Hexacyanometalate Molecular Chemistry: Heptanuclear Heterobimetallic Complexes; Control of the Ground Spin State

Abstract

Following a bottom-up approach to nanomaterials, we present a rational synthetic route from hexacyanometalates [M(CN)(6)](3-) (M=Cr(III), Co(III)) cores to well-defined heptanuclear complexes. By changing the nature of the metallic cations and using a localised orbital model it is possible to control and to tune the ground state spin value. Thus, with M=Cr(III), d(3), S=3/2, three heptanuclear species were built and characterised by mass spectrometry in solution, by single-crystal X-ray diffraction and by powder magnetic susceptibility measurements, [Cr(III)(CNbondM'L(n))(6)](9+) (M'=Cu(II), Ni(II), Mn(II), L(n)=polydentate ligand), showing spin ground states S(G)=9/2 [Cu(II)], with ferromagnetic interactions J(Cr,Cu)=+45 cm(-1), S(G)=15/2 [Ni(II)] and J(Cr,Ni)=+17.3 cm(-1), S(G)=27/2 [Mn(II)], with an antiferromagnetic interaction J(Cr,Mn)=-9 cm(-1), (interaction Hamiltonian H=-J(Cr,M) [S(Cr)Sigma(i)S(M)(i)], i=1-6). With M=Co(III), d(6), S=0, the heptanuclear analogues [Co(III)(CN-M'L(n))(6)](9+) (M'=Cu(II), Ni(II), Mn(II)) were similarly synthesised and studied. They present a singlet ground state and allow us to evaluate the weak antiferromagnetic coupling constant between two next-nearest neighbours M'-Co-M'.

Complexes of a novel multinucleating poly-β-diketonate ligand

“…Field cooled measurements of the magnetisation of smoothly powdered microcrystalline samples of (1, 25.48 mg), (2, 17.25 mg), (3, 7.10 mg) and (4,8.06 mg) were performed in the range 2-300 K with a Quantum Design MPMS-7XL SQUID magnetometer with an applied field of 1 kG. Corrections for diamagnetic contributions of the sample holder to the measured magnetization and of the sample to the magnetic susceptibility were performed experimentally and by using Pascal's constants, respectively.…”

Cyanide-Bridged CrIIIMnIIBinuclear Complexes Based on [Mn(phen)2]2+and Dicyanidechromate(III) Building Blocks: Syntheses, Crystal Structures, and Magnetic Properties

“…13 The Mn-N cyanide bond length is 2.197(18) Å for 1, 2.211(2) Å for 2, and 2.189(7) Å for 3, which are shorter than the Mn-N phen bond distances in the three complexes ranging from 2.244(2) Å to 2.35(2) Å. The Mn-N≡C linkages deviate from linearity with angles range of 165.3(6)-171.08 (19) o . The intramolecular Cr---Mn separation …”

“…The best-fit parameters are J CrMn = -2.78(5) cm -1 , zJ' = -0.05(4) cm ] through bridging cyanide group in these complexes is antiferromagnetic, [17][18][19][20][21] which can be attributed to a net overlap of the magnetic orbitals through the π t 2g -t 2g pathways. In fact, for cyanide-bridged Cr Table 3 and the plot of magnetic coupling constant (J) vs. Mn-N≡C bond angle (θ ) is illustrated in Figure 3.…”

A New Family of Bimetallic Framework Materials Showing Reversible Structural Transformations

“…52 The metal coordination environment of the hexacyanocobaltate(III) moiety is in good agreement with reported structures. 53,54 The Cd-N bond lengths vary from 2.318(2) to 2.416(2) Å. Five of the six CN groups are bridging, while the sixth hydrogen bonds to water O3w located in the channel (Figure 2a).…”