Chang-Wei Su

Synthesis and structural characterization of two chain complexes of Mn(II) containing 2-aminopyridinium

Abstract The 2-aminopyridine ligand has been exploited in preparation of divalent metal complexes of the formulae [H(2-ampy)][MnCl3(H2O)] 1 and [H(2-ampy)]2[Mn2Cl6(2-ampy)2] 2, where 2-ampy is 2-aminopyridine. Their crystal structures have been determined by X-ray crystallography. Both complexes self-assemble through similar hydrogen bonding motifs which involve three N–H⋯Cl interactions between the 2-aminopyridinium cation and the chloride atoms. Each repeating unit of complexes 1 and 2, [MnCl3(H2O)]− and [Mn2Cl6(2-ampy)]2−, respectively, is doubly edge-sharing to form one-dimensional chains which are cross-linked by hydrogen bonding to the [H(2-ampy)]+ cations. In complex 2, two different 2-aminopyridine molecules were observed. One bridges the Mn atoms directly, while the other, through hydrogen bonding interaction, bridges Mn atoms via the chloride atoms. The structural role of the 2-aminopyridinium cation on the aggregation of the metal ions is discussed.

Synthesis and structural characterization of a face-sharing bioctahedral complex [HB(Me2Pz)3)BH][Br3Mo(μ-Br)3MoTp*] and an edge-sharing tetramolybdenum complex [Mo4(μ3-O)2(μ2-O)2(μ2-OH)2(O)4(Me2PzH)6](Br)4(Me2PzH2)2 (Tp*=hydridotris(3,5-dimethylpyrazolyl)borate); Pz=pyrazolyl)

Abstract From a solution prepared by a reaction of Mo2(O2CCH3)4 with KTp* (Tp*=hydridotris(3,5-dimethylpyrazolyl)borate, HB(Me2Pz)3), in diglyme at room temperature followed by addition of excess (CH3)3SiBr to the red solution in refluxing THF, the complexes [HB(Me2Pz)3)BH][Br3Mo(μ-Br)3MoTp*] (1), [Mo4(μ3-O)2(μ2-O)2(μ2-OH)2(O)4(Me2PzH)6](Br)4(Me2PzH2)2 (2) and MoBr2Tp*(Me2PzH) (3), were obtained. Their structures have been determined by X-ray crystallography. The anion of complex 1 consists of two octahedra sharing a common triangular face so those three Br atoms bridge the Mo atoms. The metal centers are also chelated by a tridentate Tp* ligand and coordinated by three Br atoms. Structural comparison of 1 and [HB(Me2Pz)3)BH][Br3Mo(μ-Br)2(μ-H)MoTp*] shows that replacement of the bridging hydride atom by the bromide atom led to the lengthening of the Mo–Mo bond distance by about 0.36 A. In complex 2, the four octahedra are bridged together through edges. The two molybdenum atoms in the asymmetric unit have different environments although both are formally seven-coordinated. The average oxidation state of molybdenum is +5, and the four electrons available for Mo–Mo bonding form two localized Mo–Mo single bonds. Complex 2 can be classified into the structural type Mo4XaYbZc, in which a+b+c=16. The formation of the cation, [HB(Me2Pz)3)BH]+, 2 and 3 shows the ready cleavage of the B–N bond of the Tp* ligand.

N1,N2-Bis(6-methyl-2-pyridyl)formamidine

In the crystal structure of the title molecule, C13H14N4, the two pyridyl rings are not coplanar but twisted about the C—N bond with an interplanar angle of 71.1 (1)°. In the crystal, the molecules form dimers, situated on crystallographic centres of inversion, which are connected via a pair of N—H⋯N hydrogen bonds. C—H⋯π-electron ring interactions are also present in the crystal structure. The title molecule adopts an s–cis–anti–s–cis conformation in the solid state.

N1,N2-Bis(6-methyl-2-pyrid­yl)formamidine

In the crystal structure of the title molecule, C13H14N4, the two pyridyl rings are not coplanar but twisted about the C—N bond with an interplanar angle of 71.1 (1)°. In the crystal, the molecules form dimers, situated on crystallographic centres of inversion, which are connected via a pair of N—H⋯N hydrogen bonds. C—H⋯π-electron ring interactions are also present in the crystal structure. The title molecule adopts an s–cis–anti–s–cis conformation in the solid state.

N,N-Bis(6-methyl-2-pyrid-yl)formamidine.

In the crystal structure of the title molecule, C13H14N4, the two pyridyl rings are not coplanar but twisted about the C—N bond with an interplanar angle of 71.1 (1)°. In the crystal, the molecules form dimers, situated on crystallographic centres of inversion, which are connected via a pair of N—H⋯N hydrogen bonds. C—H⋯π-electron ring interactions are also present in the crystal structure. The title molecule adopts an s–cis–anti–s–cis conformation in the solid state.

N1,N2-Bis(2-pyrid­yl)formamidine

In the crystal structure of the title compound, C11H10N4, the dihedral angle between the two pyridyl rings is 36.1 (1)°. The molecules are connected via two strong N—H⋯N and two weak C—H⋯N hydrogen bonds into dimers, which are located on centers of inversion. This compound adopts the s–trans–anti–s–cis conformation in the solid state.