Cointercalation systems consisting of graphite, sodium, and some linear glycol ethers (glymes) are anticipated for use as negative electrodes in sodium ion batteries because of their superior properties such as outstanding cycle performance. We synthesized a ternary intercalation compound consisting of sodium, deuterated diglyme (diglyme-d 14 ), and graphite by a solution reaction. Then we investigated the dynamics and coordination structure of diglyme-d 14 molecules by 2 H solid-state NMR. Two diglyme molecules coordinate to each sodium ion rigidly, except for rotation of the methyl groups at low temperatures below 233 K. At room temperature, diglyme weakly coordinates to a Na ion through one oxygen atom of the ligand and rotates around the O−Na axis. The active motion of sodium−diglyme complexes is favorable for Na diffusion between graphene layers in the graphite intercalation compound.

Mononuclear [Fe(H(2)L(R))(2)](2+) and dinuclear [Fe(2)(H(2)L(R))(3)](4+) (R = H, 2-Me, 5-Me) complexes containing the new imidazole-4-carbaldehyde azine ligand (H(2)L(H)) and its derivatives (H(2)L(2-Me) and H(2)L(5-Me)) prepared from the condensation reaction of 4-formylimidazole or 2-methyl- or 5-methyl-4-formylimidazole with hydrazine (2:1) were prepared, and their magnetostructural relationships were studied. In the mononuclear complexes, H(2)L(R) acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom, while in the dinuclear complexes, H(2)L(R) acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate. At room temperature, [Fe(2)(H(2)L(H))(3)](ClO(4))(4) and [Fe(2)(H(2)L(2-Me))(3)](ClO(4))(4) were in the high-spin (HS) and low-spin (LS) states, respectively. The results are in accordance with the ligand field strength of H(2)L(2-Me) with electron-donating methyl groups being stronger than H(2)L(H), with the order of the ligand field strengths being H(2)L(2-Me) > H(2)L(H). However, in the mononuclear [Fe(H(2)L(H))(2)](ClO(4))(2) and [Fe(H(2)L(2-Me))(2)](ClO(4))(2) complexes, a different order of ligand field strengths, H(2)L(H) > H(2)L(2-Me), was observed because [Fe(H(2)L(H))(2)](ClO(4))(2) was in the LS state while [Fe(H(2)L(2-Me))(2)](ClO(4))(2) was in the HS state at room temperature. X-ray structural studies revealed that the interligand steric repulsion between a methyl group of an H(2)L(2-Me) ligand and the other ligand in [Fe(H(2)L(2-Me))(2)](ClO(4))(2) is responsible for the observed change in the spin state. Two kinds of crystals, needles and blocks, were isolated for [Fe(2)(H(2)L(H))(3)](BF(4))(4), and both exhibited a sharp spin transition, [LS-HS] <--> [HS-HS]. The spin transition of the block crystals is more abrupt with a hysteresis, T(c) upward arrow = 190 K and T(c) downward arrow = 183 K with DeltaT = 7 K.

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A chiral complex, [Fe(HL) 2 ](PF 6 ) 2 (1), where HL denotes 2-pyridylmethylidenehydrazono-4-(2methylimidazolyl)methane, was prepared. X-ray structure analysis revealed that it crystallizes as a kryptoracemate of sesquihydrate chiral crystals in the orthorhombic noncentrosymmetric space group P2 1 2 1 2 1 (Z = 8, Z′ = 2). Two diastereomeric cationic complexes with opposite configuration reside within the asymmetric unit. KBr pellets prepared using selected single crystals showed enantiomorphous circular dichroism patterns.

Mononuclear [Fe(H2L2-Et-5-Me)2]2+ and dinuclear [Fe2(H2L2-Et-5-Me)3]4+ complexes, where H2L2-Et-5-Me denotes 2-ethyl-5-methylimidazole-4-carbaldehyde azine, were prepared and isolated as the perchlorate salts, and their structures and magnetic properties were studied. In the mononuclear complex, the ligand acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom. The complex was in the HS state above 50 K. In the dinuclear complex, each ligand acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate structure. Two types of crystals, plates and blocks, were isolated for the dinuclear complex. The plate crystals exhibited a sharp spin transition, [LS–HS] ↔ [HS–HS], with no [LS–LS] state being observed. The block crystals remained in the [HS–HS] state above 50 K.