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Non‐Innocent Ligand Effects on Low‐Oxidation‐State Indium Complexes
Author(s) -
Allan Christopher J.,
Cooper Benjamin F. T.,
Cowley Hugh J.,
Rawson Jeremy M.,
Macdonald Charles L. B.
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201301881
Subject(s) - chemistry , reactivity (psychology) , ligand (biochemistry) , oxidation state , electron paramagnetic resonance , disproportionation , photochemistry , radical , indium , lone pair , trifluoromethanesulfonate , diimine , medicinal chemistry , crystallography , metal , molecule , organic chemistry , catalysis , medicine , biochemistry , physics , receptor , alternative medicine , pathology , nuclear magnetic resonance
Attempts to coordinate neutral ligands to low oxidation state indium centers are often hindered by disproportionation pathways that produce elemental indium and higher oxidation state species. In contrast, we find that reactions of the salt, InOTf (OTf=trifluoromethanesulfonate), with α‐diimine ligands yielded intensely colored compounds with no evidence of decomposition. X‐ray structural analysis of InOTf ⋅ Mes DAB Me ( Mes DAB Me = N , N ‐dimesityl‐2,3‐dimethyl‐diazabutadiene; 1 ) reveals a discrete molecular compound with a pyramidal coordination environment at the indium center, consistent with the presence of a stereochemically active lone pair of electrons on indium and a neutral diazabutadiene chelate ligand. The use of the less‐electron‐rich Mes DAB H ligand ( Mes DAB H = N , N ‐dimesityl‐diazabutadiene) engenders dramatically different reactivity and produces a metallopolymer (InOTf ⋅ Mes DAB H ) ∞ ( 2 ) linked via CC and InIn bonds. The difference in reactivity is rationalized by cyclic voltammetry and DFT studies that suggest more facile electron transfer from In I to the Mes DAB H and bis(aryl)acenaphthenequinonediimine (BIAN) ligands. Solution EPR spectroscopy indicates the presence of non‐interacting ligand‐based radicals in solution, whereas solid‐state EPR studies reflect the presence of a thermally accessible spin triplet consistent with reversible CC bond cleavage.