| Abstract
| - Treatment of Cp*2UI2 with KCN in thf led to the formation of Cp*2U(CN)2 (2), which further reactedwith NR4CN to give [Cp*2U(CN)3][NR4] (R = Et, 3; R = nBu, 3‘) and [Cp*2U(CN)5][NR4]3 (R = Et, 4;R = nBu, 4‘). While the triscyanide 3‘ adopts the familiar bent sandwich configuration, the pentacyanide4 is, after the [Cp*2U(NCMe)5]2+ cation, the second example of a linear metallocene resulting fromcomplete saturation of the equatorial girdle. Compound 3‘ was also obtained by oxidation of the trivalentcompound [Cp*2U(CN)3][NnBu4]2; the rapid and reversible electron transfer between the U(III) and U(IV)complexes was revealed by 1H NMR spectroscopy. The NMR spectra also revealed that 4 is partiallydissociated in thf into 3, providing the first example of an equilibrating couple of bent and linearmetallocenes [K = 4.24(4) × 10-5 at 25 °C, ΔH = 199(6) kJ mol-1, and ΔS = 586(20) J mol-1 K-1].The trinuclear compound [Cp*2UCl2(μ-CN)]2Mg(thf)4 (1) and the 2D polymeric complex [Cp*2U(dmf)3(μ-NC)2(AgI)2]n (5), which were obtained during initial attempts on the synthesis of 2−4 and uranium(V) derivatives, exhibit a bent and linear sandwich structure, respectively.
- Addition of KCN to Cp*2UI2 in thf led to Cp*2U(CN)2, which was transformed into [Cp*2U(CN)3][NR4] (R = Et, nBu) and [Cp*2U(CN)5][NR4]3 (R = Et, nBu) upon addition of NR4CN. The pentacyanide complex, which is the second example of a linear metallocene with complete saturation of the equatorial girdle, is partially dissociated in thf, being in equilibrium with the bent triscyanide derivative [K = 4.24(4) × 10-5 at 25 °C, ΔH = 199(6) kJ mol-1, and ΔS = 586(20) J mol-1 K-1]. The trinuclear compound [Cp*2UCl2(μ-CN)]2Mg(thf)4 and the 2D polymeric complex [Cp*2U(dmf)3(μ-NC)2(AgI)2]n exhibit a bent and linear sandwich structure, respectively.
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