Crystalline metal (Li, Mg, Ca, Sr, Ba, Sn, Pb) complexes of the new chelating N,N′-dianionic [1,2-N(R)C6H4(CH2NR)]2−ligand (R = SiMe3, CH2But)

Abstract

2-Aminomethylaniline was converted into the N,N′-bis(pivaloyl) (1) or -bis(trimethylsilyl) (2) derivative, using 2 Bu^tC(O)Cl or 2 Me₃SiCl ( RCl), respectively, with 2 NEt₃, or for 2 from successively using 2 LiBuⁿ and 2 RCl. N,N′-Bis(neopentyl)-2-(aminomethyl)aniline (3) was prepared by LiAlH₄ reduction of 1. From 2 or 3 and 2 LiBuⁿ, the appropriate dilitiodiamide {2-[{N(Li)R}C₆H₄{CH₂N(Li)R}(L)]₂ (L absent, 4a; or L = THF, 4b) or the N,N′-bis(neopentyl) analogue (5) of 4a was prepared. Treatment of 4a with 2 Bu^tNC, 2 (2,6-Me₂C₆H₃NC) or 2 Bu^tCN ( L′) furnished the corresponding adduct [2-N{Li(L′)R}C₆H₄{CH₂N(Li)R}] (4c, 4d or 4e, respectively), whereas 4b with 2 PhCN afforded [2-{N(Li)R}C₆H₄{CH₂C(Ph) = NLi(NCPh)}] (6). The dimeric bis(amido)stannylene [Sn{N(R)C₆H₄(CH₂NR)-1,2}]₂ (7) was obtained from 4a and [Sn(μ-Cl)NR₂]₂, while the N,N′-bis(neopentyl) analogue 8 of 7 was similarly derived from [Sn(μ-Cl)NR₂]₂ and 5. Reaction of two equivalents of the diamine 2 with Pb(NR₂)₂ yielded 9, the lead homologue of 7. Oxidative addition of sulfur to 7 led to the dimeric bis(diamido)tin sulfide 10. Treatment of 2 successively with ‘MgBu₂’ in C₅H₁₂ and THF gave [Mg{N(R)C₆H₄(CH₂NR)}(THF)]₂ (11a), which by displacement of its THF by an equivalent portion of Bu^tCN or PhCN produced [Mg{N(R)C₆H₄(CH₂NR)}(CNR')_n] [R′ = Bu^t, n = 1 (11b); R′ = Ph, n = 2 (11c)]. The Ca (12), Sr (13) or Ba (14) analogues of the Mg compound 11a were isolated from 2 and either the appropriate compound M(NR₂)₂ (M = Ca, Sr, Ba), or successively 2 LiBuⁿ and 2 M(OTos)₂. The new compounds 1–14 were characterized by microanalysis (C, H, N; not for 1, 2, 3, 5), solution NMR spectra, ν_max (CN) (IR for 4c, 4d, 4e, 6, 11b, 11c), selected EI-MS peaks (for 1, 2, 3, 7, 8, 9, 10), and single crystal X-ray diffraction (for 4a, 4b, 11a).