The half-sandwich diiodide complexes [Cp*­LnI2] x (Ln = Y, Lu), obtained in high yields from Cp*Ln­(AlMe4)2 (Cp*= C5Me5) and 2 equiv of ISiMe3, reacted with 2 equiv of potassium benzyl KCH2Ph in THF to afford complexes Cp*Ln­(CH2Ph)2­(thf). Protonolysis of Cp*Ln­(CH2Ph)2­(thf) with 3,5-bis­(trifluoro­methyl)­aniline (H2N­C6H3­(CF3)2-3,5 = H2NArCF3) in toluene gave rare-earth-metal imide complexes [Cp*Ln­(NC6H3­(CF3)2-3,5)­(thf) x ]2 (Ln = Y (x = 2), Lu (x = 1)). The dimeric structure of [Cp*Ln­(NC6H3­(CF3)2-3,5)­(thf) x ]2 with two bridging imido ligands forming a planar Ln2N2 core was analyzed by X-ray crystallography. Treatment of Cp*Y­(CH2Ph)2­(thf) with H2N­C6H3­(CF3)2-3,5 in THF led to the monomeric bis­(amide) complex Cp*Y­(NH­C6H3­(CF3)2-3,5)2­(thf)2. The reaction of Cp*Y­(CH2Ph)2­(thf) with 2,6-diisopropyl­aniline in toluene gave also the bis­(amide) complex Cp*Y­(NH­C6H3­iPr2-2,6)2­(thf), whereas, in a THF solution, the formation of the labile mixed benzyl amide complex Cp*Y­(HN­C6H3­iPr2-2,6)­(CH2Ph)­(thf) was observed.

A series of solvent‐free heteroleptic terminal rare‐earth‐metal alkyl complexes stabilized by a superbulky tris(pyrazolyl)borato ligand with the general formula [TptBu,MeLnMeR] have been synthesized and fully characterized. Treatment of the heterobimetallic mixed methyl/tetramethylaluminate compounds [TptBu,MeLnMe(AlMe4)] (Ln=Y, Lu) with two equivalents of the mild halogenido transfer reagents SiMe3X (X=Cl, I) gave [TptBu,MeLnX2] in high yields. The addition of only one equivalent of SiMe3Cl to [TptBu,MeLuMe(AlMe4)] selectively afforded the desired mixed methyl/chloride complex [TptBu,MeLuMeCl]. Further reactivity studies of [TptBu,MeLuMeCl] with LiR or KR (R=CH2Ph, CH2SiMe3) through salt metathesis led to the monomeric mixed‐alkyl derivatives [TptBu,MeLuMe(CH2SiMe3)] and [TptBu,MeLuMe(CH2Ph)], respectively, in good yields. The SiMe4 elimination protocols were also applicable when using SiMe3X featuring more weakly coordinating moieties (here X=OTf, NTf2). X‐ray structure analyses of this diverse set of new [TptBu,MeLnMeR/X] compounds were performed to reveal any electronic and steric effects of the varying monoanionic ligands R and X, including exact cone‐angle calculations of the tridentate tris(pyrazolyl)borato ligand. Deeper insights into the reactivity of these potential precursors for terminal alkylidene rare‐earth‐metal complexes were gained through NMR spectroscopic studies.

Protonolysis of lanthanide tris(tetramethylaluminate)s with two equivalents of 2,6-diisopropylaniline affords La III and Ce III diimide compounds Ln[(m-NC 6 H 3 iPr 2 -2,6) 2 AlMe 2 ](thf) 4 featuring ab identate AlMe 2 -linked diimido ligand. As revealed for the corresponding Ce(GaMe 4 ) 3reaction, formation of the diimidec omplexes proceedsv ia tetrametallic complexes of the type[ Ce{(m-NC 6 H 3 iPr 2 -2,6)(HNC 6 H 3 iPr 2 -2,6)(MMe 3 )}] 2 (Me = Al, Ga). Oxidation of the cerium(III) complexw ith hexachloroethanel eads to a neutralC e IV diimides pecies. Partialp rotonolysis with phenylacetylene andh ydrogenolysis via H 3 SiPh give conclusive insights into the reactive coordination sites of such diimidec omplexes.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.

The four-membered metallacyclic lutetium complexes Tp tBu,MeLu­[CH2(SiMe2)­NR] were synthesized via protonolysis of Tp tBu,MeLuMe2 (Tp tBu,Me = hydrotris­(3-methyl-5-tert-butylpyrazolyl)­borato) with silylamines HN­(SiMe3)­R (R = SiMe3, C6H3(CF3)2-3,5 (ArCF3)). The sterically less demanding amine HN­(SiHMe2)2 led to the isolation of the heteroleptic complex Tp tBu,MeLuMe­[N­(SiHMe2)2]. The accessibility of the complex Tp tBu,MeLu­[CH2(SiMe2)­NArCF3] to intramolecular ring opening was explored using HOCH2 tBu, affording lutetium neopentoxide complexes Tp tBu,MeLu­[N­(SiMe3)­ArCF3]­(OCH2 tBu) and Tp tBu,MeLu­(OCH2 tBu)2. Treatment of Tp tBu,MeLu­[CH2(SiMe2)­NArCF3] with H3SiPh resulted in an unusual ring hydrogen/silyl group exchange and formation of Tp tBu,MeLu­[CH­(SiH2Ph)­(SiMe2)­NArCF3], retaining the four-membered lutetaheterocycle. All complexes were fully characterized by NMR/IR spectroscopy, elemental analysis, and X-ray crystallography.