Novel Malonate-Containing Coordination Compounds with Ligands Having N- and NO-Donors: Synthesis, Structures, and Magnetic Properties

Abstract

In our efforts to tune the structures of mixed-ligands malonate-containing coordination compounds, four copper(II) and two high-spin cobalt(II) complexes of formulas [Cu(mal)(H2O)(dpo)] n (1), [Cu2(mal)2(H2O)2(dpp)] n ·7nH2O (2), [Cu2(mal)2(H2O)2(bpe)] n ·2nH2O (3), {[Cu(mal)2(H2O)2][Cu(dien)]} n ·4nH2O (4) [Co2(mal)2(H2O)6(dpo)]·2H2O (5) and [Co(mal)(H2O)(phen)] n ·2nH2O (6) [H2mal = malonic acid, dpo =4,4′-bipyridine-N,N′-dioxide, dpp = 2,3-bis(pyridyl)pyrazine, bpe =1,2-bis(4-pyridyl)ethylene, dien = diethylenetriamine and phen = 1,10-phenanthroline] have been synthesized and structurally characterized by X-ray diffraction on single crystals. Complexes 1, 2, 4, and 6 are chain compounds, 5 is a dinuclear species, and 3 has a sheet-like structure. The malonate ligand in this family acts as either a blocking (1 and 5) or bridging ligand (2–6). The rod-like molecules dpo (1 and 5) and bpe (3) exhibit the bis-monodentate (1 and 3) and monodentate (5) coordination modes, whereas dpp (2), dien (4), and phen (6) act as bis-bidentate (2), tridentate (4), and bidentate (6) ligands. The neutral motifs of 1–6 are interlinked through hydrogen bonds and weak C–H···π and π–π type interactions affording supramolecular three-dimensional networks. Variable-temperature magnetic susceptibility measurements show the occurrence of weak ferro- (2, 3, 5, and 6) and antiferromagnetic (1 and 4) interactions, the exchange pathways being the carboxylate-malonate (3–6), oxo-carboxylate (2), bis-bidentate (dpp) (2) or hydrogen bonds (1). Remarkably, the equatorial-apical exchange pathway through the carboxylate bridge present in 4 provides the first case of the occurrence of an antiferromagnetic interaction in a malonate-containing copper(II) complex.

Structurally Diverse Polynuclear Copper(I) Complexes Bridged by Pyrimidine–, Pyrazine–, and Triazine–based Ligands with Several 2–Pyridyl Groups

“…Mononuclear bppz complexes of Co(II), Cu(I), Cu(II), Ru(II), Rh(III), Pd(II), Ir(III), Re(I), Pt(II), Pt(IV), and Ln(III) (Ln=Nd, Eu, and Tb) have been reported in coordination mode (ii–a), together with multinuclear and polymeric bppz complexes of Mn(II), Cu(II), Cu(II)/Mo m O n , Re(0), Os(0), Os(I), and Pb(II) containing coordination mode (ii–a). The most likely homometallic dinuclear bppz complexes of Mn(II), Co(II), Ni(II), Cu(II), Ru(II), Re(I), and Pt(II) have been widely known in coordination mode (ii–d), together with multinuclear and polymeric complexes of Cu(I), Cu(II), and Re(0) containing coordination mode (ii–d). Heterometallic dinuclear bppz complexes of Ru(II)/Cu(I), Ru(II)/Pd(II), Ru(II)/Pt(II), Ru(II)/Os(II), Pt(II)/Nd(III), Re(I)/Nd(III), and Re(I)/Gd(III) have also been reported in this coordination mode.…”

Copper aromatic dicarboxylate complexes with a very long conformationally flexible dipyridyl ligand: Coordination polymers and a supramolecular nanotube

“…The overwhelming majority of divalent metal coordination polymers are built from organic dicarboxylate ligands that can provide both the necessary charge balance and structural scaffolding for the self-assembly of stable frameworks. Divalent copper aromatic dicarboxylate coordination polymers display a veritable cornucopia of coordination polymer structural topologies [7], due to the ion's flexible coordination preferences and tendency to form clusters. The specific donor dispositions and numerous possible binding modes of the dicarboxylate components prevents a priori structure prediction; the inclusion of neutral dipyridyl-type ligands results in an even wider scope of coordination polymer structural diversity with some cases displaying intriguing physical properties [8][9][10][11][12][13][14][15][16][17].…”

Diverse topologies in copper aromatic dicarboxylate coordination polymers containing 3-pyridylmethylnicotinamide: Effect of geometric isomerism and ring substituent

“…Aromatic dicarboxylate ligands have been used for the construction of a large majority of divalent metal coordination polymers, due to their ability to impart the necessary charge balance and covalent and supramolecular points of contact for the self-assembly of stable structural motifs. Divalent copper coordination polymers containing organic dicarboxylates manifest a very wide scope of structural topologies [7]. This metal ion's flexible coordination preferences (square planar, square pyramidal, trigonal bipyramidal, octahedral) [8] and tendency to form clusters [9] play a key role in this enhanced level of structural diversity.…”