver complexes

Richardson, Christopher; Steel, Peter J.

doi:10.1039/b206990c

Cited by 68 publications

(59 citation statements)

References 37 publications

(26 reference statements)

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“…torsional angle = 179.6 (2) o ] and coordination by the less sterically hindered N3 nitrogens, as was observed for the CuCl 2 complex of the related ligand with a methylene spacer group. [11] As a result The benzotriazole rings are both coordinated through the N3 nitrogens in preference to the more sterically congested N2 nitrogens. Within the complex 4 the bridging ligand exists in a more compact conformation than was observed in 3.…”

Section: Resultsmentioning

confidence: 99%

“…The parent heterocycle can coordinate up to three metals in its deprotonated form, [9] with particular emphasis having been placed on copper complexes, due to the importance of benzotriazole as a corrosion inhibitor. [10] We have recently reported the incorporation of benzotriazole groups into a number of chelating ligands [11] and into a bidentate bridging ligand which forms a triple stranded helicate. [12] We now describe complexes of two symmetrical isomeric ligands, 1 and 2, which contain benzotriazole groups separated by flexible propylene spacer units …”

Section: Introductionmentioning

confidence: 99%

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Synthesis and X‐ray Crystal Structures of Cobalt and Copper Complexes of 1,3‐Bis(benzotriazolyl)propanes

Børsting

Steel

2004

Eur J Inorg Chem

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and X‐ray Crystal Structures of Cobalt and Copper Complexes of 1,3‐Bis(benzotriazolyl)propanes

Børsting

Steel

2004

Eur J Inorg Chem

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“…The minor isomer crystallised as small red blocks in the monoclinic space group C2/c with half the dinuclear cation, two PF 6 -anions and an acetonitrile solvate molecule in the asymmetric unit ( Figure 5). The other half of the complex is related by a crystallographic centre of inversion at the centre of the bridging ligand.…”

Section: Syntheses and Crystal Structures Of Metal Complexes Ofmentioning

confidence: 99%

“…5 In complexes of 2 the metals are laterally displaced relative to the plane of the ligand. As part of a programme involving the study of ligands containing less commonly studied heterocyclic ring systems, 6 we recently described the preparations and complexes of two new bridging ligands, (3) and (4), incorporating 1,2,5-oxadiazole and 1,2,5-thiadiazole bridging subunits. 7 Electrochemical studies of dinuclear ruthenium complexes of these ligands revealed unusually strong metal-metal interactions, greater than those found in the corresponding complexes of 1, despite the greater inter-metal separation (6.0 Å).…”

Section: Introductionmentioning

confidence: 99%

Diastereoisomeric dinuclear ruthenium complexes of 2,5-di(2-pyridyl)thiazolo[5,4-d]thiazole

2004

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The first metal complexes of 2,5-di(2-pyridyl)thiazolol [5,4-d]thiazole (5) are described. X-Ray crystal structures are reported for the free ligand 5, a dinuclear copper complex 6 and the two diastereoisomers, 7meso and 7rac, of the dinuclear bis(2,2'-bipyridine)ruthenium complex. The two diastereoisomers of 7 and the 4,4'-dimethyl-2,2'-bipyridine analogue 8 are readily separated by cation exchange chromatography.1 H NMR and visible absorption spectra and electrochemical data for the four dinuclear ruthenium complexes reveal that these have relatively small HOMO-LUMO energy gaps and exhibit relatively weak metal-metal interactions.

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“…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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Benzotriazole as a structural component in chelating and bridging heterocyclic ligands; ruthenium, palladium, copper and silver complexes

Cited by 68 publications

References 37 publications

Synthesis and X‐ray Crystal Structures of Cobalt and Copper Complexes of 1,3‐Bis(benzotriazolyl)propanes

Synthesis and X‐ray Crystal Structures of Cobalt and Copper Complexes of 1,3‐Bis(benzotriazolyl)propanes

Diastereoisomeric dinuclear ruthenium complexes of 2,5-di(2-pyridyl)thiazolo[5,4-d]thiazole

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

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