Preparation and reactivity of diazoalkane complexes of ruthenium stabilised by an indenyl ligand

Gabriele Albertin; Stefano Antoniutti; Jesús Castro; Gianluca Dottorello

doi:10.1039/C5DT00755K

Preparation and reactivity of diazoalkane complexes of ruthenium stabilised by an indenyl ligand†

Gabriele Albertin,*^a Stefano Antoniutti,^a Jesús Castro^b and Gianluca Dottorello^a

* Corresponding authors

^a Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Dorsoduro 2137, 30123 Venezia, Italy
E-mail: albertin@unive.it

^b Departamento de Química Inorgánica, Universidade de Vigo, Facultade de Química, Edificio de Ciencias Experimentais, 36310 Vigo, Galicia, Spain

Abstract

Diazoalkane complexes [Ru(η⁵-C₉H₇)(N₂CAr1Ar2)(PPh₃)L]BPh₄ (1–3) [L = PPh₃, P(OMe)₃, P(OEt)₃; Ar1 = Ar2 = Ph; Ar1 = Ph, Ar2 = p-tolyl; Ar1Ar2 = C₁₂H₈ fluorenyl] were prepared by allowing chloro-complexes [RuCl(η⁵-C₉H₇)(PPh₃)L] to react with an excess of diazoalkane in ethanol. Complexes 1–3 reacted with ethylene CH₂ [double bond, length as m-dash] CH₂ (1 atm) and maleic anhydride [ma, CHCHCO(O)CO] to afford η²-alkene complexes [Ru(η⁵-C₉H₇)(η²-CH₂CH₂)(PPh₃)L]BPh₄ (4, 5) and [Ru(η⁵-C₉H₇){η²-CHCHCO(O)CO}(PPh₃)L]BPh₄ (7). Further, complexes 1–3 underwent cycloaddition with acrylonitrile CH₂ [double bond, length as m-dash] C(H)CN, giving 1H-pyrazoline derivatives [Ru(η⁵-C₉H₇){η¹-NC(CN)CH₂C(Ar1Ar2)NH}(PPh₃)L]BPh₄ (6). Treatment of diazoalkane complexes 1–3 with acetylene CH [triple bond, length as m-dash] CH under mild conditions (1 atm, room temperature) led to dipolar cycloaddition, affording 3H-pyrazole complexes [Ru(η⁵-C₉H₇)-{η¹-N [double bond, length as m-dash] NC(Ar1Ar2)CHCH}(PPh₃)L]BPh₄ (8), whereas reaction with terminal alkynes RCCH (R = Ph, p-tolyl, Bu^t) gave vinylidene derivatives [Ru(η⁵-C₉H₇){CC(H)R}(PPh₃)L]BPh₄ (9). The latter reacted with nucleophiles such as amines and alcohols to give amino- and alkoxy-carbene derivatives [Ru(η⁵-C₉H₇){ [double bond, length as m-dash] C(NHPrⁿ)(CH₂Ph)}(PPh₃)L]BPh₄ (11) and [Ru(η⁵-C₉H₇){C(CH₃)(OEt)}(PPh₃)L]BPh₄ (10), respectively. In addition, complexes 9 reacted with phenylhydrazine to afford nitrile derivatives [Ru(η⁵-C₉H₇)(N [triple bond, length as m-dash] CCH₂R)(PPh₃)L]BPh₄ (12) and phenylamine, whereas the reaction with water led to hydrolysis of the alkyne and formation of carbonyl complexes [Ru(η⁵-C₉H₇)(CO)(PPh₃)L]BPh₄ (13). Lastly, treatment of vinylidene complexes 9 with the phosphines PPh₃ and P(OMe)₃ afforded alkenylphosphonium derivatives [Ru(η⁵-C₉H₇){C(H) [double bond, length as m-dash] C(R)PPh₃}(PPh₃)L]BPh₄ (14) and [Ru(η⁵-C₉H₇){C(R)C(H)P(OMe)₃}(PPh₃)L]BPh₄ (15), respectively. Compound [Ru(η⁵-C₉H₇){C(H)C(H)PPh₃}(PPh₃)L]BPh₄ (16) was also prepared. The complexes were characterised by spectroscopy (IR and NMR) and X-ray crystal structure determinations of [Ru(η⁵-C₉H₇){N₂C(C₁₂H₈)}(PPh₃){P(OEt)₃}]BPh₄ (3c), [Ru(η⁵-C₉H₇){ [double bond, length as m-dash] CC(H)Ph}(PPh₃){P(OEt)₃}]BPh₄ (9d) and [Ru(η⁵-C₉H₇){C(H)C(Ph)PPh₃}(PPh₃){P(OEt)₃}]BPh₄ (14d).