Reactivity with alkene and alkyne of pentamethylcyclopentadienyl half-sandwich diazoalkane complexes of ruthenium

Treatment of diazoalkane complexes [Ru(eta(5)-C5Me5)(N(2)CAr1Ar2){P(OR)(3)}L]BPh4 (1-5) [Ar1=Ar2=Ph, Ar1=Ph, Ar2=p-tolyl, Ar1Ar2=C12H8; R=Me, Et; L=P(OR)(3), PPh3] with ethylene and maleic anhydride (ma) afforded eta(2)-alkene derivatives [Ru(eta(5)-C5Me5)(eta(2)-CH2=CH2){P(OR)(3)}(PPh3)]BPh4 (7, 8) and [Ru(eta(5)-C5Me5)(eta(2)-ma){P(OR)(3)}L]BPh4 (6, 9), respectively. Acrylonitrile also reacted with diazoalkane complexes 1-5 to give dipolar (3 + 2) cycloaddition, affording 3H-pyrazole derivatives [Ru(eta(C5Me5)-C-5){eta(1)=N=NC(C12H8)CH=CH}{P(OR)(3)}(PPh3)]BPh4 [A] and [Ru(eta(5)-C5Me5) {P(OR)(3)}(PPh3)]BPh4 [B] (10, 11). Treatment of complexes 1-5 with acetylene HC = CH under mild conditions (1 atm, room temperature) led to dipolar cycloaddition, affording 3H-pyrazole complexes [Ru(eta(C5Me5)-C-5) (eta(1)-}{eta(1)=N=NC(Ar1Ar2)CH=CH}{P(OR)3} L] BPh4 (12, 15), whereas reaction with terminal alkynes HC= CR gave vinylidene derivatives [Ru(eta(5)-C5Me5){=C=C(H)R}{P(OR)(3)}L]BPh4 (13, 14, 16, 17). The complexes were characterised spectroscopically (IR and H-1, P-31, C-13 NMR) and by X-ray crystal structure determination of [Ru(eta(5)-C5Me5){eta(1)=N=NC(C12H8)CH=CH}{P(OEt)(3)}(2)]BPh4 (12). A DFT study on the reaction of diazoalkane complexes with CH2=CH2 is also reported. (C) 2016 Elsevier B. V. All rights reserved.