Pyrazolylborate−Zinc Complexes of RNA Precursors and Analogues Thereof

Abstract

The Tp ligand tris(3-cumenyl-5-methylpyrazolyl)borate was found to stabilize zinc complexes of nucleobases, of their natural precursors, and of nucleoside and nucleotide derivatives. Dihydroorotic acid and orotic acid are bound as monodentate carboxylate ligands. Uracil is coordinated via its deprotonated N1; 6-methylthiouracil acts as a bidentate ligand via N1 and S. Analogously, xanthine is a monodentate ligand bound by its deprotonated N7, while 6-mercaptopurine seems to bind in a bidentate fashion via N7 and S. Spectroscopic evidence indicates coordination of uridine and 2',3'-O-isopropylideneuridine via their deprotonated N3, as well as of xanthosine via N7. The hydrolytic cleavage of 2',3'-O-isopropylideneuridine 5'-(bis(p-nitrophenyl) phosphate) by TpZn-OH is preceded by an attachment of one TpZn unit to the deprotonated uracil base, presumably via N3.

Theoretical and spectroscopic studies of lanthanum (III) complex of 5-aminoorotic acid

“…The laser power of 100 mW was used in our measurements. 1 H NMR spectra were recorded at room temperature in DMSO-d 6 using a Bruker 250 WM (250 MHz) spectrometer. Chemical shifts are given in ppm, downfield from TMS.…”

“…1) has been studied [1][2][3][4][5][6][7][8][9][10][11][12][13][14] in the area ranging from bioinorganic to pharmaceutical and materials chemistry. Orotic acid occupies a unique position in biology by being the only effective precursor in the biosynthesis of pyrimidine bases of nucleic acids in living organisms [15,16].…”

“…Despite the interest in orotate metal complexes, the coordination chemistry of the orotic acid derivatives has received rather scant attention [1,[9][10][11][24][25][26][27][28]. One of these derivatives is 5-aminoorotic acid (HAOA) (5-amino-2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid, Fig.…”

Uracilato and 5-halouracilato complexes of Cu(II), Zn(II) and Ni(II). X-ray structures of [Cu(uracilato-N1)2(NH3)2]·2(H2O), [Cu(5-chlorouracilato-N1)2(NH3)2](H2O)2, [Ni(5-chlorouracilato-N1)2(en)2]·2H2O and [Zn(5-chlorouracilato-N1)(NH3)3]·(5-chlorouracilato-N1)·(H2O)

“…A great number of metal 1-methyluracilato [9] and uracilato complexes with Cd(II) [10], Ni(II) [11,12], Hg(II) [13], Pt(II) [12,14,15] and Zn(II) [16][17][18] have been described, but, to our knowledge, only an example of Xray structure of metal complexes with 5-halouracilatos is known: the [Cu(5-fluorouracilato-N 1 ) 2 (NH 3 ) 2 (H 2 O)] complex, where the metal is bound to 5-fluorouracilato via N 1 in a limit 4 + 1 square-pyramidal coordination [7]. Recently, the interaction 5-fluorouracil with cisplatin derivatives has been studied [19].…”

Organometallic Complexes of Uracil and Orotic Acid Derivatives: Coordination Mode, Structure, and Reactivity

“…[13,14] Recently, we have examined the coordination modes of uracils and orotic acid derivatives to zero-valent group-6 carbonylmetal compounds, focusing our studies on the ability of the ring nitrogen atoms to serve as π-donor ligands and to facilitate CO dissociation. [15,16] Previously, investigations of the coordination chemistry of uracils have revealed a wide range of metal-dependent binding modes, including via N1, N3, the exocyclic oxygen atoms, [1,2] both an endocyclic nitrogen and an exocyclic oxygen (or sulfur) atom, [15,17] and finally, though less common, through C5. [18] Herein, we wish to communicate a continuation of our studies of organometallic derivatives of uracils and orotic acid derivatives.…”