Syntheses of low coordination number divalent lanthanoid organoamide complexes, and the x-ray crystal structures of Bis[(N-2,6-diisopropylphenyl)(N-trimethylsiIyl)amido]bis(tetrahydrofuran) samarium(II) and -ytterbium(II)

Article abstract of DOI:10.1002/cber.19971300316

The mercury(II) amide complex Hg[N(SiMe₃)(2,6-iPr₂C₆H₃)] ₂ (1) was prepared by reaction of HgBr₂ with Li[N(SiMe₃)(2,6-iPr₂C₆H₃)] in diethyl ether solvent. Redox transmetallation reactions of 1 with elemental samarium, europium or ytterbium in THF solvent (THF = tetrahydrofuran), generated the novel divalent complexes Ln[N(SiMe₃)(2,6-iPr₂C₆H₃)] ₂(THF)₂ with Ln = Sm (2), Eu (3) and Yb (4). 4 was also synthesized by reaction of elemental ytterbium, HgPh₂ and HN(SiMe₃)(2,6-]Pr₂C₆H₃) in THF solvent. This generally more convenient approach has also been applied to the preparation of Ln[N(Si-Me₃)₂]₂(THF)₂ [Ln = Sm (5), Yb (6)] by reaction of the metals with HgPh₂ and HN(SiMe₃)₂. Thermal desolvation of 4 under high vacuum gave Yb[N(SiMe₃)(2,6-jPr₂C6H₃)]₂(THF) (7), whereas under identical conditions 6 yielded the solvent-free complex (Yb[N(SiMe₃)₂]₂}₂ (8). The new compounds 1-4 and 7 are hydrocarbon soluble and ¹⁷¹Yb-NMR spectra were recorded for 4, 6, 7 and 8. X-ray crystal structure determinations of 2 and 4 revealed four-coordinate, distorted tetrahedral metal environments augmented by weak Ln...ipso-C(aryl) interactions. VCH Verlagsgesellschaft mbH,.