Phase and structural study of clathrate formation in the [Zn(MePy)2(NCS)2]-MePy system (MePy=4-methylpyridine)

Polymorphism and Pseudopolymorphism of the [Ni(4-Methylpyridine)4(NCS)2] Werner Complex, the Compound that Led to the Concept of “Organic Zeolites”

“…This type of structure forms with a wide range of guests, including p-and m-xylenes, 74 methanol, 74 p-cymene, 75 4-MePy, 76 and others. 77 This structure is also formed by other similar complexes, including [M(4-MePy) 4 (NCS) 2 ] with Mg(II), 24,72 Fe(II), 78,79 Co(II), 79,80 and Zn(II) 25 as M, [M(4vinylpyridine) 4 (NCS) 2 ] with Co(II) 81 and Ni(II), 82 and [Ni(4-ethylpyridine) 4 (NCS) 2 ]. [83][84][85] A remarkable property of β-phases of the title complex and some of its analogues is that they survive total guest removal, producing empty microporous β-polymorphs.…”

“…While some hosts persistently form the same architecture with a wide range of guests, [14][15][16][17][18] others may exhibit a number of inclusion architectures to accommodate different guests. [19][20][21][22][23] In addition, there are examples where the same host forms several crystalline clathrates with the same guest, [24][25][26][27][28][29][30][31][32][33][34][35][36] this phenomenon also being referred to as solvatomorphism. 37 Finally, some inclusion compounds have exactly the same composition but different crystal structures, thus being true polymorphs.…”

“…The cage-type clathrates form with nitrotoluene and chloronitrobenzene isomers. 71 Details of this architecture were obtained from studies of isostructural clathrates of the Mg(II), 24,72 Mn(II), 73 Cu(II), 73 Zn(II), 25 and Cd(II) 73 host analogues with a 4-MePy guest. As a rule, guest molecules can be extracted from this type of host structure only with chemical decomposition of the host.…”

“…Pseudopolymorphism is most commonly defined as the existence of structurally different crystalline modifications of a host compound, embracing both unsolvated forms and various solvates (inclusion compounds) of the host. − Indeed, in a broad sense, inclusion compounds may be considered as polymorphic modifications of the host component, which are stabilized by the presence of a templating guest. While some hosts persistently form the same architecture with a wide range of guests, − others may exhibit a number of inclusion architectures to accommodate different guests. − In addition, there are examples where the same host forms several crystalline clathrates with the same guest, − this phenomenon also being referred to as solvatomorphism . Finally, some inclusion compounds have exactly the same composition but different crystal structures, thus being true polymorphs. , …”

Syntheses and crystal structures of bis(4-methylpyridine-κN)bis(selenocyanato-κN)zinc(II) and catena-poly[[bis(4-methylpyridine-κN)cadmium(II)]-di-μ-selenocyanato-κ2 N:Se;κ2 Se:N]

“…With Zn(NCS) 2 , compounds include three discrete complexes with the composition Zn(NCS) 2 (4-methylpyridine) 4 , in which the Zn cations are octahedrally coordinated by two terminal N-bonded thiocyanate anions and four 4-methylpyridine ligands [Cambridge Structural Database (Groom et al, 2016) refcodes EFESOX and YORHAO (Lipkowski et al, 1994) as well as QQQBUD (Ratho & Patel, 1969)]. Two of them (EFESOX and YORHAO) represent clathrates with additional 4-methylpyridine molecules or 4-methylpyridine and water molecules.…”