A six-membered ring phosphorochloridite (5-tert-butyl-2-chloro-l,3,2-dioxaphosphorinane) and a geometrically isomeric pair of six-membered ring phosphites (cis-and Zram-5-/er/-butyl-2-methoxy-l ,3,2-dioxaphosphorinane) have been synthesized, and their conformational and configurational properties have been investigated. The m-phosphite is shown to be the more stable isomer by about 1.4 kcal/mol at 25°and by nmr analysis to be a chair-form conformer with the ieri-butyl equatorial and the methoxy axial. The predominate conformer of the trans isomer is the chair form with both substituents axial. The axial preference of the methoxy substituent in the phosphite series, as in the corresponding cyclic sulfites, is found to be greater than for the 5-te/V-butyl-2-methoxy-1,3-dioxanes. A true boat form for the other conformer(s) of the tra«s-phosphite is ruled out, but present data indicate both chair and twist conformers to be worthy of further consideration.
T h e title compounds crystallize in the orthorhombic system, the 2-methoxy compound (I) in the space group Pnma, and the 2-tert-butyl material (11) in space group Pmcn. Lattice parameters are: (I) a = 6.123 (41, b = 10.02 ( l ) , c = 17.65 (1) A, z = 4: (11) a = 10.077 ( 3 ) , b = 10.662 (3), c = 12.703 (3) A, z = 4. Compounds I and I1 both havechair-form ring conformations with the 5-tert-butyl group axial in both. For I the methoxy on phosphorus is axial and the phosphoryl oxygen is equatorial. The 2-tert-butyl is equatorial in I1 with the thiophosphoryl sulfur axial. In comparison to the structures of a large number of other phosphoranes, these rings systems, especially 11, appear to be somewhat flattened about the C(5) end of the molecule. This apparently results from steric interactions involving the axial tert-butyl groups and the ring atoms C(4), O ( l j , and O ( 3 ) and hydrogens bonded thereto. Bond angle deformations within the 5-tert-butyl and a t its point of attachment to the ring also attest t o this fact. T h e phosphorus end of the ring associated with I1 is highly puckered. This property is shown to be a general one for lJ.2-dioxaphosphorinanes with double-bonded 0, S, or Se axial. For I1 the ring pucker is unusually large. Explanations based on nonbonded interactions of the 2-tert-butyl with ring oxygens O(1) and O ( 3 ) or across the ring with the axial
The photoelectron spectra of tris(dimethylaminophosphine) (I), tris (diethylaminophosphine) (II), and tris(dipropylaminophosphine) (III) have been studied in an effort to resolve a controversy pertaining to the interpretation of the spectrum of I. The current interpretation concludes that I, II, and III have Cs skeletal symmetry with two nitrogen lone pairs interacting in a manner, while the remaining nitrogen lone pair interacts in a fashion with the phosphorus lone pair. The second and third ionization bands correspond to the phosphorus-nitrogen lone-pair interaction.
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