Reactions of the stable bis(amino)silylene Si[{N(CH2tBu)}2C6H4-1,2] with group 3 or lanthanide metal organic compounds. Crystal structures of [Ln(η5-C5H5)3Si{[N(CH2tBu)]2C6H4-1,2}]·C7H8 (Ln = Y or Yb)

Abstract

Treatment of the thermally stable aminosilylene Si[{N(CH2tBu)}2C6H4-1,2] [= Si(NN)] with a tris(cyclopentadienyl)- group 3 or -lanthanide metal compound LnCp3 (Cp = η5-C5H5 and Ln = Y or Yb) in toluene at ambient temperature afforded the first earliest transition or f-block metal-silylene complexes [LnCp3{Si(NN)}]·C7H8 (Ln = Y (1) or Yb (2)), characterized by NMR spectroscopy and X-ray crystallography: complex 1 (monoclinic, space group P21/c (no. 14), a = 15.641(5), b = 15.895(7), c = 14.876(5) Å, β = 112.93(3), Z = 4, R1 = 0.067 for 6194 observed data), and2 (monoclinic, space group P21/c (no. 14), a = 15.635(3), b = 15.795(2), c = 14.842(2) Å, β = 112.87(2), Z = 4, R1 = 0.044 for 9829 observed data). The Ln atom in each of the isoleptic complexes 1 and 2 has distorted trigonal monopyramidal geometry, with the approximately trigonal silicon atom in the apical position. The Ln-Si bond length is 3.038(2) (1) or 2.984(2) Å (2). Variable temperature 29Si{1H} NMR spectra in toluene-d8 show that each complex readily dissociates (Y > Yb) into its factors; at 188 K, the 29Si{1H} signal for (1) was a doublet centred at δ 119.5, 1J(29Si-89Y) = 59 Hz.Key words: crystallography, NMR, silylene, yttrium, ytterbium, organometallic complexes.