The First Open‐Paddlewheel Structures in Diruthenium Chemistry: Examples of Intermediate Magnetic Behaviour between Low and High Spin in Ru 2 5+ Species

The reaction of [Ru 2 Cl(O 2 CMe)(DPhF) 3 ] (DPhF= N , N ′‐diphenylformamidinate) with aqueous HCl leads to the substitution of the acetate ligand to give the complex [Ru 2 Cl 2 (DPhF) 3 ] ( 1 ). Similar reaction of [Ru 2 (O 2 CMe)(DPhF) 3 (H 2 O)]BF 4 with aqueous HBr or HI produces [Ru 2 Br 2 (DPhF) 3 ] ( 2 ), and [Ru 2 I 2 (DPhF) 3 ] ( 3 ), respectively. The reaction of 1 with AgBF 4 to form the highly unsaturated unit [Ru 2 (DPhF) 3 ] 2+ , which is isolated as [Ru 2 (BF 4 )(DPhF) 3 (H 2 O)]BF 4 ( 4 ), and [Ru 2 (MeCN) 2 (DPhF) 3 ](BF 4 ) 2 ( 5 ), is also reported. The use of AgNO 3 instead of AgBF 4 leads to [Ru 2 (NO 3 ) 2 (DPhF) 3 ] ( 6 ). The magnetic behaviour of complexes 1 – 4 and 6 is intermediate between high‐ and low‐spin configurations. A relationship between the magnetic behaviour and the visible‐near‐infrared (Vis‐NIR) spectra is apparent. In addition, the crystal structure determinations of 2 , 4⋅ THF, and 6 , have been carried out. Complexes 1 – 3 , 5 and 6 are the first examples of open‐paddlewheel structures in diruthenium chemistry. The BF 4 − bridging the metal centres in 4⋅ THF is activated and forms very short RuF bonds.