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  • 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
Title: 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+).  more » « less
Award ID(s):
2018753
PAR ID:
10473895
Author(s) / Creator(s):
; ; ; ;
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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