Reactivity of hydride bridges in a high-spin [Fe 3 (μ-H) 3 ] 3+ cluster: reversible H 2 /CO exchange and Fe-H/B-F bond metathesis

• Published in: Chemical science (Cambridge) Vol. 8; no. 5; pp. 4123 - 4129
• Main Authors: Anderton, Kevin J, Knight, Brian J, Rheingold, Arnold L, Abboud, Khalil A, García-Serres, Ricardo, Murray, Leslie J
• Format: Journal Article
• Language: English
• Published: England 01.05.2017
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/C6SC05583D

The triiron trihydride complex Fe H ( ) [where is a tris(β-diketiminate)cyclophanate] reacts with CO and with BF ·OEt to afford (Fe CO) Fe (μ -H) ( ) and Fe F ( ), respectively. Variable-temperature and applied-field Mössbauer spectroscopy support the assignment of two high-spin (HS) iron(i) centers and one HS iron(ii) ion in . Preliminary studies support a CO-induced reductive elimination of H from , rather than CO trapping a species from an equilibrium mixture. This complex reacts with H to regenerate under a dihydrogen atmosphere, which represents a rare example of reversible CO/H exchange and the first to occur at high-spin metal centers, as well as the first example of a reversible multielectron redox reaction at a designed high-spin metal cluster. The formation of proceeds through a previously unreported net fluoride-for-hydride substitution, and is surprisingly chemically inert to Si-H bonds and points to an unexpectedly large difference between the Fe-F and Fe-H bonds in this high-spin system.