Advancing the applications of s-block heterobimetallic complexes in catalysis, we report the use of potassium magnesiate (PMDETA) 2 K 2 Mg(CH 2 SiMe 3 ) 4 [PMDETA = N,N,N',N',N''-pentamethyldiethylenetriamine] for the catalytic hydrophosphinylation of styrenes under mild conditions. Exploiting chemical cooperation, this bimetallic approach offers greater catalytic activity and chemoselectivity than the single-metal components KCH 2 SiMe 3 and Mg(CH 2 SiMe 3 ) 2 . Stoichiometric studies between (PMDETA) 2 K 2 Mg(CH 2 SiMe 3 ) 4 and Ph 2 P(O)H help to elucidate the constitution of the active catalytic species, and illustrate the influence of donors on the potassium cation coordination, and how this may impact catalytic activity. Mechanistic investigations support that the rate determining step is the insertion of the olefinic substrate.
Exploiting bimetallic cooperation alkali‐metal manganate (II) complexes can efficiently promote oxidative homocoupling of terminal alkynes furnishing an array of conjugated 1,3‐diynes. The influence of the alkali‐metal on these C−C bond forming processes has been studied by preparing and structurally characterizing the alkali‐metal tetra(alkyl) manganates [(TMEDA)2Na2Mn(CH2SiMe3)4] and [(PMDETA)2K2Mn(CH2SiMe3)4]. Reactivity studies using phenylacetylene as a model substrate have revealed that for the homocoupling to take place initial metalation of the alkyne is required. In this regard, the lack of basicity of neutral Mn(CH2SiMe3)2 precludes the formation of the diyne. Contrastingly, the tetra(alkyl) alkali‐metal manganates behave as polybasic reagents, being able to easily deprotonate phenylacetylene yielding [{(THF)4Na2Mn(C≡CPh)4}∞] and [(THF)4Li2Mn(C≡CPh)4]. Controlled exposure of [{(THF)4Na2Mn(C≡CPh)4}∞] and [(THF)4Li2Mn(C≡CPh)4] to dry air confirmed their intermediary in formation of 1,4‐diphenyl‐1,3‐butadiyne in excellent yields. While the Na/Mn(II) partnership proved to be the most efficient in stoichiometric transformations, under catalytic regimes, the combination of MC≡CAr (M= Li, Na) and MnCl2 (6 mol %) only works for lithium, most likely due to the degradation of alkynylsodiums under the aerobic reaction conditions.
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