Pyrimidine complexes

A measure of the promiscuity of these diacids was attempted with pyrimidine 26 vs pyrazine 20. The two heterocycles differ in size, shape and also basicity in addition, stacking interactions can be observed in the pyrimidine complex but not with pyrazine. These four variables make interpretation with confidence somewhat futile since it is difficult to attribute the binding differences to any particular feature. 

Pyridinium tetrachloroantimonite, secondary bonding by, 15 32-33 p-Pyrimidine complexes, osmium, 37 307 2-Pyrimidinethiolato complexes, osmium, 37 295-296... 

Little is known about the chemistry of silver(I) complexes of unsubstituted pyrimidine however, an extensive range of substituted pyrimidine complexes have been investigated due to their use in the preparation of nucleic acid constituents.85 94 In these reactions, which lead to the formation of glycosides, silver salts of uracils or thymines are treated with poly-0-... 

Metallomesogens (continued) examples, 12, 273 imine complexes, 12, 254 pyrimidine complexes, 12, 270 overview, 12, 195-293 via palladacycles, 8, 288 thermotropic liquid crystals, 12, 197 Metalloorganic chemical-vapor deposition, for semiconductor growth, 12, 8... 

In 1-substituted pyrimidine complexes, migration of platinum from en-docyclic to exocyclic nitrogen has been observed, i.e., migration of PtIV from N(3) to the exocyclic C(4)-NH2 group in 1 -MeCyt (1 -MeCyt = 1 -meth-ylcytosine) [36]. In the initial complex trans, trans, trans-[Pt(OH)2(NH3)2(l-MeCyt-N(3))2]2+, the V(3),A(4 )-chelate is formed with the elimination of H20 from the complex (Scheme 7). Addition of H20 to the chelated com-... 

Tamasi G, Botta F, Cini R (2006) DFT-molecular modeling analysis of C-H- -N and C-H- - -S hydrogen bond type interactions in selected platinum-purine/pyrimidine complexes. J Mol Struct... 

Uracil-cytosine base pairs are mixed pyrimidine-pyrimidine complexes, which are biologically less or even not at all important. There are six two-bond configurations, of which only CU52, CU62 could occur in nucleic acids. 

And finally, more types of activity are being studied. The first edition listed activities in only 11 categories. This volume discusses activities in 18 categories, including enzymes for metabolism of lipids, vitamins, xenobiotics, pyrimidines, complex saccharides, and glycoproteins, and activities that modify proteins and peptides, as well the modification of nucleic acids and their expression. 

Aggarwal SK, Wagner RW, McAllister PK, Rosenberg B. Cell-surface-associated nucleic acid in mmorigenic cells made visible with platinum-pyrimidine complexes by electron microscopy. Proc. Natl. Acad. Sci. U.S.A. 1975 72 928-932. 

Conformational Properties of Purine and Pyrimidine Complexes of cis-Platinum... 

Mixed Purine/Pyrimidine Complexes. Unfortunately, only very limited structural information is available (15, 16) for mixed purine/pyrimidine complexes of Pt(II). In fact, so far only complexes containing N(7)-bound 9-ethylguanine (or its N(l)-depro-tonated monoanion) and N(3)-bonded 1-methyIcytosine have been structurally characterized. Conformational drawings for these complexes are presented in Figure 5. 

Nevertheless, these restrictions obtain for most purine and pyrimidine complexes with (NH3) Ru(III), so that this and related equations have considerable predictive power (as will be seen below.)... 

Pyrazine forms pink insoluble [CoX2(pyz)2] and [CoX2(pyz)] complexes (X = Cl, Br, I), which are presumably polymeric and octahedral,but monomeric tetrahedral units are possible with increased methyl substitution. No direct confirmation of bridging pyrazine has been found in these Co" systems. Some orange-red 2-substituted carboxylate and carboxamide pyrazine complexes have been prepared " and a distorted octahedral geometry has been confirmed by O Connor and Sinn, with chelated ligands (Table 22). No well-characterized pyridazine or pyrimidine complexes have been reported. 

Purpureocobalt — see Cobalt, chloropentaammine-Purpureocobaltic chloride —see Cobalt, chloropentaammine-, chloride Pyridine, 2-hydroxy-5-methyl-dodecacobalt complexes, 168 Pyridine complexes linkage isomers, 186 Pyrimidine complexes... 

Figure 20 The edge-expansion approach to construct MOFs with zeolitic topologies. Distances indicated in the figure are average Si- -Si, in zeolites, and M- -M distances in dinuclear imidazolate and pyrimidine complexes (CSD V5.30, Jan 2011).

In structural work, the exact conformation may be affected by a combination of intra- and inter-complex interactions such as counterion, medium of recrystallization, hydrogen bonding and steric effects of the particular substituted nucleobase studied [4, 5]. These effects have to be somewhat separated from inherent effects such as the dihedral angles discussed above, although the interplay is complicated. The various parameters have been summarized for bis(purine), bis(pyrimidine) and mixed purine and pyrimidine complexes and for hydrogen bonding patterns. The reader is referred to the references [69—71] for detailed analysis of these points. 

The cytosine structures also reflect thermodynamic tendencies, although, as stated, exocyclic amine binding has been observed. For bis(pyrimidine) complexes, the trends are in fact opposite to those observed for the bis(guanine) systems and result in severe crowding for the [Pt(NH3)2(l-MeCyt)2] cation. 

T. J. Kistenmacher, J. D. Orbell, and L. G. Marzilli Conformational Properties of Purine and Pyrimidine Complexes of cis-Platinum Implications for Platinum(II)— DNA Crosslinking Modes (Platinum, Gold and Other Metal Chemotherapeutic Agents, ACS Symposium Series v. 209, Ed. S. J. Lippard), p. 191. ACS, Washington... 

The reaction of ci>[Pt(NH3)2(H20)2] with 1-MeU or 1-MeT anions in basic solution gives the bis(pyrimidine) complexes [32, 33] which with HCl yield the mono complexes [34] e.g. ... 

The many pyrimidine complexes synthesized and structurally characterized in the foregoing work will clearly be of great use in elucidating the full potential of the biological activity of these complexes. The suggestion has been made that the activity reported could be due to slow release, by hydrolysis, of dimers and monomers [69]. Initial studies on some of these... 

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