Four-Membered Lutetaheterocycles

The four-membered metallacyclic lutetium complexes TptBu,MeLu[CH2(SiMe2)NR] were synthesized via protonolysis of TptBu,MeLuMe2 (TptBu,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 TptBu,MeLuMe[N(SiHMe2)2]. The accessibility of the complex TptBu,MeLu[CH2(SiMe2)NArCF3] to intramolecular ring opening was explored using HOCH2tBu, affording lutetium neopentoxide complexes TptBu,MeLu[N(SiMe3)ArCF3](OCH2tBu) and TptBu,MeLu(OCH2tBu)2. Treatment of TptBu,MeLu[CH2(SiMe2)NArCF3] with H3SiPh resulted in an unusual ring hydrogen/silyl group exchange and formation of TptBu,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.