Transition metal induced derivatisations resulting in novel coordination behaviour of bis(oxamato) ligands

Abstract

Two mononuclear bis(oxamato) complexes with the formula [nBu4N]2[M(2,3-acbo)] (M=Ni (), Cu (), with acbo=anthra-9,10-chinone-2,3-bis(oxamato) have been synthesized starting from symmetric diethyl N,N'-anthra-9,10-chinone-2,3-bis(oxamate) (, 2,3-acboH2Et2). The crystal structures of and have been determined, verifying that the transition metal ions are eta4(kappa2N,kappa2O) coordinated by the [2,3-acbo]4- ligands. Using the asymmetric diethyl N,N'-anthra-9,10-chinone-1,2-bis(oxamate) (, 1,2-acboH2Et2) leads, under otherwise identical reaction conditions, to the novel bis(oxamato) complex [(n)Bu4N]2[Ni(1,2-acbo)] () whereby in the case of Cu(II) the derivate [nBu4N]2[Cu(aibo)2] () (aibo=anthra[1,2-d]-(imidazole-2-carboxylato)-6,11-dione) has been obtained. The crystal structures of and have been determined, displaying that the Ni(II) ion of is eta4(kappa2N,kappa2O) coordinated by the [1,2-acbo]4- ligand. The Cu(II) ion of is coordinated by two [aibo]2- ligands, giving rise to an approximately square-planar trans-bis(aibo-N,O) arrangement. Using the symmetric diethyl N,N'-4,5-dinitro-o-phenylene-bis(oxamate) (, niboH2Et2), possessing strongly electron withdrawing NO2-groups, leads under otherwise identical reaction conditions to the bis(oxamato) complex [nBu4N]2[Ni(nibo)] (), whereby in the case of Cu(II) the derivate [nBu4N]2[Cu(niqo)2] () (niqo=7,8-dinitro-2,3-quinoxalinedionato) has been obtained. The crystal structures of and have been determined, ensuring that the Ni(II) ion of is eta(4)(kappa2N,kappa2O) coordinated by the [nibo]4- ligand. The Cu(II) ion of is coordinated by four oxygen atoms of two [niqo]2- ligands, giving rise to an approximately square-planar coordination geometry.

Dicopper(II) Anthraquinophanes as Multielectron Reservoirs for Oxidation and Reduction: A Joint Experimental and Theoretical Study

“…A significant bond length alternation typical of aminoanthraquinone derivatives is also observed in the central benzoquinone ring for 1 a and 1 b . This situation is characterized by very short CO bond lengths, as well as relatively short CC and long CC bond lengths at the central benzoquinone ring (Table 1), as earlier reported for the related mononuclear copper(II) complex of formula ( n Bu 4 N) 2 [Cu(2,3‐quanba)] [2,3‐quanba 4− = N,N′ ‐2,3‐bis(oxamate)‐9,10‐anthraquinone] 13a…”

Crystal structure of an unknown solvate of bis(tetra-n-butylammonium) [N,N′-(4-trifluoromethyl-1,2-phenylene)bis(oxamato)-κ4O,N,N′,O′]nickelate(II)

“…The Ni 2+ cation is coordinated by two deprotonated amido N atoms and two carboxylate O atoms, resulting in a slightly distorted square-planar coordination geometry. In agreement with related nickel compounds, the Ni-N bonds are significantly shorter than the Ni-O bonds, which is due to the stronger donicity of the amido nitrogens (Fettouhi et al, 1996;Rü ffer et al, 2007aRü ffer et al, ,b, 2008Abdulmalic et al, 2013;Milek et al, 2013). Compared to the respective nickel complex without the CF 3 group (Abdulmalic et al, 2013), compound (I) exhibits longer Ni-N and Ni-O bonds.…”

“…Oxamate-bridged polymetallic complexes are of interest in the discipline of supramolecular magnetism as they exhibit diverse supramolecular architectures and magnetic properties (Pardo et al, 2008;Kahn, 1987Kahn, , 2000 and have been synthesized by, for example, Ruiz et al (1997a,b), Berg et al (2002), Martín et al (2002) and Ottenwaelder et al (2005). Over the last decade, we have been interested in the synthesis of bis(oxamates) and bis(oxamate) complexes (Rü ffer et al, 2007a(Rü ffer et al, ,b, 2008(Rü ffer et al, , 2009Eya'ane Meva et al, 2012), as well as their deposition as thin films (Brä uer et al, 2006(Brä uer et al, , 2008(Brä uer et al, , 2009. In order to optimize the deposition conditions and to increase the thin-film quality, the monometallic title compound, bis(tetra-n-butylammonium) [N,N 0 -(4-trifluoromethyl-1,2-phenylene)bis(oxamato)-4 O,N,N 0 ,O 0 ]nickelate(II), (I), was prepared.…”

“…It is instructive to note that for other complexes, the presence of electron-withdrawing substituents at the benzene moiety, e.g. Cl, NO 2 , causes a shortening of the Ni-N and Ni-O bonds (Fettouhi et al, 1996;Rü ffer et al, 2008).…”

The interplay between spin densities and magnetic superexchange interactions: case studies of mono- and trinuclear bis(oxamato)-type complexes

“…For example, we reported on the first chiral bis(oxamato)-type metalloligand [ 9 ], later on used by Ferrando-Soria et al for the design of the first chiral single-chain magnets (SCMs) [ 10 ]. Additionally, we reported how to introduce the redox-active anthrachinone functionality into bis(oxamato)-type metalloligands [ 11 ], later on adapted for the design of higher nuclear complexes that could potentially act as molecular magnetic capacitors [ 12 ], or we reported to which extent a ferrocene group in multinuclear bis(oxamato)-type complexes is suited to vary magnetic properties with respect to its oxidation state [ 13 ].…”