Synthesis and characterization of a series of zinc bis[(alkyl)(trimethylsilyl)amide] compounds

A series of 21 secondary (alkyl)(trimethylsilyl)amines HNR(TMS) [R = n-prop yl (1), i-propyl (2), n-butyl (3) i-butyl (4), s-butyl (5), tert-butyl (6), c-pentyl (7), n-pentyl (8), i-pentyl (9), 1-methylbutyl (10), 2-methylbuty l (11), 1-ethylpropyl (12), 1,2-dimethylpropyl. (13), tert-pentyl (14), phe nyl (15), c-hexyl (16), n-hexyl (17), N,N-dimethyl-3-aminopropyl (18), benz yl (19), n-heptyl (20), 1,1,3,3-tert-butyl (21); TMS = Si(CH3)(3)] has been prepared and fully characterized by elemental analyses, multinuclear (LH, C-13, Si-29, N-14) NMR, IR, UV/vis, MS, and bailing point. A new method for determination of boiling points of milligram-size samples, based on DSC (d ifferential scanning calorimetry), is described. Each amine has been conver ted to the corresponding zinc bis(amide) compound Zn[N(TMS)(R)](2) [R = n-p ropyl (22), i-propyl (23), n-butyl (24), i-butyl (25), s-butyl (26), tert-b utyl (27), c-pentyl (28), n-pentyl (29), i-pentyl (30), 1-methylbutyl(31), 2-methylbutyl (32), 1-ethylpropyl (33), 1,2-dimethylpropyl (33)1 tert-penty l (35), phenyl (36), c-hexyl (37), n-hexyl (38), N,N-dimethyl-3-aminopropyl (39, benzyl (40), n-heptyl (41, 1,1,3,3-tert-butyl (32); TMS = Si(CH3)(3)] and subsequently fully characterized by elemental analyses, multinuclear ( H-1) C-13, Si-29,N-14) NMR, IR, UV/vis, MS, and TGA. The experimental IR ha s been compared to the computationally calculated one for compound 27. Obse rved trends in volatility of the compounds an discussed in the context of t he dominant intermolecular forces present in the condensed phase.