BIS(2,4-DI-TERT-BUTYLPHENYL) PENTAERYTHRITOL DIPHOSPHITE

The title compound, 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, (1), C33H50O6P2, has three different conformers in the unit cell. The structure of each is very similar to the others, differing principall y in the rotational conformations of the aryl tert-butyl groups, The r emaining portion of the structure comprises two six-membered rings, ea ch in a chair conformation and sharing a common spiro atom, Bond angle s and bond lengths in the spiro rings are very similar to those of the related molecule 3,9-dimethoxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro [ 5.5]undecane [Carpenter, Jacobson & Verkade (1979). Phosphorus Sulfur, 6, 475-479].