Chia-Jun Wu

Ligand isomerism-controlled structural diversity of cadmium(II) perchlorate coordination polymers containing dipyridyladipoamide ligands

The syntheses, structures and ligand conformations of three Cd(II) coordination polymers [Cd(L1)(ClO4)2]∞ [L1 = N,N′-di(2-pyridyl)adipoamide], 1, {[Cd(L2)2(CH3OH)2](ClO4)2·2CH3OH}∞ [L2 = N,N′-di(3-pyridyl)adipoamide], 2 and [Cd(L3)2(ClO4)2(CH3CH2OH)2]∞ [L3 = N,N′-di(4-pyridyl)adipoamide], 3, are reported. Their structures have been characterized by X-ray crystallography. Complex 1 forms 1D zigzag chains, while complex 2 forms 2D pleated sheets which are positioned in an ABAB manner. Complex 3 shows a rare 3D entanglement from parallel polycatenation of 3-fold interpenetrated square layers. While the L1 ligands in 1 adopt AAAtrans conformations and the L2 ligands in 2 adopt GAGtrans conformations, the L3 ligands in 3 adopt AAAtrans and AGAtrans conformations. The structural types of the Cd(II) coordination polymers can be directed by ligand isomerism.

Roles of I⋯I and Ag⋯I interactions on the self-assembly of Ag(I) complexes containing 2-amino-5-iodopyrimidine; formation of the unique Ag⋯I⋯I⋯Ag interaction

A series of silver(I) complexes [Ag(L)(NO3)]4, (L = 2-amino-5-iodopyrimidine), 1, [Ag(L)(PF6)]∞, 2, and [Ag(L)(ClO4)]∞, 3, have been prepared by the reactions of AgX (X = NO3−, PF6− and ClO4−, respectively) with L. All the complexes have been structurally characterized by X-ray crystallography, confirming that complex 1 forms sixteen–membered metallocycles interlinked by I⋯I and Ag⋯O interactions to create a porous structure. Complexes 2 and 3 form helical chains, with different periods of 22.584 and 11.465 A, respectively. In addition to the Ag⋯O interaction and hydrogen bonds, the unique discrete Ag⋯I⋯I⋯Ag and linear ⋯(Ag⋯I⋯I⋯Ag)n⋯ interactions with short I⋯I and Ag⋯I contacts were found in complexes 2 and 3, respectively, to support their supramolecular structures.

Roles of halide anions in the structural diversity of Zn(II) complexes containing the flexible N,N′-di(4-pyridyl)adipoamide ligand

A series of Zn(II) complexes with N,N′-di(4-pyridyl)adipoamide ligands, {[ZnX2(L)]·H2O}∞ (X = Cl, 1, Br, 2 and I, 3; L = N,N′-di(4-pyridyl)adipoamide), [Zn2X4(L)2]·2DMF (X = Cl, 4 and Br, 5) and [Zn2I4(L)2]·4DMF·C4H10O, 6, were prepared and their structures determined by X-ray crystallography. Complexes 1 and 2 form double-stranded helical chains which are supported by the N–H⋯O and O–H⋯X hydrogen bonds involving the guest water molecules and the halide anions, whereas 3 shows sinusoidal chains which are interlinked by the N–H⋯O hydrogen bonds and π–π interactions. Complexes 1–3 represent a unique example that the halide anions show significant effect on folding and unfolding of the Zn(II) double-stranded helical coordination polymers. Complexes 1–3 can be transformed to the corresponding complexes 4–6, which are dinuclear with 34-membered metallocycles. In these complexes, the chloride and bromide anions play the same role in the crystal structures, while the iodide anion is distinct.

Diverse Ag(I) complexes constructed from asymmetric pyridyl and pyrimidyl amide ligands: roles of Ag⋯Ag and π–π interactions

Reactions of silver(I) salts with the isomeric pyridyl amide ligands methyl-4-(pyridin-2-ylcarbamoyl)benzoate (L1), methyl-4-(pyridin-3-ylcarbamoyl)benzoate (L2) and methyl-4-(pyridin-4-ylcarbamoyl)benzoate (L3) and the pyrimidyl amide ligand methyl-4-(pyrimidin-2-ylcarbamoyl)benzoate (L4) afforded the complexes Ag4(L1)4(NO3)4, 1, [Ag(L2)2][Ag(NO3)2], 2, [Ag(L2)2](ClO4), 3, [Ag(L2)2](ClO4)·2CH3CN, 4, [Ag(L3)2](NO3), 5, [Ag(L3)2](ClO4)·CH3CN, 6, and [Ag(L4)2](X) (X = ClO4−, 7; BF4−, 8; PF6−, 9), which were structurally characterized by X-ray crystallography. The L1–L3 ligands in 1–6 adopt monodentate bonding modes, which coordinate to the metal centers through the pyridyl nitrogen atoms, whereas the L4 ligands of 7–9 adopt a bidentate mode, featuring chelation through one pyrimidyl nitrogen atom and the amide oxygen atom. All nine complexes adopt discrete structures with 1 being tetranuclear and 2–9 being mononuclear. Moreover, Ag⋯Ag short contacts, π⋯π stacking interactions and/or Ag⋯O interactions are found in these complexes which extend the dimensionalities of the structures. The changes of the donor atom positions and counteranions significantly affect the supramolecular structures of these complexes and the L1–L4 ligands are sufficiently flexible to adopt the cis and/or trans conformations.

Diverse Ag(I) complexes constructed from methyl-4-(5-halopyrimidin-2-ylcarbamoyl)benzoate ligands: roles of the halogen atom and anion

The synthesis and structures of eight new silver(I) complexes [Ag(L1111)(NO3)]∞ (L1111 = methyl-4-(pyrimidin-2-ylcarbamoyl)benzoate), 1, [Ag2(L222)(NO3)2]∞ (L222 = methyl-4-(5-chloropyrimidin-2-ylcarbamoyl)benzoate), 2, [Ag2(L33)(NO3)2]∞ (L33 = methyl-4-(5-bromopyrimidin-2-ylcarbamoyl)benzoate), 3, [Ag(L44)(NO3)]∞ (L44 = methyl-4-(5-iodopyrimidin-2-ylcarbamoyl)benzoate), 4, {[Ag(L33)](BF4)·0.5THF}∞, 5, [Ag2(L44)4](BF4)2·2CH3OH, 6, and [Ag2(L44)4](X)2 (X = PF6−, 7; SbF6−, 8) are reported. In complexes 1–3, the L11–L33 ligands adopt the tridentate mode, featuring chelation and bridge through two pyrimidyl nitrogen atoms and one amidecarbonyl oxygen atom and resulting in a 1D chain for 1 and 2D nets for 2 and 3 with the topology of {4·6·8}{4·62·83}{62·8}, while in 4, the L44 ligand coordinates to the silver(I) metal center through one of the two pyrimidyl nitrogen atoms, the amide oxygen atom and the iodine atom to afford a 1D chain. The L33 ligands in 5 coordinate to the silver(I) metal centers in a tetradentate bonding mode through two nitrogen and two oxygen donor atoms, resulting in a 2D net with the topology of {4·62}2{42·62·82}. In complexes 6–8, the L44 ligands show both bidentate and tridentate fashions, showing dinuclear structures with ten-membered metallocycles. While the halogen atoms of 2 and 3 are involved in the X⋯O (X = Cl for 2 and Br for 3) interactions, short Ag–I bond distances of 2.7700(5) A in 4 and 2.8925(10), 2.8353(9) and 2.8520(8) A in 6–8 are found, which appear to be due to the high polarizability of the iodine atom.

Methyl 4-[(pyrimidin-2-yl)carbamo-yl]benzoate.

Molecules of the title compound, C13H11N3O3, are connected into centrosymmetric dimers via intermolecular N—H⋯N hydrogen bonds, generating an R 2 2(8) motif. The pyrimidine and the phenyl rings are twisted with respect to each other by an interplanar angle of 61.3 (1)°.

Methyl 4-[(5-chloro-pyrimidin-2-yl)carbamo-yl]benzoate.

Molecules of the title compound, C13H10ClN3O3, form centrosymmetric dimers via intermolecular N—H⋯N hydrogen bonds generating an R 2 2(8) motif. The dimers are further connected through an O⋯Cl—C halogen bond [O⋯Cl = 3.233 (1) Å and O⋯Cl—C = 167.33 (1)°] into a chain along [110]. The secondary amide group adopts a cis conformation. Weak C—H⋯N hydrogen bonds among the methyl benzoate and pyrimidyl rings are also observed in the crystal structure.

N-(6-Methyl-2-pyrid-yl)formamide.

The molecule of the title compound, C7H8N2O, is essentially planar with a maximum deviation of 0.0439 (1) Å from the best plane. In the crystal, N—H⋯O hydrogen bonds between self-complementary amide groups join molecules into centrosymmetric dimers.

2-{5-[N-(2-Pyridyl)carbamo­yl]pentan­amido}pyridinium hexa­fluoro­phosphate

In the crystal structure of the title compound, C16H19N4O2 +·PF6 −, the cations and anions are situated on centres of inversion. Thus, the N—H H atom is disordered over both N atoms due to symmetry. In the crystal, molecules are connected via N—H⋯F and N—H⋯O hydrogen bonds. The cation adopts the ⋯AAA⋯ trans conformation in the solid state.

Methyl 4-[N-(5-bromo­pyrimidin-2-yl)carbamo­yl]benzoate

In the title compound, C13H10BrN3O3, the pyrimidine and benzene rings are twisted with an interplanar angle of 58.4 (1)°. The secondary amide group adopts a cis conformation with an H—N—C—O torsion angle of 14.8 (1)°. In the crystal, molecules are connected into inversion dimers via pairs of N—H⋯N hydrogen bonds, generating an R 2 2(8) motif. The dimers are further connected through a C—Br⋯O interaction [3.136 (1) Å and 169.31 (1)°] into a chain along [110]. Weak C—H⋯N hydrogen bonds between the methyl benzoate groups and pyrimidine rings are also observed in the crystal structure.