New Metal-Organic Systems with a Functionalized Oxamate-Type Ligand and MnII, FeII, CuII and ZnI

Abstract

Four new complexes of formula [Fe(H 2 pcpa) 2 (H 2 O) 2 ] (1), {[Mn(Hpcpa)(H 2 O) 3 ]•1/2H 2 O} n (2), {[Zn(Hpcpa)(H 2 O) 3 ]•1/2H 2 O} n (3) and [Cu 2 (Hpcpa) 2 (bipy) 2 ]•8H 2 O (4) [H 3 pcpa = N-(4-carboxyphenyl) oxamic acid; bipy = 2,2′-bipyridine] have been synthesized and their structures determined by X-ray diffraction. The structure of 1 consists of mononuclear iron(II) units where each iron(II) ion is six-coordinate by two trans-positioned water molecules and two bidentate H 2 pcpa − ligands building a distorted octahedral environment. 2 and 3 consist of neutral zigzag chains of Mn II and Zn II ions respectively, the Hpcpa 2− groups acting as linkers in a bidentate/monodentate coordination mode with three mer-positioned water molecules achieving the six-coordination around the metal centers. Compound 4 is a neutral centrosymmetric dicopper(II) complex where two Hpcpa 2− groups adopting the bidentate/monodentate coordination mode and act as bridges and bidentate bipy molecules act as end-cap ligands, describing a square pyramidal surrounding around each copper atom. Cryomagnetic measurements for 1, 2 and 4 in the temperature range 1.9-300 K reveal the occurrence of a field-induced single-ion magnet (SIM) behavior (1) and weak interchain (J =-0.22 cm-1 , 2) and intradimer (J =-0.39 cm-1 , 4) antiferromagnetic interactions, the Hamiltonian being defined as H =-J S a. S b .

Europium(III), Terbium(III), and Gadolinium(III) Oxamato-Based Coordination Polymers: Visible Luminescence and Slow Magnetic Relaxation

“…Chemicals were purchased from Sigma-Aldrich and used without further purification. The Na 2 Hpcpa salt was prepared by following a previously reported procedure . Elemental analyses (C, H, N) were performed by Fisons EA1108.…”

“…23,24 They have potential applications in light-emitting diodes, optical fibers, or activators in X-ray detection materials. 23−25 Our research group has been working with oxamato ligands, in particular with the N-(4-carboxyphenyl)oxamic acid (H 3 pcpa), 26,27 a ligand that afforded a new class of CPs of transition metals and the first reported example of a hydrogenbonded polymer based on a mononuclear six-coordinate FeO 6 high-spin iron(II) complex behaving as SIM. 26,27 Motivated by the previous works, we report a new family of oxamato-based l a n t h a n i d e 2 D C P s o f g e n e r a l f o r m u l a {[Ln 2 (Hpcpa) 3 (H 2 O) 5 ]•H 2 O} n [Ln = Eu III (1), Tb III (2), and Gd III (3)].…”

Solvothermal synthesis, structure and magnetic properties of heterometallic coordination polymers based on a phenolato-oxamato co-bidentate-tridentate ligand

“…11,12 Similar issues have been observed with the para-substitued phenyloxamate ligands, with either carboxylato or hydroxido additional groups where the oxamate and the additional coordinating groups are only partially or not at all binding (Scheme 1, b-e). [13][14][15][16] On the other hand, the ortho-substituted carboxylato-phenyloxamate ligand has been reported entirely coordinating in homometallic copper-based polymers (Scheme 1g). 17 These observations led us to recently investigate the reactivity of the ortho-subsituted N-(2-hydoxyphenyl)oxamic acid (H3ohpma).…”

Synthesis, structure and magnetic properties of an oxamate-based 1D coordination polymer built on pentametallic links

“…[1][2][3][4][5][6][7] While phenyl-based oxamate ligands, [8][9][10][11] and amino-acid-based oxamate ligands now represent the bulk of the investigations, [12][13][14][15][16][17][18][19][20][21][22][23] a sub-class of aromatic oxamate ligands that are substituted with additional -non-oxamic-coordinating groups starts to gain attention. [24][25][26][27][28][29][30][31][32][33] Like the amino-acid-based oxamate ligands, such multi-polydentate ligands bearing additional carboxylato, hydroxido or N-donor groups offer diverse coordination modes with metal ions, which give access to new structural types. Recently, this led us to investigate the reactivity of the 2-hydroyphenyloxamate ligand and we have observed the formation of two atypical structures for phenyloxamate-related chemistry: a hexametallic macrocyclic coordination ring and of a chiral coordination polymer.…”