Synthesis and crystal structure of two manganese-based 12-metallacrown-4 complexes: Na2(3-chlorobenzoate)2[12-MCMn(III)N(shi)-4](DMF)6 and MnNa(3-chlorobenzoate)3[12-MCMn(III)N(shi)-4](DMF)(H2O)4·4DMF·0.72H2O

The metallacrown (MC) complexes Na2(3-chlorobenzoate)2[12-MCMn(III) N(shi)-4](DMF)6, 1, and MnNa(3-chlorobenzoate)3[12-MCMn(III) N(shi)-4](DMF)(H2O)4·4DMF·0.72H2O, 2, where shi3− is salicylhydroximate and DMF is N,N-dimethylformamide, both have an overall square shape due to the presence of four ring MnIII ions and four shi3− ligands. The two MC complexes bind different cations in the central cavity of the molecule: two Na+ ions in 1 and one MnII ion and one Na+ ion in 2.


Chemical context
The first 12-metallacrown-4 complex synthesized, Mn(acetate) 2 [12-MC Mn(III)N(shi) -4], was based on the ligand salicylhydroxamic acid (H 3 shi) and manganese (Lah & Pecoraro, 1989). In this complex, four Mn III ions are located in the metallacrown (MC) ring and an Mn II ion is trapped in the central MC cavity produced by the four triply deprotonated salicylhydroximate (shi 3À ) ligands. The Mn II ion is further bound by two acetate anions that serve to balance the charge ISSN 2056-9890 of the molecule and to bridge between the ring Mn III ions and the central Mn II ion. Since this initial report in 1989, the [12-MC Mn(III)N(shi) -4] framework has been used to encapsulate not only manganese(II) but also alkali, alkaline earth, and lanthanide ions in the MC cavity (Mezei et al., 2007;Lah & Pecoraro, 1991;Koumousi et al., 2011;Azar et al., 2014). When only Na + or K + ions are incorporated into the [12-MC Mn(III)N(shi) -4] framework, the two metal ions and their counter-anions are typically bound on opposite faces of the MC (Gibney et al., 1996). When lanthanide ions are bound to the MC cavity, four carboxylate anions serve to tether the Ln III ion to the MC and typically an alkali metal ion is bound to the opposite face of the MC for charge balance (Travis et al., 2015(Travis et al., , 2016. Furthermore, the bridging acetate anion of the original Mn(acetate) 2 [12-MC Mn(III)N(shi) -4] molecule can be substituted by other carboxylate anions or even halide and pseudohalide anions (Gibney et al., 1996;Kessissoglou et al., 2002;Dendrinou-Samara et al., 2005;Boron et al., 2016) . This ability to substitute various components of the MC complex allows the properties of the molecules to be tailored to a particular application. For instance, the single-molecule magnet properties of a series of DyMX 4 [12-MC Mn(III)N(shi) -4] complexes, where M is Na + or K + and X is either acetate, trimethylacetate, benzoate, or salicylate, are dictated by the identity of the carboxylate anion even though the structures of the molecules are strikingly similar (Boron et al., 2016). Moreover, [12-MC Mn(III)N(shi) -4] complexes can be used as building blocks to form larger structures. They can be linked together to form either dimeric and trimeric systems or onedimensional chains, and some of these larger structures have SMM-like behavior (Mengle et al., 2015;Zaleski et al., 2015;Alaimo et al., 2017;Wang et al., 2019).
Herein we present the first use of a halogenated benzoate anion to serve as the bridging ligand between the central cavity metal ion and the ring metal ions for a [12-MC Mn(III)N(shi) -4] complex. The use of 3-chlorobenzoate leads to two different molecules: Na 2 (3-chlorobenzoate) 2 -[12-MC Mn(III)N(shi) -4](DMF) 6 , 1, where DMF is N,N-dimethylformamide, and MnNa(3-chlorobenzoate) 3 [12-MC Mn(III)N(shi) -4](DMF)(H 2 O) 4 Á4DMFÁ0.72H 2 O, 2. Complex 1 is typical of other di-sodium MCs with the Na + ions bonded to opposite faces of the MC. However, complex 2 represents a new structural motif in metallacrown chemistry. In 2 the central Mn II ion is bonded to three carboxylate anions as opposed to the typical number of two anions. This then facilitates the binding of an Na + ion to the opposite face of the MC for charge-balance purposes. This is the first instance of a 3d transition metal ion and an alkali metal ion both binding to the central cavity of a 12-MC-4 complex.

Structural commentary
Both 1 and 2 are based on the same overall 12-MC-4 framework. Four salicylhydroximate ligands and four ring Mn ions combine to generate a Mn-N-O repeat unit that recurs four times in a cyclic fashion. The fused five-and six-membered rings of the shi 3À ligands place the metal ions at 90 relative to each other, giving an overall square-shaped molecule. The ring Mn ions are either five-or six-coordinate in the structures, and the ligand atoms in the basal/equatorial planes are the same, consisting of trans six-and five-membered chelate rings: each six-membered chelate ring is formed by the phenolate oxygen atom and oxime nitrogen atom of a shi 3À ligand and each fivemembered chelate ring is formed by the carbonyl oxygen atom and the oxime oxygen atom of a different shi 3À ligand. The four Mn ions of the MC ring are assigned a 3+ oxidation state based on average bond lengths, the presence of elongated axial bond lengths typical of a high-spin d 4 electron configuration, bond-valence sum (BVS) values (Liu & Thorp, 1993), and overall charge-balance considerations ( Table 1). The four Mn III ions and four shi 3À ligands produce a neutral MC framework. The main differences between 1 and 2 are the metal ions bound to the central cavity and the number of the ancillary ligands that bind to the metal ions of the MC.
For 1 the MC framework (ring Mn III ions and shi 3À ligands) and the 3-chlorobenozate anions exhibit whole-molecule disorder over two sets of sites. Both moieties are centrosymmetric and are related to each other by a pseudo-mirror operation with an opposite sense of rotation around the NaÁ Á ÁNa axis. The occupancy ratio of the MC frameworks and 3-chlorobenzoate anions disorder refined to 0.9276 (9): 0.0724 (9). In addition, the coordinated DMF molecules show disorder as outlined in the Refinement section below. Thus, only the structures of the main moieties will be discussed. The MC framework is nearly planar, and the MC cavity, produced by the four oxime oxygen atoms of the four shi 3À ligands, captures two Na + ions on opposite faces of the MC (Fig. 1). The charge of the Na + ions is balanced by two 3-chlorobenzoate anions that are also located on opposite faces of the MC. Each 3-chlorobenzoate connects one Na + to a ring Mn III ion (Mn1). The Na + ion (Na1) is seven-coordinate, and the coordination environment consists of the four oxime oxygen atoms, a carboxylate oxygen atom from a 3-chlorobenzoate anion, a carbonyl oxygen atom of a terminal DMF molecule, and a -carbonyl oxygen atom of a DMF molecule that also bridges to Mn2 of the MC ring. A SHAPE (SHAPE 2.1; Llunell et al., 2013) analysis (Table 2) of the geometry yields the lowest continuous shape measure (CShM) values for a face-capped octahedron and a face-capped trigonal prism, 3.683 and 3.798, respectively (Llunell et al., 2013;Pinsky & Avnir, 1998;Casanova et al., 2004;Cirera et al., 2005). Although the CShM value is lower for the face-capped octahedron, it is difficult to accurately assign the geometry as both CShM values are relatively close. In addition, both CShM values are well over 3.0, which is considered an upper threshold value at which significant distortions occur (Cirera et al., 2005). The distortions may arise from the bonding nature of the MC framework. The four oxime oxygens of the MC cavity lie nearly in a plane due to the square shape of the molecule imposed by the fused chelate rings of the shi 3À ligands. Thus, this portion of the coordination environment is not flexible and likely leads to the distortion. Mn1 of the MC ring is five-coordinate with a basal ligand environment as described above. A carboxylate oxygen atom of a 3-chlorobenzoate anion occupies the apical position. A SHAPE analysis (Table 3) reveals the geometry can be best described 850 Zaleski and Zeller Two Mn-based 12-metallacrown-4 complexes Acta Cryst. (2020). E76, 848-856 research communications Table 1 Average bond-length (Å ) and bond-valence-sum (BVS) values (v. u.) used to support assigned oxidation states of the manganese ions of 1 and 2. The single-crystal X-ray structure of Na 2 (3-chlorobenzoate) 2 [12-MC Mn(III)N(shi) -4](DMF) 6 , 1, with displacement ellipsoids at the 50% probability level [symmetry code: (i) Àx + 1, Ày + 1, Àz + 1]. (a) side view with only the metal atoms and heteroatoms of the axial ligands labelled for clarity and (b) top view with the axial ligand atoms omitted for clarity. In addition, hydrogen atoms and disorder have been omitted for clarity. Color scheme: green -Mn, yellow -sodium, red -oxygen, dark bluenitrogen, gray -carbon, and light blue -chlorine. All figures were generated with the program Mercury (Macrae et al., 2020).
as square-pyramidal and the calculated tau () value of 0.15 supports this assignment, where = 0 for an ideal square pyramid and 1.0 for an ideal trigonal prism (Addison et al., 1984). Mn2 is six-coordinate with an elongated Jahn-Teller axis, and the SHAPE analysis confirms a tetragonally distorted octahedral geometry (Table 4). The ligands along the axial axis consist of two carbonyl oxygen atoms of two DMF molecules. The DMF molecule associated with O9 binds in a terminal fashion, while the oxygen atom (O10) of the second DMF molecule forms a one-atom -bridge to the central Na + ion. For 2 the MC is slightly domed with an Mn ion and Na ion bonded to opposite sides of the MC cavity. The Mn ion is bound on the convex side of the MC, and the Na ion is bonded to the concave side (Fig. 2). The Mn1 ion is assigned a 2+ oxidation state based an average bond length of 2.256 Å , a BVS value of 1.97 valence units (v. u.), and overall chargebalance considerations (Table 1). The total 3+ charge of the Mn II and Na + ions is counterbalanced by the presence of three 3-chlorobenzoate anions. The 3-chlorobenzoate anions bridge between Mn1 and three of the ring Mn III ions (Mn2, Mn4, and Mn5). The Mn II ion is seven-coordinate with a coordination environment consisting of four oxime oxygen atoms from four different shi 3À ligands and of three carboxylate oxygen atoms from three different 3-chlorobenzoate anions. A SHAPE analysis of the geometry indicates that an unambiguous assignment is difficult as in the central Na + ions in 1 (Table 5). The geometry is either face-capped octahedral (CShM = 1.589) or face-capped trigonal prismatic (CShM = 1.807). The Na + ion of 2 is eight-coordinate with four oxime oxygen atoms from the shi 3À ligands and four water molecules. The SHAPE analysis indicates that the geometry can best be described as a biaugmented trigonal prism, where two of the rectangular faces of a trigonal prism are capped by an atom ( Table 6). All of the ring Mn III ions are six-coordinate with an elongated Jahn-Teller axis. The SHAPE analysis confirms a tetragonally distorted octahedral geometry for each Mn III ion (Table 7). The axial ligands of Mn2, Mn4, and Mn5 consist of a carboxylate oxygen atom from a 3-chlorobenzoate anion and an oxygen atom of a water molecule that forms a one-atom -bridge to the Na + ion. The axial ligands of Mn3 are a carbonyl oxygen atom of a terminal DMF molecule and also an oxygen atom of a water molecule that forms a one-atom Table 3 Continuous shape measurement (CShM) values (SHAPE 2.1) for the five-coordinate manganese ion of 1.

Figure 2
The single-crystal X-ray structure of MnNa (

Supramolecular features
For 1, there are two intramolecular C-HÁ Á ÁO interactions and their symmetry equivalents per molecule (Table 8): one interaction is between a methyl group of a coordinated DMF molecule to a carbonyl oxygen atom of a second coordinated DMF molecule [C26-H26AÁ Á ÁO11 i ; symmetry code: (i) Àx + 1, Ày + 1, Àz + 1] and the other interaction is between a methyl group of a coordinated DMF molecule and a phenolate oxygen atom of a shi 3À ligand (C30-H30CÁ Á ÁO6) (Fig. 3). No strong directional intermolecular forces are observed between the molecules of 1; however, there are a few weak intermolecular C-HÁ Á ÁCl interactions between the methyl groups of a coordinated DMF molecule (associated with O11) and the chlorine atoms of 3-chlorobenzoate anions of neighboring MCs (Table 8; Fig. 4). These interactions generate a onedimensional network, and these interactions, in addition to pure van der Waals forces, contribute to the overall packing of the molecules.

Figure 4
Intermolecular C-HÁ Á ÁCl interactions in 1 between the hydrogen atoms (white) of the methyl groups of the DMF associated with O11 and the chlorine atom of the neighboring 3-chlorobenzoate anion [symmetry code: (ii) x + 1, y, z + 1]. The interactions result in a one-dimensional network. For clarity the disorder has been omitted and only the atoms involved in the interactions have been labeled. Table 9 Hydrogen-bond geometry (Å , ) for 2.  (2) 3.019 (5) 165 (8) For 2 no strong directional intermolecular interactions are observed between the molecules, but several hydrogen bonds exist between the water molecules coordinated to the Na + ion and the carbonyl oxygen atoms of the DMF molecules located in the lattice (Table 9; Fig. 5). In addition, the partially occupied water molecule associated with O28 is hydrogen bonded to the phenolate oxygen atom of a shi 3À ligand of one MC and to the chlorine atom of a 3-chlorobenzoate ligand of a neighboring MC (Fig. 6). These hydrogen-bonding interactions, in addition to pure van der Waals forces, contribute to the overall packing of the molecules. Intermolecular hydrogen bonding in 2 between the water molecules coordinated to the Na + ion and the carbonyl oxygen atoms of the lattice DMF molecules. For clarity the interactions have been divided into two sections (a) and (b), only the hydrogen atoms (white) of the water molecules have been included, the disorder and the partially occupied water molecule have been omitted, and only the atoms involved in the interactions have been labeled. See Fig. 1 for additional display details.

Figure 6
Intermolecular hydrogen bonding in 2 between the partially occupied water molecule and two neighboring MCs [symmetry code: (i) x À 1, y, z]. For clarity only the hydrogen atoms (white) of the water molecule associated with O28 have been included and only the atoms involved in the interaction have been labeled. See Fig. 1 for additional display details.
Sodium hydroxide (0.1710 g, 4 mmol) and 3-chlorobenzoic acid (0.6271 g, 4 mmol) were mixed in 8 mL of DMF resulting in a clear and colorless solution. The NaOH did not completely dissolve. In a separate vessel, salicylhydroxamic acid (H 3 shi; 0.3063 g, 2 mmol) was dissolved in 8 mL of DMF resulting in a clear and slightly yellow solution. In a third vessel, manganese(II) acetate tetrahydrate (0.4907 g, 2 mmol) was dissolved in 8 mL of DMF resulting in a light-orange solution. The manganese(II) acetate solution was added to the H 3 shi solution resulting in a dark-brown color. The sodium hydroxide/3-chlorobenzoic acid mixture was then immediately added and no color change was observed. The solution was stirred overnight and then gravity filtered the next day. A dark-brown precipitate was recovered and discarded. Also, it was observed that not all of the NaOH had dissolved after stirring overnight. The filtrate was a dark-brown solution that was left for slow evaporation at room temperature. After seven days, dark-brown/black 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 1% (0.0080 g, 0.0050 mmol) based on manganese(II) acetate tetrahydrate.
The stoichiometric ratios between the reactants and the volume of DMF were the same as for 1 with slightly different masses of the reactants: sodium hydroxide (0.1627 g, 4 mmol), 3-chlorobenzoic acid (0.6267 g, 4 mmol), H 3 shi (0.3072 g, 2 mmol), and manganese(II) acetate tetrahydrate (0.4914 g, 2 mmol). In addition, the mixing order was altered: the sodium hydroxide/3-chlorobenzoic acid mixture was first added to the H 3 shi solution, followed by the addition of the manganese(II) acetate solution. Furthermore, when the solution was filtered after stirring overnight, no precipitate was recovered. It was also observed that not all of the NaOH had dissolved. The filtrate was a dark-brown solution that was left for slow evaporation at room temperature. After three days, darkbrown/black plate 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 35% (0.2543 g, 0.1401 mmol) based on manganese(II) acetate tetrahydrate.

Refinement
For 1, the metallacrown molecule, except the central Na, exhibits whole molecule disorder over two sets of sites. Both moieties are centrosymmetric and are related to each other by a pseudo-mirror operation with opposite sense of rotation around the NaÁ Á ÁNa axis. The DMF molecules of O9 and O10 of the major moiety are additionally disordered. The DMF molecule associated with O11 was found to be disordered independently from the main disorder.
To assist in the refinement of the disorder, the geometries of the two metallacrowns (Mn and salicylhydroximate ligands), of the 3-chlorobenzoate anions, and of each DMF molecule were restrained to be similar to their disordered partner(s) (esd = 0.02 Å , SAME commands in SHELXL). The distances between Mn2 and O9 and Mn2B and O9B were restrained to be similar (esd = 0.02 Å ; SADI restraint in SHELXL). All atoms of the minor moiety of the 3-chlorobenzoate (C15B-C21B, Cl1B) as well as of the minor disordered DMF molecules of O10 (associated with O10B and O10C) were restrained to lie in the same plane (esd = 0.01 Å ; FLAT restraint in SHELXL). All disordered atoms were restrained to have similar U ij components of their ADPs (esd = 0.01 Å 2 ; SIMU restraint in SHELXL). The ADPs of C11 and C11B of a salicylhydroximate were constrained to be identical. Lastly, occupancies were constrained to sum up to unity for all sites using SUMP commands. Subject to the above conditions, the occupancy ratio of the main disorder of the metallacrown molecules and 3-chlorobenzoate anions refined to 0.9276 (9):0.0724 (9). The occupancy rates for the additionally split DMF of O9 refined to 0.799 (3) (O9) and 0.129 (3) (O9C), and those of the additionally split DMF molecule of O10 refined to 0.498 (3) (O10) and 0.430 (3) (O10C). The occupancy ratio of the DMF molecules associated with O11 refined to 0.516 (5):0.484 (5).
For 2, a partially occupied water molecule (O28) induces disorder for a neighboring DMF molecule (of O27). The two disordered moieties were restrained to have similar geometries, and the carbon, oxygen, and nitrogen atoms of the DMF molecule restrained to have similar U ij components of the ADPs (esd = 0.01 Å 2 ; SIMU restraint in SHELXL). Subject to these conditions the occupancy ratio refined to 0.718 (6):0.282 (6). Water hydrogen-atom positions were refined and O-H and HÁ Á ÁH distances were restrained to 0.84 (2) and 1.36 (2) Å , respectively. The water hydrogenatom positions of partially occupied O28 were further restrained based on hydrogen-bonding considerations.
For 1 and 2, all other hydrogen atoms were placed in calculated positions and refined as riding on their carrier atoms with C-H distances of 0.95 Å for sp 2 carbon atoms and 0.98 Å for methyl carbon atoms. The U iso values for hydrogen atoms were set to a multiple of the value of the carrying carbon atom (1.2 times for sp 2 -hybridized carbon atoms or 1.5 times for methyl carbon atoms). Additional crystallographic data and experimental parameters are provided in Table 10 and in the CIF.   For both structures, data collection: APEX3 (Bruker, 2018); cell refinement: SAINT (Bruker, 2018); data reduction: SAINT (Bruker, 2018); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015), shelXle (Hübschle et al., 2011); molecular graphics: Mercury (Macrae et al., 2020); software used to prepare material for publication: publCIF (Westrip, 2010).

Bis(µ-3-chlorobenzoato)hexakis(dimethylformamide)tetrakis(µ 4 -N,2-dioxidobenzene-1carboximidato)tetramanganese(III)disodium(I) (1)
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. The metallacrown molecule, except the central Na, exhibits whole molecule disorder over two sites. Both moieties are centrosymmetric and are related to each other by a pseudo-mirror operation with opposite sense of rotation around the Na···Na axis. The DMF molecules of O9 and O10 of the major moiety are additionally disordered. The DMF molecule associated with O11 was found to be disordered independently from the main disorder. To assist in the refinement of the disorder, the geometries of the two metallacrowns (Mn and salicylhydroximate ligands), of the 3-chlorobenzoates, and of each DMF molecule were restrained to be similar to their disordered partner(s) (esd = 0.02 Angstrom, SAME commands in Shelxl). The distances between Mn2 and O9 and Mn2B and O9B were restrained to be similar (esd = 0.02 Angstrom; SADI restraint in Shexl). All atoms of the minor moiety of the 3-chlorobenzoate (C15B-C21B, Cl1B) as well as of the minor disordered DMF molecules of O10 (associated with O10B and O10C) were restrained to lie in the same plane (esd = 0.01 Angstrom; FLAT restraint in Shexl). All disordered atoms were restrained to have similar Uij components of their ADPs (esd = 0.01 Angstrom squared; SIMU restraint in Shexl). The ADPs of C11 and C11B of a salicylhydroximate were constrained to be identical. Occupancies were constrained to sum up to unity for all sites using SUMP commands. Subject to the above conditions, the occupancy ratio of the main disorder of the metallacrown molecules and 3chlorobenzoates refined to 0.9276 (9) to 0.0724 (9). The occupancy rates for the additionally split DMF of O9 refined to 0.799 (3) (O9) and 0.047 (3) (O9C), and those of the additionally split DMF molecule of O10 refined to 0.498 (3) (O10) and 0.430 (3) (O10C). The occupancy ratio of the DMF molecules associated with O11 refined to 0.516 (5) to 0.484 (5). All hydrogen atoms were placed in calculated positions and refined as riding on their carrier atoms with C-H distances of 0.95 Angstrom for sp2 carbon atoms and 0.98 Angstrom for methyl carbon atoms. The Uiso values for hydrogen atoms were set to a multiple of the value of the carrying carbon atom (1.2 times for sp2 hybridized carbon atoms or 1.5 times for methyl carbon atoms).

Tetra-µ-aqua-tris(µ-3-chlorobenzoato)(dimethylformamide)tetrakis(µ 4 -N,2-dioxidobenzene-1carboximidato)pentamanganese(III)sodium(I) dimethylformamide tetraolvate 0.72-hydrate (2)
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. A partially occupied water molecule (O28) induces disorder for a neighboring DMF molecule (of O27). The two disordered moieties were restrained to have similar geometries, and the carbon, oxygen, and nitrogen atoms of the DMF molecule restrained to have similar Uij components of the ADPs (esd = 0.01 Angstrom squared; SIMU restraint in Shexl). Subject to these conditions the occupancy ratio refined to 0.718 (6) to 0.282 (6). Water H atom positions were refined and O-H and H···H distances were restrained to 0.84 (2) and 1.36 (2) Angstrom, respectively. The water H atom positions of partially occupied O28 were further restrained based on hydrogen bonding considerations. All other hydrogen atoms were placed in calculated positions and refined as riding on their carrier atoms with C-H distances of 0.95 Angstrom for sp2 carbon atoms and 0.98 Angstrom for methyl carbon atoms. The Uiso values for hydrogen atoms were set to a multiple of the value of the carrying carbon atom (1.2 times for sp2 hybridized carbon atoms or 1.5 times for methyl carbon atoms).