Heterometallic Copper-Vanadium Compounds: Crystal Structures of Polymers [Cu(im)(4)(V2O4(mand)(2))](n) and [Cu(im)(4)(V2O4((S)-mand)(2))](n) . 2nH2O (im = imidazole, mand = mandelato(2-))
Abstract
Two new 1D polymeric heterometallic copper-vanadium compounds were prepared. The polymers are constructed from [Cu(im)(4)](2+) cations that are coordinated to two terminal oxido ligands of [V2O4(mand)(2)](2-) anions.
The stronger coordination in [Cu(im)(4)V2O4(mand)(2)](n) (1) that contains the racemic mandelato ligand is manifested by a shorter Cu-O bond distance 2.4095(12) angstrom, while the weaker interaction in [Cu(im)(4)(V2O4((S)-mand)(2))](n) . 2nH2O (2) is exhibited by Cu-O bond distances 2.4547(16) angstrom and 2.5413(16) angstrom. The vanadate anion in compound 2 carries only the (S)-enantiomer of the initial mandelic acid and differs from the anion in 1 in parallel cis orientation of the phenyl groups of the mandelato ligand.
FT-IR spectroscopy was used for the confirmation of the coordination mode of mandelato ligand. Strong bands corresponding to the vibrations of carboxyl groups can be observed around 1650 and at 1344 cm(-1).
The stretching vibration of deprotonated hydroxyl group in the mandelato ligand occurs at 1045 and 1065 cm(-1) for 1 and 2, respectively. In addition, the very strong, characteristic band corresponding to nu(V=O) vibration can be observed at 931 cm(-1) for 1 and 925 cm(-1) for 2, as well as in Raman spectrum.
Graphic The polymeric structures of two new vanadium-copper heterometallic complexes are constructed from [Cu(imidazole)(4)](2+) cations that are coordinated to two terminal oxido ligands of [V2O4(mandelato)(2)](2-) anions with different orientation of the phenyl groups depending on the chirality of the mandelato ligand.