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Metal-metal Bonding in Tetracyanometallates (M=PtII, PdII, NiII) of monovalent Thallium. Chrystallographic and Spectroscopic Characterization of the new Compounds Tl2Ni(CN)4 and Tl2Pd(CN)4

The new crystalline compounds Tl2Ni(CN)(4) and Tl2Pd(CN)(4) were synthesized by several procedures. The structures of the compounds were determined by single-crystal X-ray diffraction. The compounds are isostructural with the previously reported platinum analogue, Tl2Pt(CN)(4). A new synthetic route to the latter compound is also suggested. In contrast to the usual infinite columnar stacking of [M(CN)(4)](2-) ions with short intrachain M-M separations, characteristic of salts of tetracyanometalates of Ni-II, Pd-II, and Pt-II, the structure of the thallium compounds is noncolumnar with the two Tl-I ions occupying axial vertices of a distorted pseudo-octahedron of the transition metal, [MTl2C4]. The Tl-M distances in the compounds are 3.0560(6), 3.1733(7), and 3.140(1) A for Ni-II, Pd-II, and Pt-II, respectively. The short Tl-Ni distance in Tl2Ni(CN)(4) is the first example of metal-metal bonding between these two metals. The strength of the metal-metal bonds in this series of compounds was assessed by means of vibrational spectroscopy. Rigorous calculations, performed on the molecules in D-4h point group symmetry, provide force constants for the Tl-M stretching vibration constants of 146.2, 139.6, and 156.2 N/m for the Ni-II, Pd-II, and Pt-II compounds, respectively, showing the strongest metal-metal bonding in the case of the Tl-Pt compound. Amsterdam density-functional calculations for isolated Tl2M(CN)(4) molecules give Tl-M geometry-optimized distances of 2.67, 2.80, and 2.84 A for M = Ni-II, Pd-II, and Pt-II, respectively. These distances are all substantially shorter than the experimental values, most likely because of intermolecular Tl-N interactions in the solid compounds. Time-dependent density-functional theory calculations reveal a low-energy, allowed transition in all three compounds that involves excitation from an a(1g) orbital of mixed Tl 6p(z)-M nd(z)(2) character to an a(2u) orbital of dominant Tl 6p(z) character

Therapy-Induced Antibodies Against the Antiviral and Antiproliferative Effects of Interferons in Patients with Chronic Hepatitis C Virus Infection

Sera from 86 patients with chronic hepatitis C virus (HCV) infection treated with recombinant interferons-α (rIFN-α) were screened for IFN-binding and antiviral effect-neutralizing antibodies. Out of the 61 patients treated with rIFN-α2b, 46% had binding and 28% had neutralizing antibodies. 44% of the 25 patients treated with rIFN-α2a developed binding antibodies and 24% had neutralizing antibodies. Contradictory data were observed concerning the appearance of anti-IFN antibodies and the outcome of IFN therapy. A significantly higher number of the patients with a sustained response to rIFN-α2b therapy formed antibodies than the number among the non-responder patients. At the same time, in the patients treated with rIFN-a2a, opposite data were found. The activity of the antibodies in some sera was studied against the antiproliferative effect of IFNs on Daudi cells by measuring the [3H]thymidine incorporation. The binding antibodies without neutralization of the antiviral effect of the IFNs inhibited the antiproliferative activity of the rIFNs, similarly to antibodies having both IFN-binding and antiviral effect-neutralizing capacities. At the same time, the antiproliferative effect of the natural IFN was less affected. It is suggested that the antiproliferative assay is more sensitive than the antiviral method for demonstration of the presence of antibodies exerting an inhibitory effect on the biological activities of IFN