Strong Exchange Coupling in a Trimetallic Radical-Bridged Cobalt(II)-Hexaazatrinaphthylene Complex

摘要

Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18-c-6 produces [{K(18-c-6)}HAN], which contains the S=1/2 radical [HAN](.-). The [HAN](.-) radical can be transferred to the cobalt(II) amide [Co{N(SiMe3)(2)}(2)], forming [K(18-c-6)][(HAN){Co(N '')(2)}(3)]; magnetic measurements on this compound reveal an S=4 spin system with strong cobalt-ligand antiferromagnetic exchange and J approximate to-290cm(-1) (-2J formalism). In contrast, the Co-II centres in the unreduced analogue [(HAN){Co(N '')(2)}(3)] are weakly coupled (J approximate to-4.4cm(-1)). The finding that [HAN](.-) can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on strongly coupled, triangular HAN building blocks.