RESUMEN
Abstract: The reaction of [Cp#2NbTe2H] (1#; Cp# = Cp* (C5Me5) or Cp(x) (C5Me4Et)) with two equivalents of [Co2(CO)8] gives a series of cobalt carbonyl telluride clusters that contain different types of niobocene carbonyl fragments. At 0 degrees C, [Cp#2NbTe2CO3(CO)7] (2#) and [Co4Te2(CO)10] (3) are formed which disappear at higher temperatures: in boiling toluene a mixture of [cat2][Co9Te6(CO)8] (5#) (cat= [Cp#2Nb(CO)2]+) and [cat2][Co11Te7(CO)10] (6#) is formed along with [cat][Co(CO)4] (4#). Complexes 6# transform into [cat][Co11Te7(CO)10] (7#) upon interaction with HPF6 or wet SiO2. The molecular structures of 2(Cp(x)), 4(Cp(x)), 5(Cp*), 6(Cp*) and 7(Cp*) have been determined by X-ray crystallography. The structure of the neutral 2(Cp(x)) consists of a [Co3(CO)6Te2] bipyramid which is connected to a [(C5Me4Et)2Nb(CO)] fragment through a mu4-Te bridge. The ionic structures of 4(Cp(x)), 5(Cp*), 6(Cp*) and 7(Cp*) each contain one (4, 7) or two (5, 6) [Cp#2Nb(CO)2]+ cations. Apart from 4, the anionic counterparts each contain an interstitial Co atom and are hexacapped cubic cluster anions [Co9Te6(CO)8]2- (5) or heptacapped pentagonal prismatic cluster anions [Co11Te7(CO)10]n- (n=2: [6]2- , n=1: [7]-), respectively. Electrochemical studies established a reversible electron transfer between the anionic clusters [Co11,Te7(CO)10]- and [Co11Te7(CO)10]2in 6# and 7# and provided evidence for the existence of species containing [Co11Te7(CO),0] and [Co11Te7(CO)0]3-. The electronic structures of the new clusters and their relative stabilities are examined by means of DFT calculations.
RESUMEN
A pathogenetic relationship is postulated for the development of membranoproliferative glomerulonephritis type I in non-Hodgkin's lymphoma (B-cell lymphoma of low-grade malignancy) and myeloproliferative syndrome, which we have observed in eight patients. This hypothesis is supported by the fact that chronic lymphatic leukaemia and immunocytoma are often associated with immunodysregulative phenomena, and by the immunohistological and ultrastructural findings in the kidney, especially the frequent electron-microscopic finding of cryoglobulins, which results in the membranoproliferative type of immune-complex glomerulonephritis, an expression of a disturbance in immune balance. The pathogenetic mechanism may involve cryoglobulins themselves as immune complexes; it is also possible that monoclonal cryoglobulins combine with an antigen to form immune complexes or lead to in situ formation of immune complexes. In addition, other immune complexes, for example with endogenous tumour-associated antigens and exogenous antigens (e.g. hepatitis antigens), may be involved in the pathogenesis.