Coupling Sign Determination and Isotope-Induced Chemical Shifts 1Δ15/14N(29Si), 1Δ15/14N(119Sn) and 1Δ29/28Si(15N): Multinuclear Magnetic Resonance Study of N-Trimethylsilyl-, -stannyl- and -plumbyl-Substituted 2-Aminopyridines, 2,6-Diaminopyridines and Analogous 2-Picolines

✍ Scribed by Bernd Wrackmeyer; Gerald Kehr; Hong Zhou; Saqib Ali

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 634 KB
• Volume: 34
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/(sici)1097-458x(199611)34:11<921::aid-omr987>3.0.co;2-9

✦ Synopsis

2-Aminopyridines (l), 2-amino-3-methylpyridines (2) and 2,6-diaminopyridines (3), bearing N-trimethylsilyl, -stannyl or -plumby1 groups, and analogously substituted 2-picolines (4) were studied by 'H, 13C, "N, 29Si, '19Sn and ' O' Pb NMR spectroscopy. Intramolecular N S n coordination became evident in the case of N,Ntrimethylsilyl(trimethylstannyl)-2-aminopyridine (le) and N,N-trimethylsilyl(trimethylstannyl)-N-trimethylsilyl-2,ddiaminopyridine (30, in particular from their 6"N(amine) and 15"~Sn data. Numerous coupling constants J(M,15N) and J(M,13C) (M = 29Si, lt9Sn, '"Pb) were measured and, in the case of 2-I trimethylsilyl(trimethylstanny1)) methylpyridine (4e), absolute signs of "J("9Sn,'3C) and n+'J(119Sn,'H) were determined by appropriate 2D I3C/'H heteronuclear shift correlations. Isotope-induced chemical shifts 1A15/14N(29Si) (range -9 to -16 ppb) and 1A15/'4N(1'9Sn) (range -32 to -55 ppb) were measured at natural abundance of I5N by using Hahn-echo extended polarization transfer pulse sequences. 1A29/28Si('5N) values (range of -2.4 to -6.0 ppb) were measured from "N NMR spectra.