A similar pair of protonated and deprotonated mononuclear oxidovanadium glycolates [VO(Hglyc)(phen)(H2O)]Cl center dot 2H(2)O (1) and [VO(glyc)(bpy)(H2O)] (2) and a mixed-(de)protonated oxidovanadium triglycolate (NH4)(2)[VO(Hglyc)(2)(glyc)]center dot H2O (3) were isolated and examined. The C-O(H) ( C-OH or C-O) groups coordinated to vanadium were spectroscopically and structurally identified. The glycolate in 1 features a bidentate chelation through protonated alpha-hydroxy and alpha-carboxy groups, whereas the glycolate in 2 coordinates through deprotonated alpha-alkoxy and alpha-carboxy groups. The glycolates in 3 coordinate to vanadium through alpha-alkoxy or alpha-hydroxy and alpha-carboxy groups and thus have both protonated C-OH and deprotonated C-O bonds simultaneously. Structural investigations revealed that the longer protonated V-C alpha-hydroxy bonds [2.234(2) angstrom and 2.244(2) angstrom] in 1 and 3 are close to those of FeV-cofactor (FeV-co) 2.17 angstrom (FeMo-co 2.17 angstrom(2)), while deprotonated V-O alpha-alkoxy bonds [2, 1.930(2); 3, 1.927(2) angstrom] were obviously shorter. This shows a similar elongated trend as the Mo-O distances in the previously reported deprotonated vs protonated molybdenum lactates (Wang, S. Y. et al. Dalton Trans. 2018, 47, 7412-7421) and these vanadium and molybdenum complexes have the same local V/Mo-homocitrate structures as those of FeV/Mo-cos of nitrogenases. The IR spectra of these oxidovanadium and the previously synthesized molybdenum complexes including different substituted C-O(H) model compounds show red-shifts for C-OH vs C-O alternation, which further assign the two IR bands of extracted FeMo-co at 1084 and 1031 cm(-1) to C-O and C-OH vibrations, respectively. Although the structural data or IR spectra for some of the previously synthesized Mo/V complexes and extracted FeMo-co were measured earlier, this is the first time that the C-O(H) coordinated peaks are assigned. The overall structural and IR results well suggest the coexistence of homocitrates coordinated with alpha-alkoxy (deprotonated) and alpha-hydroxy (protonated) groups in the extracted FeMo-co.