Heterometallic Nickel(II) Diruthenium(II, III) Carbonates by Self‐Assembly of Paddle‐Wheel Precursors: Insights into Structures and Magnetic Properties

A systematic investigation of the self‐assembling Ru 2 (CO 3 ) 4 3− paddle‐wheel precursors and Ni(H 2 O) 6 2+ cations in the presence of KX (X = Cl and Br) in aqueous solution has resulted in two Ni II ‐Ru 2 II, III hetero‐metallic compounds K{Ni(H 2 O) 4 } 2 Ru 2 (CO 3 ) 4 Cl 2 ·4H 2 O ( 1 ) and K{Ni(H 2 O) 4 } 2 Ru 2 (CO 3 ) 4 Br 2 ·4H 2 O ( 2 ). X‐ray structural analysis reveals that two isomorphous compounds are constructed from a layer [Ni(H 2 O) 4 ] 2 Ru 2 (CO 3 ) 4 X 2 − , in which Ni(H 2 O) 4 2+ connects four neighboring Ru 2 units in a pseudo cross due to the disorder atoms location. According to Raman spectrum measurements combined with theoretical calculations, the strong peaks at ∼340 cm −1 are assigned to the stretching of the RuRu bonds. The magnetic studies show that ferromagnetic interactions are propagated between the paramagnetic units ordering below ∼3.0 K. Both the particle size and defect pinning are found to play cooperative roles in affecting the variation of hysteresis loops.