Effect of the apical ligand on the geometry and magnetic properties of copper(ii)/mesoxalate trinuclear units

Abstract

Three new heterometallic metal-organic frameworks, namely, {(PhP)[MnCu(Hmesox)Br(HO)]·HO} (1), {(PhP)[CoCu(Hmesox)Br]} (2) and {(PhP)[ZnCu(Hmesox)Br]·2.5HO} (3) were prepared and their structure and magnetic properties were investigated (Hmesox = mesoxalic acid, PhP = tetraphenylphosphonium). The structure of all the compounds consist of two interpenetrating opposite-chirality supramolecular cationic and polymeric anionic 3-D (10,3)-a networks, which results in chiral compounds. The anionic network is formed from the polymerization of [Cu(Hmesox)Br] units, working as three connectors, and M(ii) cations, working as three-connecting nodes, M = Mn(ii), Co(ii) and Zn(ii). The PhP cations build the cationic chiral supramolecular network opposite to the anionic one. Compounds 1 and 2 exhibit long-range magnetic ordering with critical temperatures of 7.2 K and 6.9 K, respectively. However, compound 3 does not display long-range order, but shows ferromagnetic and antiferromagnetic coupling among the Cu(ii) ions. The magnetic interactions are studied by DFT calculations and compared with related Cu(ii)-mesoxalate compounds previously reported.

Improvement of the Proton Conduction of Copper(II)-Mesoxalate Metal–Organic Frameworks by Strategic Selection of the Counterions

“…Our studies previously observed these trinuclear units with the mesoxalate ligand. 44 , 45 , 47 , 48 , 50 , 52 , 54 The mesoxalate ligand loses the two carboxylic and one of the hydroxyl hydrogen atoms and appears as C 3 HO 6 3– (Hmesox) 3– . Each mesoxalate ligand acts as bidentate with respect to two Cu1 atoms with the alkoxido and the two carboxylate oxygen atoms forming two 5-membered chelate rings ( Figure 1 b).…”

“…Nevertheless, we can anticipate antiferromagnetic interactions for J 1 with Cu1–O3–Cu1 iii angles of 124.17(25)° and 124.18(12)° in 1 and 2 , respectively, and also antiferromagnetic coupling for the Cu(II) ions bridged by the anti–anti carboxylate groups, J 2 . 50 , 56 , 57 …”

“…L C is completely deprotonated C 3 O 6 4− (mesox 4− ), which is the second time that it has been reported in the literature 55 for this ligand and the first time we have observed it within more than 20 compounds with mesoxalate that we have synthesized and results in a shorter C−O distance in this mesoxalate (Figure 6, Scheme 1, Table S2). [44][45][46][47][48]50,51,53,54 The L C mesoxalate ligand also acts as tridentate with respect to Cu4 and bidentate with respect to Cu5 and Cu5 vii with a μ 3 -(κO:κO′; κO″:κO″; κO″:κO‴; κO‴′:κO‴″) binding mode (Scheme 2 and Figure 6a,b). This bridging mode has been found in mesoxalate compounds in which the trinuclear copper(II) entities connect to lanthanoid(III) atoms, but has not been yet observed for transition metal(II) ions connecting to the trinuclear copper(II)-mesoxalate unit.…”

Synthesis, structure and magnetic properties of a cobalt(II) mesoxalate 1D coordination polymer

“…In some of the complexes we have prepared such as (Ph 4 P)[MnCu 3 (Hmesox) 3 Cl] or [LaCu 3 (Hmesox) 3 (DMSO)], the mesoxalate ligand acted as Hmesox 3− giving the [Cu 3 (Hmesox) 3 X] 4− (X=Cl − and Br − ) and [Cu 3 (Hmesox) 3 Y] 3− (Y=H 2 O or DMSO) trinuclear copper(II) metalloligands [5–7,9,10] …”

“…This ligand has six-donor oxygens, four from the two carboxylate groups and two from the two hydroxyl groups, and it's complex formation has resulted in great structural diversity. [1][2][3][4][5][6][7][8][9][10] In some of the complexes we have prepared such as (Ph 4 P)[MnCu 3 (Hmesox) 3 Cl] or [LaCu 3 (Hmesox) 3 (DMSO)], the mesoxalate ligand acted as Hmesox 3À giving the [Cu 3 (Hmesox) 3 X] 4À (X=Cl À and Br À ) and [Cu 3 (Hmesox) 3 Y] 3À (Y=H 2 O or DMSO) trinuclear copper(II) metalloligands. [5][6][7]9,10] Furthermore, it acted as H 2 mesox 2À when linked to Ln(III) in [Ln 2 (H 2 mesox) 6 ] • 6H 2 O compounds.…”