Lead Oxychloride Borates Obtained under Extreme Conditions

Abstract

[Pb10O4]Pb2(B2O5)Cl12 (1) and [Pb18O12]Pb(BO2OH)2Cl10 (2) were obtained via high-temperature high-pressure experiments. [O12Pb18](12+) and [O4Pb10](12+) oxocentered structural units of different dimensionality are excised from the ideal [OPb] layer in tetragonal α-PbO. 2 is formed with an excess of lead oxide component, and 1 is formed with an excess of borate and halide reagents. The structure of 2 can be visualized as the incorporation of {Pb(10)Cl4(BO2OH)2} clusters into alternating PbO and chloride layers, with the existence of square vacancies in both. However, the structure of 1 is described as the intrusion of [O4Pb10](12+) tetramers linked by disordered Pb(B2O5) groups into a halogen three-dimensional matrix. The structure of 2 contains 10 symmetrically independent Pb positions. The 6s(2) lone electron pair is stereochemically active on Pb(1)-Pb(9) atoms, whereas it is inert on Pb(10). All of the Pb coordinations in the structure of 2, in accordance with ECCv (volume eccentricity) parameters and the density of states (DOS), can be subdivided into three groups. The current study is the first attempt to analyze this unusual behavior in structurally complex oxyhalide material with the rare case of Pb(2+) cations, demonstrating both stereochemically active and inactive behavior of the lone pair via charge and first-principle calculations.

Bonding Scheme and Optical Properties in BiM2O2(PO4) (M=Cd, Mg, Zn); Experimental and Theoretical Analysis

“…It is well known for post‐transition 6s 2 metal oxides (Tl + , Pb 2+ , Bi 3+ ) that strong interactions between the cation s and oxygen p orbitals results in anti‐bonding states with a large contribution of the s orbitals of the cations at the top of the valence band . Moreover, the interactions between nominally empty cation p states (Bi 3+ : 6s 2 6p 0 ) with the antibonding orbitals results in the familiar lone pair asymmetric electron density within a distorted coordination.…”

“…It is well known for post-transition 6s 2 metal oxides (Tl + ,P b 2 + , Bi 3 + )t hat strong interactions between the cation sa nd oxygen po rbitals resultsi na nti-bonding states with al arge contribution of the so rbitals of the cationsa tt he top of the valence band. [32,33,48,49] Moreover,t he interactions between nominally emptyc ation ps tates (Bi 3 + :6 s 2 6p 0 )w ith the antibonding orbitals results in the familiarlone pair asymmetric electron density within ad istorted coordination.I nt he three investigated compounds, this behavior is verifiedb yt he presence of mixed O2p, Bi 6s, and Bi 6p states at the Fermi level. Figure 4a depicts the total density of states (TDOS)a nd partial density of states (PDOS) calculated for BiMg 2 PO 6 .T he uppermost VB (À5.5 to 0eV) is essentially dominated by P3p, O2p, and Bi 6p states, and as mall contributiono fB i6ss tates just below the Fermi level.…”

Hydrocerussite-related minerals and materials: structural principles, chemical variations and infrared spectroscopy

“…Simultaneous presence of Pb 2+ cations with holodirected and hemidirected coordination environments in one structure is rare, but it was previously observed in several minerals and synthetic materials (Mills et al, 2010;Kampf et al, 2010;Siidra et al, 2016).…”

Copper–lead selenite bromides: a new large family of compounds partly having Cu2+ substructures derivable from kagome nets

“…The structure of CuPb1:6 demonstrates the smallest Cu:Pb 1:6 ratio and exhibits a 2D structure, consisting of positively charged 2 1 [Pb 6 Cu(SeO 3 ) 4 ] 6+ layers ( Fig. 1e) also found in the structures of many litharge-derived layered oxyhalides, particularly those of lead (Turner et al, 2012;Siidra et al, 2013aSiidra et al, ,b,c, 2015Siidra et al, , 2016Chukanov et al, 2018) and bismuth (Charkin, 2008;Kozin et al, 2013). These layers are sandwiched between pseudotetragonal 2…”