Reactions of various vanadyl (V-v) compounds with silyl phosphato, phosphonato, or alkyl phosphato compounds have provided the cluster compounds (VO)(6)(O(3)POSiMe(3))(8)Cl (1), [Et(4)P](+)[(V2O3)(2)(O(3)PPh)(4)F](-) (2), and the methylphosphonato and butyl phosphato analogues of compound 2. Both compounds 1 and 2 oxidize 1,4-cyclohexadiene to benzene, and the reduction product of the methylphosphonato analogue of compound 2 has been characterized as [Et(4)P](+)(1.5) [(4-tert-butylpyridine)(2)H](+)(0.5)[(V2O3)(2)(MePo(3))(4)F](2-) (3). In the mixed-valence compounds 1 and 3 the odd electron is determined by EPR spectroscopy to be localized on a single VO unit in compound 1 and delocalized in compound 3. Compound 1 crystallizes in the tetragonal space group I4/m with cell constants (at -100 degrees C) a = b = 13.788(2) Angstrom A, c = 19.126(3) Angstrom A, V = 3636(1) Angstrom A(3), Z = 2; compound 2 crystallizes in the triclinic space group P ($) over bar 1 with cell constants (at -70 degrees C) a = 12.541(5) Angstrom A, b = 13.177(4) Angstrom A, c = 14.761(5) Angstrom A, alpha = 83.26(4)degrees, beta = 68.91(4)degrees, gamma = 72.23(3)degrees, V = 2167(1) Angstrom A(3), Z = 2; compound 3 crystallizes in the orthorhombic space group Iba2 with cell constants (at -100 degrees C) a = 17.462(3) Angstrom A, b = 33.787(6) Angstrom A, c 14.623(2) Angstrom A, V = 8627(2) Angstrom A(3), Z = 8. Features common to all compounds are the encapsulated halide ion and the role played by the phosph(on)ato moieties : by allowing only three oxygen atoms per phosphorus to participate in cluster bonding, the phosphorus centers become sites of positive Gaussian curvature and support closure into polyhedral structures. Compound 1 realizes "Tenne’s prospect" of expressing a layered structure, in this case alpha-VOPO4, in closed polyhedral form.