Hydrothermal synthesis and crystal structural characterization of two new modified polyoxometalates constructed of positive and negative metal–oxo cluster ions

Two new interesting polyoxometalate derivatives { [ Ni ( 2 , 2 ′ ‐ bipy ) 2 H 2 O ] 2 [ Mo 3 V Mo 5 VI V 8 IV O 40 ( PO 4 ) ] } { [ Ni ( 2 , 2 ′ ‐ bipy ) 2 H 2 O ] 2 [ Mo 3 V Mo 5 VI V 8 IV O 40 ( PO 4 ) ] } · 5 H 2 O 1 and { [ Co ( 2 , 2 ′ ‐ bipy ) 2 H 2 O ] 4 [ Mo 4 V Mo 4 VI V 8 IV O 40 ( PO 4 ) ] } { [ Co ( 2 , 2 ′ ‐ bipy ) 2 H 2 O ] 2 [ Mo 3 V Mo 5 VI V 8 IV O 40 ( PO 4 ) ] } ( H 3 O ) · 4 H 2 O 2 constructed of modified metal–oxo cluster ions carrying positive and negative changes, respectively, was hydrothermally prepared and structurally characterized by IR, ESR, XPS, elemental analysis and X-ray crystallography. The result of structure determination shows that compound 1 and 2 are isostructural and both contain polyoxocation and polyoxoanion, and both cation and anion are built on mixed Mo–V tetra-capped pseudo-Keggin units with P centre, [Mo8V8O40(PO4)]n−, bonded to four or two [Ni(2,2′-bipy)2H2O]2+ complexes, respectively, via terminal oxygen of the capping V atoms. Magnetism measurement indicates that there exists antiferromagnetic interaction in complex 1 and 2.