Correlation of electrochemical and ab initio investigations of iron poly-bipyridine coordination complexes for battery applications: impact of the anionic environment and the local geometries of the redox complexes on the electrochemical response.

Although they exhibit huge versatility, coordination complexes have been rarely investigated in the field of cathode materials for batteries. Despite their relatively high molecular mass, according to the nature of the metallic center and that of the ligand, the E° value and the electron transfer kinetics can be adjusted to develop a performant material compatible with the electrolyte. Here, we propose to investigate FeII poly-bipyridine complexes with a view to check the impact of the nature of the electrolyte as well as the influence of the distance between two redox centers when polymerized on the electrochemical response in battery conditions. To understand these changes, three lithium salts have been studied: LiClO4, LiPF6 and LiTFSI (TFSI = bis(trifluoromethane)sulfonimide). In order to mimic these impacts, monomer complexes (mono- and binuclear) have been electrochemically studied, whereas, thanks to ab initio calculations, their redox behavior has been correlated to the ligand environment of the metallic center. Finally, despite their expected low mass capacity, these polymeric coordination complexes have been involved in battery conditions.

Crystal structures of two CuII compounds: catena-poly[[chlorido-copper(II)]-µ-N-[eth-oxy(pyridin-2-yl)methyl-idene]-N'-[oxido(pyridin-3-yl)methyl-idene]hydrazine-κ4 N,N',O:N''] and di-µ-chlorido-1:4κ2 Cl:Cl-2:3κ2 Cl:Cl-di-chlorido-2κCl,4κCl-bis[µ3-eth-oxy(pyridin-2-yl)methano-lato-1:2:3κ3 O:N,O:O;1:3:4κ3 O:O:N,O]bis-[µ2-eth-oxy(pyridin-2-yl)methano-lato-1:2κ3 N,O:O;3:4κ3 N,O:O]tetracopper(II).

Two CuII complexes [Cu(C14H13N4O2)Cl] n , I, and [Cu4(C8H10NO2)4Cl4] n , II, have been synthesized. In the structure of the mononuclear complex I, each ligand is coordinated to two metal centers. The basal plane around the CuII cation is formed by one chloride anion, one oxygen atom, one imino and one pyridine nitro-gen atom. The apical position of the distorted square-pyramidal geometry is occupied by a pyridine nitro-gen atom from a neighbouring unit, leading to infinite one-dimensional polymeric chains along the b-axis direction. Each chain is connected to adjacent chains by inter-molecular C-H⋯O and C-H⋯Cl inter-actions, leading to a three-dimensional network structure. The tetra-nuclear complex II lies about a crystallographic inversion centre and has one core in which two CuII metal centers are mutually inter-connected via two enolato oxygen atoms while the other two CuII cations are linked by a chloride anion and an enolato oxygen. An open-cube structure is generated in which the two open-cube units, with seven vertices each, share a side composed of two CuII ions bridged by two enolato oxygen atoms acting in a µ3-mode. The CuII atoms in each of the two CuO3NCl units are connected by one µ2-O and two µ3-O atoms from deprotonated hydroxyl groups and one chloride anion to the three other CuII centres. Each of the penta-coordinated CuII cations has a distorted NO3Cl square-pyramidal environment. The CuII atoms in each of the two CuO2NCl2 units are connected by µ2-O and µ3-O atoms from deprotonated alcohol hy-droxy groups and one chloride anion to two other CuII ions. Each of the penta-coordinated CuII cations has a distorted NO2Cl2 square-pyramidal environment. In the crystal, a series of intra-molecular C-H⋯O and C-H⋯Cl hydrogen bonds are observed in each tetra-nuclear monomeric unit, which is connected to four tetra-nuclear monomeric units by inter-molecular C-H⋯O hydrogen bonds, thus forming a planar two-dimensional structure in the (01) plane.

Dichlorido{N'-[phen-yl(pyridin-2-yl-κN)methyl-idene]isonicotinohydrazide-κ(2)N',O}zinc.

The title compound, [ZnCl(2)(C(18)H(14)N(4)O)], crystallizes with two mol-ecules in the asymmetric unit, which differ in the tautomeric (neutral and zwitterionic) forms of the coordin-ating organic ligand. In both mol-ecules, the Zn(II) atom adopts a distorted square-pyramidal geometry by two N and one O atoms of the Schiff base ligand and two Cl atoms acting as monodentate chloride anions. The crystal packing is stabilized by N-H⋯N and N-H⋯Cl hydrogen bonds, forming a two-dimensional network parallel to the ac plane.

(S,E)-3-[(2-Hy-droxy-benzyl-idene)amino]-2-(2-hy-droxy-phen-yl)-2,3-dihydro-quinazolin-4(1H)-one.

In the title compound, C(21)H(17)N(3)O(3), the dihydro-quinazoline ring adopts a screw-boat conformation and its stereogenic C atom has an S configuration. The dihedral angle between the mean planes of the two hy-droxy-phenyl rings is 86.61 (12)°. The amino H atom forms an intra-molecular hydrogen bond with a phenol O atom, while the hydrazine N atom acts as an acceptor for the H atom of the other phenol group. In the crystal, O-H⋯N and O-H⋯O hydrogen bonds and weak C-H⋯centroid(π-ring) inter-molecular inter-actions are observed, forming chains along [1-10] and [110].

Bis(N,N'-dimethyl-ethylenediammonium) tris-(oxalato-κO,O)cobaltate(II) dihydrate: an ion-pair complex.

The Co(II) ion in the title complex, (C(4)H(14)N(2))(2)[Co(C(2)O(4))(3)]·2H(2)O, is coordinated by three oxalate ions, resulting in a distorted octa-hedral geometry. Two uncoordinated water mol-ecules are present in asymmetric unit. Inter-molecular N-H⋯O and O-H⋯O hydrogen bonds between the different entities stabilize the crystal structure.

Poly[di-µ-aqua-diaqua-di-µ(6)-malonato-cobalt(II)dipotassium(I)].

In the title complex, [CoK(2)(C(3)H(2)O(4))(2)(H(2)O)(4)](n), the Co atom is located on a position with site symmetry 2/m, the K atom and one water mol-ecule are located on a mirror plane, and the malonate and one water mol-ecule are located on a twofold rotation axis. The K(I) atom is seven-coordinated by four carboxyl-ate O atoms from four malonate ligands and by three water O atoms, forming a distorted polyhedron. The Co(II) atom is in an almost octa-hedral environment formed by four carboxyl-ate O atoms from two malonate ligands and two water O atoms. The structure consists of layers parallel to (20[Formula: see text]) built up from edge-sharing KO(7) and CoO(6) polyhedra, which are connected by O-H⋯O hydrogen bonding including water mol-ecules into a three-dimensional network.

1-(Thio-phen-2-yl)ethanone thio-semi-carbazone.

The title compound, C(7)H(9)N(3)S(2), crystallizes with two unique mol-ecules in the unit cell, both present as thio-semicarbazide tautomers. The mol-ecules differ principally in the dihedral angles between the thio-phene ring planes and the planes through the non-H atoms of the hydrazinecarbothio-amide units, viz. 9.80 (8)° for one mol-ecule and 19.37 (7)° for the other. The hydrazinecarbothio-amide units are reasonably planar, with r.m.s. deviations of 0.001Å for each of the mol-ecules. In the crystal, N-H⋯S hydrogen bonds link like mol-ecules into R(2) (2)(8) inversion dimers. A three-dimensional network structure is generated by additional N-H⋯S hydrogen bonds and weak C-H⋯S contacts between the unique mol-ecules.

Bis(imidazole-κN)bis-(nitrato-κO)zinc(II).

The title complex, [Zn(NO(3))(2)(C(3)H(4)N(2))(2)], contains a Zn(II) centre with a slightly distorted tetra-hedral coordination environment, involving two N atoms from imidazole ligands and two O atoms from nitrate anions. The imino NH groups participate in inter-molecular N-H⋯O hydrogen bonds.