Synthesis and crystal structure of a pentacopper(II) 12-metallacrown-4: cis-diaquatetrakis(dimethylformamide-κO)manganese(II) tetrakis(μ3-N,2-dioxidobenzene-1-carboximidate)pentacopper(II) dimethylformamide monosolvate

The title compound [Mn(OH2)2(C3H7NO)4][Cu5(C7H4NO3)4]·C3H7NO or cis-[Mn(H2O)2(DMF)4]{Cu[12-MCCu(II)N(shi)-4]}·DMF, where MC is metallacrown, shi3− is salicylhydroximate, and DMF is N,N-dimethylformamide, consists of a pentacopper(II) 12-metallacrown-4 anion that is charged-balanced with the cis-[Mn(DMF)4(OH2)2]2+ cation. In the {Cu[12-MCCu(II)N(shi)-4]}2− anion, all four CuII ions of the metallacrown ring and the one CuII ion of the central cavity are four-coordinate with a square-planar geometry. The MnII counter-cation is six-coordinate with an octahedral geometry.


Structural commentary
Two crystallographically independent metallacrown anions are present in the structure, and both are located on crystallographic inversion centers with the central copper ions situated on the inversion center (Figs. 1 and 2). Both anions exhibit minor main-molecule disorder by an approximate (non-crystallographic) 180 rotation with an occupancy ratio of 0.9010 (9) to 0.0990 (9) for the anion associated with Cu1 and an occupancy ratio 0.9497 (8) to 0.0503 (8) for the anion associated with Cu4. Thus, only the structures of the main moieties will be discussed. The metallacrowns have an overall square shape as a result of the fused five-and six-membered chelate rings of the salicylhydroximate (shi 3À ) ligands, and the MCs are slightly non-planar. In each MC, a copper ion is captured in the central cavity and surrounded by four copper ions of the MC ring. The MC ring has a Cu-N-O pattern that repeats four times to generate the MC central cavity. All five copper ions of each MC are assigned a 2+ oxidation state based on bond-valence-sum (BVS) values (Liu & Thorp, 1993), average bond length distances, and overall chargebalance considerations (Table 1). In addition, all five Cu II ions of each MC are four-coordinate, and a SHAPE (SHAPE 2.1; Llunell et al., 2013)  The single-crystal X-ray structure of {Cu[12-MC Cu(II)N(shi) -4]} 2À associated with Cu4 with displacement ellipsoids at the 50% probability level [symmetry code: (ii) 1 À x, Ày, 1 À z]. For clarity, only non-carbon atoms have been labeled, and the MC associated with Cu1, the Mn II countercation, the lattice DMF molecule, H atoms, and disorder have been omitted. See Fig. 1 for additional display details. Table 1 Average bond-length (Å ) and bond-valence-sum (BVS; v.u.) values used to support the assigned oxidation states of the copper and manganese ions.

Figure 1
The single-crystal X-ray structure of the ionic pair cis- ( Table 2), which is typical for a d 9 electron configuration (Llunell et al., 2013;Pinsky & Avnir, 1998;Casanova et al., 2004;Cirera et al., 2005).  (v.u.), and overall charge-balance considerations (Table 1). A SHAPE analysis confirms the octahedral geometry of the cation (Table 3). The coordination environment of the Mn II ion consists of four DMF molecules and two water molecules in a cis configuration. Lastly, a DMF molecule is located in the lattice.

Supramolecular features
No strong directional intermolecular interactions are observed between the {Cu[12-MC Cu(II)N(shi) -4]} 2À anions, but a number of hydrogen bonds exist between the MCs and the countercation cis-[Mn(H 2 O) 2 (DMF) 4 ] 2+ and between the countercation and the lattice DMF molecule (Table 4, Fig. 3). The water molecule associated with O18 of the Mn II cation forms hydrogen bonds to both MC anions. The hydrogen bonds are to phenolate oxygen atoms (O18-H18CÁ Á ÁO3 and O18-H18DÁ Á ÁO9) of the neighboring MCs. The water molecule associated with O19 of the Mn II cation forms hydrogen bonds to a carbonyl oxygen atom of the MC associated with Cu1 (O19-H19CÁ Á ÁO5) and to the carbonyl oxygen atom of the lattice DMF molecule (O19-H19DÁ Á ÁO17). These hydrogenbonding interactions, in addition to pure van der Waals forces, contribute to the overall packing of the molecules.

Synthesis and crystallization
Manganese(II) chloride tetrahydrate (Certified ACS) was purchased from Fisher Scientific. Copper(II) chloride dihydrate was purchased from J. T. Baker Chemical Company. Salicylhydroxamic acid (99%) was purchased from Alfa Aesar. Triethanolamine (98%) was purchased from Sigma-Aldrich. N,N-Dimethylformamide (DMF, Certified ACS) was purchased from BDH Chemicals. All reagents were used as received without further purification. Salicylhydroxamic acid (H 3 shi; 0.1541 g, 1 mmol) and copper(II) chloride dihydrate (0.1705 g, 1 mmol) were dissolved in 10 mL of DMF resulting in a green-brown solution. Triethanolamine (0.3764 g, 2.5 mmol) was then added to the CuCl 2 /H 3 shi solution, resulting in a dark-green color. Separately, manganese(II) chloride tetrahydrate (0.7891 g, 4 mmol) was dissolved in 20 mL of DMF, resulting in a clear and colorless solution. The MnCl 2 solution was then added to the CuCl 2 /H 3 shi/triethanolamine solution and no color change was observed. The solution was stirred overnight and then gravity filtered the next day. A dark-green precipitate was recovered and discarded. The filtrate was a dark-green color. The solution was left for slow evaporation at room temperature, and after 26 days dark-green plate-shaped crystals were collected for X-ray analysis. The remaining crystals were collected, washed with cold DMF, and dried. The percentage yield of the reaction was 57% (0.1576 g, 0.1147 mmol) based on copper(II) chloride dihydrate.

Refinement
Two crystallographically independent metallacrown anions are present in the structure. Both are located on crystal-lographic inversion centers with the central of the five copper atoms situated on the inversion center. Both anions exhibit minor main molecule disorder by an approximate (non-crystallographic) 180 rotation. A cis-[Mn(H 2 O) 2 (DMF) 4 ] 2+ cation and a solvate DMF molecule are located in the lattice and are not disordered. The major and minor disordered moieties of both anions were each restrained to have similar geometries (SHELXL SAME commands). U ij components of ADPs for disordered atoms closer to each other than 2.0 Å were restrained to be similar. Subject to these conditions the occupancy ratio refined to 0.9010 (9) to 0.0990 (9) for the anion associated with Cu1 and 0.9497 (8) to 0.0503 (8) for the anion associated with Cu4. Water hydrogen-atom positions were refined and O-H distances restrained to 0.84 (2) Å . Additional crystallographic data and experimental parameters are provided in Table 5 and the CIF of the compound.
Hydrogen atoms attached to carbon atoms as well as hydroxyl hydrogen atoms were positioned geometrically and constrained to ride on their parent atoms. Carbon-hydrogen bond distances were constrained to 0.95 Å for aromatic and aldehyde C-H moieties, and to 0.98 Å for CH 3 moieties. Oxygen-hydrogen distances of alcohols were constrained to 0.84 Å and were allowed to rotate but not to tip to best fit the experimental electron density. U iso (H) values were set to  Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2018/1 (Sheldrick, 2015), SHELXLE Rev859 (Hübschle et al., 2011); molecular graphics: Mercury (Macrae et al., 2020); software used to prepare material for publication: publCIF (Westrip, 2010).