Synthesis and Characterization of [Mn^III₆(N-formylsalicylhydrazidate)₆(MeOH)₆]:  A New Type of Macrocyclic Hexanuclear Manganese Cluster

Abstract

The macrocyclic hexanuclear metal cluster, [Mn(III)(6)(fshz)(6)S(6)], 1 (S = MeOH), was prepared using a trianionic pentadentate ligand, N-formylsalicylhydrazidate (fshz(3)(-)). Due to the meridional coordination of the ligand to the metal ion, the ligand is not only bridging the ring metal ions using a hydrazide N-N group but also enforcing the stereochemistry of the metal ions as a propeller configuration. The alternations of the chiralities of the metal centers expand the cyclic ring system of complex 1 to the 24-membered ring system. The neutral hexanuclear manganese complex with noncrystallographic pseudo-C(3)(i)() symmetry is in the crystallographic inversion center. The disc-shaped hexanuclear cluster is 1.8 nm in diameter and 0.8 nm in thickness and has a vacant cavity in the center of the cluster. Three solvent molecules coordinated at the metal centers with Lambda configuration are in one face of the cluster, and the remaining three solvent molecules coordinated at the other metal centers with Delta configuration are in the other face of the cluster. The two faces of the cluster have opposite chiralities to each other. The crystal packing structure of complex 1 shows that the disc-shaped hexanuclear clusters are aligned approximately along the crystallographic a axis. The cavities of the clusters in the crystal structure are also aligned, and one-dimensional channels are formed. The solution integrity of the cluster was addressed using solution mass spectrometry, paramagnetically shifted (1)H NMR spectroscopy, and UV-visible spectroscopy. Crystallographic data for 1: triclinic, P&onemacr;, a = 10.0237(9) Å, b = 15.096(1) Å, c = 15.617(1) Å, alpha = 112.142(5) degrees, beta = 106.615(5) degrees, gamma = 99.958(7) degrees, V = 1989.8(3) Å(3), Z = 2, D(calcd) = 1.510 g cm(-)(1), R1 = 0.0502 and wR2 = 0.1424 for 4249 reflections with I > 2sigma(I), GOF = 1.065.

A 2D Layered Metal–Organic Framework Constructed by Using a Hexanuclear Manganese Metallamacrocycle as a Supramolecular Building Block

“…[5] Because each distorted octahedral metal center in the hexanuclear manganese metallamacrocycle has been coordinated by five donor atoms from two chelating pentadentate ligands, the one replaceable solvent site left can be utilized as a nodal point in framework construction. Hence, these potential hexatopic metallamacrocycles were used as SBBs for the construction of three-dimensional (3D) network structures, where the metallamacrocycles have served either as rectangular tetratopic or octahedral hexatopic nodes.…”

A novel 18-membered metallacrown containing a double-azathiacrown

“…The dihydrazide derivative template ligands (Fig. 1a) were used to synthesize the second type of metallacrowns, the rings of the metallacrowns were expanded from 15-MC-5 to 18-MC-6 [11][12][13][14][15], 24-MC-8 [16,17], 30-MC-10 [18,19], 36-MC-12 [20,21], even to 60-MC-20 [22].…”

Synthesis, structural characterization, and magnetism of a butterfly-shaped hexanuclear Ni(II) complex

“…The trianionic pentadentate N-acyl-salicylhydrazide ligands, have been utilized to construct many interesting polynuclear complexes. Trivalent metal ions such as Co, Fe and Mn that can easily form stable octahedral coordination are found to yield hexanuclear, octanuclear, decanuclear and dodecanuclear metallamacrocycles with these kinds of ligands, known as metallacrowns [6,7]. Concerning bivalent metal complexes of N-acyl-salicylhydrazide ligands, only a few trinuclear nickel(II)/copper(II) compounds have been obtained up to date [8].…”