Abstract
The title compound, [Fe(C3H7NO)6][Cd2Cl7], crystallizes in the trigonal space group R and is assembled from discrete [Fe(DMF)6]3+ cations (DMF = N,N-di-methyl-formamide) and [Cd2Cl7]3- anions. In the cation, the iron(III) atom, located on a special position of site symmetry, is coordinated by six oxygen atoms from DMF ligands with all Fe-O distances being equal [2.0072 (16) Å]. A slight distortion of the octa-hedral environment of the metal comes from the cis O-Fe-O angles deviating from the ideal value of 90° [86.85 (7) and 93.16 (7)°] whilst all the trans angles are strictly 180°. The central Cl atom of the [Cd2Cl7]3- anion is also located on a special position of site symmetry and bridges two corner sharing, tetra-hedrally coordinated CdII atoms. The two Cd atoms and the central Cl atom are colinear. The two sets of terminal chloride ligands on either side of the dumbbell-like anion are rotated relative to each other by 30°. In the crystal, the cations and anions, stacked one above the other along the c-axis direction, are held in place principally by electrostatic inter-actions. There are also C-H⋯Cl and C-H⋯O inter-actions, but these are rather weak. Of the six crystal structures reported to date for ionic salts of [Fe(DMF)6] n+ cations (n = 2, 3), five contain FeII ions. The title compound is the second example of a stable compound containing the [Fe(DMF)6]3+ cation. The existence of both [Fe(DMF)6]2+ and [Fe(DMF)6]3+ cations shows that the DMF ligand coordination sphere can accommodate changes in the charge and spin states of the metal centre.
Highlights
In our ongoing research into the new functions and applications of coordination compounds with Schiff-base ligands, we have utilized a synthetic scheme involving a zerovalent metal as the source of metal ions, together with another metal salt, in order to prepare new heterometallic complexes (Kokozay et al, 2018; Vassilyeva et al, 2018, 2021)
Open air worked a different way than expected and led to the isolation of the title compound, the mixed-metal ionic salt [FeIII(DMF)6][Cd2Cl7], (1), the identity of which was established by X-ray crystallography and confirmed by chemical analysis
The iron(III) atom sits on a special position of 3 site symmetry and is coordinated by six oxygen atoms from the DMF ligands with all the Fe—O bond lengths being equal at 2.0072 (16) A (Fig. 1, Table 1)
Summary
In our ongoing research into the new functions and applications of coordination compounds with Schiff-base ligands, we have utilized a synthetic scheme involving a zerovalent metal as the source of metal ions, together with another metal salt, in order to prepare new heterometallic complexes (Kokozay et al, 2018; Vassilyeva et al, 2018, 2021). To facilitate formation of the desired compound, an additional basic agent, N-phenyldiethanolamine, was introduced following the previous successful participation of diethanolamine in the formation of a mixed-ligand Schiff base NiII/ZnII dimer (Vassilyeva et al, 2021). In the latter compound, the deprotonated aminoalcohol molecules provide additional alkoxo-bridges between the metal centres. The treatment of cadmium powder and FeCl3Á6H2O with a solution of the in situ-formed Schiff base in Figure 1 Molecular structure and labelling of [FeIII(DMF)6][Cd2Cl7] (1) with displacement ellipsoids at the 50% probability level. [Symmetry codes: (i) Ày + 1, x À y + 1, z; (ii) Àx + y, Àx + 1, z; (iii) y À 13, Àx + y + 13, Àz + 43; (iv) Àx + 23, Ày + 43, Àz + 43; (v) x À y + 23, x + 13, Àz + 43; (vi) Àx + 23, Ày + 43, Àz + 13; (viii) y À 13, Àx + y + 13, Àz + 13; (ix) x À y + 23, x + 13, Àz + 13.]
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