Biomedical subjects
Publications and source records attributed to Thomas P. Fehlner.
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The reaction of W(2)(OOCCF(3))(4) with (CO)(9)Co(3)CCOOH and Na[OOCCF(3)] in a nonpolar solvent mixture leads to the formation of the cluster of clusters {[Na][W(2){OOCCCo(3)(CO)(9)}(2)(OOCCF(3))(4)(THF)(2)]}(2), 1, in 40% yield. The structure of 1.3C(6)H(5)CH(3) in the solid state corresponds to a dimer of W(2) dinuclear complexes (monoclinic P2(1)/c, a = 15.234(6) Å, b = 23.326(11) Å, c = 20.658(7) Å, beta = 102.46(3) degrees; V = 7,168(5) Å(3); Z = 4; R(F)() = 8.39%). Each W(2) unit is bridged by two cis cluster carboxylates, and the remaining four equatorial sites are occupied by monodentate [OOCCF(3)](-) ligands. The axial positions contain coordinated THF. The W(2) carboxylate is opened up (W-W distance of 2.449(2) Å) so that the free ends of the [OOCCF(3)](-) ligands on both W(2) carboxylate units can cooperate in chelating two Na(+) ions thereby forming a dimer of W(2) complexes. A distinctive EPR spectrum with g = 2.08 is consistent with each W(2) carboxylate being a mixed-valent W(II)-W(III) species. The reaction of W(2)(OOCCF(3))(4) with (CO)(9)Co(3)CCOOH in THF in the absence of Na[OOCCF(3)] leads to the expected diamagnetic W(II)-W(II) cluster carboxylate W(2){OOCCCo(3)(CO)(9)}(3)(OOCCF(3))(THF)(2), 3.
The reaction of lead acetate with (CO)(9)Co(3)(&mgr;(3)-CCOOH) leads to the formation of [Pb{(CO)(9)Co(3)(&mgr;(3)-CCO(2))}(2)](n)(), I, in high yield. The structure of I exhibits unusual six-coordinate Pb(II) centers with two asymmetrical chelating cluster carboxylates (C(22)Co(6)PbO(22); triclinic P&onemacr;; a = 8.119(1), b = 14.346(2), c = 14.660(2) Å; alpha = 102.18(1), beta = 99.01(1), gamma = 97.30(1) degrees; Z = 2). One oxygen of each cluster carboxylate ligand bridges between adjacent lead atoms such that a chainlike extended structure is found in the solid state without the presence of solvent or water. I is converted stepwise on pyrolysis into two metastable forms of solid materials (designated LT and HT), each of which has been characterized spectroscopically. The hydrogenation of 2-butenal as a test reaction shows that the LT catalyst exhibits selectivities similar to previous LT materials derived from other cobalt cluster metal carboxylates and that the HT material is totally inactive. The observed release of the lead core metal under HT activation conditions totally inactivates the catalyst and demonstrates exposure of the core metal in the HT form of these novel catalysts.