Structural analyses of the compounds di-μ-acetato-κ 4 O : O ′-bis{[2-methoxy- N , N -bis(quinolin-2-ylmethyl)ethanamine-κ 4 N , N ′, N ′′, O ]manganese(II)} bis(tetraphenylborate) dichloromethane 1.45-solvate, [Mn 2 (C 23 O 2 ) 2 (C 23 H 23 N 3 O) 2 ](C 24 H 20 B)·1.45CH 2 Cl 2 or [Mn(DQMEA)(μ-OAc) 2 Mn(DQMEA)](BPh 4 ) 2 ·1.45CH 2 Cl 2 or [1] (BPh 4 ) 2 ·1.45CH 2 Cl 2 , and (acetato-κ O )[2-hydroxy- N , N -bis(quinolin-2-ylmethyl)ethanamine-κ 4 N , N ′, N ′′, O ](methanol-κ O )manganese(II) tetraphenylborate methanol monosolvate, [Mn(CH 3 COO)(C 22 H 21 N 3 O)(CH 3 OH)](C 24 H 20 B)·CH 3 OH or [Mn(DQEA)(OAc)(CH 3 OH)]BPh 4 ·CH 3 OH or [2] BPh 4 ·CH 3 OH, by single-crystal X-ray diffraction reveal distinct differences in the geometry of coordination of the tripodal DQEA and DQMEA ligands to Mn II ions. In the asymmetric unit, compound [1] (BPh 4 ) 2 ·(CH 2 Cl 2 ) 1.45 crystallizes as a dimer in which each manganese(II) center is coordinated by the central amine nitrogen, the nitrogen atom of each quinoline group, and the methoxy-oxygen of the tetradentate DQMEA ligand, and two bridging-acetate oxygen atoms. The symmetric Mn II centers have a distorted, octahedral geometry in which the quinoline nitrogen atoms are trans to each other resulting in co-planarity of the quinoline rings. For each Mn II center, a coordinated acetate oxygen participates in C—H...O hydrogen-bonding interactions with the two quinolyl moieties, further stabilizing the trans structure. Within the crystal, weak π – π stacking interactions and intermolecular cation–anion interactions stabilize the crystal packing. In the asymmetric unit, compound [2] BPh 4 ·CH 3 OH crystallizes as a monomer in which the manganese(II) ion is coordinated to the central nitrogen, the nitrogen atom of each quinoline group, and the alcohol oxygen of the tetradentate DQEA ligand, an oxygen atom of OAc, and the oxygen atom of a methanol ligand. The geometry of the Mn II center in [2] BPh 4 ·CH 3 OH is also a distorted octahedron, but the quinoline nitrogen atoms are cis to each other in this structure. Hydrogen bonding between the acetate oxygen atoms and hydroxyl (O—H...O) and quinolyl (C—H...O and N—H...O) moieties of the DQEA ligand stabilize the complex in this cis configuration. Within the crystal, dimerization of complexes occurs by the formation of a pair of intermolecular O3—H3...O2 hydrogen bonds between the coordinated hydroxyl oxygen of the DQEA ligand of one complex and an acetate oxygen of another. Additional hydrogen-bonding and intermolecular cation–anion interactions contribute to the crystal packing.
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This content will become publicly available on June 27, 2024
The versatility of 1,4,8,11-tetraazacyclotetradecane (cyclam) in the formation of compounds of Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ with metal ions in and out of the cyclic ligand ring
Herein we report the results of preparing metal compounds (where the metal ions are Co2+, Ni2+, Cu2+, Zn2+) with the cyclic ligand 1,4,8,11-tetraazacyclotetradecane [cyclam] under a variety of conditions of metal-ligand ratios and solvent media. In all cases, we used metal Cl2 . nH2O salts (except for anhydrous CoCl2), as specified. Outcome: we isolated species with a four-coordinate metal in the N4 cavity of the ligand alone, and also with either one or two additional axial ligands. Those axial ligands can be (a) a single chloride, leading to penta-coordinated+ products; (b) two chlorides, leading to octahedral-neutral compounds; (c) two waters, giving rise to hexa-coordinated [(cyclam)metal(H2O)2]2+ species. Finally, in the case of HCl added to the reaction medium, the cyclam can be di-protonated and appears as [(cyclam)H2]2+ in the crystals. With such a variety of products, it is not surprising that since the metal coordination numbers vary, the cyclam ligand stereochemistries are thereby affected. Interestingly, the [(cyclam)metal] species are invariably hydrogen-bonded to one another in infinite strings of two kinds: (1) those for which the crystal’s Z’ = 1 have single strings; (2) when Z’ = 2, there is a pair of homogeneous strings attached to one another by a variety of hydrogen-bonding linkages. Finally, we observed an interesting pair of hydroxonium cations: the first is hydoxonium cations in a pleated 2-D sheet consisting of fused pentagons located between sheets of [(cyclam)metal] moieties; the second one is an infinite string of composition (H3O+)-(H2O)-(H3O+)-(H2O)-(H3O+)-(H2O)-(H3O+).
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- Award ID(s):
- 2018753
- NSF-PAR ID:
- 10473895
- Publisher / Repository:
- De Gruyter
- Date Published:
- Journal Name:
- Zeitschrift für Kristallographie - Crystalline Materials
- Volume:
- 238
- Issue:
- 7-8
- ISSN:
- 2194-4946
- Page Range / eLocation ID:
- 243 to 251
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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