Hemi- and holo-directed lead(ii) complexes in a soft ligand environment

Abstract

To investigate the geometry and stereochemical activity of the lone pair at the lead atom, lead(ii) complexes () with one tripodal (L(1)), one dipodal (L(2)) boron-centred soft ligand and eight other small soft heterocyclic ligands, 2-mercaptobenzimidazole (L(3)), 2-mercapto-5-methylbenzimidazole (L(4)), 3-mercapto-1,2,4-triazole (L(5)H), 3-mercapto-4-methyl-1,2,4-triazole (L(6)), 2-mercapto-1,3,4-thiadiazole (L(7)H), 2-mercapto-5-methyl-1,3,4-thiadiazole (L(8)H), 5-mercapto-1-methyltetrazole (L(9)H) and 2-mercapto-4-phenylthiazole (L(10)H) were prepared. The structures of these complexes were elucidated on the basis of X-ray crystallography, elemental analyses as well as (1)H NMR, (1)H DOSY, (13)C NMR and (207)Pb NMR spectroscopy. The coordination numbers of these complexes vary from 4 to 8. The majority of the complexes are polymeric and possess a hemi-directed environment around the lead atoms. Solution studies revealed that most of the complexes are dissociated in highly polar solvents. Most of the complexes are emissive both under ambient conditions and at 77 K in the solid state. However, no obvious relationship between their solid state structures and luminescence behaviour with respect to the nature of the excited state could be identified.

Synthesis and Structural Studies of Bismuth-piroxicam Complex

“…Furthermore, it can be attributed to high spin orbital coupling (SOC) of bismuth [11,12]. The observed value of emission fluorescence of Bi(III) complex is comparable with previously reported complexes in literature [13][14][15].…”

Crystal and molecular structures of a binuclear mixed ligand complex of silver(I) with thiocyanate and 1H-1,2,4-triazole-5(4H)-thione

“…In [Cu(HtrzS)] n (TEHYIQ; Zhang et al, 2012), this is achieved by bidentate, 2 -bridging by the thiolate-S atom and the participation of one of the triazolyl-N atoms in coordination. In [Pb(HtrzS)(NO 3 )OH 2 ] n (MOKKAA; Imran et al, 2015), the thiolate-S and two triazolyl-N atoms are involved in coordination. A similar coordination mode is found for one of the independent anions in [Cd 2 (HtrzS) 2 (SO 4 )] n (LOFJUM; Zhang et al, 2008).…”

Directionality of Pb2+ lone pair electrons dictated hemi‐directed coordination mode of methyl‐ and ferrocenylcarboxylate complexes

“…But it has been reported that Pb 2+ dictates the ligands even in high density and higher denticity (greater than five) to follow the definite structural pattern in the entire globe . Based on the available literature, the structural effects in Pb 2+ can be categorized into holo‐directed (Full sphere) and hemi‐directed (Half sphere) by disposition of ligands around the metal ion . The holo‐ and hemi‐directed structural patterns are further distinguished in the surface of globe without and with void in the distribution of coordination bonds to ligands, respectively which is shown in Figure .…”

“…[13] Based on the available literature, the structural effects in Pb 2+ can be categorized into holo-directed (Full sphere) and hemi-directed (Half sphere) by disposition of ligands around the metal ion. [14][15][16][17][18][19][20][21][22] The holo-and hemi-directed structural patterns are further distinguished in the surface of globe without and with void in the distribution of coordination bonds to ligands, respectively which is shown in Figure 1. In hemi-directed geometry of two or more Pb 2+ systems, the lone pair electrons follow two different structural fashions namely, linear (occupation of lone pair in the same sides) and zig-zag (occupation of lone pair in the opposite sides).…”