Details

Autor(en) / Beteiligte

• Sarkar, Sabyasachi
• Tiwari, Rupesh Kumar
• Samanta, Deepannita
• Guchhait, Tapas
• Sañudo, E. Carolina
• Rajaraman, Gopalan
• Rath, Sankar Prasad

Titel

Unusual Stabilisation of Remarkably Bent Tetra‐Cationic Tetra‐radical Intermolecular Fe(III) μ‐Oxo Tetranuclear Complexes

Ist Teil von

• Angewandte Chemie, 2024-05, Vol.136 (21), p.n/a

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Wiley Online Library

Beschreibungen/Notizen

• A hitherto unknown series of air stable, π‐conjugated, remarkably bent tetra‐cation tetra‐radical intermolecular Fe(III) μ‐oxo tetranuclear complex, isolated from the dication diradical diiron(III) porphyrin dimers, has been synthesised and spectroscopically characterised along with single crystal X‐ray structure determination of two such molecules. These species facilitate long‐range charge/radical delocalisation through the bridge across the entire tetranuclear unit manifesting an unusually intense NIR band. Assorted spin states of Fe(III) centres are stabilised within these unique tetranuclear frameworks: terminal six‐coordinate iron centres stabilise the admixed intermediate spin states while the central five‐coordinate iron centres stabilise the high‐spin states. Variable temperature magnetic susceptibility measurements indicated strong antiferromagnetic coupling for the Fe(III)−O−Fe(III) unit while the exchange interactions between the Fe centres and the porphyrin π‐cation radicals are weaker as supported both by magnetic data and DFT calculations. The nature of orbital overlap between the SOMOs of Fe(III) and π* orbital of the porphyrin was found to rationalise the observed exchange coupling, establishing such a complex magnetic exchange in this tetranuclear model with a significant bioinorganic relevance. A hitherto unknown series of air stable, π‐conjugated, remarkably bent tetra‐cation tetra‐radical intermolecular μ‐oxo tetranuclear complexes has been reported and structurally characterised. These species facilitate long‐range charge/radical delocalisation through the bridge across the entire tetranuclear unit, manifesting unusually intense NIR bands. Assorted spin states of Fe(III) centres are stabilised: terminal six‐coordinate iron centres stabilise the admixed‐intermediate spin states, while the central five‐coordinate iron centres stabilise the high‐spin states. A strong exchange coupling among the centres, coupled with the bent nature of the Fe−O−Fe moiety, promotes intense NIR bands.