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13C NMR chemical shifts and uC-31P coupling constants of fourteen derivatives from 3,9-di(aIkylphenoxy)-2,4,S,lO-tetraoxa-3,9-diphosphaspiro[5.5]undecane and of eight derivatives of the 3,g-dioxo type are reported. All investigated compounds possess a chair conformation with the lone pair or the phosphoryl oxygen in the equatorial position. The allrylphenoxy groups are in a cis position with respect to the lone pair or the phosphoryl oxygen. Conformational changes about the aryl-0 bond can be monitored via P-0-GuC couplings and their angular dependence was found to be non-symmetric. 31