[(Pyridylcarbonyl)pyridyl]triazolopyridines, Useful Ligands for the Construction of Polynuclear Coordination Compounds – Synthesis, Crystal Structure and Magnetic Properties of a Novel Tetranuclear Copper(II) Cubane

A μ3‐Alkoxo‐Bridged Tetranuclear [Cu4L2] Copper(II) Complex of a Hexadentate N2O4 Donor Ligand with a [6 + 0] Cu4O4 Cubane Core: Synthesis, Crystal Structure, and Magnetic Properties

“…Inspection of the crystal structure (vide supra) reveals that the used ligand is sufficiently bulky to efficiently separate the [Cu 4 We have attempted to fit the χT data using a well-known model invoking a [Cu 4 O 4 ] cubane that has pseudo-S 4 site symmetry that essentially treats the [Cu 4 O 4 ] core as two coupled Cu II dimer pairs. [41][42] The topology of the [Cu 4 O 4 ] core is thus viewed as shown in Scheme 2 in which J 1 is the exchange between two Cu II sites forming a regular square and J 2 is the cross exchange between the opposite vertex of the square. The isotropic exchange Hamiltonian based on this topology is shown in Equation (1) H = -2J 1 (S Cu1 + S Cu2 )·(S Cu3 + S Cu4 ) -2J 2 (S Cu1 ·S Cu2 + S Cu3 ·S Cu4 ) (1) in which J 1 and J 2 are the exchange constants as shown in Scheme 2, and S i are the spin operators for each Cu II metal ion for the "i" site.…”

New Cu(ii) complexes based on the hydroxo-bridged dinuclear [Cu(OH)2Cu] units: step-like di- and trimerizations of [Cu(OH)2Cu] units

“…cores have been reported and the magneto-structural correlation has been well established. 9-10 On the other hand, we are aware that the dinuclear hydroxo-bridged [Cu 2 (m 2 -OH) 2 ] entities with four equatorial Cu-O bonds could, via the out-of-plane Cu-O(H) bonds, be assembled to generate heterocubane tetranuclear cluster cores as well as step-like tetranuclear [Cu 4 (m 2 -OH) 2 (m 3 -OH) 2 ] cores, [11][12][13][14][15][16] which are practically an isomer of the cubane-like cluster, [17][18][19][20] and even to form step-like hexanuclear [Cu 6 (m 2 -OH) 2 (m 3 -OH) 4 ] cores 21 (Scheme 1). The first two complexes with the step-like tetranuclear [Cu 4 (m 2 -OH) 2 (m 3 -OH) 2 ] cores were serendipitously obtained from ambient reaction of CuCl 2 •6H 2 O and aromatic diimine ligands such as 2,2¢-bipyridine (bpy) and 1,10-phenanthroline (phen) in the presence of aliphatic a,w-dicarboxylic acids in a methanolic or an ethanolic aqueous solution at pH = 6.5-11.0, 12 ) in an ethanolic aqueous solution at pH = 10, which was originally initiated to prepare Cu(II) adipate complex with the tetranuclear [Cu 4 (m 2 -OH) 2 (m 3 -OH) 2 ] core and these observations provide us sufficient imagination that the dicarboxylate anions seems to be good accelerants for the…”

Enantiospecific Syntheses of Copper Cubanes, Double‐Stranded Copper/Palladium Helicates, and a (Dilithium)–Dinickel Coronate from Enantiomerically Pure Bis‐1,3‐diketones—Solid‐State Self‐Organization Towards Wirelike Copper/Palladium Strands

“…[8,13] In addition, reaction of one equivalent of H 2 L (S,S) (3 b,c) with two equivalents of alkali acetate and subsequent addition of two equivalents of copper(II) acetate monohydrate resulted in the formation of (C,C,C,C)-[Cu 4 (L A C H T U N G T R E N N U N G (S,S) ) 2 A C H T U N G T R E N N U N G (OMe) 4 ] (4 b,c) in yields of 90 and 82 %, respectively (Scheme 2). [14,15] Cubane 4 b is isostructural with 4 a, exists as a single enantiomer, crystallizes in the chiral monoclinic space group C2, and possesses a [Cu 4 A C H T U N G T R E N N U N G (m 3 À O) 4 ] cubane core unit [16] consisting of two interpenetrating tetrahedra: one made up of four copper ions and one of four m 3 -OMe ligands. The metal-metal separations in 4 b are 2.97 (Cu1 À Cu1'), 3.25 (Cu1 À Cu2), and 3.29 (Cu1 À Cu2').…”