Synthesis and structure of a heptanuclear nickel(ii) complex uniquely exhibiting four distinct binding modes, two of which are novel, for a hydroxamate ligand

Abstract

The reaction of 2-(dimethylamino)phenylhydroxamic acid (2-dmAphaH) with NiSO(4).6H2O gives the complex [Ni7(2-dmAphaH-1)2(2-dmApha)8(H2O)2]SO(4).15H2O uniquely exhibiting four distinct hydroxamate binding modes, two of which are novel, and showing both antiferromagnetic and ferromagnetic interactions in contrast to [Cu5(2-dmAphaH-1)4(HSO4)2(MeOH)2].2MeOH, a strongly antiferromagnetic metallacrown formed with CuSO(4).5H2O.

Supramolecular Maleate Adducts of Copper(II) 12‐Metallacrown‐4: Magnetism, EPR, and Alcohol Sorption Properties

“…In the case of monocation salts of anionic metallacrowns {such as NMe 4 + , NEt 4 + , [Na(15‐crown‐5)] + , K + } the metallacrowns are non‐oligomerized , , , . Complexes with cationic metallacrowns and monoanions [NO 3 – , ClO 4 – , OAc – , Cu(OAc) 3 – , Cl – , NO 3 – , HSO 4 – ] generate 1D chains formed by metallacrown units connected through long Cu–O contacts (three compounds), , or non‐oligomerized metallacrowns (nine compounds, including complexes 1 and 2 , vide infra) , , . The presence of counter‐anions or counter‐cations with charges of –2 or +2 {phthalate dianions, SO 4 2– , [Cu(en) 2 ] 2+ } has led to the dimerization of metallacrown units (observed in six complexes),, , , while only one complex containing a counter‐anion of –3 charge, {[Cr(C 2 O 4 )] 3 3– }, has been assembled – with trimerized metallacrown units …”

Hydroxamic Acids − An Intriguing Family of Enzyme Inhibitors and Biomedical Ligands

“…An intriguing heptanuclear nickel() complex that uniquely exhibits four distinct hydroxamate binding modes, two of which are novel, and which shows both antiferromagnetic and ferromagnetic interactions has also recently been reported by us. [76] Reaction of 2-(dimethylamino)-phenylhydroxamic acid (2-dmAphaH) with NiSO 4 ·6H 2 O results in the formation of [Ni 7 (2-dmAphaH Ϫ1 ) 2 (2-dmApha) 8 (Figure 15), which contains a trigonal-bipyramidal array of nickel() ions with another two nickel() ions annexed to the apical sites. This complex in which each nickel ion is octahedrally coordinated contains monodeprotonated 2-dmApha and doubly deprotonated 2-dmAphaH Ϫ1 hydroxamate ligands.…”

Synthesis, Solution Thermodynamics, and X‐ray Study of CuII [12]Metallacrown‐4 with GABA Hydroxamic Acid: An Unprecedented Crystal Structure of a [12]MC‐4 with a γ‐Aminohydroxamate

“…The Cu-O and Cu-N distances are in agreement with those of other similar Cu II metalla-A C H T U N G T R E N N U N G macrocycles. [7,8,[27][28][29][30] The Cu2ÀCl1 and Cu3ÀO1w apical-bond lengths, 2.774(1) and 2.349(3) , respectively, are significantly greater than the average Cu À Cl and Cu À Ow bond lengths, 2.323 and 2.189 , respectively, in pentacoordinated Cu II complexes. [31] These data are consistent with the Cu À Cl and Cu À Ow apical-bond elongation, due to the Jahn-Teller effect, observed in Cu II complexes.…”