Abstract
The solid state structures of three phosphorus heterocycles trans- and cis-4-methyl-4-phosphatetracyclo [3.3.0.02,8.03,6]octane 4-sulfide (3a and 3b, respectively) and truns-4-phenyl-4-phosphatetracyclo[3.3.0.02,8.03,6]octane 4-oxide (5a), were established by X-ray crystallography. Although the ring structure in each was expected to be conformationally rigid, some differences were noted when 3a, 3b, 5a, and 4- methyl-4-p-nitrobenzyl-4-phosphoniatetracyclo[3.3.0.0.2,8.03,6]octane bromide (4) were compared. Examination of both bond lengths and angles indicates that the phosphetane ring is greatly affected by the tetracyclic system. Semi-empirical calculations at the PM3 level were used to estimate the relative energy of cis and trans 5. The single crystal data are as follows: (trans-3a), triclinic, P-1, with a = 6.2227(4) Å, b = 6.5205(6) Å, c = 10.3651(13) Å, α = 86.670(10)°, β = 87.340(8)°, γ = 83.712(6)°, V = 416.99(7) Å3, Z = 2, Dcalc = 1.356 g/cm3, 743 observed reflections, and R = 0.040; (cis-3b), triclinic, P-1, with a = 6.6575(6) Å, b = 7.9834(9) Å, c = 8.8722(9) Å, α =108.746(8)°, β = 104.473(7)°, γ = 69.611(7)°, V = 413.47(7) Å3, Z =2, Dcalc = 1.367 g/cm3, 729 observed reflections, and R =0.041; (trans-5a), orthorhombic, Pna21, with a = 15.3191(17) Å, b = 8.3260(8) Å, c = 8.583(2) Å, V = 1094.7(5) Å3, Z = 4, Dcalc = 1.31 g/cm3, 980 observed reflections, and R = 0.038.
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