η5-Cyclopentadienyl derivatives of tin(II) studied by two-dimensional multinuclear magnetic resonance in solution and by13C and119Sn CP/MAS NMR in the solid state

Abstract

Absolute coupling signs of 1J(119Sn, 13C) ( O) in (n5-C5Me5)2Sn (2) were determined using advanced direct and indirect two-dimensional methods. These are based on Ψ-BIRD techniques and z-filtering, leading to pseudotriple-resonance experiments of the type 1H{119Sn(13C)} and 13C{1H(119Sn)}, respectively. A mixed n5-cyclopentadienyltin(II) amide was prepared and characterized by 1H, 13C, 29Si and 119Sn NMR in solution in the presence of its symmetrical redistribution products 1 and [(Me3Si)2N]2Sn. Solid-state 119Sn CP/MAS NMR spectra of 1 shows the presence of two tin sites (in accord with the x-ray analysis) with a 62.2 ppm difference in 119Sn chemical shifts, the mean value being in close agreement with the solution-state δ119Sn value. The symmetries of the shielding tensor for the two tin sites are different and there appears to be a correlation between this property and the ring centroid—Sn—ring centroid angle α. 13C CP/MAS NMR proved insensitive to the structural differences between the two types of molecules of 1 in the unit cell.