PbMSeO6 (M = Mo and W): New quaternary mixed metal selenites with asymmetric cationic coordination environments

Abstract

Two new isostructural mixed metal selenites, PbMSeO(6) (M = Mo(6+) or W(6+)), that are only composed of second-order Jahn-Teller (SOJT) distortive cations have been synthesized by standard solid-state reaction techniques using PbO, SeO(2), and MoO(3) (or WO(3)) as reagents. The structures of the reported materials were determined by single-crystal and powder X-ray diffraction. The materials show a three-dimensional framework structure consisting of chains of corner-shared MO(6) octahedra connected by SeO(3) and PbO(8) polyhedra. All of the constituent cations (M(6+), Se(4+), and Pb(2+)) are in distorted environments attributable to second-order Jahn-Teller (SOJT) effects. While the Mo(6+) cations undergo a C(2)-type intraoctahedral distortion toward an edge, the Se(4+) and Pb(2+) cations are in asymmetric coordination environments attributable to their lone pairs. The SeO(3) polyhedra strongly influence the direction of the Mo(6+) intraoctahedral distortion. Infrared spectroscopy, thermogravimetric analysis, the magnitudes of out-of-center distortions, and dipole moment calculations are also presented. Crystal data: PbMoSeO(6), triclinic, space group P-1 (No. 2), with a = 6.8944(6) Å, b = 7.2219(6) Å, c = 10.8294(9) Å, α = 99.751(2)°, β = 99.996(2)°, γ = 90.041(2)°, V = 523.09(8) Å(3), and Z = 2; PbWSeO(6), triclinic, space group P-1 (No. 2), with a = 6.8689(2) Å, b = 7.2398(2) Å, c = 10.9037(3) Å, α = 99.699(4)°, β = 100.348(3)°, γ = 90.139(4)°, V = 525.50(3) Å(3), and Z = 2.

Stabilization of O–O Bonds by d0 Cations in Li4+xNi1–xWO6 (0 ≤ x ≤ 0.25) Rock Salt Oxides as the Origin of Large Voltage Hysteresis

“…Sites 2 and 6 have only five W 6+ cations in the three neighboring cation shells at T 1 , T 2 , and T 3 (Table S2 in Supporting Information), compared to eight for the other sites, making them more likely to contain Ni 2+ as a result of lower electrostatic repulsion. The d 0 configuration of W 6+ leads to asymmetric displacement from the center of its octahedron, moving away from site 6 and toward the edge shared with site 2 (Tables S3 and S4 in Supporting Information), attributed to second-order Jahn–Teller effects. , This destabilizes one site at the expense of the other, leading to a high occupation of site 6 by Ni 2+ (57%) and a low occupation of site 2 (8.9%). For the same reason, site 3 is further away from the W 6+ cations and has a higher Ni 2+ content (27.6%) compared to that of site 5 (4.2%).…”

“…The d 0 configuration of W 6+ leads to asymmetric displacement from the center of its octahedron, moving away from site 6 and toward the edge shared with site 2 (Tables S3 and S4 in Supporting Information), attributed to second-order Jahn−Teller effects. 19,20 This destabilizes one site at the expense of the other, leading to a high occupation of site 6 by Ni 2+ (57%) and a low occupation of site 2 (8.9%). For the same reason, site 3 is further away from the W 6+ cations and has a higher Ni 2+ content (27.6%) compared to that of site 5 (4.2%).…”

Cation Size Effect on the Framework Structures in a Series of New Alkali-Metal Indium Selenites, AIn(SeO3)2 (A = Na, K, Rb, and Cs)

“…In fact, an examination of 36 examples of SeO 3 polyhedra found in indium selenites materials reveals that the dipole moments range from 6.99 D to 11.00 D, with an average value of 8.01 D. The values are consistent with those reported dipole moments for SeO 3 polyhedra. 25,26,38,39 A complete calculation of dipole moments for the SeO 3 polyhedra is listed in Table 3.…”

Toward the Rational Design of Novel Noncentrosymmetric Materials: Factors Influencing the Framework Structures

“…and cations possessing stereochemically active lone pairs (Pb 2+ , Sb 3+ , Bi 3+ , Se 4+ , Te 4+ , I 5+ , etc. ), − (2) d 10 transition metal cations revealing highly polar displacement in the center of the coordination environment (Zn 2+ , Cd 2+ , etc. ), − and (3) anions with trigonal-planar geometry exhibiting asymmetric π-conjugated molecular orbitals (NO 3 – , CO 3 2– , BO 3 3– , etc.…”