Networks, anionic, magnetically

Chiral-at-metal cations can themselves serve as chirality inducers. For example, optically pure Ru[(bipy)3] proved to be an excellent chiral auxihary for the stereoselective preparation of optically active 3D anionic networks [M(II)Cr(III)(oxalate)3]- n (with M = Mn, Ni), which display interesting magnetic properties. In these networks all of the metalhc centers have the same configuration, z or yl, as the template cation, as shown by CD spectroscopy and X-ray crystallography [43]. 

In [Co(Cp )2][Ni(dmit)2], where the [Co(Cp )2]+ cations are diamagnetic (S — 0), the paramagnetic susceptibility arises only from the contribution of the anionic network, where S — 1/2 for [Ni(dmit)2]. The magnetic behavior of this compound is dominated by weak FM interactions (6 — 0.5 K) [54]. The observed dominance of the FM interactions in this compound confirms that the FM interactions between the i(dmit>2 units in the dimers are stronger than the AF A A intrachain interactions. 

SCO Cationic Complexes Encapsulated in Magnetically Coupled Anionic Networks... 

While the encapsulation of SCO cations within anionic networks needs further development, particularly by use of cations having abrupt SCO transitions, the results to date show that the cationic and anionic networks remain independent, magnetically, with little cooperativity being evident. 

The present status of attempts to encapsulate SCO complex cations in magnetically coupled anionic frameworks was described in Sect. 3. To date, there is no evidence for magnetic or cooperative interactions between cation and host network, for the anionic oxalato or dicyanamido types. 

The synthesis, structure, and electrical and magnetic characteristics were recently described for two other salts formed with BEDT-TTF and hexacyanoferrate, (Et4N+)3 [Fe(CN)6 3 or nitroprusside, K2 [Fe(CN)5NO]2. The study sheds light on the general peculiarities of making two-network solids by combining magnetic anions, which provide lo-... 

Aromatic polycarboxylates easily form 2D or 3D networks, for instance [Nd2(122)3(dmf)4]-H2O which present a 2D structure in which the 1,4-naphthalenedicarboxylate anions link Ndm ions of two adjacent double chains keeping them at a short distance of about 4.1 A (J. Yang et al., 2006). This allows up-conversion to take place, albeit with very low efficiency a blue emission is seen at 449.5 nm upon excitation at 580 nm (corresponding to the 4Gs/2 magnetic properties an energy-transfer up-conversion mechanism involving no excited state absorption is more likely. 

There are also carboxylates15 (Section 17-E-10), phosphates, catecholates, and oxalates. Most of the divalent iron oxalato compounds have a chain structure but the product of photoreduction of mononuclear [bipyH] [Feni(ojc)2(H20)2] gives a three-dimensional anionic polymeric network of [Fe2I(ox)3]2 1 and [Fen(bipy)3]2+ ions.16 Magnetic exchange typically occurs through the oxalate bridges.17 Six-coordinate iron(II) a-amino acid complexes are readily obtained from the reaction of the 4-coordinate Fe(mes)2(phen) and the protic amino add, AH, in THF 18... 

The oxalate anion is a versatile ligand in the synthesis of heterometallic magnetic networks as the oxalate can act as a mono-, di-, tri-, and tetradentate... 

Figure 9.9 (a) Top view of the tetrameric chains and (b) the 2D-anionic network (terminal TCNQ have been omitted for clarity) in [Gd2(TCNQ)5(H20)9] [Gd(TCNQ)4 (H20)3] -4H20. [86]. (Reprinted with permission from H. Zhao, et al., A rare-earth metal TCNQ magnet synthesis, structure, and magnetic properties of [Gd2(TCNQ)5(H20)9][Gd(TCNQ)4(H20)3]]4H20, Chemie International... 

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