Preparations and properties of transition-metal pterin complexes. Models for the metal site in phenylalanine hydroxylase

Synthesis, Characterization of New Tungsten(IV)?Pterin Complexes and their Reactivity Studies towards Trimethylamine N-Oxide, Sodium Borohydride and Potassium Ferricyanide

“…Absence of such vibrations in the corresponding complexes (2,3,4) indicate deprotonation of such functional groups in forming the pterin ligand anion, L 2- (Figure 2). On the other hand, a new distinct band of variable intensity is observed at 1261 cm -1 for the present complexes, which may be assigned to the ν(C-O) mode of the O(4) phenoxide group [28]. For (1) the ν(C=N) and ν(C=C) vibrations of the pterin ring appear at 1660 cm -1 , 1589 cm -1 and 1481 cm -1 as strong-to-medium intensity bands [29]; the positions and shapes of these bands undergo moderate alteration in the corresponding complexes due to tautomerism/deprotonation/ electronic redistribution during the complex formation process involving the N( use of a combination of PPh3 and the ancillary ligands, leads to the formation of the desired complexes (3) and (4) from (2) [21,22].…”

“…This data also support Scheme 1, indicating the formation of a mononuclear species relevant to (3) and (4) IR spectral data (KBr pellets) of the present compounds, are helpful in characterizing some of their functional groups. For the pterin ligand (1) ( Figure 1 shows the structural formulas of its tautomers) two medium intensity broad bands at 1363 cm -1 and 1209 cm -1 could be assigned to the δ(N-H) and δ(N-H)+ν(C-N) vibrations respectively, of its NH(3) and NH(5) groups [28]. Absence of such vibrations in the corresponding complexes (2,3,4) indicate deprotonation of such functional groups in forming the pterin ligand anion, L 2- (Figure 2).…”

Studies on a new dinuclear CoII–pterin complex exhibiting reactivity towards phenylalanine and bromobenzene

“…Table 2 shows a comparison of relevant optimized bond length data (Å ) of (1) and (2), indicating changes in few of them during the complex formation process. A perusal of these data indicates ( Figure 2 in the light of Schemes 1 and 2) that the dianion of (1) (Scheme 2) is attached to the 6-coordinate Co II atom through the O(4), N(5) and Oð2 0 Þ atoms, involving the amide function in position 3,4 and the vinylogous amide in position 5 [7][8][9][11][12][13]. From changes in the Cð1 00 Þ À Oð1 00 Þ, N(3)-C(4) and N(3)-C(2) bond lengths, it can be inferred that the 5-coordinate Co II atom is bonded to the pterin ligand residue via the N(3) and Oð2 00 Þ atoms.…”

“…The ability of pterins to exhibit multiple redox activity parallels that of the transition metal counterparts in these systems [5,6]. Development of different facets of coordination chemistry of pterin ligands is valuable for understanding the role of this unique organic moiety in biological systems [7][8][9][10][11][12][13][14]. Here we concentrate our attention on the complex forming ability of Co II ion towards 2-pivaloylamino-6-acetonylisoxanthopterin (1, H 2 L, Scheme 1) and reactivity of the resulting complex towards phenylalanine (as well as towards bromobenzene) in presence of O 2 .…”

A Ruthenium Pterin Complex Showing Proton‐Coupled Electron Transfer: Synthesis and Characterization

“…The imidate coordination has been observed in [M(NDMP À ) 2 (MeOH) 2 ] (M = Fe, Co, Ni; HNDMP = 2-dimethylamino-4(3H)-pteridinone) [13] and [Cu(tppb)(pterin)] (tbbp = tris(3-phenylpyrazolyl)hydroborate). [19] This difference probably stems from the interactions of pterins with metal d orbitals and the Lewis acidity of the Ru-TPA unit, in which three pyridine moieties act as p acceptors to increase the acidity on the metal center which facilitates the deprotonation of Hdmdmp, and which results in the imidate binding. The cyclic voltammogram (CV) of 1 was measured in CH 3 CN.…”