X-RAY CRYSTALLOGRAPHIC STRUCTURES OF TWO POLYMORPHIC FORMS OF CIS-6-CARBOXY-2,10-DIOXA-1-PHOSPHABICYCLO-[4.4.0JDECANE 1-OXIDE

Abstract The title compound, cis-6-carboxy-2,10-dioxa-1-phosphabicyclo[4.4.0]decane 1-oxide (4), crystallizes in two different crystalline forms: 4a, monoclinic, P21/c, a = 7.7702(5) A, b = 7.1115(3) A, c = 17.8577(10), β = 99.146(5)°, V = 974.46(10) A3, Z = 4, Dcule = 1.501 Mg m−3, Cu Kα, λ = 1.54178 A, a = 2.51 mm−1, F(000) = 464, T = 298(2) K, R = 0.041 and 4b; orthorhombic, P212121, a = 7.9188(8) A, b = 10.8147(6) A, c = 11.261(2), V = 964.4(3) A3, Z = 4, Dcalc.lc = 1.515 Mg m−3, Cu Kα, λ = 1.54178 A, μ = 2.54 mm−1, F(000) = 464, T = 295(2)K, R = 0.046. In each form the structures are found to consist of two as-fused six-membered rings, with each ring in the chair conformation. Both structures exhibit intermolecular hydrogen bonding of the form P[dbnd]O…H[sbnd]O[sbnd]C[dbnd]O with 4a in the form of dinners and 4b in the form of helical chains. All corresponding bond lengths and angles are statistically the same for 4a and 4b. A significant difference in the orientation of the carboxy group in 4a and 4...