Synthesis, Structures, and Spectroscopy of the Metallostannylenes (η5-C5H5)(CO)3M−S̈n−C6H3-2,6-Ar2 (M = Cr, Mo, W; Ar = C6H2-2,4,6-Me3, C6H2-2,4,6-Pri3)

Abstract

The metallostannylene compounds (η5-C5H5)(CO)3MSnC6H3-2,6-Mes2 (Mes = C6H2-2,4,6-Me3; M = Cr (1), Mo (2), W (3)), (η5-C5H5)(CO)3MSnC6H3-2,6-Trip2 (Trip = C6H2-2,4,6-Pri3; M = Cr (4), Mo (5), W (6)), and (η5-1,3-ButC6H3)MoSnC6H2-2,6-Trip2 (7) were synthesized by the reaction of the appropriate aryltin(II) halide with the alkali-metal salt of the cyclopentadienylcarbonylmetalate. The compounds, which were isolated as purple (1−6) or turquoise (7) crystals, are monomeric with V-shaped two-coordinate geometries at tin. The tin−transition-metal bonds are slightly longer than the distances predicted from metallic and covalent radii or those observed in related tin(IV)−transition-metal species. The compounds were also characterized by IR and UV−vis spectroscopy as well as 1H, 13C, and 119Sn NMR spectroscopy. The 119Sn NMR spectra displayed singlet resonances whose chemical shifts were in the range 2116−2650 ppm. These shifts were consistent with the two-coordination at tin. With use of 119Sn NMR and UV−visible spectroscopic data for 1−7, together with data for other two-coordinate tin(II) species, it was shown that there is a rough correlation between the 119Sn NMR chemical shift and the wavelength of the n−p transition. This correlation underlines the importance of the paramagnetic shielding term in determining 119Sn chemical shifts.