Dimerization of Molecular PhosphorusOxides.-The colorless compound P 8 O 12 ·2BH 3 (II) is characterized by 31 P-MAS NMR spectroscopy and mass spectrometry. As revealed by single crystal XRD, (II) crystallizes in the orthorhombic space group Pbca with Z = 8. Its principal building block is a novel P 8 O 12 framework, which originates from the fusion of two P 4 O 6 cages after cleavage of one P-O bond in each cage. -(TELLENBACH, AKBAR; JANSEN, MARTIN; Angew. Chem., Int. Ed. 40 (2001) 24, 4691-4694; MPI Festkoerperforsch., D-70569 Stuttgart, Germany; EN)