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Crystals of the title compound are triclinic, a = 8.533(5), b = 11.106(6), c = 8.815(5) Å, a = 107.83(6), β = 104.99(6), γ = 81.30(5)°, Z = 2, space group P1̄. The structure was determined by multisolution direct methods and electron density methods. Refinement by least-squares techniques gave a final R = 0.081 for the 1753 independent reflections. The molecule adopts a butterfly-type conformation such that the fused phenyl rings are inclined to each other at an angle of 56.8°. The P-0 bond distance is 1.506(4) Å; the endocyclic angle at phosphorus is 107.2(3)° and the exocyclic angles vary from 106.5 to 111.9(3)°.

Novel alkaline earth metal thiocyanate complexes are formed by the template condensation of furan-2,5-dicarbaldehyde with 1,11-diamino-3,6,9-trioxaundecane and 1,5-bis(2-aminophenoxy)-3-oxapentane; the X-ray structure of aqua-(3,15-diaza-6,9,12,20-tetraoxabicyclo[15,2,1]eicosa-2,15,17,19-tetraene)-di-isothio-cyanatostrontium(II) has been determined.

Crystals of the title compound are monoclinic, a= 25.685(15), b= 10.444(6), c= 18.818(11), β= 119.18(5)°, Z= 8 in space group C2/c, with the oxygens of water molecules present in the crystals lying along two-fold axes. The structure was determined by Patterson and electron-density methods and refined by least-squares techniques to R= 0.066 for 992 independent reflections. The fused ring system of the dibenzophospholium cation is almost planar and while the exocyclic C–P–C angles lie in the range 110–117°, the endocyclic angle is 93.9°. It is suggested that this low value is consistent with the presence of considerable ring strain, which is relieved either on phosphorane formation following nucleophilic attack at phosphorus, or on dealkylation of dibenzophospholium salts. The implications of ring strain in dibenzophospholium salts are discussed in connection with the possible aromaticity of the dibenzophospholes.