Cadmium(II) iodide and thiocyanate complexes adopted by polycyclic 1,4-bis(pyridazin-4-yl)benzene: interplay of coordination and π–π stacking interactions

Abstract

New complexes containing the 1,4-bis(pyridazin-4-yl)benzene ligand, namely diaquatetrakis[1,4-bis(pyridazin-4-yl)benzene-κN(2)]cadmium(II) hexaiodidodicadmate(II), [Cd(C14H10N4)4(H2O)2][Cd2I6], (I), and poly[[μ-1,4-bis(pyridazin-4-yl)benzene-κ(2)N(2):N(2')]bis(μ-thiocyanato-κ(2)N:S)cadmium(II)], [Cd(NCS)2(C14H10N4)]n, (II), demonstrate the adaptability of the coordination geometries towards the demands of slipped π-π stacking interactions between the extended organic ligands. In (I), the discrete cationic [Cd-N = 2.408 (3) and 2.413 (3) Å] and anionic [Cd-I = 2.709 (2)-3.1201 (14) Å] entities are situated across centres of inversion. The cations associate via complementary O-H...N(2') hydrogen bonding [O...N = 2.748 (4) and 2.765 (4) Å] and extensive triple π-π stacking interactions between pairs of pyridazine and phenylene rings [centroid-centroid distances (CCD) = 3.782 (4)-4.286 (3) Å] to yield two-dimensional square nets. The [Cd2I6](2-) anions reside in channels generated by packing of successive nets. In (II), the Cd(II) cation lies on a centre of inversion and the ligand is situated across a centre of inversion. A two-dimensional coordination array is formed by crosslinking of linear [Cd(μ-NCS)2]n chains [Cd-N = 2.3004 (14) Å and Cd-S = 2.7804 (5) Å] with N(2):N(2')-bidentate organic bridges [Cd-N = 2.3893 (12) Å], which generate π-π stacks by double-slipped interactions between phenylene and pyridazine rings [CCD = 3.721 (2) Å].

Cooperativity in Noncovalent Interactions

“…Several examples of coexistence of π–π interactions along with other noncovalent interactions abound in literature. ,,,− The presence of halogen bonding and π–π interactions in the solid state structure of a butadiynylene linked bidentate halogen bond donor was recently shown by Taylor and co-workers . A cocrystal with tetra- n -butylammonium iodide was also studied.…”

“…An interplay of coordination and π−π stacking interactions has been studied in cadmium(II) iodide and thiocyanate complexes adopted by polycyclic 1,4bis(pyridazin-4-yl)benzene. 377 Mattay and co-workers have reported the synthesis of arene-functionalized 2-aminopyrimidines, where hydrogen bonding and π−π interaction have a significant contribution in the process of self-assembly on account of their coexistence. 372 Fu et al revealed the crystal structure of methyl 4-hydroxy-3-nitrobenzoate where 12 hydrogen bonding and two π-stacking interactions are shown linking the molecules into infinite stacked sheets.…”

“…A cocrystal with tetra- n -butylammonium iodide was also studied. An interplay of coordination and π–π stacking interactions has been studied in cadmium­(II) iodide and thiocyanate complexes adopted by polycyclic 1,4-bis­(pyridazin-4-yl)­benzene . Mattay and co-workers have reported the synthesis of arene-functionalized 2-aminopyrimidines, where hydrogen bonding and π–π interaction have a significant contribution in the process of self-assembly on account of their coexistence .…”

Formation of Excimers in Isoquinolinyl Pyrazolate Pt(II) Complexes: Role of Cooperativity Effects

“…The cooperativity between π–π interactions and other noncovalent interactions (i.e., ion−π, hydrogen bonding, etc.) has been the scope of multiple investigations. − The cooperative effects might be seen on the bonding distances between the molecular units, usually leading to shorter distances in the supramolecular complexes when synergistic effects arise. Scheme displays, for example, the synergistic effects arising due to the coexistence of ion−π and π–π noncovalent interactions.…”