Oxidative Additions to Ti(IV) in [(dadi)4–]TiIV(THF) Involve Carbon–Carbon Bond Formation and Redox-Noninnocent Behavior

An attempt at transferring the imide of (dadi)­TiNAd (2NAd, dadi2–, dadi n = [{−CHN­(1,2-C6H4)­N­(2,6-iPr2-C6H3)}2] n )­to C2H4 led instead to low yields of trans-C6H4-{1,2-(N,2-N(2,6-iPr2-C6H3)-C6H4)2Ti-NHAd}2 (3), a product that features four new C–C bonds to two new carbons. Mechanistic evaluation of its formation led to oxidative addition studies of SnX4 (X = Cl, Br, I) and RX to (dadi)­Ti­(THF) (1-THF, dadi4–), in which the oxidation occurs at the dadi ligand. Products include (dadi)­TiX2 (2-X2, X = Cl, Br, I) and the imine-triamide (R-ita)­TiX (5-RX, R = Me, Bn; X = Cl, Br; R-ita = [{−CH2N­(1,2-C6H4)­N­(2,6-iPr2-C6H3)}­{CRN­(1,2-C6H4)­N­(2,6-iPr2-C6H3)}]). Studies of the RX additions, including implementation of radical clocks, pointed toward concerted process­(es). Rearrangements of 2-X2 and 2NAd revealed a new tridentate benzimidazole diamide chelate (bida) structurally characterized in (bida)­TiCl2 (4-Cl2) and (bida)­TiNAd (OPMe2Ph) (6). The nature of various products suggests that the (dadi n )Ti core can act as a nucleophile (n = 4), electrophile (n = 2), or as a radical center (n = 3) under certain conditions.