Abstract
We report herein on three zigzag one-dimensional coordination polymers of {[Ru2(μ-NHOCR)4](μ-SCN)}n (R = o-Me-C6H4 (2), m-Me-C6H4 (3), p-Me-C6H4 (4)) formula. These new compounds have been obtained by reaction of the corresponding [Ru2(μ-NHOR)4(THF)2](BF4) complex with (NBu4)(SCN) under different synthetic conditions. The crystal structure of [Ru2(μ-NHOCC6H4-o-Me)4(THF)2](BF4) (1), 2 and 3 are presented. A cis-(2,2) arrangement of the amidate ligands of the [Ru2(μ-NHOCR)4]+ units is observed in all cases. Interestingly, the structures of 2 and 3 show linkage isomerism in alternated tetraamidatodiruthenium units whose axial positions are occupied by the same type of donor atom of the SCN ligands. This results in zigzag chains with a Ru-S-C angle of 98.97° and Ru-N-C angle of 169.36° in the case of 2 and 97.99° and 159.26°, respectively, in the case of 3. The magnetic data obtained for 2–4 are indicative of a σ2π4δ2(π*δ*)3 ground state (S = 3/2) and a large zero-field splitting (ZFS) in all cases (D = 54.57, 62.72 and 43.00 cm−1 for 2–4, respectively). Similar small antiferromagnetic interactions between diruthenium units (zJ = −0.93, −0.79 and −1.11 cm−1 for 2–4, respectively) are estimated for all the polymers, suggesting an analogous zigzag arrangement of the chains for 4.
Highlights
Tetraamidato compounds [Ru2X(μ-NHOCR)4] (X = halide ion) are types of Ru25+ paddlewheel complexes with four N,O-donor ligands bridging the two ruthenium atoms [1,2,3,4,5]
We report on three zigzag one-dimensional coordination polymers of {[Ru2 (μ-NHOCR)4](μ-SCN)}n (R = o-Me-C6H4 (2), m-Me-C6H4 (3), p-Me-C6H4 (4)) formula
The [Ru2Cl(μ-NHOCR)4]n compounds (R = o-Me-C6H4, m-Me-C6H4, p-Me-C6H4) were used as starting materials. The reaction of these compounds with AgBF4 in THF gives the intermediate compounds, [Ru2(μ-NHOCR)4(THF)2](BF4), that were used in a subsequent reaction without isolation. [Ru2(μ-NHOCC6H4-o-Me)4(THF)2](BF4) (1) was crystallographically characterized in order to confirm the nature of these species
Summary
Tetraamidato compounds [Ru2X(μ-NHOCR)4] (X = halide ion) are types of Ru25+ paddlewheel complexes with four N,O-donor ligands bridging the two ruthenium atoms [1,2,3,4,5]. The paramagnetic [Ru2(μ-NHOCR)4]+ units (S = 3/2) are linked by halide ions giving zigzag chains and the unpaired electrons are essentially delocalized over the Ru-Ru bond, making the compounds formally valent-averaged compounds. In these polymeric complexes four different isomers are possible depending on the bridging coordination mode of the amidate ligands (Figure 1).
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