Synthesis, Structure and Reactivity of Organoindium 1,2‐Benzenedithiolates and 2‐Amidobenzenethiolates

Abstract

Organoindium compounds of redox active 1,2-benzenedithiolate and 2-amidobenzenethiolate ligands were synthesized and tested for reactivity against mild oxidants. The reaction of Me 3 In and (NCN)InMe 2 [NCN = 2,6-bis(dimethylaminomethy)phenyl] with 3,4-toluenedithiol (H 2 tdt) at room temperature afforded [MeIn(tdt)(py)] 2 (1) and (NCN)In(tdt) (2), respectively. A similar reaction of Me 3 In with 2-aminobenzenethiol (H 2 abt) in toluene under reflux afforded [MeIn(abt)(py)] 2 (3). The reaction of (NCN)InCl 2 with one equivalent of Li 2 (abt) or two equivalents of Li(Habt) afforded the compounds [(NCN)In(abt)]•LiCl(thf) 2 (4•LiCl(thf) 2 ) and (NCN)In(Habt) 2 (5), respectively. The X-ray crystal structures of 1 and 3 are similar and show dimeric structures via μ-S-(tdt) and μ-N-(abt) ligands, respectively. Compounds 2 and 4 possess similar monomeric structures and tridentate NCN pincer ligands. DFT computational studies have been used to rationalize the observed solid-state structures and discern the potential reactivity of compounds 1-4 against oxidants. The reaction of 1 and 2 with excess iodine resulted in loss of the 3,4-toluenedithiolate ligand and the formation of the oligomeric disulfide [tdt] n , while 3 and 4 showed no reactivity under similar conditions. This contrasts the reactivity of previously reported organoindium o-amidophenolate complexes which undergo oxidative addition of iodine to afford ligand-centered radical species.

Redox-active ligands – a viable route to reactive main group metal compounds

“…More recently, it has been shown via CV that indium compounds (NCN)In(tdt) [NCN = 2,6-bis(dimethylaminomethyl) phenyl] and dimeric [MeIn(tdt)( py)] 2 undergo irreversible oneelectron and two-electron electrochemical oxidations, respectively. 75 Chemical oxidation of both compounds with diiodine did not give one-electron oxidation radical products (NCN)In (tdt • )I and [MeIn(tdt • )( py)] 2 , as observed for indium o-amidophenolate (1) and catecholate (11,12) complexes. Instead, a spontaneous two-electron oxidation of the tdt ligand and formation of [tdt] n disulfide oligomers and RInI 2 (R = NCN, Me) was observed, regardless of reaction stoichiometry.…”