Crystal structures of two dysprosium–aluminium–sodium [3.3.1] metallacryptates that form two-dimensional sheets

The two [3.3.1] metallacryptate complexes [DyAl6Na5(OAc)(Hshi)2(shi)7(DMF)8]·H2O·4DMF, 1, and [DyAl6Na5(OAc)(Hshi)2(shi)7(DMF)8.5]2·6.335DMF, 2, where shi3− is salicylhydroximate and DMF is N,N-dimethylformamide, both consist of an aluminium-based metallacryptand. In 1 and 2, the metallacryptand encapsulates a dysprosium(III) ion in the central cavity, and the resulting metallacryptates are connected to each other to generate a two-dimensional sheet.


Chemical context
Metallacrowns, first recognized in 1989 by Pecoraro (Pecoraro, 1989), belong to a class of molecules known as metallamacrocycles that also include, but are not limited to, metallahelices and metallahelicates (Kramer et al., 1993;Piguet et al., 1997), metallacryptands and metallacryptates (Ma et al., 1980;Saalfrank et al., 1988;Zaleski et al., 2005), and metallic wheels and rings (Taft et al., 1994;Mü ller et al., 1995;Murrie et al., 1999). The archetypal metallacrown (MC) framework is based on a cyclic metal-nitrogen-oxygen repeat unit similar to the crown ether cyclic carbon-carbon-oxygen repeat unit. Since their inception metallacrowns have been considered not only structural analogues of crown ethers, but also functional analogues, as metallacrowns typically bind a metal ion in the central cavity. In addition, as cryptands can be considered the three-dimensional analogues of crown ethers (Lehn, 1978), metallacryptands with an M-N-O repeat unit ( Fig. 1) can be considered the three-dimensional analogues of metallacrowns (Lutter et al., 2018). Metallacrown and metallacryptate chemistry has mainly focused on incorporating transition metal ions in the ring repeating unit as these ions impart interesting magnetic and spectroscopic properties. The use of main-group metal ions has mainly been limited to gallium (Lah et al., 1993;Jiang et al., 2019;Athanasopoulou et al., 2019), tellurium (Kü bel et al., 2010;Ho et al., 2016;Ho et al., 2017;Ho et al., 2019;Wang et al., 2019), and tin (Zhao et al., 2010a;Zhao et al., 2010b). Recently though, gallium-based metallacrowns and metallacryptates have gained renewed interest as potential optical imaging agents (Chow et al., 2016;Nguyen et al., 2018;Lutter et al., 2018Lutter et al., , 2019Lutter et al., , 2020. For many metallacrowns and metallacryptates, a common ligand is salicylhydroxamic acid (H 3 shi), which can be triply deprotonated to produce salicylhydroximate (shi 3À ), and when this ligand set is combined with transition-metal ions in a 3+ oxidation state, a plethora of structural arrangements is possible (Mezei et al., 2007). In addition, one hallmark of MC chemistry is the ability to easily substitute components of the complexes and still generate similar structures. For instance, in a series of Ln III  structures with ring manganese(III) ions, the Mn III ions can be substituted with gallium(III) to generate comparable 12-MC-4 structures (Chow et al., 2016). Thus, a logical extension would be to include aluminum(III) into the MC ring, as this would maintain the charge balance of the overall complexes. However, to date aluminum has not been used to generate either an archetypal metallacrown or metallacryptand complex. Herein we present two [3.3.1] metallacryptate complexes [DyAl 6 Na 5 (OAc)(Hshi) 2 -(shi) 7 (DMF) 8 ]ÁH 2 OÁ4DMF, 1, and [DyAl 6 Na 5 (OAc)(Hshi) 2 -(shi) 7 (DMF) 8.5 ] 2 Á6.335DMF, 2, where DMF is N,N-dimethylformamide. Complexes 1 and 2 represent the first metallacrowns or metallacryptates to contain aluminum as a ring metal. Future studies will focus on the luminescent and magnetic properties of these and related compounds, as the aluminum ions do not quench the luminescence of the Ln III ions and the diamagnetic nature of the aluminum ions generates a potential single-ion magnet with the paramagnetic lanthanide ion at the center of the molecule.

Structural commentary
The two-dimensional structures of the metallacryptates of 1 and 2 are very similar; however, there are key structural differences. Both compounds are synthesized in the same manner with a 1:16:16:32 ratio between the reactants, Dy(NO 3 ) 3 : Al(OAc) 2 OH: H 3 shi: NaOAc; however, the crystals have different space groups (Cc for 1 and Pc for 2). At this time it is not clear what factors induce the crystallization of 1 or 2. In 1 there is only one type of metallacryptate in the twodimensional network (Fig. 2), while in 2 there are two different but very similar metallacryptates. Compound 2 can be considered a dimeric unit of two metallacryptates (Fig. 3). When it is necessary to distinguish the two metallacryptates  for 2, the designations 2A (associated with Dy1) and 2B (associated with Dy2) will be used. Each metallacryptate is connected to its nearest neighbors to generate a two-dimensional sheet (Figs. 4 and 5), which will be described in greater detail below. The individual repeat unit of the two-dimensional network is akin to a metallacrown but can more accurately be described as a metallacryptate. As a cryptand is considered a three-dimensional analogue to a crown ether, the aluminum-based shells of 1 and 2 can be considered as threedimensional metallacrowns, thus as metallacryptands (Fig. 6a). Furthermore, upon binding a metal ion in the central cavity, a cryptand is transformed into a cryptate. Compounds 1 and 2 bind a Dy III ion in the central cavity to produce a metallacryptate (Figs. 6b and 7). Each metallacryptate unit consists of one Dy III ion, six Al III ions, and five Na + ions to provide a total charge of 26+, which is counterbalanced by one acetate, seven triply deprotonated shi 3À ligands, and two Hshi 2À ligands with a total charge of 26-. For the Hshi 2À ligands, the phenolate and oxime oxygen atoms are deprotonated, while the oxime nitrogen atom remains protonated and does not coordinate to any metal ions. Beyond overall molecular charge considerations, the oxidation state assignments of the Dy III and Al III ions are also confirmed by bond-valence-sum (BVS) values (Table 1) (Brese & O'Keeffe, 1991;Trzesowska et al., 2004). The Na + ions do not participate in the metallacryptate structure, but serve to connect neighboring molecules in a twodimensional sheet. The single-crystal X-ray structure of [DyAl 6 Na 5 (OAc)(Hshi) 2 (shi) 7 -(DMF) 8 ]ÁH 2 OÁ4DMF, 1, including connections to neighboring sodium ions [symmetry codes: (i) x À 1 2 , y À 1 2 , z; (ii) x + 1 2 , y + 1 2 , z; (iii) x À 1 2 , y + 1 2 , z; (iv) x + 1 2 , y À 1 2 , z]. The displacement ellipsoids are at the 50% probability level. For clarity, labels have only been added to the metal ions and some of the carbon, nitrogen, and oxygen atoms. In addition, the solvent water and DMF molecules, the hydrogen atoms, and disorder have been omitted. Color scheme: green -Al, yellow -Dy, light blue -Na, redoxygen, dark blue -nitrogen, and gray -carbon. All figures were generated with the program Mercury (Macrae et al., 2020).
The metallacryptand structure can best be described as a [3.3.1] complex based on the similar [3.3.1] cryptand (Krakowiak et al., 1993), where the numbers indicate the number of oxygen atoms in each linkage of the metallacryptand (Fig. 1). In the metallacryptand, two Al III ions serve as the anchor points of the structure, akin to the nitrogen atoms of a cryptand ( Fig. 1 & 6). There are two linkages between the anchor Al III ions consisting of an O-N-Al-O-N-Al-O-N pattern and one shorter linkage with an N-O pattern, thus the [3.3.1] nomenclature. This metal-nitrogen-oxygen repeating pattern is that of the archetypal metallacrown; thus, these structures can be considered three-dimensional metallacrowns. The repeating units of the metallacryptand strands are generated from the seven shi 3À ligands with the hydroximate group of the ligand providing the N-O linkage. The oxime oxygen atoms of the linkages bind a Dy III ion in the central cavity to generate the metallacryptate. The two remaining Hshi 2À ligands are not involved in the metallacryptand structure but instead bind on the periphery of the structure and provide two additional oxime oxygen atoms to complete the coordination The two-dimensional network of 1 generated by the bridging Na + ions between the metallacryptate units. Each metallacryptate is connected to four adjacent metallacryptates. The view is along the c axis of the unit cell. See Fig. 2 for additional display details.

Figure 5
The two-dimensional network of 2 generated by the bridging Na + ions between the dimeric metallacryptate units. Each metallacryptate is connected to four adjacent dimeric metallacryptates. The view is along the c axis of the unit cell. See Fig. 2 for additional display details.

Figure 6
The (a) metallacryptand and (b) metallacryptate views of 1 highlighting the [3.3.1] connectivity between the metal ions. See Fig. 2 for additional display details. Table 1 Average bond length (Å ) and bond-valence-sum (BVS) values (v.u.) used to support assigned oxidation states of the dysprosium and aluminium ions of 1 and 2. of the Dy III ion and serve as bridging ligands to the Al III ions; however, the Hshi 2À ligands do not provide an N-O repeat unit in the structure between the metal ions as the nitrogen atoms remain protonated, thus negating their participation in the metallacryptand linkages. Each Dy III is nine-coordinate with nine oxime oxygen atoms providing the coordination sphere. As stated above, seven of the oxime oxygen atoms are provided by the seven shi 3À ligands, which participate in the formation of the metallacryptand and form bridges to all six Al III ions. The two remaining oxime oxygen atoms are provided by the two Hshi 2À ligands. Each oxime oxygen atom of the Hshi 2À ligands also serves as a one atom 3 -bridge between the Dy III ion, one Al III ion, and one Na + ion. A SHAPE (SHAPE 2.1; Llunell et al., 2013) analysis of the Dy III geometry (  The metallacryptate views of (a) 2A and (b) 2B demonstrating that the two metallacryptates of the dimeric unit are enantiomers. See Fig. 2 for additional display details.

Figure 9
Coordination geometries for the Al III ions of 1: (a) Al1 -trigonal pyramidal; (b) Al2 -octahedral, Á; (c) Al3 -octahedral, Ã; (d) Al4octahedral, Á; (e) Al5 -octahedral, Ã; (f) Al6 -trigonal pyramidal. See Fig. 2 (Llunell et al., 2013;Pinsky & Avnir, 1998;Cirera et al., 2005). A muffin geometry can best be described as a configuration with a trigonal base, a pentagonal equatorial plane, and a single point vertex (Ruiz-Martínez et al., 2008). There are six Al III ions per metallacryptate; two of the Al III ions are five coordinate while the remaining four are six coordinate . For the five-coordinate Al III ions, the geometries are either trigonal bipyramidal or spherical square pyramidal. For Al1 and Al6 of 1, the CShM values (Table 3) slightly favor a trigonal-bipyramid geometry over a spherical square pyramid (1.533 vs 1.880 for Al1 and 1.220 vs 1.797 for Al6). For 2, Al3 is clearly trigonal pyramidal with a CShM value below 1.0 (CShM = 0.874), where a value less than 1.0 typically indicates only minor distortions from the ideal shape (Cirera et al., 2005). However, the remaining Al III ions, Al4, Al8, and Al10, are spherical square pyramidal with CShM values of 1.168, 0.540, and 1.324, respectively, though for Al10 the CShM value for a trigonal bipyramid is 1.759, indicating the geometry is between the two ideal scenarios. For all of the five-coordinate Al III ions of 1 and 2, the coordination environment is composed of two chelate rings, a five-membered  Table 3 Continuous shapes measures (CShM) values for the geometry about the five-coordinate Al III ions of 1 and 2.

Shape
Pentagon (D 5h ) Vacant octahedron (C 4v ) Trigonal bipyramid (D 3h ) Spherical square pyramid (C 4v ) Johnson trigonal bipyramid (J12; D 3h )     ring formed from the oxime oxygen and carboxylate oxygen atoms of one shi 3À and a six-membered ring formed from the oxime nitrogen and phenolate oxygen atoms of a second shi 3À ligand. The coordination is completed by a phenolate oxygen atom of a Hshi 2À ligand. For the six-coordinate Al III ions (Al2-Al5 for 1 and Al1, Al2, Al5, Al6, Al7, Al9, Al11, Al12 for 2) the geometries are clearly octahedral with all CShM values below 2.0 ( Table 4). All of the six-coordinate Al III ions adopt a propeller configuration with two Á and two Ã stereoconfigurations per metallacryptate. For Al2 of 1, the Á stereoconfiguration is composed of three cis chelate rings: one five-membered chelate ring formed by the oxime and carboxylate oxygen atoms of a shi 3À ligand, one fivemembered chelate ring formed by the oxime and carboxylate oxygen atoms of an Hshi 2À ligand, and a six-membered chelate ring formed from the oxime nitrogen and phenolate oxygen atoms of another shi 3À ligand. For Al4, the Á stereoconfiguration has three chelate rings: two fivemembered chelate rings and one six-membered chelate ring from three different shi 3À ligands. For Al3, the Ã configuration consists of three cis chelate rings: one five-membered ring and two six-membered rings from three shi 3À ligands. For Al5, the Ã stereoconfiguration is formed by cis five-and sixmembered chelate rings of two shi 3À ligands and two cis oxygen atoms, a -carboxylate oxygen atom of an acetate anion and the oxime oxygen atom of an Hshi 2À ligand. Thecarboxylate atom of the acetate anion connects Al5 to Na5. For 2A, the Á and Ã Al III ions (Á: Al1 and Al5; Ã: Al2 and Al6) have the same coordination environment as their Al III ions counterparts in 1; however, for 2B, the Á and Ã envir-onments are reversed relative to 1 and 2A . The Ã stereoconfiguration of Al7 has three cis chelate rings: one fivemembered ring of a shi 3À ligand, one five-membered ring of an Hshi 2À ligand, and one six-membered ring of a shi 3À ligand. The Ã stereoconfiguration of Al12 has cis chelate rings from three shi 3À ligands (two five-membered rings and one sixmembered ring), while the Á stereoconfiguration of Al9 has cis chelate rings from three shi 3À ligands (one five-membered ring and two six-membered rings). For Al11, the Á stereoconfiguration is completed by cis five-and six-membered chelate rings of two shi 3À ligands and two cis oxygen atoms, a -carboxylate oxygen atom of an acetate anion and the oxime oxygen atom of an Hshi 2À ligand. Thus, the metallacryptand portions of 2A and 2B can be considered enantiomers (Fig. 7). The Na + ions of 1 and 2 are either five-or six-coordinate. The SHAPE analysis indicates that the geometries are severely distorted in each case with the CShM values typically above 3.0, which can be considered an upper threshold value where below 3.0 is still considered an adequate description of the geometry though there are significant distortions (Cirera et al., 2005). For the five-coordinate Na + ions (Na4 of 1, and Na4 and Na7 of 2), Na4 of 1 can best be described as a spherical square pyramid, while for Na4 and Na7 of 2, the geometry can best be described as trigonal bipyramidal (Table 5). The coordination environment of each Na + ion is the same and consists of a five-membered chelate ring from the carboxylate oxygen and oxime oxygen atoms of an Hshi 2À ligand, an oxime oxygen atom of a different Hshi 2À ligand, a carboxylate oxygen atom of an acetate ion, and a carbonyl oxygen atom of a DMF molecule. In addition to the Al III propeller stereo-   configurations described above, the differences between 1 and 2 stem from the acetate anions and DMF molecules of the fivecoordinate Na + ions. In 1, the acetate anion forms a threeatom bridge to a neighboring Na + ion (Na5) and the acetate anion does not connect to a neighboring metallacryptate. In 2, the acetate anions not only form a three-atom bridge to a neighboring Na + of the same metallacryptate (Na4 to Na5 of 2A and Na7 to Na6 of 2B), but also form -oxygen bridges to an Na + ion of a neighboring metallacryptate unit (Na4 to Na6 and Na7 to Na5). In addition, the DMF molecules of Na4 of 1 and Na7 of 2B bind in a terminal fashion; however, for Na4 of 2A the carbonyl oxygen atom of the DMF forms a -bridge between Na4 and Na6, which contributes to the linkage between 2A and 2B. Overall the connections between Na4, Na5, Na6, and Na7 of 2 connect the two metallacryptates to form a dimeric unit. For the six-coordinate Na + ions, the geometries can best be described as severely distorted octahedra with most CShM values above 3.0 and an average value of 3.591 for 1 and 4.039 for 2 (Table 6). For both 1 and 2, the six-coordinate Na + ions serve as connection points between neighboring metallacryptate units and this connectivity generates the twodimensional sheet. A description of the coordination environment of Na1-Na3 and Na5 of 1 and the connectivity to neighboring metallacryptates follows. For Na1, the coordination environment consists of three -carbonyl oxygen atoms of three different bridging DMF molecules, a carbonyl oxygen atom of a terminal DMF molecule, a phenolate oxygen atom of a shi 3À ligand, and a carboxylate oxygen atom of a different shi 3À ligand. The three bridging DMF molecules connect Na1 to the Na3 ion of a neighboring metallacryptate. For Na2, the coordination environment consists of three -carbonyl oxygen atoms of bridging DMF molecules, two phenolate oxygen atoms of two different shi 3À ligands, and a carboxylate oxygen atom of a third shi 3À ligand. The three bridging DMF molecules connect Na2 to the Na5 ion of a neighboring metallacryptate. For Na3, the coordination environment consists of three -carbonyl oxygen atoms of bridging DMF molecules, two carboxylate oxygen atoms of two different shi 3À ligands, and a phenolate oxygen atom of a third shi 3À ligand. The three bridging DMF molecules connect Na3 to the Na1 ion of a neighboring metallacryptate. For Na5, the coordination environment consists of three -carbonyl oxygen atoms of bridging DMF molecules, a carboxylate oxygen atom of an acetate anion that bridges between Na5 and Al5, a phenolate oxygen atom of a shi 3À ligand, and a carboxylate oxygen atom of an Hshi 2À ligand. The three bridging DMF molecules connect Na5 to the Na2 ion of a neighboring metallacryptate. The series of -bridging DMF molecules between the peripheral Na + ions of the metallacryptates generate the twodimensional network of the compound (Fig. 4). If the shape of the metallacryptate of 1 is approximated as a square, then the Na + ions Na1, Na2, Na3, and Na5 lie at each corner. Each Na + ion connects to one adjacent MC via three -carbonyl oxygens of the bridging DMF molecules. Thus, each metallacryptate unit is connected to four adjacent metallacryptates via the peripheral Na-DMF-Na connections and a two-dimensional sheet of metallacryptates is generated (Na1 to an adjacent Na3, Na2 to an adjacent Na5, Na3 to an adjacent Na1, and Na5 to an adjacent Na2).
A description of the coordination environment of Na1-Na3, Na5, Na6, and Na8-Na10 of 2 and the connectivity to neighboring metallacryptates follows. For Na1, the coordination environment consists of two -carbonyl oxygen atoms of two different bridging DMF molecules, a carbonyl oxygen atom of a terminal DMF molecule, two phenolate oxygen atoms of two different shi 3À ligands, and a carboxylate oxygen atom of a third shi 3À ligand. The two bridging DMF molecules connect Na1 to the Na10 ion of a neighboring metallacryptate. For Na2, the coordination environment consists of three -carbonyl oxygen atoms of bridging DMF molecules, a carbonyl oxygen atom of a terminal DMF molecule, a phenolate oxygen atom of a shi 3À ligand, and a carboxylate oxygen atom of a different shi 3À ligand. The three bridging DMF molecules connect Na2 to the Na3 ion of a neighboring metallacryptate. For Na3, the coordination environment consists of three -carbonyl oxygen atoms of bridging DMF molecules, a carboxylate oxygen atom of a shi 3À ligand, a phenolate oxygen atom of a different shi 3À (Fig. 5). For the dimeric unit, there are six connection points (Na1, Na2, Na3, Na8, Na9, and Na10) to neighboring metallacryptates. If the shape of the dimeric metallacryptate unit of 2 is approximated as a rectangle with Na2 and Na8 along one long edge, Na3 and Na9 along the opposite long edge, and Na1 and Na10 on opposite short edges, then each dimeric unit connects to one other dimeric unit along each edge via the -carbonyl oxygen atoms of the bridging DMF molecules. Thus, each dimeric unit is connected to four adjacent dimeric metallacryptate units via the peripheral Na-DMF-Na connections and a two-dimensional sheet of metallacryptates is generated (Na1 to an adjacent Na10 on a short edge, Na10 to an adjacent Na1 on the opposite short edge, Na2 to an adjacent Na3 and Na8 to an adjacent Na9 along the same long edge, and Na3 to an adjacent Na2 and Na9 to an adjacent Na8 along the other long edge).
For both 1 and 2, several solvent molecules are located within the two-dimensional networks. For 1 there are four DMF molecules and one water molecule per metallacryptate. One of the DMF molecules (associated with N21) is flip disordered over two sites and refined to 0.50 (2):0.50 (2). For 2 there are 6.335 DMF molecules per dimeric metallacryptate unit. The DMF molecules associated with N36 and N42 are disordered over two positions and refined to 0.700 (13): 0.300 (13) and to 0.661 (12):0.339 (12), respectively. In addition, three DMF molecules associated with N38, N40, and N41 are partially occupied and refined to 0.806 (9), 0.682 (16), and 0.847 (14), respectively. Moreover, both 1 and 2 contain solvent-accessible voids of 988 and 832 Å 3 , respectively. The residual electron density peaks were not arranged in an interpretable pattern; thus, the SQUEEZE routine as implemented in PLATON was used to account for the residual electron density (van der Sluis & Spek, 1990;Spek, 2015). The SQUEEZE procedure accounted for 313 and 235 electrons within the solvent-accessible voids of 1 and 2, respectively.

Supramolecular features
For 1 and 2, numerous hydrogen bonds and weak C-HÁ Á ÁO interactions exist within each metallacryptate, between components of the metallacryptate and the bridging DMF molecules, and between the two-dimensional network and the solvent molecules (Tables 7 and 8). For 1, the protonated oxime nitrogen atoms of the two Hshi 2À ligands each form a hydrogen bond to the oxime oxygen atom of a neighboring shi 3À ligand (N7-H7Á Á ÁO22 and N9-H9Á Á ÁO13). The water molecule (O42) forms hydrogen bonds to the phenolate oxygen atom of a shi 3À ligand (O42-H42AÁ Á ÁO3) and to the carbonyl oxygen atom of a DMF molecule coordinated to Na4 (O42-H42BÁ Á ÁO37). In addition, O42 interacts with the methine group of a -DMF molecule (C66-H66Á Á ÁO42). Two C-HÁ Á ÁO interactions exist between the carbon-hydrogen atoms of the benzene rings of the shi 3À ligands with the carbonyl oxygen atoms of the -DMF molecules that bridge between two Na + ions (associated with C20 and C41). Furthermore, the DMF molecules form numerous C-HÁ Á ÁO interactions with neighboring oxygen atoms through either the methine or the methyl groups of the DMF molecules. The methine groups form interactions with the oxime oxygen atom of a shi 3À ligand (associated with C69), the carboxylate oxygen atom of Hshi 2À (associated with C78) or shi 3À (associated with C84) ligands, and the carbonyl oxygen atom of neighboring DMF molecules (associated with C78). The methyl groups form interactions with the carbonyl oxygen atoms of neighboring DMF molecules (associated with C67, C74, C79, C80, C83, C94, C95, and C97), the oxime oxygen atom of a shi 3À ligand (associated with C71), and the phenolate oxygen atom of shi 3À (associated with C73, C79, C98) or Hshi 2À (associated with C92) ligands.
Complex 2 has similar hydrogen bonds and weak C-HÁ Á ÁO interactions as 1. For 2, the protonated oxime nitrogen atoms of the four Hshi 2À ligands each form a hydrogen bond to the oxime oxygen atom of a neighboring shi 3À ligand (N5-H5NÁ Á ÁO7, N6-H6NÁ Á ÁO10, N11-H11NÁ Á ÁO46, and N14-H14NÁ Á ÁO37). Four C-HÁ Á ÁO interactions exist between the carbon-hydrogen atoms of the benzene rings of the shi 3À ligands with the carbonyl oxygen atoms of the DMF molecules coordinated to the Na + ions (associated with C4, C60, C81, and C123). The methyl groups of the acetate anions also form C-HÁ Á ÁO interactions to the carbonyl oxygen atom of a DMF molecule coordinated to a Na + ion (C128-H12CÁ Á ÁO69B) and to a phenolate oxygen atom of an Hshi 2À ligand (C130-H13BÁ Á ÁO14). Furthermore, the DMF molecules form C-HÁ Á ÁO interactions with neighboring oxygen atoms through either the methine or the methyl groups of the DMF molecules. The methine groups form interactions with the oxime oxygen atom of shi 3À ligands (associated with C137 and C173) and the carbonyl oxygen atom of neighboring DMF molecules (associated with C140 and C191). The methyl groups form interactions with the carbonyl oxygen atoms of neighboring DMF molecules (associated with C144, C157, C159, C169, C171, C172, and C204), the oxime oxygen atoms of shi 3À ligands (associated with C139 and C175), the phenolate oxygen atoms of shi 3À (associated with C168, C183, and C184) or Hshi 2À (associated with C201 and C223) ligands, and the carboxylate oxygen atom of shi 3À (associated with C153, C162, C163, C183, and C199) or Hshi 2À (associated with C159) ligands.

Database survey
A survey of the Cambridge Structural Database (CSD version 5.41, update March 2020, Groom et al., 2016) reveals that there is only one other comparable metallacryptate, which is based on gallium (DIBLOS; Lutter et al., 2018). The structure contains a [3.3.1] metallacryptand topology built with six Ga III ions instead of Al III ions and also contains seven shi 3À ligands as in 1 and 2, but the gallium-based structure has one H 2 shi À and one Hshi 2À ligand as opposed to the two Hshi 2À ligands in 1 and 2. For the gallium-based structure, a Tb III ion is captured in the central cavity to form the metallacryptate. The major difference between 1 and 2 and the gallium-based structure is that the latter is only a discrete molecule and not a twodimensional network. For the gallium-based structure, there are no sodium ions. Instead charge neutrality is maintained by the presence of three triethylammonium cations, which are not coordinated to the metallacryptates and which do not form bridges between them.  Table 7 Hydrogen-bond geometry (Å , ) for 1.  Symmetry codes: (i) x þ 1; y; z; (ii) x À 1; y; z; (iii) x; Ày þ 1; z þ 1 2 ; (iv) x; Ày; z À 1 2 ; (v) x; y þ 1; z; (vi) x; Ày; z þ 1 2 .

Synthesis and crystallization
(certified ACS grade) was purchased from Fisher Scientific. N,N-Dimethylformamide (DMF, certified ACS grade) and diethyl ether (certified ACS grade) were purchased from Pharmco-Aaper. All reagents were used as received and without further purification. General preparation of [3.3.1]DyAl 6 Na 5 -metallacryptate compounds The same procedure was used to synthesize 1 and 2; however, the syntheses resulted in the crystallization of the compound in two different structures. Dysprosium(III) nitrate pentahydrate (0.125 mmol, 55.7 mg for 1, 54.8 mg for 2), sodium acetate trihydrate (4 mmol, 544.7 mg for 1, 545.3 mg for 2), and salicylhydroxamic acid (2 mmol, 306.4 mg for 1, 307.2 mg for 2) were mixed in 10 mL of DMF resulting in a cloudy, slightly pink mixture. In a separate beaker, hydroxyaluminum diacetate (2 mmol, 324.6 mg for 1, 325.1 mg for 2) was mixed in 10 mL of DMF, resulting in a cloudy, white mixture. The two solutions were mixed, resulting in a cloudy, slightly pink mixture and allowed to stir overnight. The solution was filtered the next day to remove a white precipitate, which was discarded, and a pale-yellow filtrate was recovered. X-ray quality crystals were grown via diethyl ether diffusion at room temperature. White, slightly pink, thin, needle-shaped crystals were recovered after 11 days for 1 and 28 days for 2.

Refinement
For complex 1, the crystal under investigation was found to have two components, but the domains were not related by any meaningful twin relationship. The orientation matrices for the two components were identified using the program CELL_NOW (Sheldrick, 2008b), with the two components being related by a 3.5 rotation around the reciprocal axis 0 0 1. The structure was solved by direct methods with only the non-overlapping reflections of component 1, and the structure was refined using all reflections of component 1 (including the overlapping ones), resulting in a BASF value of 0.40356 (9). The R int value given is for all reflections and is based on agreement between observed single and composite intensities and those calculated from refined unique intensities and domain fractions (TWINABS; Sheldrick, 2012).
The geometry of the DMF molecule associated with N18 was restrained to be similar to the DMF molecule associated with N10 (esd = 0.02 Å ), and the atoms of the DMF molecule were restrained to have similar U ij components of their ADPs (esd = 0.01 Å 2 ; SIMU restraint in SHELXL).
A DMF molecule, associated with N21, is flip disordered over two sites. The geometries of the two DMF molecules were restrained to be similar to the DMF molecule associated with N10 (esd = 0.02 Å ). The atoms of the DMF molecules were restrained to have similar U ij components of the ADPs (esd = 0.01 Å 2 ; SIMU restraint in SHELXL), and the U ij components of the atoms were restrained to approximate isotropic behavior (esd = 0.01 Å 2 ). Subject to these restraints, the occupancy ratio of the disordered DMF molecule refined to 0.50 (2):0.50 (2).
For the water molecule associated with O42, the oxygenhydrogen bond distances were restrained to 0.84 (2) Å , the hydrogen-hydrogen distance was restrained to 1.36 (2) Å , and the hydrogen atoms were refined as riding on the oxygen atoms. Several hydrogen-bond distances between the hydrogen atom and the acceptor atom were restrained to expected target values (H42A to O3, H42B to O37, H7 to N7 and O21, and H9 to N9 and O27).
The amide N-H groups were refined subject to a distance constraint of 0.88 Å .
To avoid conflict between the hydrogen atoms and neighboring carbon atoms of DMF molecules, the distances between the atoms (C100 with H94A, H94B, and H94C and C94 with H10G, H10H, and H10I) were restrained to at least 2.80 Å .
For the methyl-group carbon atoms C85, C86, C91, C92, C95, C101, C102, and C103, hydrogen atoms were placed in tetrahedral positions with an ideal staggered geometry (AFIX 33 in SHELXL). All other carbon-bound 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 Â for sp 2 -hybridized carbon and nitrogen atoms or 1.5 Â for methyl carbon atoms and water oxygen atoms).
In addition, the structure of 1 contains solvent-accessible voids of 988 Å 3 . The residual electron density peaks are not arranged in an interpretable pattern. The structure factors were instead augmented via reverse Fourier transform methods using the SQUEEZE routine (van der Sluis & Spek, 1990;Spek, 2015) as implemented in the program PLATON (Spek, 2020). The resultant files were used in the further refinement. (The 'FAB' file with details of the SQUEEZE results is appended to the CIF file). The SQUEEZE procedure accounted for 313 electrons within the solvent-accessible voids. Additional crystal data, data collection and structure refinement details are summarized in Table 9.
For complex 2, the structure was refined as a twocomponent inversion twin. The BASF value refined to 0.097 (3). In addition, several solvate DMF molecules and one salicylhydroximate ligand of the molecule show disorder or were partially occupied. Several DMF molecules were also refined as disordered over two positions. Areas with extensively disordered unidentified solvate molecules are present, which were accounted for using the SQUEEZE routine.
To model the disorder of the DMF molecules, the following conditions were applied: For all of the solvate DMF molecules except the DMF associated with N19, neighboring atoms were restrained to have similar U ij components of their ADPs (SIMU restraints in SHELXL). All DMF molecules were restrained to have similar geometries to that of the DMF molecule associated with N19 (esd = 0.02 Å ). The atoms of the DMF molecule associated with N36, N37, N39 and N42 and the atoms C1, C6, and C99 were restrained to be approximately isotropic. The atom pairs O60 and O60B, O63 and O63B, and O70 and O70B were each given identical coordinates and thermal parameters to avoid correlation of their positional and thermal parameters. An anti-bumping restraint was applied to avoid close contacts for partially occupied or disordered DMF molecules (BUMP À0.04 in SHELXL). Subject to the above conditions, the occupancy ratio of the DMF molecules associated with N20, N23, N24, N29, N30, N34, N36, and N42 refined to 0.847 (14) (12), respectively. Three DMF molecules associated with N38, N40, and N41 were refined as partially occupied and subject to the above conditions, their occupancy fractions refined to 0.806 (9), 0.682 (16), and 0.847 (14), respectively.
To model the disorder of the salicylhydroximate ligand associated with N8, the neighboring atoms of the ligand were restrained to have similar U ij components of their ADPs (SIMU restraint in SHELXL). The atom pair C50 and C50B were each given identical coordinates and thermal parameters to avoid correlation of their positional and thermal parameters. To maintain planarity of the benzene rings, the carbon atoms were restrained to lie in a common plane (esd = 0.1 Å 3 ). Subject to the above conditions, the occupancy ratio for the ligands associated with N8 refined to 0.56 (5):0.44 (5). The amide N-H groups were refined subject to a distance constraint of 0.88 Å . To avoid correlation, the atoms Al9 and N12 were each given identical thermal parameters.
For the methyl-group carbon atoms C147, C166, C186, C187, C192, C193, C195, C196, C198, C199, C201, C202, C210, C211, C216, C217, C222, C223, C225, C226, C231, and C232,  hydrogen atoms were placed in tetrahedral positions with an ideal staggered geometry (AFIX 33 in SHELXL). 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 Â for sp 2 -hybridized carbon and nitrogen atoms and 1.5 Â for methyl carbon atoms). In addition to the disordered solvate molecules described above, there are additional solvent-accessible voids of 832 Å 3 . The structure factors of 2 were augmented via reverse Fourier transform methods using the SQUEEZE routine (van der Sluis & Spek, 1990;Spek, 2015), which accounted for 235 electrons within the solvent-accessible voids. Lastly, the following low-angle reflection (1 0 0) was obscured by the beam stop and was omitted from the refinement. Further crystal data, data collection and structure refinement details are summarized in Table 9.

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. For complex 1 the crystal under investigation was found to have two components, but the domains were not related by any meaningful twin relationship.

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. Refined as a 2-component inversion twin.