Trapping ionic dimers of dinuclear peroxido mandelato complexes of vanadium(V) into cavities constructed from Δ- and Λ-[Ni( phenanthroline ) 3 ] 2+ cations: a precursor to Ni(VO 3 ) 2

A nickel‒vanadium metal–organic hybrid compound [Ni( phen ) 3 ] 2 [(V 2 O 2 (O 2 ) 2 (( S )- mand ) 2 )][(V 2 O 2 (O 2 ) 2 (( R )- mand ) 2 )]·18H 2 O ( phen = 1,10-phenanthroline, mand 2− = mandelato(2−) ligand, C 6 H 5 –CO–COO 2− ) ( 1 ) was prepared and characterized by spectral methods, X-ray structure analysis and simultaneous DTA and TG measurements. The crystal structure of 1 contains both Δ and Λ enantiomers of the [Ni( phen ) 3 ] 2+ cations that construct sandwich layers along the crystallographic axis c , in between which sit the vanadium(V) complex anions. These are present as ionic dimers in the form of a robust {[(V 2 O 2 (O 2 ) 2 (( S )- mand ) 2 )][(V 2 O 2 (O 2 ) 2 (( R )- mand ) 2 )]} 4− species. The two individual anions are coupled by a pair of weak, yet significant attractions between two vanadium atoms and two peroxido ligands of the adjacent anion at V‒O distances 2.660 Å. The 51 V NMR spectrum of the compound in DMSO solution revealed a complicated course of decomposition reactions of the anion, which led to formation of the [(V 2 O 4 ( S , R - mand ) 2 ] 2− anion as a single product. The metal–organic hybrid compound 1 is converted by thermal decomposition into a potential anode material for lithium-ion batteries Ni(VO 3 ) 2 .