The Crystal and Molecular Structure of Lead(II) Nitrate : 18-Crown-6.

The condensation of two molecules of 3,s-di-tert-butylcatechol (dbc) with ammonia under oxidizing conditions is believed to proceed via a keto-imine radical. Further condensation, and subsequent reaction with tin(I1) or lead(I1) halides, yields complexes of identical composition, M [dbqdi],, where dbqdi is 3,5-di-tertbutyl-1,2-quinone-1-(2-hydroxy-3,5-di-tert-butylphenyl)imine anion; this name is used without prejudice as to the actual structure of the ligand. The two compounds differ in crystallographic and magnetic properties, and ESR measurements show that the tin compound has a triplet ground state. Both involve six-coordination of the metal in a distorted environment; tin is in the +IV state, but lead is +II, and there are corresponding differences in the form of the ligand. For snIv(dbqdi),, the crystal parameters are orthorhombic, space group C222,, a = 19.597(4), b = 24.375(4), c = 23.755(6) A, Z = 8, and R = 0.073 for 1405 unique reflections. For pbU(dbqdi),, monoclinic, space group P2,ln, a = 14.56(1), b = 25.967(9), c = 15.13(1) A, P = 99.81(7)', Z = 4, R = 0.065 for 491 1 unique reflections. The different complexation behaviour is shown to be a consequence of the redox properties of the two metallic elements.Key words: tin, lead, ESR, coordination chemistry, electron transfer.Resume : On croit gtntralement que la condensation de deux moltcules de 3,s-di-tert-butylcattchol (dbc) avec de I'ammoniac, dans des conditions oxydantes, se produit par le biais d'un radical ctto-imine. Une condensation substquente, avec rtaction ulterieure avec des halogenures d1Ctain(II) ou de plomb(II), fournit des complexes de composition identique, M(dbqdi),, dans lesquels dbqdi est l'anion 3,s-di-tert-butyl-1.2-quinone-1-(2-hydroxy-3,s-di-tert-butylphtny1)imine; on utilise ce nom sans tgard B la structure rtelle du coordinat. Les proprietts cristallographiques et magnetiques des deux composts sont differentes et les mesures de RPE indiquent que le derive de l'ttain possbde une ttat fondamental triplet. Les deux impliquent un niveau de coordination de six pour le metal, avec un environnement dtformt; l'ttain est dans un &tat +IV alors que pour le plomb il est de +I1 et on peut observer des differences correspondantes dans le forme du coordinat. Pour le snIv(dbqdi),, les cristaux sont orthorhombiques, groupe d'espace C222,, avec a = 19,597(4), b = 24,375(4) et c The reactions of substituted orthobenzoquinones with main group elements, or the low oxidation state derivatives of such elements, have been the subject of a number of recent papers from this laboratory. In general, the products of these processes are the appropriate catecholate or semiquinone derivatives, which have been characterized by spectroscopic and crystallographic methods. An important feature of these results is that the redox reactions in question have been shown to be one-electron transfer processes (1).We have now extended this research to an investigation of the structure of the compounds formed when tin or lead in the +I1 state react with a ...

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“…(25,26). In general, these results point to the presence of lead in the +I1 state, with one weak and one strong Pb-0 bond.…”

Section: Structuralmentioning

confidence: 80%

Tin and lead derivatives of a Schiff base – bis(orthoquinone) ligand

McGarvey¹,

Ożarowski²,

Zhi-hong³

et al. 1995

Can. J. Chem.

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“…There are several other derivatives [143,145,139,105,147,148] where the overall geometry is best described as a 2-6-2 polyhedron with two capping nitrate ligands. In essence there is no evidence that the lone pair on the lead atom is stereochemical^ active.…”

Section: Comentioning

confidence: 99%

Lead Coordination and Organometallic Compounds: Classification and Analysis of Crystallographic and Structural Data

Holloway¹,

Melnı́k²

1997

Main Group Metal Chemistry

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This review covers over three hundred and sixty coordination and organometallic complexes of lead. About 20% of these contain lead in its +4 oxidation state, of which one fifth are dilead(+6) units, and two are anionic clusters. The Pb(IV) derivatives are predominantly organometallic, many stabilized by sandwich ligation. The majority of the Pb(ll) compounds are typical coordination complexes. Mon-to polynuclear derivatives are found, with coordinations numbers from 2 to 12. The effect of the non bonded pair of valence electrons is observed in lower coordination number Pb(ll) complexes. Examples of distortion, geometric and coordination isomerism are observed. Factors affecting bond lengths and bond angles are discussed, and some ambiguities in coordination polyhedra are outlined.

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“…A: Two Independent Molecules (7) 16.131 (6) 12.889 (5) 9.576(2) 14.151 (4) 16.175 (4) 9.08(1) 11.26(1) 17.14(1) 6.343 (2) 12.286 (5) 16.593 (6) 9.720(1) 10 Footnotes: a. Where more than one chemically equivalent distance or angle is present, the mean value is tabulated.…”

Section: Refmentioning

confidence: 99%

“…There are nineteen lead complexes (Table 6) There are two colourless dimeric derivatives, triclinic Pb 2 (o-tol) 6 /42/ and trigonal Pb 2 (p-tol) 6 Pb(II) atom is pseudo -octahedrally coordinated (Table 5). …”

Section: Ligand Isomerismmentioning

confidence: 99%

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Isomers in the Chemistry of Lead Compounds

Melnı́k¹,

Garaj²,

Holloway³

2007

Main Group Metal Chemistry

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Chemistry of lead compounds covers a wide field, as shown by a recent survey covering the crystallographic and structural data of almost one thousand derivatievs. About 7 % of these derivatives exist as isomers and are summarised in this review. Included are distortion (60 %), ligand (20 %), coordination (12 %) and polymerisation (8 %) isomerism. These are discussed in terms of coordination about the lead atom, and correlations are drawn between donor atom, bond lengths and interbond angles.Distortion isomers, differing only by degree of distortion in Pb -L and L-Pb-L angles, are the most common. Distortion and ligand isomerism spread over a wider range of oxidation state of lead + 2 (most common), + 3 and + 4, than coordination number and polymerisation isomerism ( + 2 only). CONTENTS ABBREVIATIONS

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The Crystal and Molecular Structure of Lead(II) Nitrate : 18-Crown-6.

Cited by 15 publications

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Tin and lead derivatives of a Schiff base – bis(orthoquinone) ligand

Tin and lead derivatives of a Schiff base – bis(orthoquinone) ligand

Lead Coordination and Organometallic Compounds: Classification and Analysis of Crystallographic and Structural Data

Isomers in the Chemistry of Lead Compounds

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