Facile C–H activation by lutetium–methyl and lutetium–hydride complexes

Abstract

Bis(pentamethylcyclopentadienyl)lutetium complexes Lu( 75-C5Me5) 2R (R = Me, H) react at 20-50 "C in hydrocarbon solvents with benzene, pyridine, the ylide CH2PPh3, and tetramethylsilane to give stable, isolatable products of C-H activation, i.e. metallation at a carbon of the reagent with extrusion of R-H.I report here that lutetium-alkyl and -hydride derivatives can activate sp2 C-H bonds in both intra-and inter-molecular reactions and even activate the sp3 bonds of SiMe,. That these reactions occur under mild conditions with hydrocarbons of very low acidity is extraordinary for stable, isolatable complexes.The hydride Lu(q5-C5Me5),H (2) [VL" -H(Nujol) 1345 cm-'1 is readily formed?' by hydrogenolysis of (1) [reaction (i), Scheme 1 ; pentane solution, 20 "C, 1 atm H,]. This hydride rapidly undergoes H / D exchange when dissolved in deuteriated arenes [benzene or toluene, reaction (ii)] at 20 "C forming the deuteride, Lu(q5-CSMe5),D [vLu-D(NujoI) 975 cm-l]. As shown in reaction (ii), Scheme 1, exchange with D, also occurs in pentane at 20 "C.A more important non-degenerate intermolecular C-H activation between the hydride (2) and benzene occurs

Reactivity of TpMe2‐Supported Yttrium Alkyl Complexes toward Aromatic N‐Heterocycles: Ring‐Opening or CC Bond Formation Directed by CH Activation

“…The reaction of [Tp Me2 Y(CH 2 Ph) 2 (THF)] with two equivalents of 1-methylimidazole in THF at room temperature afforded a double C-H activation product [Tp Me2 Y (h 2 -N,C-Im)(m-Im)] 6 (1; Im = 1-methylimidazolyl) in 93 % isolated yield, as shown in Scheme 1. It should be noted that the formation of complex 1 is independent of the reaction stoichiometry; the equimolar reaction of [Tp Me2 Y(CH 2 Ph) 2 (THF)] with 1-methylimidazole under the same conditions also gave complex 1 and the original material [Tp Me2 Y(CH 2 Ph) 2 (THF)].…”

“…The structure of complex 2 was also characterized by single-crystal X-ray diffraction analysis ( Figure 2). The C1ÀC8 bond [1.455 (7) ] is clearly indicative of a CÀC single bond, whereas the lengths of the C8ÀC9 and C9ÀN3 bonds [1.356(7) and 1.324 (6) , respectively] are between the CÀC and CÀN single and double bonds, revealing the delocalization character of the p electrons of the C8=C9 bond. Moreover, the bond angles around C8 and C9 are consistent with sp 2 hybridization.…”

“…[5] However, little is known of the reactivity of rare-earth dialkyl complexes towards aromatic N-heterocycles. [6] On the other hand, metal-mediated inactive C-H bond activation [including C(sp 3 )-H and C(sp 2 )-H bonds] has become a productive research field in organic and organometallic chemistry, [7] and this approach serves as one of the most powerful tools for the construction of carbon-carbon or carbon-heteroatom bonds. [8] However, only one or two C(sp 2 or sp 3 )ÀH bond is activated (the latter was also termed crossdehydrogenative-coupling, CGC) and forms a new carboncarbon or carbon-heteroatom single bond in most cases.…”

Sixty Years of the Chemistry of Rare-earth Organometallic Complexes

“…1982 年合成得到了二(五甲基环戊二烯基) 镥氢配合物 [113] , 发现它能与苯和甲烷等惰性底物进行 反应 [82,84] . [(C 5 Me 5 ) 2 LuH] 2 的制备是通过甲基配合物氢 解反应来实现, 后来发现氢解二(三甲基硅)甲基配合物 也能合成氢化物[式 (9)].…”

Transition‐Metal Complexes with Sterically Demanding Ligands: Facile Thermal Intermolecular CH Bond Activation in a Square‐Planar IrI Complex

“…Overall, the outcome of the CÀH activation reaction resembles a s-bond metathesis process, which is the anticipated mechanism for d 0 early-transition-metal and lanthanide row complexes. [8,18,19] For d n -configured complexes with n ! 2 there are other mechanistic alternatives, for example, a CÀH oxidative-addition step, followed by CÀH reductive elimination.…”