Lead(II): misleading or merely hermaphroditic?

Soudi, Ali A.; Marandi, Farzin; Ramazani, Ali; Ahmadi, Ebrahim; Morsali, Ali

doi:10.1016/j.crci.2004.09.004

Cited by 64 publications

(36 citation statements)

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“…An explanation of the difference in these alkali metal arrays may be that only Rb is involved in coordinative interaction with uranyl-O [Rb-O 3.035(6) Å]. As seems to be commonly the case with heavy and apparently weakly coordinating metals, [6,21,[27][28][29][30][31] it is difficult to define a precise cutoff distance for interactions considered to be bonding but the coordination numbers of both Rb and Cs here appear to be high, involving O-donors only, with rather irregular geometry about the metals. Interestingly, the extreme M···O separations approach those of M···U, which, if they are correctly considered as contacts of closed-shell species of similar charge, would be regarded as involving negligible interactions, thus indicating that the extreme M···O contacts must also be of little significance.…”

Section: Resultsmentioning

confidence: 95%

Solid‐State Luminescence and π‐Stacking in Crystalline Uranyl Dipicolinates

et al. 2006

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Section: Resultsmentioning

confidence: 95%

Solid‐State Luminescence and π‐Stacking in Crystalline Uranyl Dipicolinates

et al. 2006

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Section: Introductionmentioning

confidence: 99%

“…Pb(II) complexes with 2,2 0 -bipyridine and 4,4 0 -bipyridine ligands [18][19][20] were subject to frequent studies. Since 4,4 0 -bipyridine can potentially act as a spacer ligand, a vast number of coordination polymers of its metal ions (e.g., with Pb(II), [20,21]) have been previously reported. Although, 2,2 0 -bipyridine ligand can also act as a bridging ligand [22] (by free rotation along the central C-C bond), but the most common mode of binding for this ligand and its derivatives are the chelating fashion.…”

Section: Introductionmentioning

confidence: 99%

Two new lead(II) coordination polymer and discrete complex containing bipyridine ligands with different positioned methyl substituents: synthesis, characterization, crystal structure determination, and luminescent properties

Alizadeh

Amani

2011

Struct Chem

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Lead(II) coordination polymer [Pb(5,5 0 -dmbpy) (l-NO 3 ) 2 ] n (1) and mononuclear complex [Pb(6,6 0 -dmbpy) (NO 3 ) 2 ] (2) (where 5,5 0 -dmbpy is 5,5 0 -dimethyl-2,2 0 -bipyridine and 6,6 0 -dmbpy is 6,6 0 -dimethyl-2,2 0 -bipyridine) were synthesized from reaction of lead(II) nitrate with 5,5 0 -dmbpy and 6,6 0 -dmbpy, respectively. Both complexes were thoroughly characterized by elemental analysis, infrared, 1 H and 13 C NMR, UV-Vis, emission spectroscopy, as well as single-crystal X-ray diffraction. Polymer 1 possesses one-dimensional (1D) chain structure, whilst complex 2 exhibits a discrete complex which provide an extended chain parallel to the [001] direction, via weak intermolecular C-HÁÁÁO hydrogen bonding. Coordination number of Pb 2? in 1 and 2 are 8 and 6, respectively, with the stereochemically active lone pair, resulting in the hemidirected geometry for both complexes. The nitrate anions exhibit a tridentate chelating/bridging mode in 1, and a bi-chelating mode in 2. The supramolecular features in these complexes are guided/influenced by weak directional intermolecular C-HÁÁÁO hydrogen bonding (1 and 2) together with p-p and C-HÁÁÁp (1) interactions. The luminescence studies of 1 and 2 confirmed that the position of methyl substituent on 2,2 0 -bipyridine rings has a profound effect on the fluorescence emissions.

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“…There is little unusual in such a range of distances for Na I [7], but it is even more true of Pb II that Pb (donor atom) separations associated with coordination can vary over a wide range [3 ± 5]. Justification has been advanced for consideration of PbÀO separations at least as great as 3.1 ä, as indicative of (single) bonding [8], and there are many instances of significantly longer contacts, where a similar conclusion appears plausible [5] 1 ). Thus, it must be noted that in [NaPb(en)(ClO 4 )(NO 2 ) 2 ] n , the two nitrite ligands described as unidentate on Pb (PbÀO 2.604(5) and 2.629(5) ä, resp.)…”

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The Enigma of Lead(II) Coordination – Some Comments

Harrowfield

2005

Helvetica Chimica Acta

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In a recent report [1] of the crystal structure of polymeric [NaPb(en)(ClO 4 )-(NO 2 ) 2 ] n (en ethane-1,2-diamine), Morsali has drawn the conclusions that the Pbatoms are four-coordinate and that a stereochemically active lone pair is present. Although the coordination chemistry of Pb II has been subjected to detailed analyses [2 ± 4], it is frequently the case that the establishment of the coordination number of the metal, and, hence, of its coordination geometry, remain somewhat arbitrary tasks [3 ± 5]. Thus, instances where the situation appears to be clear-cut are of particular interest.The claim of a strongly hemidirected four-coordination of Pb II in [NaPb(en)-(ClO 4 )(NO 2 ) 2 ] n implies certain limits, not stated, upon PbÀN and PbÀO distances considered to involve bonding interactions, the general issue of how to describe the origins of atomic contacts within crystalline solids being of considerable current interest [6]. Similarly, a limit must be defined for the NaÀO separations taken as bonding, and the eight-coordination assigned to Na in [NaPb(en)(ClO 4 )(NO 2 ) 2 ] n is associated with NaÀO distances varying from 2.363(6) to 2.949(8) ä. There is little unusual in such a range of distances for Na I [7], but it is even more true of Pb II that Pb (donor atom) separations associated with coordination can vary over a wide range [3 ± 5]. Justification has been advanced for consideration of PbÀO separations at least as great as 3.1 ä, as indicative of (single) bonding [8], and there are many instances of significantly longer contacts, where a similar conclusion appears plausible [5] 1 ). Thus, it must be noted that in [NaPb(en)(ClO 4 )(NO 2 ) 2 ] n , the two nitrite ligands described as unidentate on Pb (PbÀO 2.604(5) and 2.629(5) ä, resp.) could be taken as asymmetrically bidentate, since there are contacts from the other anion O-atoms at 2.922(5) and 2.875(5) ä, respectively, to the same metal center 2 ). Further, the N-atoms of the NO À 2 groups, considered to be bound (via oxygen) to two other Pb atoms, are found at distances of 3.243(6) and 3.317(6) ä, respectively, from Pb.If all four of these longer contacts are taken to indicate coordinate bonding, then Pb II is eight-coordinate, a far-from-unusual situation for the metal [2 ± 4]. The coordination geometry, however, remains strongly hemidirected, and, now, further analysis becomes ambiguous. One feature of the lattice of [NaPb(en)(ClO 4 )(NO 2 ) 2 ] n is that Pb(en) units can be considered to lie in columns in such a way that the ethylene bridge of a diamine chelate on one metal lies directly over what could be considered the Helvetica Chimica Acta ± Vol. 88 (2005) 2430 ¹ 2005 Verlag Helvetica Chimica Acta AG, Z¸rich 1 ) For similar difficulties in interpreting Pb ¥¥¥ Pb separations in terms of metal ± metal bonds, see [9]. 2 ) As chelates, the NO À 2 groups form a D pair at all Pb centers, consistent with the observation that the material crystallizes as a conglomerate, with all the en chelates being of d-conformation in the chosen crystal.

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Lead(II): misleading or merely hermaphroditic?

Cited by 64 publications

References 33 publications

Solid‐State Luminescence and π‐Stacking in Crystalline Uranyl Dipicolinates

Solid‐State Luminescence and π‐Stacking in Crystalline Uranyl Dipicolinates

Two new lead(II) coordination polymer and discrete complex containing bipyridine ligands with different positioned methyl substituents: synthesis, characterization, crystal structure determination, and luminescent properties

The Enigma of Lead(II) Coordination – Some Comments

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