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Iron(II)–alkoxide and –aryloxide complexes of a tris(thioether)borate ligand: synthesis, molecular structures, and implications on the origin of instability of their iron(II)–catecholate counterpart
Author(s) -
Wang Peng,
Yap Glenn P. A.,
Riordan Charles G.
Publication year - 2021
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229621008500
Subject(s) - alkoxide , ligand (biochemistry) , chemistry , thioether , tris , nucleophile , bioinorganic chemistry , stereochemistry , medicinal chemistry , catalysis , organic chemistry , receptor , biochemistry
The phenyltris[( tert ‐butylthio)methyl]borate ligand, [PhTt t Bu ], has been studied extensively as a platform for coordination, organometallic, and bioinorganic chemistry, especially with 3 d metals. While [PhTt t Bu ]Co(3,5‐DBCatH) (3,5‐DBCatH is 3,5‐di‐ tert ‐butylcatecholate), a Co II –monoanionic catecholate complex, was successfully isolated to model the active site of cobalt(II)‐substituted homoprotocatechuate 2,3‐dioxygenase (Co‐HPCD) [Wang et al. (2019). Inorg. Chim. Acta , 488 , 49–55], its iron(II) counterpart, [PhTt t Bu ]Fe(3,5‐DBCatH), was not accessible via similar synthetic routes. Switching the nucleophile from catecholate to alkoxide or aryloxide, however, led to the successful isolation of three highly air‐sensitive Fe II –alkoxide and –aryloxide complexes, namely, (triphenylmethoxo){tris[( tert ‐butylsulfanyl)methyl]phenylborato‐κ 3 S , S ′, S ′′}iron(II), [Fe(C 21 H 38 BS 3 )(C 19 H 15 O)], (2), (2,6‐dimethylphenolato){tris[( tert ‐butylsulfanyl)methyl]phenylborato‐κ 3 S , S ′, S ′′}iron(II), [Fe(C 21 H 38 BS 3 )(C 8 H 9 O)], (3), and bis{μ‐tris[( tert ‐butylsulfanyl)methyl]phenylborato‐κ 3 S , S ′: S ′′}bis[(phenolato‐κ O )iron(II)] toluene disolvate, [Fe 2 (C 21 H 38 BS 3 ) 2 (C 6 H 5 O) 2 ]·2C 7 H 8 , (4). In the solid state, compounds (2) and (3) are monomeric, with [PhTt t Bu ] acting as a tridentate ligand. In contrast, compound (4) crystallizes as a dimeric complex, wherein each [PhTt t Bu ] ligand binds to an iron centre with two thioethers and binds to the other iron centre with the third thioether. The molecular structures of (2)–(4) demonstrate a diversity in the binding modes of [PhTt t Bu ] and highlight its potential use for assembling multinuclear complexes. In addition, the successful isolation of (2)–(4), as well as the structural information of a [PhTt t Bu ] modification product, namely, bis{μ‐tris[( tert ‐butylsulfanyl)methyl](2‐oxidophenolato)borato‐κ O , O ′, S , S ′: O ′}dicobalt(II), [Co 2 (C 21 H 37 BO 2 S 3 ) 2 ], (5), obtained from the reaction of [PhTt t Bu ]CoCl with potassium monoanionic catecholate, shed light on the origin of the instability of [PhTt t Bu ]Fe(3,5‐DBCatH).