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Treatment of pyrophoric strontium powder in tetrahydrofuran with ArOH (Ar = C6H2Buf3-2,4,6) or HNR'2 at ambient temperature affords crystalline [Sr(OAr)2(THF)4] or [Sr(NR',),(THF),]

The reaction of [Yb(q-CSMes)2(OEt2)] with 1 equiv. of [Li{Si(SiMe3)3)(thf)3] in toluene affords [Yb(q-C5MeS){Si-(SiMe3)3)(thf)2] 1 in high yield; a single-crystal X-ray analysis and multinuclear 1 7 l Y b and 29Si NMR spectroscopic data for 1 are reported.Since their proposed role in the catalytic dehydrocoupling of primary silanes to polysilanes, much interest has recently focused on the exploration of chemistry of lanthanide-siliconbonded species.' Nevertheless only three routes to such compounds are known, and four complexes have been structurally characterised (Scheme 1, Table l).2-5We now report the synthesis and molecular structure of [Yb(q-CSMeS)( Si(SiMe3)3}(thf)2] 1. The reaction of [Yb(q-C5Me5)2(OEt2)] with 1 equiv. of [Li( Si(SiMe&}(thf)3] in toluene afforded 1 in high yield (75%).t The elimination of LiC5Me5 has been previously employed for complexes of main-group697 and lanthanides elements in substitution reactions in which the CSMeS-group was replaced by alkyl, alkoxide or amide but not, to our knowledge, by silyl derivatives. 1 was initially characterised by its 17lYb NMR spectrum, in toluene solution, which displayed a single resonance at 6 421 with satellites corresponding to 1J(171Yb_29Si) 829 Hz [Fig. l(a)]. The 29Si NMR spectrum (Fig. l(b)] comprised two resonances at 6 -2.9 and -158, the latter assigned to Si(SiMe)3 possessing satellites confirming the previously measured 1J(171Yb-29Si) coupling and also displaying IJ(29Si-29Si) 26 Hz; the former, assigned to Si(SiMe)3 showed a 2J(29Si-171Yb) coupling of 11.5 Hz and a 1J(29Si-13C) coupling of 40 Hz. The 13C NMR spectrum of 1 revealed 2J(13C-29Si) of 8 Hz for Si(SiMe)3 and a lJ(l3C-171Yb) coupling of 10 Hz for C5Me5.Recry stallisation of 1 from hexane afforded orange needles. The molecular structure was determined from a single-crystal X-ray diffraction study (Fig. 2).$ The ligand geometry about the Yb atom is distorted tetrahedral, with the angle between the Compound Ln-SilA Ref.

Supplementary Material Available: Tables of atom coordinates, bond distances and angles, and anisotropic temperature factors (4 pages); tables of observed and calculated structure factors (9 pages). Ordering information is given on any current masthead