Organoactinide complexes of the type Cp* 2 AnMe 2 (An ) Th, U) have been found to be efficient catalysts for the hydroamination of terminal alkynes with aliphatic primary amines. The chemoselectivity and regioselectivity of the reactions depend strongly on the nature of the catalyst and the nature of the amine and show no major dependence on the nature of the alkyne. The hydroamination reaction of the terminal alkynes with aliphatic primary amines catalyzed by the organouranium complexes produces the corresponding imines where the amine and the alkyne are regioselectively disposed in a syn-regiochemistry, whereas for similar reactions with the organothorium complex besides the methyl alkylated imine, dimeric and trimeric alkyne oligomers are also produced. For (TMS)CtCH and EtNH 2 both organoactinides produced the same imine compounds when the reaction is carried out in THF or toluene. In benzene, both imines E and Z (TMS)CH 2 CHNdEt are obtained, the earlier undergo a 1,3-silyl Brook sigmatropic rearrangement toward the enamine, whereas the latter remains unchanged. Mechanistic studies on the hydroamination of (TMS)CtCH and EtNH 2 promoted by the organouranium complex show that the first step in the catalytic reaction is the formation of the bis(amido) complex, found in equilibrium with the corresponding bisamido-amine complex, which loses an amine, yielding a uranium-imido complex. Insertion of the alkyne into the imido bond with subsequent amine protonolysis, isomerization, and product release comprise the primary steps in the catalytic cycle. The kinetic rate law was found to follow an inverse kinetic order in amine, a first order in complex, and a zero order in alkyne, with ∆H q ) 11.7(3) kcal mol -1 , ∆S q ) -44.5(8) eu. The turnoverlimiting step is the release of an amine from the bisamido complex yielding the imido complex.The key organoactinide intermediate for the intermolecular hydroamination reaction was found to be the corresponding actinide-imido complexes. For both actinides the complexes have been characterized, and for thorium the single-crystal X-ray diffraction was studied. A plausible mechanistic scenario is proposed for the hydroamination of terminal alkynes and aliphatic primary amines.3

Organoactinide complexes of the type Cp* 2 AcR 2 (Ac ) Th, U) catalyze the intermolecular hydroamination of terminal alkynes with aliphatic amines. The regioselectivity of the products can be tuned by the alkyne and the metal. Mechanistic studies shows that the ratelimiting step is the formation of an actinide imido complex. For thorium, the imido intermediate has been characterized by standard techniques, including X-ray diffraction.

Reactions of [UMe,(C,Me,),] with primary aromatic or aliphatic amines led to the rapid formation of monomeric uranium(1v) complexes [U(C,Me,),(NHR),] (R = 2,6-dimethylphenyl I, Et 2 or But 3). The

Various organoactinides of the type Cp*2An(C⋮CR)2 (Cp* = C5Me5; An = Th, U) have been synthesized from the corresponding Cp*2AnMe2 complexes by addition of an equimolar amount or an excess of the corresponding terminal alkyne. Attempts to trap the mono(acetylide) complexes Cp*2An(C⋮CR)(Me) were successful for only the transient species Cp*2U(C⋮C(i-Pr))(Me). The bis(acetylide) complexes are active catalysts for the linear oligomerization of terminal alkynes HC⋮CR. The regioselectivity and the extent of oligomerization depend strongly on the alkyne substituent R, whereas the catalytic reactivities are similar for both organoactinides. Reaction with tert-butylacetylene regioselectively yields the 2,4-disubstituted 1-butene-3-yne dimer, whereas (trimethylsilyl)acetylene is regioselectively trimerized to (E,E)-1,4,6-tris(trimethylsilyl)-1,3-hexadiene-5-yne, with small amounts (3−5%) of the corresponding 2,4-disubstituted 1-butene-3-yne dimer. Oligomerization with less bulky alkyl- and aryl-substituted alkynes produces a mixture of oligomers. Cross-oligomerizations reactions induce the formation of specific cross dimers and trimers. Mechanistic studies on the selective trimerization of HC⋮CSiMe3 show that the first step in the catalytic cycle is the C⋮C bond insertion of the terminal alkyne into the actinide−acetylide bond. The kinetic rate law is first order in organoactinide and in alkyne, with ΔH ⧧ = 11.1(3) kcal mol-1 and ΔS ⧧ = − 45.2(6) eu. The turnover-limiting step is the release of the organic oligomer from the alkenyl−actinide complex. The latter key organometallic intermediate has been characterized by spectroscopic and poisoning studies. A plausible mechanistic scenario is proposed for the oligomerization of terminal alkynes.

Various actinide alkyl and hydride metallocenes effectively and selectively catalyze a variety of C-H bond activation and hydrogenation reactions.1 In their "cationic" form, these d°/f°m etallocene complexes have recently been shown to be very