Pentamethylcyclopentadienyl Half-Sandwich Diazoalkane Complexes of Ruthenium: Preparation and Reactivity

The diazoalkane complexes [Ru­(η5-C5Me5)­(N2CAr1Ar2)­{P­(OR)3}­L]­BPh4 (1–4) [R = Me, L = P­(OMe)3 (1); R = Et, L = P­(OEt)3 (2); R = Me, L = PPh3 (3); R = Et, L = PPh3 (4); Ar1 = Ar2 = Ph (a); Ar1 = Ph, Ar2 = p-tolyl (b); Ar1Ar2 = C12H8 (c); Ar1 = Ph, Ar2 = PhC­(O) (d)] and [Ru­(η5-C5Me5)­{N2C­(C12H8)}­{PPh­(OEt)2}­(PPh3)]­BPh4 (5c) were prepared by allowing chloro-compounds RuCl­(η5-C5Me5)­[P­(OR)3]­L to react with the diazoalkane Ar1Ar2CN2 in the presence of NaBPh4. Treatment of complexes 1–4 with H2O afforded 1,2-diazene derivatives [Ru­(η5-C5Me5)­(η2-NHNH)­{P­(OR)3}­L]­BPh4 (6–9) and ketone Ar1Ar2CO. A reaction path involving nucleophilic attack by H2O on the coordinated diazoalkane is proposed and supported by density functional theory calculations. The complexes were characterized spectroscopically (IR and 1H, 31P, 13C, 15N NMR) and by X-ray crystal structure determination of [Ru­(η5-C5Me5)­(N2CC12H8)­{P­(OEt)3}2]­BPh4 (2c) and [Ru­(η5-C5Me5)­(η2-NHNH)­{P­(OEt)3}2]­BPh4 (7).

本工作合成了重氮烷配合物[Ru(η⁵-C₅Me₅)(N₂CAr¹Ar²){P(OR)₃}L]BPh₄（1~4），其中R=Me，L=P(OMe)₃（1）；R=Et，L=P(OEt)₃（2）；R=Me，L=PPh₃（3）；R=Et，L=PPh₃（4）；Ar¹=Ar²=Ph（a）；Ar¹=Ph，Ar²=p-tolyl（b）；Ar¹Ar²=C₁₂H₈（c）；Ar¹=Ph，Ar²=PhC(O)（d），以及配合物[Ru(η⁵-C₅Me₅){N₂C(C₁₂H₈)}{PPh(OEt)₂}(PPh₃)]BPh₄（5c），该系列配合物由氯代前体RuCl(η⁵-C₅Me₅)[P(OR)₃]L与重氮烷Ar¹Ar²CN₂在NaBPh₄存在下反应制备得到。将配合物1~4与水作用，可得到1,2-二氮烯衍生物[Ru(η⁵-C₅Me₅)(η²-NH=NH){P(OR)₃}L]BPh₄（6~9）以及酮类产物Ar¹Ar²CO。本文提出了一条涉及水对配位重氮烷的亲核进攻的反应路径，并通过密度泛函理论（Density Functional Theory，DFT）计算对该路径予以佐证。所有配合物均通过光谱手段（红外光谱及¹H、³¹P、¹³C、¹⁵N核磁共振波谱）以及X射线晶体结构测定进行了表征，其中完成了[Ru(η⁵-C₅Me₅)(N₂CC₁₂H₈){P(OEt)₃}₂]BPh₄（2c）与[Ru(η⁵-C₅Me₅)(η²-NH=NH){P(OEt)₃}₂]BPh₄（7）的晶体结构解析。