Reactions of [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru(COD) with Lewis bases: Synthesis, structure, and electrochemistry of ruthenium amine, nitrile, carbene, phosphite and phosphine complexes

Abstract

Treatment of [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru(COD) ( 1) with phosphites, phosphines, amines or N-heterocyclic carbene in THF afforded the COD displacement complexes [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru[P(OEt) 3] 2 ( 2), [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru[PPh 2(OEt)] 2 ( 3), [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru[NH 2CH 2CH 2Pr i ] 2 ( 4), [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru(NH 2Pr n ) 2 ( 5), [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru (η 2-NH 2CH 2CH 2NH 2) ( 6), [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru[η 2-NH(CH 3)CH 2CH 2NH(CH 3)] ( 7) or [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru[NHC] 2 ( 8, NHC = 1,3,4,5-tetramethylimidazol-2-yilidene), respectively. Ruthenium–amine complexes were much more labile than 1. Upon exposure to moisture, 5 was converted into [{η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)}Ru(μ-H 2O)] 2 ( 9). Reactions of 5 with PR 3 (R = PPh 3, Cy), TMEDA (TMEDA = N, N, N′, N′-tetramethylethylenediamine) and CH 3CN afforded the corresponding amine replacement products[η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru(NH 2Pr n )(PPh 3) ( 10), [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru(NH 2Pr n )(PCy 3) ( 11), [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru(TMEDA) ( 12) and [η 5:σ-Me 2C(C 5H 4)(C 2B 10H 10)]Ru(NCCH 3) 2 ( 13). These results indicated that the steric factor dominated these substitution reactions. The electrochemical studies showed that the electron richness of the Ru atom decreased in the order L 2Ru(NHC) 2 > L 2Ru(amine) 2 > L 2Ru(NCMe) 2 > L 2Ru(P) 2. All of these complexes were fully characterized by various spectroscopic techniques and elemental analyses. The molecular structures of 2, 3, 5– 10, 12 and 13 were further confirmed by single-crystal X-ray analyses.