Tribenzyl(methyl)ammonium: A Versatile Counterion for the Crystallization of Nanojars with Incarcerated Selenite and Phosphite Ions and Tethered Pyrazole Ligands

Abstract

One hundred and thirty-five years after its initial discovery, the crystal structure of the tribenzyl(methyl)ammonium (TBMA + ) cation is reported for the first time (as the nitrate salt). It is shown that TBMA + is an excellent counterion for the crystallization of large supramolecular assemblies. Thus, single crystals of previously uncrystallizable nanojars with incarcerated selenite and phosphite ions, as well as tethered pyrazole ligands, have been successfully grown by solvent vapor diffusion into solutions with added (TBMA)NO 3 . X-ray diffraction studies reveal a variety of possible noncovalent interactions between pairs of TBMA + cations. Indeed, the structurally adaptable TBMA + dimer can take on different shapes and sizes to maximize supramolecular interactions with neighboring molecules and to fill up voids in the crystal lattice. The new nanojar crystal structures (TBMA)(Bu 4 N)[SeO 3 ⊂{Cu(OH)(pz)} 28 ] and (TBMA) 2 [HPO 3 ⊂{Cu(OH)(pz)} 29 ] (pz = pyrazolate) provide unprecedented examples of noncovalently bound selenite and phosphite ions in supramolecular complexes. The use of TBMA + counterions has also allowed for the crystallization of a nanojar based on tethered pyrazole ligands, (TBMA) 2 [SO 4 ⊂{Cu 28 (OH) 28 (pzCH 2 CH 2 pz) 14 }]. The synthesis and mass spectrometric studies of the new nanojars are presented along with crystallographic studies detailing the nanojar structure, anion binding, and nanojar− counterion/counterion−counterion supramolecular interactions in the crystal lattice. Finally, the binding of SeO 3 2− and SO 4 2− ions by the same Cu 28 nanojar and the binding of HPO 3 2− , CO 3 2− , and SO 4 2− ions by the same Cu 29 nanojar are contrasted, and the δ/λ chelate-ring isomerism in the tethered-ligand nanojar is discussed.

Supramolecular Incarceration and Extraction of Tetrafluoroberyllate from Water by Nanojars

“…Nanojars, supramolecular coordination complexes of the formula [anion⊂{ cis -Cu II (μ-OH)­(μ-pz)} n ] 2– [Cu n ; n = 26–36; pz = pyrazolate (C 3 H 3 N 2 – )], have been successfully used for the binding of oxoanions with large hydration energy such as CO 3 2– , − SO 4 2– , − SeO 3 2– , HPO 3 2– , HPO 4 2– , and HAsO 4 2– . Herein, we demonstrate that nanojars are excellent supramolecular binding agents not only for oxoanions but also for the fluoroanion BeF 4 2– , which was extracted from water and transferred into organic solvents (including aliphatic hydrocarbons) by liquid–liquid extraction.…”

Effects on the magnetic interaction caused by molecular recognition in complexes of 1,2-azole-based oxamate and [Cu(bpca)]+ units

“…Focusing on 1H-pyrazole-based ligands, their coordination chemistry is very rich due to the possibility of coordinating to metal atoms in their neutral or deprotonated form since its NH group can be easily deprotonated in the presence of transition metal ions and a base (apparent pK a = 19,8 for 1Hpyrazole in DMSO). The pyrazolate anion acts as a bismonodentate kN:kN′ ligand, forming di-, [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] tri-, [22][23][24][37][38][39][40][41][42][43][44][45][46][47] tetra- 22,[48][49][50][51][52][53][54] and polymetallic synthons [55][56][57][58][59][60] or even coordination polymers. [61][62]…”

Isomorphous but No Dead Ringer: Contrasting the Supramolecular Binding of Tetrafluoroberyllate and Sulfate Ions by Nanojars

“…Each nanojar consists of three [ cis -Cu II (μ-OH)(μ-pz)] x ( x = 6−14, except 11) metallamacrocycles, which are bound together by multiple H-bonds and axial Cu···O interactions. Although similar complexes containing an incarcerated SO 4 2– anion have been previously prepared and studied, − details of the supramolecular binding of sulfate by H-bonding in nanojars have only been available so far for an analogue with tethered pz ligands, [SO 4 ⊂{ cis -Cu 28 (μ-OH) 28 (μ-pzCH 2 CH 2 pz) 14 }] 2– . , Herein, we describe the isomorphism of the Cu 28 BeF 4 and Cu 31 BeF 4 nanojars with the corresponding Cu 28 SO 4 and Cu 31 SO 4 analogues and contrast it with significant differences in bonding within the two anions, leading to the selectivity of nanojars for sulfate. Also, pseudopolymorphism in Cu n BeF 4 ( n = 28, 31, and 32) and Cu 31 SO 4 nanojars will be discussed based on novel single-crystal X-ray structures of (Bu 4 N) 2 [BeF 4 ⊂{Cu(OH)(pz)} 6+12+10 ] (Cu 28 BeF 4 , 1a (nitrobenzene/pentane) and 1b (chlorobenzene/pentane)), (Bu 4 N) 2 [BeF 4 ⊂{Cu(OH)(pz)} 8+14+9 ] (Cu 31 BeF 4 , 3a (toluene) and 3b (bromobenzene/hexane)), (Bu 4 N) 2 [SO 4 ⊂{Cu(OH)(pz)} 8+14+9 ] (Cu 31 SO 4 , 4a (chlorobenzene/pentane) and 4b (1,2-dichlorobenzene/heptane)) and (Bu 4 N) 2 [BeF 4 ⊂{Cu(OH)(pz)} 9+14+9 ] (Cu 32 BeF 4 , 5a (1,2-dichlorobenzene/heptane)), as well as previously published structures of (Bu 4 N) 2 [BeF 4 ⊂{Cu(OH)(pz)} 6+12+10 ] (Cu 28 BeF 4 , 1c (toluene)), (Bu 4 N) 2 [SO 4 ⊂{Cu(OH)(pz)} 6+12+10 ] (Cu 28 SO 4 , 2 (toluene)), (Bu 4 N) 2 [BeF 4 ⊂{Cu(OH)(pz)} 8+14+9 ] (Cu 31 BeF 4 , 3c (chlorobenzene/heptane)), and (Bu 4 N) 2 [BeF 4 ⊂{Cu(OH)(pz)} 9+14+9 ] (Cu 32 BeF 4 , 5b (1,2-dichlorobenzene/pentane)) …”

“…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 0.631(18)/0.369 (18) for C103 through C105, and to 0.570(8)/0.430 (8) for the second cation.…”

“…details of the supramolecular binding of sulfate by H-bonding in nanojars have only been available so far for an analogue with tethered pz ligands, [SO 4 ⊂{cis-Cu 2 8 (μ-OH) 2 8 (μ-pzCH 2 CH 2 pz) 14 }] 2− 18,19. Herein, we describe the isomorphism of the Cu 28 BeF 4 and Cu 31 BeF 4 nanojars with the corresponding Cu 28 SO 4 and Cu 31 SO 4 analogues and contrast it with significant differences in bonding within the two anions, leading to the selectivity of nanojars for sulfate.…”