title: Silver(I) complexes in coordination supramolecular system with bulky acridine-based ligands: syntheses, crystal structures, and theoretical investigations on C-H...Ag close interaction.
abstract: In our efforts to investigate the coordination architectures of transition metals and organic ligands with tailored structures, we have prepared two structurally related rigid bulky acridine-based ligands, 9-[3-(2-pyridyl)pyrazol-1-yl]- acridine (L(1)) and 9-(1-imidazolyl)acridine (L2), and synthesized and characterized four of their Ag(I) complexes, {[AgL1](ClO4)}2 (1), {[AgL1](NO3)}2 (2), [AgL2(2)](ClO4) (3), and {[(Ag3L2(3))(NO3)](NO3)2(H2O)}(infinity) (4). The single-crystal X-ray diffraction analysis shows that the structures of 1 and 2 are similar to each other, with the two intramolecular Ag(I) centers of each complex being encircled by two L1 ligands; this forms a unique boxlike cyclic dimer, which is further linked to form one-dimensional (1D) chains of 1 and a two-dimensional (2D) network of 2 by intermolecular face-to-face pi...pi stacking and/or weak C-H...O hydrogen-bonding interactions, respectively. 3 has a mononuclear structure, which is further assembled into a 2D network via intermolecular Ag...O and pi...pi stacking weak interactions. 4 possesses two different 1D motifs that are further interlinked through interlayer face-to-face pi...pi stacking and Ag...O weak interactions, resulting in a 2D network. It is worth noting that one of the interesting structural features of 1, 2, and 4 is the presence of obvious C-H...M hydrogen-bonding interactions between the Ag centers and some acridine ring H atoms identified by X-ray diffraction on the basis of the van der Waals radii. Furthermore, as a representative example, full geometry optimization on the basis of the experimental structure, the natural bond orbital (NBO), and topological analysis of 1 were carried out by DFT and AIM (Atoms in Molecules) calculations. The total C-H...Ag interaction energy in 1 is estimated to be about 14 kJ/mol. Therefore, this work offers three new rare examples (1, 2, and 4) that exhibit C-H...Ag weak interactions, in which the N donors of the acridine rings coordinate to Ag(I) ions. Also, these results strongly support the existence of C-H...Ag close interactions and allow us to have a better understanding of the nature of such interactions in the coordination supramolecular systems.
authors.affiliation: Department of Chemistry and Institute of Elemento-Organic Chemistry and State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P. R. China.
authors.forename: Chun-Sen
authors.initials: CS
authors.lastname: Liu
authors.forename: Pei-Quan
authors.initials: PQ
authors.lastname: Chen
authors.forename: En-Cui
authors.initials: EC
authors.lastname: Yang
authors.forename: Jin-Lei
authors.initials: JL
authors.lastname: Tian
authors.forename: Xian-He
authors.initials: XH
authors.lastname: Bu
authors.forename: Zheng-Ming
authors.initials: ZM
authors.lastname: Li
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Sun
authors.forename: Zhenyang
authors.initials: Z
authors.lastname: Lin