Structure of 5-methyl-2'-deoxycytidine 5'-monophosphate dihydrate

CloHI6N307P.2H20 , Mr = 357.2, triclinic, P1, a = 4-8520 (8), b = 8"3703 (8), c = 10.0199 (12) A, a= 104.578 (9),/3= 102.332 (13), 7=93.670(11) o, V = 381"75 A 3, Z = 1, Dx = 1"55, Dm = 1"53 Mg m -3, a(Cu Ka) = 1.5418 A,/z = 2.01 mm- l, F(000) = 188, T= 290 K, R = 0-049 for 1568 unique reflections.

Stability of CU(2)Ln(2)O(5) compounds - Comparison, assessment and systematics

Phase diagram studies show that at ambient pressure only one ternary oxide, Cu(2)Ln(2)O(5), is stable in the ternary systems Cu-Ln-O (Ln = Tb, Dy, Ho, Er, Tm, Yb, Lu) at high temperatures. The crystal structure of Cu(2)Ln(2)O(5) can be described as a zig-zag arrangement of one-dimensional Cu2O5 chains parallel to-the a-axis with Ln atoms occupying distorted octahedral sites between these chains. Four sets of emf measurements on Gibbs energy of formation of Cu(2)Ln(2)O(5) (Ln = Tb, Dy, Ho, Er, Tm, Yb, Lu; Y) from component binary oxides and one set of high-temperature solution calorimetric data on enthalpy of formation have been reported in the literature. Except for Cu2Y2O5, the measured values for the Gibbs energies of formation of all other Cu(2)Ln(2)O(5) compounds fall in a narrow band (+/-1 kJ mol(-1)) and indicate a regular increase in stability with decreasing ionic radius of the lanthanide ion. The values for the second law enthalpy of formation, derived from the temperature dependence of emf obtained in different studies, show larger differences, as high as 25 kJ mol(-1) for Cu2Tm2O5. Though associated with an uncertainty of +/-4 kJ mol(-1), the calorimetric measurements help to identify the best set of emf data. The trends in thermodynamic data correlate well with the global instability index (GII) based on the overall deviation from the valence sum rule. Low values for the index calculated from crystallographic information indicate higher stability. Higher values are indicative of the larger stress in the structure.

Interaction of metal ions with 6-oxopurine nucleotides. Part 2. X-Ray structures of ternary nickel(II) complexes with 2'-deoxyguanosine 5'-monophosphate or guanosine 5'-monophosphate

The ternary metal nucleotide complexes [Ni(en)1.3(H2O)1.4(H2O)2][Ni(5?-dGMP)2(en)0.7-(H2O)0.6(H2O)2]·7H2O (1) and [Ni(en)2(H2O)2][Ni(5?-GMP)2(H2O)4]·6H2O (2)(en = ethylenediamine, 5?-dGMP = 2?-deoxyguanosine 5?-monophosphate, 5?-GMP = guanosine 5?-monophosphate) have been prepared and their structures analyzed by X-ray diffraction methods. Both compounds crystallise in the space group C2221 with a= 8.810(1), b= 25.090(4), c= 21.084(1)Å, and Z= 4 for (1) and a= 8.730(1), b= 25.691(4), c= 21.313(5)Å, and Z= 4 for (2). The structures were deduced from the analogous CoIII complexes and refined by full-matrix least-squares methods to final R values of 0.087 and 0.131 for 1 211 and 954 reflections for (1) and (2) respectively. An interesting feature of the deoxyribonucleotide complex (1) is that en is not totally labilized from the metal centre on nucleotide co-ordination, as observed in corresponding ribonucleotide complexes. Apart from extensive intra- and inter-molecular hydrogen bonding, the structures are stabilized by significant intracomplex base�base and base�sugar interactions. The nucleotides in both complexes have an anti base, C(2?)-endo sugar pucker, and gauche�gauche conformation about the C(4?)�C(5?) bond.

Synthesis, structure and magnetic properties of the polyoxovanadate cluster Zn-2(NH2(CH2)(2)NH2)(5)]{Zn(NH2(CH2)(2)NH2)(2)}(2){V18O42(H2O)\ ]center dot xH(2)O (x similar to 12), possessing a layered structure

A hydrothermal reaction of a mixture of ZnCl2, V2O5, ethylenediamine and water gave rise to a layered poly oxovanadate material. clusters. These clusters, with all the vanadium ions in the +4 state, are connected together through Zn(NH2(CH2)(2)NH2)(2) linkers forming a two-dimensional structure. The layers are also separated by distorted trigonal bipyramidal [Zn-2(NH2(CH2)(2)NH2)(5)] complexes. The Structure, thus, presents a dual role for the Zn-ethylenediamine complex. The magnetic susceptibility studies indicate that the interactions between the V centres in I are predominantly antiferromagnetic in nature and the compound shows highly frustrated behaviour. The magnetic properties are compared to the theoretical calculations based oil the Heisenberg model, in addition to correlating to the structure. Crystal data for the complexes are presented.

Synthesis Of (+/-)-2-Isopropyl-5,6-Dimethylbicyclo[3.2.1]Oct-6-En-8-One

Methanolic hydrogen chloride cyclization of the triketone 8, prepared from the Mannich base 7 and 2-methylcyclopentane-1,3-dione, gives ketones 9 and 10. NaBH4 reduction of 9 followed by Grignard reaction with CH3MgI affords the diol 12. Catalytic hydrogenation of 12 followed by PCC oxidation yields the ketoalcohol 13. Dehydration of 13 with SOCl2/pyridine results in a 1:1 mixture of the endo-14 and exo-15 olefins, separated by chromatography.

Synthetic investigations on illudinine: a new synthesis of methyl 8-methoxy-2,2-dimethyl-7-oxo-1,2,3,5,6,7-hexahydro-s-indacene-4-carboxylate

A new strategy for the total synthesis of methyl 8-methoxy-2,2-dimethyl-7-oxo-1,2,3,5,6,7-hexahydro-s-indacene-4-carboxylate 4, a key intermediate in the synthesis of illudalanes, is reported. The key step in this strategy is a new method of preparation of indanones from tetralones. Thus, the furfurylidene derivative of 6-methoxy-3,4-dihydronaphthalen-1-(2H)-one is oxidised to the dicarboxylic acid 9a which is cyclodehydrated to methyl 7-methoxy-1-oxoindan-4-carboxylate 10. Similar reactions on the tetrahydronaphthalenone 25, obtained from 6-methoxy-1,2,3,4-tetrahydronaphthalene-7-carbaldehyde 11 by sequential transformations including a regiospecific benzylic oxidation resulted in the hexahydro-s-indacenone 4, thus completing a formal synthesis of illudinine 1.

Charge Transfer Complexes of Crown Ethers with 2, 3, 5, 6 - Tetracyano Pyrazine

The interaction of five crown ethers, 15-crown-5, 18-crown-6, benzo-15-crown-5, dibenzo-l8-crown-6, and dibenzo-24-crown-8 with 2, 3, 5, 6 - tetracyano pyrazine has been studied by spectroscopic methods. The association constants and thermodynamic parameters of the 1:1 complexes formed by donor ethers with the acceptor have been evaluated. There is an indication that oxygens of the ethers and aryl part of the ether act cooperatively in binding of the acceptor.

Bridgehead substitution of 1-methoxybicyclo[2.2.2]oct 5-en-2-one derivatives: towards the synthesis of (±)-allo-cedrol [khusiol]1

Preparation of the key intermediates, 11 and 21, required for the synthesis of (+/-)-allo-cedrol (khusiol) is reported by a novel methodology involving the substitution at the bridgehead position of 1-methoxybicyclo[2.2.2]oct-5-en-2-one derivatives

Influence of acetyl and bromine substitutions on stacking. Crystal and molecular structures of 8-bromo-2',3',5'-triacetyl adenosine and 8-bromo 2',3',5'-triacetyl guanosine

The three dimensional structures of 8-bromo 2',3',5' triacetyl adenosine (8-Br Tri A) and 8-bromo 2',3',5'-triacetyl guanosine (8-Br Tri G) have been determined by single crystal X-ray diffraction methods to study the combined effect of bromine and acetyl substitutions on molecular conformation and interactions. The ribose puckers differ from those found in unbrominated Tri A and Tri G and unacetylated 8-Br A and 8-Br G analogues

Linear electro‐optic dispersion in (‐)‐2‐(α‐methylbenzylamino)‐5‐nitropyridine single crystals

The variation of the linear electro-optic effect in (-)-2-(alpha-methylbenzylamino)-5-nitropyridine with the wavelength of the incident light at room temperature has been measured. The reduced half-wave voltages have been found to have the values 2.1, 2.8, and 6.0 kV at 488, 514.5, and 632.8 nm respectively and the corresponding values of the linear electro-optic coefficient have been evaluated.;The interpretation of the results in terms of the structures of the molecule and the crystal is discussed. The thermal variation of the birefringence has also been investigated and the coefficient for the temperature variation of the refractive index difference is found to have the value (d Delta n/dT)=9.3X10(-5) K-1.