title: Model Investigations for Vanadium-Protein Interactions. Synthetic, Structural, and Physical Studies of Vanadium(III) and Oxovanadium(IV/V) Complexes with Amidate Ligands.
abstract: Reaction of the amide ligand N-[2-((2-pyridylmethylene)amino)phenyl]pyridine-2-carboxamide (Hcapca) with VCl(3) affords the compound trans-[VCl(2)(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 (H(2)phepca), 1-(2-hydroxybenzamido)-2-(2-pyridinecarboxamido)benzene (H(3)hypyb), and 1,2-bis(2-hydroxybenzamido)benzene (H(4)hybeb) yields the complexes [VO(phepca)] (2), Na[VO(hypyb)].2CH(3)OH (4.2CH(3)OH), and Na(2)[VO(hybeb)].3CH(3)OH (5.3CH(3)OH) respectively. The preparation of the complex {N-[2-((2-thiophenoylmethylene)amino)phenyl]pyridine-2-carboxamido}oxovanadium(IV) (3) has been achieved by reaction of N-(2-aminophenyl)pyridine-2-carboxamide and 2-mercaptobenzaldehyde with [VO(CH(3)COO)(2)](x)(). Oxidation of complex 5.3CH(3)OH with silver nitrate gives its vanadium(V) analogue (8.CH(3)OH), which is readily converted to its corresponding tetraethylammonium salt (10.CH(2)Cl(2)) by a reaction with Et(4)NCl. The crystal structures of the octahedral 1.CH(3)CN, and the square-pyramidal complexes 3, 4.CH(3)CN, 5.2CH(3)OH, and 10 were demonstrated by X-ray diffraction analysis. Crystal data are as follows: 1.CH(3)CN, C(18)H(13)Cl(2)N(4)OV.CH(3)CN M(r) = 464.23, monoclinic, P2(1)/n, a = 10.5991(7) Å, b = 13.9981(7) Å, c = 14.4021(7) Å, beta = 98.649(2)(o), V = 2112.5(3) A(3), Z = 4, R = 0.0323, and R(w) 0.0335; 3, C(19)H(13)N(3)O(2)SV, M(r) = 398.34, monoclinic, P2(1)/n, a = 12.1108(10) Å, b = 19.4439(18) Å, c = 7.2351(7) Å, beta = 103.012(3) degrees, V = 1660.0(4) Å(3), Z = 4, R = 0.0355, and R(w) = 0.0376; 4.CH(3)CN, C(19)H(12)N(3)O(4)VNa.CH(3)CN, M(r) = 461.31, monoclinic, P2(1)/c, a = 11.528(1) Å, b = 11.209(1) Å, c = 16.512(2) Å, beta = 103.928(4)(o), V = 2071.0(5) Å(3), Z = 4, R = 0.0649, and R(w) = 0.0806; 5.2CH(3)OH, C(20)H(10)N(2)O(5)VNa(2).2CH(3)OH, M(r) = 519.31, triclinic, P1, a = 12.839(1) Å, b = 8.334(1) Å, c = 12.201(1) Å, alpha = 106.492(2) degrees, beta = 105.408(2) degrees, gamma = 73.465(2) degrees, V = 1175.6(3) Å(3), Z = 2, R = 0.0894, and R(w) = 0.1043; 10, C(28)H(32)N(3)O(5)V M(r) = 541.52, monoclinic, P2(1)/c, a = 11.711(3) Å, b = 18.554(5) Å, c = 12.335(3) Å, beta = 95.947(9) degrees, V = 2666(2) Å(3), Z = 4, R = 0.0904, and R(w) = 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 (1)H, (13)C{(1)H}, and (51)V nuclear magnetic resonance [of oxovanadium(V) complex] properties are reported as well. This study represents the first systematic study of vanadium(III), V(IV)O(2+), and V(V)O(3+) species containing a vanadium-deprotonated amide nitrogen bond.
authors.affiliation: Department of Chemistry, Section of Inorganic and Analytical Chemistry, University of Ioannina, 45110 Ioannina, Greece, Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., 116 35 Athens, Greece, and NRPCS Demokritos, Institute of Materials Science, 15310 Aghia Paraskevi Attikis, Greece.
authors.forename: Anastasios D.
authors.initials: AD
authors.lastname: Keramidas
authors.forename: Aggelos B.
authors.initials: AB
authors.lastname: Papaioannou
authors.forename: Antonis
authors.initials: A
authors.lastname: Vlahos
authors.forename: Themistoklis A.
authors.initials: TA
authors.lastname: Kabanos
authors.forename: George
authors.initials: G
authors.lastname: Bonas
authors.forename: Alexandros
authors.initials: A
authors.lastname: Makriyannis
authors.forename: Cathrin P.
authors.initials: CP
authors.lastname: Rapropoulou
authors.forename: Aris
authors.initials: A
authors.lastname: Terzis