Metallosupramolecular helices constructed from nickel(II) and multidentate “click” triazole ligands

• Published in: Polyhedron Vol. 191; p. 114805
• Main Authors: Pokharel, Uttam R., Theriot, Jordan C., Fronczek, Frank R., Maverick, Andrew W.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-11-2020
• Subjects: Aminomethyltriazole; Binuclear triple helicate; Nickel(II); Pyridyltriazole; Supramolecular coordination; Pyridyltriazole; Aminomethyltriazole; Nickel(II); Supramolecular coordination; Binuclear triple helicate
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2020.114805

The tetradentate bis(pyridyltriazole) or bis(aminomethyltriazole) ligands, separated with ortho-, meta-, or para-xylylene linkers, give similar binuclear triple helices with Ni2+ regardless of modification in their coordination pocket or spacer groups.
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•Helical complexes [Ni2(LL)3]4+ form with LL = six different tetradentate N ligands.•These include the first reported metal complexes of xylylenebis(aminomethyltriazoles).•Crystal structures of four of the six new complexes were determined by X-ray analysis.•The new structures contain racemic mixtures of (P,P) and (M,M) helicates.•Ni···Ni distances increase in the order ortho < para < meta.
A series of binuclear metallosupramolecular helices [Ni2L3]4+ has been synthesized from Ni(II) salts and bis(bidentate) pyridyltriazole or aminomethyltriazole ligands, separated by ortho- (o-xpt and o-xamt, respectively), meta- (m-xpt, m-xamt), and para-xylylene (p-xpt, p-xamt) spacers. All complexes were characterized by elemental analysis, ESI-MS, and in four cases, the structures confirmed by X-ray crystallography. The xpt and xamt ligands, derived by “click” reactions, exhibit similar bonding behavior regardless of modifications in their coordination pockets and spacer groups, forming triple-helical binuclear complexes with pseudo-octahedral geometry at Ni. The crystallographically characterized complexes show shorter Ni···Ni separations with the ortho spacer ([Ni2(o-xpt)3]4+, 9.332(2); [Ni2(o-xamt)3]4+, 8.9718(10) Å) than with the para spacer ([Ni2(p-xpt)3]4+, 11.574(2); [Ni2(p-xamt)3]4+, 11.899(2), 11.924(2) Å).