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The synthesis, structures, and magnetic properties of four cyano-bridged M(II)Ru(III)2 compounds prepared from the paramagnetic Ru(III) building blocks, trans-[Ru(salen)(CN)2]- 1 [H2salen = N,N'-ethylenebis(salicylideneimine)] and trans-[Ru(acac)2(CN)2]- (Hacac = acetylacetone), are described. Compound 2, {Mn(CH3OH)4[Ru(salen)(CN)2]2}.6CH3OH.2H2O, is a trinuclear complex that exhibits antiferromagnetic coupling between Mn(II) and Ru(III) centers. Compound 3, {Mn(H2O)2[Ru(salen)(CN)2]2.H2O}n, has a 2-D sheetlike structure that exhibits antiferromagnetic coupling between Mn and Ru, leading to ferrimagnetic-like behavior. Compound 4, {Ni(cyclam)[Ru(acac)2(CN)2]2}.2CH3OH.2H2O (cyclam = 1,4,8,11-tetraazacyclotetradecane), is a trinuclear complex that exhibits ferromagnetic coupling. Compound 5, {Co[Ru(acac)2(CN)2]2}n, has a 3-D diamond-like interpenetrating network that exhibits ferromagnetic ordering below 4.6 K. The density functional theory (DFT) method was used to calculate the molecular magnetic orbitals and the magnetic exchange interaction between Ru(III) and M(II) (Mn(II), Ni(II)) ions.

The field of molecule-based magnetic materials has made significant advances in recent years. [1] A popular approach to the synthesis of these materials has been to use a paramagnetic [M(CN) 6 ] nÀ (M Cr III , Mn III , Fe III , or V II ) building block in conjunction with another paramagnetic 3d metal ion, and this resulted in the formation of a large number of one-, two-, and three-dimensional polymers that exhibit various magnetic behaviors. [2] We are interested in extending this approach to 4d and 5d metal ions, since their orbitals are more diffuse, and enhanced magnetic interactions can therefore be expected. In general, however, it is much more difficult to construct polymers from 4d or 5d metal complexes, since they are usually much more substitution-inert than 3d metal complexes. Our strategy is to use a 4d or 5d metal cyanide in conjunction with a 3d metal ion to produce 4d ± 3d and 5d ± 3d polymers, and we note that examples of such polymers are limited to Mo À C N À Mn [3] and NBu 4 [M II Ru III (ox) 3 ] (M Mn, Fe, Cu; ox oxalato). [4] We initially planned to use this strategy to prepare 3d ± Ru III polymers from [Ru(CN) 6 ] 3À , since a number of novel Fe III -containing magnetic materials were prepared from [Fe(CN) 6 ] 3À . However, whereas [Fe(CN) 6 ] 3À is robust and readily available, [Ru(CN) 6 ] 3À is very unstable, especially in solvents such as water and alcohols. [5] We therefore attempted to design alternative stable cyano complexes of ruthenium(iii) as building blocks, and here we report on the synthesis and structure of trans-Ph 4 P[Ru III (acac) 2 (CN) 2 ] (1, Hacac acetylacetone) and its reaction with Mn 2 to produce the novel cyano-bridged Mn II Ru III polymer {Mn[Ru(acac) 2 (CN) 2 ] 2 } n (2), which has a diamond-like structure and exhibits ferromagnetic ordering below T C 3.6 K. A diamond-like structure was also proposed for Mn II [Mn II (CN) 4 ], which is antiferromagnetic. [6] Reaction of trans-Ph 4 P[Ru III (acac) 2 Cl 2 ] with KCN in methanol produced 1. The IR spectrum showed a strong CN stretching band at 2099 cm À1 . The structure of 1 was determined by X-ray crystallography (Figure 1). [7] The ruthenium Figure 1. ORTEP plot of the anion of 1. Selected bond lengths [] and angles [8]:atom is octahedrally coordinated by the four oxygen atoms of the two acac ligands and the carbon atoms of the cyanide ions in a trans configuration. The four RuÀO distances are almost identical (1.98 ± 2.03 ) and are also similar to that of [Ru(acac) 3 ] (av 2.003 ). [8] The two RuÀCN distances are also similar, as are the two CÀN distances. The cyclic voltammogram of 1 in CH 3 CN (with 0.1m Bu 4 NPF 6 ) shows two reversible waves at 0.70 and À 1.15 V (vs Ag/Ag ), which are assigned to the Ru IV /Ru III and the Ru III /Ru II couples, respectively. These electrochemical data indicate that [Ru(acac) 2 (CN) 2 ] À is very stable with respect to oxidation and reduction. Electrospray mass spectrometry (ES-MS) on a methanolic solution of 1 in the anionic mode showed only a peak at m/z 352 for [Ru(acac) 2...

Two novel cyano Cu II -Au I bimetallic complexes, Cu-(cyclen)[Au(CN) 2 ] 2 1 (cyclen ‫؍‬ 1,4,7,10-tetraazacyclododecane) and Cu(pyz)[Au(CN) 2 ] 2 2 (pyz ‫؍‬ pyrazine) were prepared; 1 has a dimeric structure arising from Au I ؒ ؒ ؒ Au I interactions, while 2 consists of linear pyrazine-bridged copper chains intercalated to produce a 2-D pleated sheet structure.

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