Hypercoordinated Organotin(IV) Compounds Containing ĸ²-C,O- And ĸ²,N- Chelating Ligands: Synthesis, Characterization, and Polymerization Behaviour

Abstract

Rigid homopolystannanes and alternating polystannanes containing a benzyl methoxy ether (C,O) or benzyl dimethyl amine (C,N) ligand were prepared using either a direct approach, lithiation and transmetallation, or an alternative approach, either sequential chlorinations or brominations. X-ray crystallographic studies of 41 and 45 were conducted to find 41 in a distorted tetrahedral geometry with moderate hypercoordinate interaction (Sn-N: 2.917 Å) while 45 in a distorted trigonal bipyramidal with strong hypercoordinate interaction (Sn-N: 2.403 Å). Hydrogenation of 31 and 33 produced 42 and 43 in moderate-to-good yields. Dehydrocoupling polymerization produced modest molecular weight, rigid C,O- (Mw = 3.03 × 10⁴ Da, PDI: 1.4) and C,N- (Mw = 3.10 × 10⁴ Da, PDI: 1.82) homopolymers 56 and 57. Finally, condensation polymerization was attempted to produce low molecular weight (Mw = 1.30 × 10⁴ Da, PDI: 2.0) C,O- alternating polymer 60 and oligomer 61 (Mw = 0.92 × 10⁴ Da, PDI: 2.71).