Differential Reactivity of [TpRu(κ2P,N‐iPr2PXPy)Cl] (X = NH, S) Bearing Hemilabile Coligands Towards NaBArF4, Lithium Acetylide, and Acetylenes

In contrast with [TpRu(κ2P,N-iPr2PNHPy)Cl] (1a, Tp = trispyrazolylborate), [TpRu(κ2P,N-iPr2PSPy)Cl] (1b) reacts with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF4) in fluorobenzene under nitrogen to afford the dinuclear complex [{TpRu(κ2P,N-iPr2PSPy)}2(μ-Cl)][BArF4] (1b′). Through diverse synthetic strategies, a series of neutral acetylides [TpRu(C≡CR)(κ2P,N-iPr2PXHPy)] [X = NH; R = Ph (2a), SiMe3 (2b); X = S; R = Ph (2c), p-C6H4Br (2d), COOMe (2e)], cationic vinylidene complexes [TpRu(=C=CHR)(κ2P,N-iPr2PNHPy)]+ [X = NH; R = Ph (3a), SiMe3 (3b); X = S; R = Ph (3c), p-C6H4Br (3d)] and [TpRu(=C=CH2)(κ2P,N-iPr2PNHPy)]+ (3e), and a cationic η2-alkyne complex [TpRu(η2-HC≡CCOOMe)(κ2P,N-iPr2PSPy)][BArF4] have been efficiently synthesized from 1a and 1b. The methoxy(methyl)carbene complexes [TpRu{=C(OMe)CH3}(κ2P,N-iPr2PXPy)][BPh4] [X = NH (5a), S (5b)] were isolated from the reactions of 1a and 1b with acetylene gas in the presence of NaBArF4 in methanol. The deprotonation of the cationic vinylidenes derived from 1b with KtBuO affords the corresponding neutral acetylide complexes, which undergo facile protonation with CF3SO3H to reproduce the cationic vinylidenes quantitatively.