Synthesis and characterization of a stable bis-naphthyltin(II) compound. Bis[8-(dimethylamino)-1-naphthyl-C,N]tin(II) and its W(CO)5 adduct

Reaction of [8-(dimethylamino)-1-naphthyl-C,N]lithium with SnCl₂ affords the new monomeric stannylene bis[8-(dimethylamino)-1-naphthyl-C,N]tin(II) (3). The reaction between W(CO)₅(NME₃) and 3 yields {bis[8-(dimethylamino)-1-naphthyl-C,N]tin(II)} tungsten pentacarbonyl (4). The crystal structures of 3 and 4 have been determined by X-ray diffraction methods. 3: C₂₄H₂₄N₂Sn, orthorhombic, space group Pbca with a 22.383(4), b 30.865(5), c 12.127(2) Å and Z = 16, final R = 0.067 for 4983 observed reflections. 4: C₂₉H₂₄N₂O₅SnW, a 12.509(3), b 15.191(1), c 9.780(1) Å, α 98.42(1), β 104.33(1), γ 107.27(1)°, space group P1, Z = 2, triclinic; R = 0.046 for 7116 observed reflections. The geometry about tin in 3 is distorted ψ-trigonal bypyramidal, and that in 4 is distorted trigonal bipyramidal. In both 3 and 4 the 8-(dimethylamino)-1-naphthyl groups are C,N-chelate bonded, with the C(1) atoms at equatorial sites and the nitrogen atoms at axial sites. The Sn lone pair in 3 and the W(CO)₅ moiety in 4 occupy the remaining equatorial sites. ¹H, ¹³C, and ¹¹⁹Sn solution NMR spectroscopic studies of 3 and 4 show that at low temperature (≤ - 15°C) they retain the structures found in the solid state. At higher temperatures fluxional processes become operative.