Crystal structure of tetraaqua(dimethylformamide)tetrakis(μ-N,2-dioxidobenzene-1-carboximidato)tetrakis(μ-trimethylacetato)tetramanganese(III)sodiumyttrium–dimethylformamide–water (1/8.04/0.62)

The title compound is an example of a 12-metallacrown-4 self-assembled supramolecular coordination complex with ring MnIII ions. A YIII ion and Na+ ion are captured on opposite sides of the metallacrown cavity, and the YIII ion is tethered to the metallacrown with four trimethylacetate anions.


Chemical context
Since 1989 metallacrowns (MCs) have served as an excellent example of the controllable self-assembly of supramolecular coordination complexes (Mezei et al., 2007). Considered the structural and functional inorganic analogues to crown ethers, metallacrowns self-assemble in solution to form coordination complexes with multiple metal centers. Not only can homometallic complexes be synthesized, but heterobimetallic and heterotrimetallic metallacrowns can also be prepared through one-step reactions (Mezei et al., 2007;Azar et al., 2014). The deliberate formation of supramolecular coordination complexes, especially those with multiple metal types, remains a synthetic challenge (Cook & Stang, 2015;Saalfrank et al., 2008); however, metallacrowns provide a class of molecules that allows the investigation of the formation of multi-metal supramolecular coordination complexes.
Recently we reported the first synthetic strategy for heterotrimetallic metallacrowns: Ln III M(OAc) 4 [12-MC Mn(III)N(shi) -4], where Ln III is Pr III to Yb III (except Pm III ) and Y III , M is Na I or K I , À OAc is acetate, and shi 3À is salicylhydroximate (Azar et al., 2014). In the previous report, we demonstrated the ability to systematically replace the central metal ions; however, the metallacrown framework has other points of alteration, in particular the bridging carboxylate anion. In these alkali metal-lanthanide-manganese ion complexes, four acetate anions serve as bridges between the central lanthanide ion and the ring Mn III ions. Potentially the acetate anions could be replaced with other carboxylate monoanions. ISSN 2056-9890 Herein we report the synthesis and crystal structure of Y III Na(OTMA) 4 [12-MC Mn(III)N(shi) -4](H 2 O) 3.76 (DMF) 0.24 Á-8.04DMFÁ0.62H 2 O, (1), where OTMA is trimethylacetate and DMF is N,N-dimethylformamide. This metallacrown demonstrates the ability to vary the bridging carboxylate monoanion of this heterotrimetallic class of metallacrowns.

Structural commentary
The structure of the title compound Y III Na(OTMA) 4 [12-MC Mn(III)N(shi) -4](H 2 O) 3.76 (DMF) 0.24 Á8.04DMFÁ0.62H 2 O, (1), is based on the typical [12-MC Mn(III)N(shi) -4] core. Four shi 3À framework ligands and four Mn III ions self-assemble to form an overall square geometry with a -[Mn-N-O] 4 -repeat unit. The MC ring forms a central cavity with a pseudo-fourfold rotation axis that is capable of binding central metal ions, in this structure an Y III ion and a Na I ion. The two ions are bound on opposite faces of the MC, and the metallacrown is slightly domed with the Y III ion residing on the convex side of the central cavity and the Na I ion residing on the underside of the dome. The Y III ion is also connected to the MC core by four trimethylacetate monoanions that serve to bridge the Y III ion to each ring Mn III ion. The molecular structure is shown in Figs. 1 and 2.
The ring Mn III ions and the central Y III ion are assigned a 3+ oxidation state based on average bond lengths, calculated bond-valence-sum (BVS) values (Liu & Thorp, 1993), and overall molecular charge considerations. For Mn1, Mn2, Mn3, and Mn4, the average bond lengths are 2.05, 2.04, 2.06, and 2.05 Å , respectively, and the calculated BVS values for Mn1-Mn4 are 3.04, 3.06, 3.07, and 3.05 v. u., respectively. In addition, each Mn III possesses elongated axial bond lengths, which would be expected for a high-spin d 4 ion. The Y1 ion has an average bond length and BVS value of 2.35 Å and 3.32 v. u., respectively. Molecular charge neutrality considerations also support the assigned oxidation states as the four shi 3À ligands and four trimethylacetate monoanions (total 16-charge) are balanced by the presence of four Mn III ions, one Y III ion, and one Na I ion (total 16+ charge).
The Y III ion is eight-coordinate with a distorted square antiprismatic geometry. The first coordination sphere is provided by two planes of four oxygen atoms each. One plane consists of four carboxylate oxygen atoms from the bridging trimethylacetate anions, and the second plane is formed by four oxime oxygen atoms of the MC ring. The Y III ion lies The molecular structure of (1) in top view with displacement ellipsoids at the 50% probability level. For clarity, H atom and lattice solvent molecules have been omitted, and only atom labels for all non-H atoms of the 12-MC-4 framework have been provided. Color scheme: aqua -Y III , green -Mn III , yellow -Na + , red -oxygen, blue -nitrogen, and graycarbon.

Figure 2
The molecular structure of (1) in side view. For clarity, only atom labels for all non-H atoms of the trimethylacetate anions and the coordinating water molecules and of the metal ions have been provided. For the solvent coordination site to Mn4, a water molecule and DMF molecule are disordered with an occupancy ratio of 0.758 (8):0.242 (8). Only the water molecule is displayed. See Fig. 1 for display details. closer to the mean plane of the carboxylate oxygen atoms (O car MP), 1.07 Å , than the mean plane of the oxime oxygen atoms (O ox MP), 1.57 Å . Also, the two planes are twisted relative to each other with an average skew angle of 50.02 o about the Y III ion (AlDamen et al., 2008(AlDamen et al., , 2009). The skew angles were calculated with the program Mercury (Macrae et al., 2006) and determined as previously described (Azar et al., 2014). For an ideal square-prismatic geometry, the skew angle is 0 o , while for an ideal square-antiprismatic geometry, the skew angle is 45 o . Given the measured skew angle and the placement of the Y III ion relative to the two planes of oxygen atoms, the best description of the geometry is distorted square antiprismatic.
The Na I ion is eight-coordinated with a severely distorted square-antiprismatic geometry. As in the Y III ion, the first coordination sphere is supplied by two planes of four oxygen atoms each. One plane is composed of the four oxime oxygen atoms of the MC ring, and the second plane consists of oxygen atoms from solvent molecules. Three of the four coordination sites are occupied by water molecules, while a water molecule and DMF molecule are disordered over the fourth site with an occupancy ratio of 0.758 (8):0.242 (8) (complete refinement details are given below). The Na I ion lies closer to the mean plane of the solvent oxygen atoms (O solvent MP), 0.67 Å , than the mean plane of the oxime oxygen atoms, 1.97 Å . Also, the two planes are twisted relative to each other with an average skew angle of 29.18 o about the Na I ion. Lastly, the solvent oxygen atoms bridge the central Na I ion to the ring Mn III ions. The water and DMF molecules disordered over the coordination site to the Na I ion bridge the Na I ion to Mn4.
Each ring Mn III is six-coordinate with a tetragonally distorted octahedral geometry. The equatorial plane is comprised of a six-membered chelate ring and a trans fivemembered chelate ring. The six-membered chelate ring is formed from the oxime nitrogen atom and the phenolate oxygen atom of one shi 3À ligand, and the five-membered chelate ring is formed from the oxime oxygen atom and the carbonyl oxygen atom of a second shi 3À ligand. Each Mn III ion possesses an elongated axial axis, which is composed of a carboxylate oxygen atom from a bridging trimethylacetate anion and a bridging solvent oxygen atom from either a water or a DMF molecule. The Mn III -O solvent bond lengths are rather long (2.4-2.5 Å ), which is likely due to the simultaneous coordination to the central Na I ion.
The metallacrown is slightly domed toward the central Na I ion. As previously reported, the doming effect is not likely due to the presence of either central metal ion, but likely due to the displacement of each ring Mn III ion from the equatorial mean plane of its first coordination sphere ligand atoms (Azar et al., 2014). For (1), the average distance of the ring Mn III ions above the equatorial ligand atom mean plane is 0.15 Å . Another indication of the doming effect in the MC is the angle between the axial carboxylate oxygen atom, the ring Mn III ion, and the calculated centroid of the oxime oxygen atoms (Mercury; Macrae et al., 2006) (3) 179 (5) Symmetry codes: (i) Àx þ 2; Ày þ 1; Àz þ 1; (ii) Àx þ 2; Ày þ 1; Àz; (iii) Àx þ 1; Ày þ 1; Àz; (iv) Àx þ 1; Ày þ 1; Àz þ 1.

Figure 3
Intermolecular C-HÁ Á ÁO interactions between adjacent metallacrowns. For clarity the interactions have been divided into two sections (a) and (b), only the H atoms (white) involved in the interactions have been included, and only the atoms involved in the interactions have been labelled. See Fig. 1 for display details. [Symmetry codes: (ii) Àx + 2, Ày + 1; (iii) Àx + 2, Ày + 1, Àz.] (complete refinement details are given below). Three different DMF molecules are flipped disordered over two sites, one DMF molecule is disordered over two sites with different orientations, and two DMF molecules are partially occupied. In addition, the disordered water/DMF binding site of the Na I ion is correlated to two DMF molecules, one of which is disordered over two sites with different orientations, and to two partially occupied water molecules. Overall there is a total of 8.04 DMF and 0.62 water molecules located in the lattice.

Supramolecular features
No strong directional intermolecular interactions are observed between the Y III Na(OTMA) 4 [12-MC Mn(III)N(shi) -4](H 2 O) 3.76 -(DMF) 0.24 molecules, but intermolecular C-HÁ Á ÁO interactions exist between adjacent metallacrowns (Table 1). The interactions exist between the carboxylate oxygen atoms (O14 and O20) of the trimethylacetate anions and the benzene carbon atoms (C18 and C25) of the shi 3À ligands on adjacent metallacrowns (Fig. 3). In addition, the water molecules (O21, O22, O23, and O24C) coordinating to the Na I ion are hydrogen bonded to several lattice water and DMF molecules (Fig. 4), and the lattice DMF molecules interact with the MC molecule through C-HÁ Á ÁO interactions (Fig. 5). The C-HÁ Á ÁO interactions occur between either a phenolate oxygen atoms (O3 and O12) of shi 3À ligands, a carboxylate oxygen atom (O8) of a shi 3À ligand, or a coordinating water oxygen atom (O21) and carbonyl carbon atoms (C55, C61, and C64B) or a methyl carbon atom (C71B) of lattice DMF molecules (Fig. 5). Lastly, several C-HÁ Á ÁO interactions exist between Intermolecular hydrogen bonding between the water molecules coordinating to the Na + ion and the water and DMF molecules of the lattice. For clarity the hydrogen bonding has been divided into two sections (a) and (b), only the H atoms (white) involved in the hydrogen bonding have been included, and only the atoms involved in the hydrogen bonding have been labelled. See Fig. 1 for display details.  adjacent solvent molecules (Fig. 6). The carbonyl (C49) or methyl (C51, C53, C56, C59, C63B, C72B, C74, and C75) carbon atoms of DMF molecules interact with either an oxygen atom (O34) of a lattice water molecule or carbonyl oxygen atoms (O27, O29, O31, O32, and O32B) of lattice DMF molecules. The hydrogen bonding and weak C-HÁ Á ÁO interactions, in addition to pure van der Waals forces, contribute to the overall packing of the molecules.

Database survey
The crystal structure of one other yttrium-based heterotrimetallic 12-MC-4 has been reported: Y III Na ( (Table 2). These features were calculated and measured using the program Mercury (Macrae et al., 2006) and in the same manner as previously described (Azar et al., 2014 (1) and (2) ( Table 2). The greatest deviations between the structures is the distance of the Na I ion from the mean plane of the solvent oxygen atoms. This is likely due to the difference in the first coordination sphere of the Na I ions. In (2A) and (2B) only water molecules bind to the Na I ions, while in (1) a mixture of water and DMF molecules bind to the Na I ion.
The identity of the bridging ligand does not significantly alter the domed feature of the metallacrown. As stated in the Structural commentary for (1), the average distance of the ring Mn III ions above the equatorial ligand atom mean plane is 0.15 Å , and the average angle about the Mn III ions with respect to the axial carboxylate oxygen atom and the calculated centroid of the oxime oxygen atoms is 101.

Figure 6
Intermolecular C-HÁ Á ÁO interactions between adjacent water and DMF molecules. For clarity the interactions have been divided into two sections (a) and (b), only the H atoms (white) involved in the interactions have been included, and only the atoms involved in the interactions have been labelled. See Fig. 1 for display details. [Symmetry codes: (iv) Àx + 1, Ày + 1, Àz; (v) Àx + 1, Ày + 1, Àz + 1.]

Synthesis and crystallization
The title compound (1) was synthesized by first mixing yttrium(III) nitrate hexahydrate (0.125 mmol), sodium trimethylacetate hydrate (4 mmol based on an assumption of three waters of hydration), and salicylhydroxamic acid (2 mmol) in 10 mL of DMF resulting in a cloudy, white mixture. In a separate beaker, manganese(II) acetate tetrahydrate (2 mmol) was dissolved in 10 mL of DMF resulting in an orange-red solution. The two solutions were mixed resulting in a dark-brown solution and then allowed to stir overnight. The solution was then filtered to remove a darkbrown precipitate, which was discarded. Slow evaporation of the dark-brown filtrate yielded X-ray quality black/darkbrown crystals after 9 days. The yield was 20% based on yttrium(III) nitrate hexahydrate.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The following low angle reflections were affected by the beam stop and were omitted from the refinement: 1 0 0, 0 1 0, 1 1 1, and 1 1 0. For all of the disordered solvate water and DMF molecules, neighboring atoms were restrained to have similar U ij components of their ADPs if closer than 1.7 Å (SIMU restraints in SHELXL).
The geometries of the DMF molecules associated with N7, N8B, N9, N9B, N10, N10B, N11, N12, N12B, N13, and N13B were restrained to be similar to the DMF molecule associated with N5 (esd = 0.02 Å ). For the DMF molecules associated with N7B and N11B, the geometries were restrained to be similar to the DMF molecule associated with N5 (esd = 0.001 Å ). For the DMF molecules associated with N8B, N11B, and N13B, the carbon, oxygen, and nitrogen atoms were restrained to lie in the same plane (e.s.d. = 0.01 Å 3 ).
A water molecule (O24C) and DMF molecule associated with N13 are disordered over a binding site to Na1. The atoms O24 and O24C were given identical coordinates, and to avoid correlation of the thermal parameters, the ADPs of O24 and O24C were constrained to be identical. Subject to these and the above conditions, the occupancy ratio of the disordered water and DMF molecules refined to 0.758 (8) to 0.242 (8). Correlated to the occupation of the binding site to Na1 is a DMF molecule associated with N13B and a DMF molecule associated with N7 that is disordered over two sites with different orientations. Subject to the above restraints, the occupancy ratio of the DMF molecule associated with N13B refined to 0.252 (5), and the occupancy ratio of the disordered DMF molecule associated with N7 refined to 0.748 (5):0.252 (5). In addition, two partially occupied water molecules associated with O33 and O34 are correlated to these water and DMF molecules. The occupancy of the water molecule of O33 and the water molecule of O34 are 0.257 (14) and 0.361 (13), respectively.
Several DMF molecules are disordered, and the above restraints were used to model the data. The DMF molecule associated with N8 is flipped disordered over two sites, and the occupancy ratio refined to 0.813 (7):0.187 (7). The DMF molecule associated with N9 is flipped disordered over two sites, and the occupancy ratio refined to 0.813 (7):0.187 (7). The DMF molecule associated with N10 is disordered over two sites with different orientations, and the occupancy ratio refined to 0.795 (6):0.205 (6). The DMF molecule associated with N11 is flipped disordered over two sites, and the occupancy ratio refined to 0.790 (9):0.210 (9). Two DMF molecules associated with N12 and N12B are partially occupied. The occupancy of the DMF molecule N12 and the DMF molecule 12B are 0.662 (8) and 0.129 (7), respectively.
For the water molecules, the oxygen-hydrogen bond lengths were restrained to 0.84 (2) Å . The hydrogen-hydrogen distances for the water molecules associated with O24, O33, and O34 were restrained to 1.36 (2) Å . For the water molecule O24C, the hydrogen atoms were restrained to a distance of at least 2.90 (2) Å from Na1. For the water molecules associated with O33 and O34, the hydrogen atoms were refined as riding on the oxygen atoms.
For the methyl group carbon atoms C56B, C62B, C63B, C69, C69B, C71B, C72B, C74, C74B, C75, and C75B, hydrogen atoms were placed in tetrahedral positions with an ideal staggered geometry (AFIX 33). All other methyl group hydrogen atoms were allowed to rotate. 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 and water oxygen atoms). Several larger than desired residual electron density peaks remain after refinement of the data, which is typical for this class of compounds. The origin of these peaks is usually caused either by minor twinning, excessive twinning with multiple components that is beyond what can be completely handled with current integration and absorption correction software, pseudosymmetry (and correlation), or additional disorder not defined well enough to be modeled. In the case of the presented structure, the residual electron density is mostly due to additional disorder. The 3 rd , 4 th , 5 th and 7 th largest residual electron density peaks are due to alternative positions of manganese atoms of a minor moiety of the metallacrown unit (whole molecule disorder). The height of these peaks, 1.3 to 1.2 electrons per Å 3 , indicate the presence of less than 5% of the second moiety, and most other atoms (carbon, nitrogen, and oxygen) are not resolved. The 2 nd largest residual density peak (1.71 electrons per Å 3 ) is located close to the yttrium atom and is within the typical range of residual electron density peaks close to heavy atoms. The two remaining residual electron density peaks, the largest (1.73 electrons per Å 3 ) and 6 th largest (1.23 electrons per Å 3 ) are due to minor twinning by a 180.0 degree rotation about the 1 1 0 reciprocal lattice direction (twin law 0.215 0.785 À0.203, 1.215 À0.215 À0.203, 0 0 À1). Refinement as a non-merohedric twin does reduce these peaks to 1.14 and 0.71 electrons per Å 3 , respectively; however, the R1 value slightly increases to 0.0553 from 0.0525. Also, the other larger residual electron density peaks (see above) are not improved by inclusion of twinning, nor is the structural model in any way changed. Considering the very minor effect, non-merohedric twinning was not used.

Tetraaqua(dimethylformamide)tetrakis(µ-N,2-dioxidobenzene-1-carboximidato)tetrakis(µtrimethylacetato)tetramanganese(III)sodiumyttrium-dimethylformamide-
Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. For all of the disordered solvate water and DMF molecules, neighboring atoms were restrained to have similar U ij components of their ADPs if closter than 1.7 Angstoms (SIMU restraints in SHELXL). The geometries of the DMF molecules associated with N7, N8B, N9, N9B, N10, N10B, N11, N12, N12B, N13, and N13B were restrained to be similar to the DMF molecule associated with N5 (e.s.d. = 0.02 Angstrom). For the DMF molecules associated with N7B and N11B, the geometries were restrained to be similar to the DMF molecule associated with N5 (e.s.d. = 0.001 Angstrom). For the DMF molecules associated with N8B, N11B, and N13B, the carbon, oxygen, and nitrogen atoms were restrained to lie in the same plane (0.01 Angstroms cubed). A water molecule (O24C) and DMF molecule associated with N13 are disordered over a binding site to Na1. The atoms O24 and O24C were given identical coordinates, and to avoid correlation of the thermal parameters, the ADP of O24 and O24C were constrained to be identical. Subject to these and the above conditions, the occupancy ratio of the disordered water and DMF molecules refined to 0.758 (8) to 0.242 (8). Correlated to the occupation of the binding site is a DMF molecule associated with N13B and a DMF molecule associated with N7 that is disordered over two sites with different orientations. Subject to the above restraints, the occupancy ratio of the DMF molecule associated with N13B refined to 0.252 (5), and the occupancy ratio of the disordered DMF molecule associated with N7 refined to 0.748 (5) to 0.252 (5). In addition, two partially occupied water molecules associated with O33 and O34 are correlated to these water and DMF molecules. The occupancy of the water molecule of O33 and the water molecule of O34 are 0.257 (14) and 0.361 (13), respectively. Several DMF molecules are disordered, and the above restraints were used to model the data. The DMF molecule associated with N8 is flipped disordered over two sites, and the occupancy ratio refined to 0.813 (7) to 0.187 (7). The DMF molecule associated with N9 is flipped disordered over two sites, and the occupancy ratio refined to 0.813 (7) to 0.187 (7). The DMF molecule associated with N10 is disordered over two sites with different orientations, and the occupancy ratio refined to 0.795 (6) to 0.205 (6). The DMF molecule associated with N11 is flipped disordered over two sites, and the occupancy ratio refined to 0.790 (9) to 0.210 (9). Two DMF molecules associated with N12 and N12B are partially occupied. The occupancy of the DMF molecule N12 and the DMF molecule 12B are 0.662 (8) and 0.129 (7), respectively. For the water molecules, the oxygen-hydrogen bond distances were restrained to 0.84 (2) Angstrom. The hydrogenhydrogen distances for the water molecules associated with O24, O33, and O34 were restrained to 1.36 (2) Angstroms. For the water molecule O24C, the hydrogen atoms were restrained to a distance of at least 2.90 (2) Angstroms from Na1. For the water molecules associated with O33 and O34, the hydrogen atoms were refined as riding on the oxygen atoms. For the methyl group carbon atoms 56B, 62B, 63B, 69, 69B, 71B, 72B, 74, 74B, 75, and 75B, hydrogen atoms were placed in tetrahedral positions with an ideal staggered geometry (AFIX 33). All other methyl group hydrogen atoms were allowed to rotate. 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 U iso 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 and water oxygen atoms). The following low angle reflections were affected by the beam stop and were omitted from the refinement: 1 0 0, 0 1 0, −1 − 1 1, and −1 1 0. 0.091 (7) 0.172 (9) 0.088 (7) −0.045 (7) 0.037 (6) 0.031 (7) (7) 0.019 (7) 0.017 (7)  N13B 0.099 (7) 0.107 (7) 0.090 (7 (7) −0.002 (7) 0.042 (7)  C72 0.094 (7) 0.098 (7) 0.129 (9) −0.055 (6) −0.002 (7) 0.018 (7) (7) 0.085 (7) −0.042 (7) 0.017 (6) 0.018 (6)  O34 0.073 (7) 0.091 (7) 0.070 (7