Supplementary Material for Chemical Communications This journal is © The Royal Society of Chemistry 2003 Synthesis magnesium of the mixed lithium-potassium-(bis) N-metallated/N,C-dimetallated amide [Li2K2Mg4{But(Me3Si)N}4{But[Me2(H2C)Si]N4}]: an inverse crown molecule with an atomless cavity Glenn C. Forbes, Fiona R. Kenley, Alan R. Kennedy, Robert E. Mulvey, Charles T. O’Hara and John A. Parkinson Supporting Information i Figure S1: 2D [1H, 13C] HSQC NMR spectrum acquired at a magnetic field strength of 9.4 T and optimised for 1J(1H, 13C) = 136 Hz (1/4J = 1.8 ms). a) N-methyl region; b) Silyl-methyl region. 10 b) ppm 5 10 15 1 13 20 C (ppm) 25 30 a) 35 40 1.5 1.0 0.5 ppm -1.5 2 – 1H (ppm) -2.0 ppm ii 2D [1H, 29Si] HSQC NMR spectrum acquired at a magnetic field strength of 9.4 T and optimised for 2J(1H, 29Si) = 6.6 Hz (1/4J = 38 ms). a) 0.0-0.7 ppm (1H) region; b) Low ppm region indicating that the signal at -1.9 ppm is associated with a CH2 group adjacent to 29Si (nonequivalent geminal protons giving rise to two signals with strong coupling [large ‘roof effect’]). At this temperature the broad 1H resonance at –1.5 ppm does not give rise to a correlation with 29Si. Figure S2: 10 ppm 1 29 a) b) -90 Si (ppm) -80 -70 0.6 0.4 0.2 ppm -1.5 -2.0 ppm 2 - 1H (ppm) iii Figure S3: N-methyl region of the 1H 2D EXSY NMR spectrum acquired at a magnetic field strength of 9.4 T (mixing time = 500 ms). 1D 1H NMR spectra of the same regions are shown as projections (top and side). Cross-peaks indicate the presence of exchange. ppm 1.2 1.4 1.6 1.7 1.6 1.5 1.4 1.3 1.2 1.1 2 – 1H (ppm) 1.8 ppm iv Figure S4: Low-temperature 1H NMR spectra acquired at 400 MHz. Temperature/K 220 230 240 250 260 270 280 290 300 1.5 Temperature/K 220 230 240 250 260 270 280 290 300 1.0 0.5 0.0 2 –1H (ppm) 10 ppm-1.0 -1.5 -2.0 v ppm