Showing papers by "Thomas A. Hamor published in 1998"
TL;DR: The reaction between [Mo(NO)(Tp)I(2)] [Tp(-) = hydrotris(3,5-dimethylpyrazol-1-yl)borate] and tetrahexylcalix[4]resorcinarene (resH(8)) affords a mixture of metalated macrocycles that reveal differing patterns of redox potentials depending upon the number and geometric arrangement of metal centers in the macrocyclic structure.
Abstract: The reaction between [Mo(NO)(Tp)I2] [Tp- = hydrotris(pyrazol-1-yl)borate] and tetrahexylcalix[4]resorcinarene (resH8) affords a mixture of metalated macrocycles from which [{Mo(NO)(Tp)}2(resH4)], [{Mo(NO)(Tp)}3(resH2)], and [{Mo(NO)(Tp)}4(res)] can be isolated. In the solid state the tetrametalated compound can act as a host for CH2Cl2 which forms a weak hydrogen bond to the oxygen of a coordinated nitric oxide: H···O1 2.47 A, angle C−H···O1 161°. Direct reaction of [Mo(NO)(Tp*)I2] [Tp*- = hydrotris(3,5-dimethylpyrazol-1-yl)borate] with resorcinol itself offers a route to the related resorcinol-based tetrametallomacrocycle [Mo(NO)(Tp)(1,3-O2C6H4)]4. This reaction also produces the cyclic trimer [Mo(NO)(Tp)(1,3-O2C6H4)]3 together with some cyclic dimer. A similar reaction involving 1,4-dihydroxybenzene and [M(NO)(Tp*)I2] (M = Mo, W) also affords cyclic trimers and cyclic tetramers, but in this case, cyclic dimers are not formed. It has been possible to separate the single isomers syn,syn-[Mo(NO)(Tp*)(1,4-...
48 citations
TL;DR: The dithiol ligand 1,2dicarbaborane-1,2-dithiol, 1, 2-(HS)2-1-2-C2B10H10 (H2cbdt) as mentioned in this paper reacted with anhydrous PdI2 to form [Pd(cldt)I2]2], isolated as its [4-MeC5H4NMe]+ salt, and with MoCl5 in tetrahydrofuran afforded the oxo-bridged molybdenum(V)
Abstract: The dithiol ligand 1,2-dicarbaborane-1,2-dithiol, 1,2-(HS)2-1,2-C2B10H10 (H2cbdt), reacted with anhydrous PdI2 to form [Pd(cbdt)I2]2–, isolated as its [4-MeC5H4NMe]+ salt 1 and with [{Mo(η5-C5H5)(NO)I2}2] in the presence of NEt3 to afford the mononuclear complex [NEt3H][Mo(η5-C5H5)(NO)(cbdt)I] 2. Complete halide substitution occurred with [NBu4][Re(O)Cl4] to give [NBu4][Re(O)(cbdt)2] 3 and the reaction with MoCl5 in tetrahydrofuran afforded the oxo-bridged molybdenum(V) dimer [4-MeC5H4NMe]2[Mo(O)(µ-O)(cbdt)}2] 4 which is diamagnetic. The salts 1–4 have been characterised by single crystal X-ray diffraction studies. In all cases only very limited conjugation appears to occur between the sulfur atoms and the carbon atoms of the carbaborane cage, C–S bond lengths averaging 1.785 A, slightly shorter than the pure single bond value. The electrochemical properties of the new complexes were investigated but no simple reversible electron transfer processes were observed.
22 citations
TL;DR: Molecular modelling showed that the inhibitors fit well in the active site of HSV-1 TK, provided the conformation of the sugar moiety is the same for thymidine in the complex.
Abstract: The synthesis and X-ray crystal structures of a series of 5-substituted-6-aza-2′-deoxyuridines is reported. These nucleoside analogues inhibit the phosphorylation of thymidine by HSV-1 TK but have no effect on the corresponding human enzyme. Detailed examination of one analogue proves it to be a competitive inhibitor of thymidine with a Ki of 0.34 μM and is a very poor substrate. The analogues are not substrates for the enzyme and also do not inhibit the degradation of thymidine by thymidine phosphorylase. Molecular modelling showed that the inhibitors fit well in the active site of HSV-1 TK, provided the conformation of the sugar moiety is the same for thymidine in the complex.
18 citations
TL;DR: In this paper, a comparison of reactions of selenium and tellurium compounds with [Fe3(CO)12] may assist the development of an understanding of the complex reaction pathways.
Abstract: The reaction of 2-telluraphthalide, C8H6OTe, with [Fe3(CO)12] gave as the major characterised species compound 1, [C6H4CH2TeFe(CO)3]2. An iron atom has inserted into the telluracyclic ring, and it is probable that one co-ordinated CO ligand arises from the initially organic carbonyl group. X-Ray single crystal investigations revealed a dimeric structure containing an Fe2Te2 core. The reaction of 2-telluraphthalic anhydride, C8H4O2Te, with [Fe3(CO)12] gave a known, but unexpected, organic product phthalide, C8H6O2. X-Ray crystallography confirmed its isolation; the main feature of interest is the significant double bond character of C(8)–O(1) at 1.352(4) A. 2-Selenaphthalic anhydride, C8H4O2Se, gave intractable products on reaction with [Fe3(CO)12], but 2-selenaphthalide, C8H6OSe, on reaction with the carbonyl gave a major product 2, [Fe(CO)3{C6H4CH2SeFe(CO)3}] and a minor product 3, [Fe(CO)2{η6-C6H4CH2SeFe2(CO)6}] which is an intermediate in the formation of 2. Compound 2 was shown by X-ray methods to be very similar to 1 except that the 18 electron rule is satisfied by co-ordination of an Fe(CO)3 moiety, rather than by dimerisation. Compound 3, also studied by X-ray crystallography, differs from 2 mainly in the addition of an η6-bonded Fe(CO)2 moiety, but the selenaferrole ring is more distorted. It is proposed that comparative studies of reactions of selenium and tellurium compounds with [Fe3(CO)12] may assist the development of an understanding of the complex reaction pathways.
14 citations
TL;DR: The reactions between cyclic dimers and cyclic trimers were analyzed in this article, where the authors showed that cyclic trimmed dimers [Mo(NO)(tp*)(E-E)]2 can afford cyclic light dimers.
Abstract: The reactions between [Mo(NO)(tp*)I2] {tp* = HB(3,5-Me2C3HN2)3} and HE-EH {HE-EH = 1,3-(HSCH2)2C6H4 and 1,4-(HSCH2)2C6H4} afford the cyclic dimers [Mo(NO)(tp*)(E-E)]2 and cyclic trimers [Mo(NO)(tp*...
12 citations
TL;DR: The new compounds [Fe(η5-C5H5) as mentioned in this paper ] and [Fe[1,4-{(CN)2C]-2C6H4] have been synthesized and characterized by their mass, IR and 1H NMR spectra.
9 citations
TL;DR: The structure of the synthesised tellurium compounds, however, were not as expected as mentioned in this paper, and they yielded a hydrated analogue of benzo-2-telluroxo-1,3-diazole.
Abstract: The syntheses of 2,1,3-benzotellaradiazole and 3,4-dimethylbenzo-2,1,3-telluradiazole were attempted by reacting tellurium dioxide with the relevant diamine. The structures of the synthesised tellurium compounds, however, were not as expected. The attempted synthesis of 2,1,3-benzotelluradiazole yielded, instead, its hydrated analogue; benzo-2-telluroxo-1,3-diazole (1). The high melting point and lack of solubility in all common solvents of (1) suggests that it may exist in a polymeric form in the solid state. The attempted synthesis of 3,4-dimethylbenzo-2,1,3-telluradiazole afforded, in small yield, an organic compound, 1 -amino-3,4,7,8-tetraethylphenazine (2), the crystal structure of which was elucidated. This compound is believed to have arisen from the removal of tellurium from the expected diazole, thus yielding a highly reactive intermediate. An attempt to trap this intermediate using dimethyl fumarate proved unsuccessful. The use of tellurium tetrachloride as the tellurium source, in plac...
8 citations
TL;DR: Molecular modelling showed that the inhibitors fit well in the active site of HSV-1 TK, provided the conformation of the sugar moiety is the same for thymidine in the complex.
Abstract: The synthesis and X-ray crystal structures of a series of 5-substituted-6-aza-2′-deoxyuridines is reported. These nucleoside analogues inhibit the phosphorylation of thymidine by HSV-1 TK but have no effect on the corresponding human enzyme. Detailed examination of one analogue proves it to be a competitive inhibitor of thymidine with a Ki of 0.34 μM and is a very poor substrate. The analogues are not substrates for the enzyme and also do not inhibit the degradation of thymidine by thymidine phosphorylase. Molecular modelling showed that the inhibitors fit well in the active site of HSV-1 TK, provided the conformation of the sugar moiety is the same for thymidine in the complex.