FormateThe Analogue of Azide:  Structural and Magnetic Properties of M(HCOO)₂(4,4‘-bpy)·nH₂O (M = Mn, Co, Ni; n = 0, 5)

Abstract

Reaction of transition metal formate M(HCOO)(2).2H2O (M = Mn, Co, Ni) with 4,4'-bpy (4,4-bipyridine) has led to four new compounds with the formula M(HCOO)2(4,4'-bpy).nH2O (M = Mn, Co (1.Mn, 2.Co), n = 0; M = Co, Ni (3.Co, 4.Ni), n = 5). Compounds 1.Mn and 2.Co are isomorphous and crystallized in the tetragonal crystal system with the chiral space group P4(1)2(1)2. They are of three-dimensional diamondoid structure connected by anti-anti formate with 4,4'-bpy in the cavities of the framework reinforcing the intermetallic connections; the diamond-like net was observed also in their azide analogue (Mn(N3)2(4,4'-bpy)). Compounds 3.Co and 4.Ni are isomorphous also but crystallized in the monoclinic crystal system with the space group Cc. Both structures are uninterpenetrated 3D "CdSO4" type with big channels, constructed by anti-anti formate and 4,4'-bpy. This type of net was not observed in their azide analogue. Residing in the channels, water molecules form a new type of 1D tape constructed by vertex-sharing cyclic pentamers. Magnetic measurements were performed on all of these four compounds. 1.Mn and 2.Co are weak ferromagnets with the critical temperature Tc = 5.3 and 7.4 K, respectively. 3.Co is an antiferromagnet with Neel temperature TN = 3.0 K, and 4.Ni is a weak ferromagnet below 20 K. Hysteresis loop can be observed for 2.Co and 4.Ni at 1.8 K. As an analogue of azide, formate can be used to construct molecular architectures, which structurally and magnetically have great similarities to and also differences from those of azide. This offers a promising method for the design of new molecular architectures with formate.

Stringing Oxo‐Centered Trinuclear [MnIII3O] Units into Single‐Chain Magnets with Formate or Azide Linkers

“…Azide usually mediates a much stronger coupling between metal ions than formate. [20] A comparison of the magnetic coupling in compounds 2 and 3 shows that the two kinds of bridges not only mediate the different interactions but also influence the intra-trinuclear coupling. The shortest inter-trinuclear distance between the Mn III ions in compounds 1-3 also decreases from 7.531 in 1 to 6.471 in 2 and 5.964 in 3.…”

A Rational Route to Coordination Polymers with Condensed Networks and Cooperative Magnetic Properties

“…azido, formato, oxalate, and carboxylato anions. [92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107][108] In contrast, magnetic coordination compounds based on thio-or selenocyanato anions are less reported, especially those, in which the metal cations are linked by the anionic ligands. [109][110][111][112][113][114][115] This is obvious from a search in the Cambridge Structure Database, where roughly equal numbers of terminal and bridging structures based on e.g.…”

Effect of the structure of bridging ligands on the structure and adsorption properties of 3D-coordinated copper(II) and cobalt(II) formate polymers

“…Nevertheless, analysis of this model indicates that elongation of the bridging ligand linking the (M(HCO 2 ) 2 ) n layers does not lead to a sharp increase in the volume of the cavities in the structure relative to the analogous complexes with pyrazine and 4,4¢-bipyridyl, whose structure was established by X-ray diffraction structural analysis [6,7]. However, despite the dense packing, micropores are formed in I as indicated by the adsorption data for this complex.…”

“…Thus, we have coordination polymers [Cu(HCO 2 )(pz)] n , [Cu(HCO 2 ) 2 (bipy)] n , and [Co(HCO 2 ) 2 (bipy)] n , which are not porous despite possessing bridges longer than 7 Å [6,7].…”

“…Since the structures of a series of analogous complexes was solved by X-ray diffraction structural analysis (XDSA) and were found to be similar [5][6][7]11], we were able to propose a model for the structure of complexes I-III. These compounds are probably constructed of two-dimensional (M(HCO 2 ) 2 ) n networks, which are connected by bridging ligands L1 or L2 coordinated to the axial positions of the metal ions.…”