In a large cohort of patients undergoing ablation for AF, the prevalence of LVZ was higher and LVZ areas larger in patients with persistent as compared with paroxysmal AF. The most frequent localization of LVZ was anterior wall, septum and posterior wall. Presence of LVZ was associated with higher age, female gender, larger LA surface area, and sinoatrial node dysfunction.
Polyoxoanion-Supported Catalyst Precursors. Synthesis and Characterization of the Iridium(I) and Rhodium(I) Precatalysts [(n-C4H9)4N]5Na3[(l,5-C0D)M-P2Wi5Nb3062] (M =
The Dawson-type P(2)W(15)Nb(3)O(62)(9)(-) polyoxoanion-supported Re(CO)(3)(+) complex, [Re(CO)(3).P(2)W(15)Nb(3)O(62)](8)(-) (1), has been synthesized and characterized in two different counter-cation compositions. The [(n-C(4)H(9))(4)N](8)(8+) complex provides a highly soluble compound which exists as a single isomer in solution. The carbonyl stretching infrared frequencies suggest that the P(2)W(15)Nb(3)O(62)(9)(-) ligand serves as a strong electron donor to the Re(CO)(3)(+) fragment. The P(2)W(15)Nb(3)O(62)(9)(-) polyoxoanion-supported Ir(CO)(2)(+) complex [Ir(CO)(2).P(2)W(15)Nb(3)O(62)](8)(-) (2) has also been synthesized and characterized as its octakis(tetrabutylammonium), [(n-C(4)H(9))(4)N](8)(8+), salt. This compound was characterized by NMR and IR, results which demonstrate that 2 also exists as a single isomer in solution. The [Ir(CO)(2).P(2)W(15)Nb(3)O(62)](8)(-) complex is stable in the absence of water, but decomposes quickly in the presence of even 1 equiv of water. Attempted preparation of the analogous P(2)W(15)Nb(3)O(62)(9)(-) -supported Rh(CO)(2)(+) complex (3), while monitoring by (31)P NMR, revealed that this compound is unstable in solution at room temperature. In addition, we have discovered that added Na(+) can induce the formation of non-C(3)(v)() symmetry isomers of supported Re(CO)(3)(+) and Ir(CO)(2)(+) and, by inference, supported Ir(1,5-COD)(+). When Na(+) is removed from these systems by addition of Kryptofix[2.2.2], the non-C(3)(v)() isomers convert back to the single, C(3)(v)() isomer with heating, thereby providing a model system for the little studied mobility of M(CO)(n)()(+) cations across a soluble-oxide surface. When [Rh(CO)(2).P(2)W(15)Nb(3)O(62)](8)(-) is irradiated in the presence of hydrogen and cyclohexene a novel polyoxoanion-stabilized Rh(0)(n)() nanocluster is formed, results that bear a strong analogy to Yates' work studying atomically-dispersed Rh(CO)(2)(+) on solid Al(2)O(3).(10e) Yates and co-workers observe that Rh(CO)(+).Al(2)O(3) loses a CO upon photolysis, and that the resultant Rh(CO)(1)(+).Al(2)O(3) is reduced under H(2) to form Rh(0), which in turn yields Rh(0)(n)() clusters on Al(2)O(3)-a process that, intriguingly, is largely reversible if CO is readded. Also briefly discussed is other relevant literature of solid-oxide-supported Re(CO)(3)(+) and M(CO)(2)(+) (M = Ir, Rh), literature that makes apparent the potential significance of these complexes as EXAFS and other spectroscopic models of solid-oxide-supported M(CO)(n)()(+).
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