Syntheses and characterization of phosphonates and diphosphonates of molybdenum, A 4 [(MoO 3 ) 5 (O 3 PR) 2 ]·xH 2 O, A 2 [Mo 2 O 5 (O 3 PR) 2 ] and A 2 [Mo 2 O 5 (O 3 P-R-PO 3 )] (A = K, Rb, Cs, Tl, NH 4 ).

Twenty new molybdenum phosphonates and diphosphonates have been synthesized and structurally characterized by single crystal and powder X-ray diffraction, CHN analyses, spectroscopic and thermal studies. Four of them are molecular phenyl- and benzyl-phosphonates containing discrete [(MoO3 )5 (O3 PR)2 ]4- (R = Ph or CH2 Ph) cyclic anions. The sixteen non-molecular compounds are layered isostructural phenylphosphonates, A2 [Mo2 O5 (O3 PPh)2 ] (A = NH4 , Tl, Rb, Cs) and K1.5 (H3 O)0.5 [Mo2 O5 (O3 PPh)2 ] and the corresponding diphosphonate compounds with pillared anionic layers, A2 [Mo2 O5 (O3 P(CH2 )3 PO3 )], A2 [Mo2 O5 (O3 P(CH2 )4 PO3 )] and A2 [Mo2 O5 (O3 P(C6 H4 )PO3 )]. The A+ ions reside in the interlayer region as well as in the cavities within the anionic layers.