Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2017

In organoactinide chemistry, a rare homoleptic uranium(III) tris(aryl) complex, (Terph)3U (Terph = C6H3-2,6-(C6H4-4-tBu)2), has been reported, and the synthesis and reactivity of homoleptic uranium(IV) tetrabenzyl complexes have been studied. Also notable among non-cyclopentadienyl actinide complexes is the phosphorano-stabilized Th(IV) carbene complex Th(CHPPh3)[N(SiMe3)2]3. Moreover, the synthesis, characterization, and reactivity of new heteroleptic Th and U complexes supported by the macrocyclic TMTAA ligand (TMTAA = tetramethyl-tetraazaannulene) have been reported. Interesting derivative chemistry has been developed around the bis(NHC)borate-supported thorium bis(phosphido) complex Th(BcMes)2[HP(Mes)]2 (BcMes = [H2B(C3H2N2Mes)2]−, Mes = 2,4,6-trimethylphenyl). A Novel diuranium µ-phosphido complex have also been prepared and structurally characterized, and the formation of a uranium-coordinated η1‑cyaphide (CP−) ligand via activation and CO bond cleavage of the phosphaethynolate (OCP−) anion has been reported. Thorough reactivity studies have been carried out for actinide metallocene complexes such as ThCp″3 (Cp″ = [C5H3(SiMe3)2-1,3], [η5-1,3-(Me3C)2C5H3]2U(η4-C4Ph2), Cp′4U (Cp′ = C5H4SiMe3), Cp∗2U[η4-C4(SiMe3)2], Cp∗2U(bipy), Cp∗2ThN(mesityl)(DMAP) (DMAP = 4-dimethylaminopyridine) and Cp∗2Th[CHPPh3]X (X = Br, I). The complexes Cp∗2Th(EHTipp)2 (E = P, As; Tipp = 2,4,6-triisopropylphenyl) have been used to access Th-E multiple bonds as in the terminal phosphinidene complex [K(2,2,2-cryptand)][Cp∗2Th = PTipp(PHTipp)]. The synthesis, structure, and reactivity of the sterically crowded Th3+ complex Cp∗3Th have also been investigated in detail. Remarkable achievements have been made in 2017 in the organometallic chemistry of neptunium and plutonium. Structurally characterized compounds included e.g. Cp3Np, Cp3Np(NCMe)2, K[NpCp4], and Cp′3Np. Yet another highlight in this field was the first identification of the formal +2 oxidation state of plutonium in the organometallic complex [K(2.2.2-cryptand)][PuIICp″3]. This complex was prepared by reduction of Cp″3Pu with KC8 in the presence of 2.2.2-crypt and structurally characterized by X-ray diffraction. In a second contribution, the first X-ray crystal structure determination of an organometallic plutonium(IV) complex, the tetrasubstituted plutonocene complex Pu(1,3-COT″)(1,4-COT″) [COT″ = η8-bis(trimethylsilyl)cyclooctatetraenyl], has been reported. Interesting studies involving organoactinides complexes in homogeneous catalysis have addressed e.g. the dimerization of aldehydes.