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Structure and Bonding of High‐Spin Nitrosyl–Iron(II) Compounds with Mixed N,O‐Chelators and Aqua Ligands
Author(s) -
Wolf Markus,
Klüfers Peter
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201601329
Subject(s) - chemistry , denticity , aqueous solution , ferrous , crystallography , covalent bond , ring (chemistry) , inorganic chemistry , crystal structure , organic chemistry
High‐spin nitrosyl–iron centres of the Enemark–Feltham {FeNO} 7 type exist in aqueous solution. Examples include the tentative “brown‐ring” species [Fe(H 2 O) 5 (NO)] 2+ and a tentative Fe II /edta/NO species formed in the processes for scrubbing NO from flue‐gas streams. Inert‐gas bubbling through the solutions subdivides the ferrous nitrosyl complexes in a less stable subclass – a prominent member being the brown‐ring complex – and a more stable subclass to which the edta species belongs. The structural chemistry of the less stable subclass of {FeNO} 7 ‐type complexes from aqueous media is presented here. They contain aminecarboxylato co‐ligands of limited denticity and aqua ligands that complete an OC ‐6 environment of the Fe atom. Crystalline compounds for single‐crystal structure analysis were obtained for various co‐ligands: [Fe(H 2 O) 2 (ida)(NO)] ( 2a ), [Fe(H 2 O)(heida)(NO)] ( 2b ), [Fe(H 2 O) 2 (NO)(oda)] ( 2c ), [Fe(H 2 O) 2 (NO)(phida)] · H 2 O ( 2d ), [Fe(bnida)(H 2 O) 2 (NO)] ( 2e ), [Fe(brbnida)(H 2 O) 2 (NO)] ( 2f ) and [Fe(dipic)(H 2 O) 2 (NO)] ( 2g ) (ida = iminodiacetate, heida = hydroxyethyliminodiacetate, oda = oxodiacetate, phida = N ‐phenyliminodiacetate, bnida = N ‐benzyliminodiacetate, brbnida = N ‐4‐bromobenzyliminodiacetate, dipic = dipicolinate). The Fe–NO interaction was studied by DFT and CASSCF methods. Due to mostly covalent Fe–NO π bonds, the charge distribution in the less stable subclass is close to Fe II (NO) with a small Fe III (NO – ) contribution.