Model Investigations for Vanadium-Protein Interactions. Synthetic, Structural, and Physical Studies of Vanadium(III) and Oxovanadium(IV/V) Complexes with Amidate Ligands

Abstract

3, C19H13N3O2SV, Mr = 398.34, monoclinic, P21/n, a = 12.1108(10) Å, b = 19.4439(18) Å, c = 7.2351(7) Å, β = 103.012(3)°, V = 1660.0(4) Å3, Z = 4, R = 0.0355, and Rw = 0.0376

4·CH3CN, C19H12N3O4VNa·CH 3CN, Mr = 461.31, monoclinic, P21/c, a = 11.528(1) Å, b = 11.209(1) Å, c = 16.512(2) Å, β = 103.928(4)°, V = 2071.0(5) Å3, Z = 4, R = 0.0649, and Rw = 0.0806

5·2CH3OH, C20H10N2O5VNa 2·2CH3OH, Mr = 519.31, triclinic, P1, a = 12.839(1) Å, b = 8.334(1) Å, c = 12.201(1) Å, α = 106.492(2)°, β = 105.408(2)°, γ = 73.465(2)°, V = 1175.6(3) Å3, Z = 2, R = 0.0894, and Rw = 0.1043

Reaction of the amide ligand N-[2·((2-pyridylmethylene)amino)phenyl]pyridine-2-carboxamide (Hcapca) with VCl3 affords the compound trans·[VCl2(capca)] (1), the first example of a vanadium(III) complex containing a vanadium-deprotonated amide nitrogen bond, while reaction of bis(pentane-2,4-dionato)oxovanadium(IV) with the related ligands N-[2-((2-phenolylmethylene)amino)phenyl]pyridine-2-carboxamide (H2phepca), 1-(2-hydroxybenzamido)-2-(2-pyridinecarboxamido)benzene (H3hypyb), and 1,2-bis(2-hydroxybenzamido)benzene (H4hybeb) yields the complexes [VO(phepca)] (2), Na[VO(hypyb)]·2CH3OH (4·2CH3OH), and Na2[VO(hybeb)]·3CH3OH (5·3CH3OH) respectively. The preparation of the complex {N-[2-((2-thiophenoylmethylene)amino)phenyl]pyridine2-carboxamido} oxovanadium(IV) (3) has been achieved by reaction of N-(2-aminophenyl)pyridine-2-carboxamide and 2-mercaptobenzaldehyde with [VO(CH3COO)2]x. Oxidation of complex 5·3CH3OH with silver nitrate gives its vanadium(V) analogue (8·CH3OH), which is readily converted to its corresponding tetraethylammonium salt (10·CH2Cl2) by a reaction with Et4NCl. The crystal structures of the octahedral 1·CH3CN, and the square-pyramidal complexes 3, 4·CH3CN, 5·2CH3OH, and 10 were demonstrated by X-ray diffraction analysis. Crystal data are as follows: 1·CH3CN, C18H13Cl2N4OV·CH 3CN Mr = 464.23, monoclinic, P21/n, a = 10.5991(7) Å, b = 13.9981(7) Å, c = 14.4021(7) Å, β= 98.649(2)°, V = 2112.5(3) Å3, Z = 4, R = 0.0323, and Rw 0.0335

10, C28H32N3O5V Mr = 541.52, monoclinic, P21/c, a = 11.711(3) Å, b = 18.554(5) Å, c = 12.335(3) Å, β = 95.947(9)°, V = 2666(2) Å3, Z = 4, R = 0.0904, and Rw = 0.0879. In addition to the synthesis and crystallographic studies, we report the optical, infrared, magnetic, and electrochemical properties of these complexes. Electron paramagnetic resonance [of oxovanadium(IV) species] and 1H, 13C{1H}, and 51V nuclear magnetic resonance [of oxovanadium(V) complex] properties are reported as well. This study represents the first systematic study of vanadium(III), VIVO2+, and VVO3+ species containing a vanadium-deprotonated amide nitrogen bond.