Uninodal 4-connected 3D nets. II. Nets with 3-rings

Abstract

A description is given of nineteen 4-connected nets with one kind of vertex and containing 3-rings. Many of them are believed to be new.

Li2CaSi2N4 and Li2SrSi2N4 – a Synthetic Approach to Three‐Dimensional Lithium Nitridosilicates

“…[24] This network is the first nitridosilicate representative of Net39 according to the classification of cubic unit cells from O'Keeffe regarding unit cells consisting of 24 tetrahedra (8 dreier rings, 6 siebener rings). [25] The dreier rings are perpendicular to the four threefold axes, respectively. Furthermore, Net39 is unprecedented for silicates so far.…”

Nitridosilicate und Oxonitridosilicate: von keramischen Materialien zu struktureller und funktioneller Diversität

“…[86][87][88] [90] und Eu [91] kristallisieren isotyp in der Raumgruppe Pmn2 1 . Die Kristallstruktur basiert auf einem Raumnetz eckenverknüpfter [SiN 4 ]-Tetraeder, in dem die eine Hälfte der Stickstoffatome zwei (N [2] ) und die andere drei Si-Atome verbindet (N [3] ).…”

Enumeration of periodic tetrahedral frameworks

“…To date, a large number of 3-dimensional 4-connected framework topologies have been identified, many of which possess an intricacy that belies the simplicity of the crystallographic and topological rules that generate them. This rapidly-expanding list of topologies owes much to the early pioneering work of Wells [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and, latterly, to the systematic enumerative studies of Smith [15][16][17][18][19][20][21][22][23][24][25][26][27][28] and O'Keeffe [29][30][31][32][33]. Only about 100 of the known topologies occur in nature or have been synthesized, although that number is steadily increasing [34].…”

“…They performed a dense grid search over all possible atom positions in the asymmetric units of the orthorhombic, tetragonal, trigonal, hexagonal and cubic space groups, and identified the optimal tetrahedral configurations. To date, O'Keeffe has categorized and published details of 64 of the 128 optimized uninodal tetrahedral frameworks obtained by this method [29][30][31][32][33].…”

“…One of the earliest systematic computerized searches for tetrahedral frameworks was carried out by O'Keeffe and Brese [29][30][31][32][33], who imposed the constraints that (i) there is one crystallographically unique tetrahedral atom, (ii) frameworks are 3-dimensional and periodic. They performed a dense grid search over all possible atom positions in the asymmetric units of the orthorhombic, tetragonal, trigonal, hexagonal and cubic space groups, and identified the optimal tetrahedral configurations.…”