Samarium Polystibides Derived from Highly Activated Nanoscale Antimony

Abstract

Zintl ions in molecular compounds are of fundamental interest for basic research and application. Two reactive antimony sources are presented that allow direct access to molecular polystibide compounds. These are Sb amalgam (Sb/Hg) and ultrasmall Sb nanoparticles (d=6.6±0.8 nm), which were used independently as precursors for the synthesis of the largest f-element polystibide, [(Cp* Sm) Sb ]. Whereas the reaction of the nanoparticles with [Cp* Sm] directly led to [(Cp* Sm) Sb ], Sm/Sb/Hg intermediates were isolated when using Sb/Hg as the precursor. These Sm/Sb/Hg intermediates [{(Cp* Sm) Sb} (μ-Hg)] and [{(Cp* Sm) (μ ,η -Sb )} Hg] were synthetically trapped and structurally characterized, giving insight in the formation mechanism of polystibide compounds.

Samarium Polyarsenides Derived from Nanoscale Arsenic

“…Thus, the compound is similar to Evans′s dinitrogen complex [(Cp* 2 Sm) 2 ( μ ‐ η 2 : η 2 ‐N 2 )] and the heavier antimony and bismuth analogues [(Cp* 2 Sm) 2 ( μ ‐ η 2 : η 2 ‐E 2 )] reported by us and by Evans et al. (Figure ) . Formally, an {As 2 } 2− dumbbell bridges two [Cp* 2 Sm] + moieties to form a coplanar {Sm 2 As 2 } rhombus (Figure ).…”

“…Very recently, Scheer and co‐workers developed a facile storage system for white phosphorus and yellow arsenic, in which intact Pn 4 molecules were reversibly captured and released in porous activated carbon and subsequently used for the synthesis of transition metal complexes . At the same time, we developed an alternative approach by utilizing either Sb–Hg alloys (amalgams) or nanoscale antimony Sb 0 nano for the synthesis of purely f‐element coordinated polystibides . By alloying or shrinking of the particle size, conveniently accessible and storable element modifications were generated, which featured enhanced reactivity as compared to the bulk material.…”

“…In this report, we present a nanoscale arsenic source, As 0 nano , which was used and compared with As 4 solutions for the synthesis of rare‐earth polyarsenides. Ultimately, the previously missing arsenic analogue of the first rare‐earth dinitrogen complex, [(Cp* 2 Sm) 2 ( μ ‐ η 2 : η 2 ‐N 2 )], as well as the As 8 4− Zintl anion in the [(Cp* 2 Sm) 4 Pn 8 ] series were successfully isolated . The latter compound is the largest polyarsenide of the f‐elements ever reported.…”

Recent Advances in Rare‐Earth Polypnictides

“…Furthermore, well‐dispersed elemental antimony has also employed by Roesky and co‐workers to prepare the (Cp* 2 Sm) 2 (μ‐ŋ 2 :ŋ 2 ‐Sb 2 ) (Figure A) . In this reaction, Cp* 2 Sm was treated with either Sb/Hg amalgam or Sb 0 nanoparticles to afford the samarium polystibides.…”

“…In 1991, Evans and co‐workers synthesized the first example of dibismuthide complex containing rare earth cations, in which the Bi 2 2 – coordinates side‐ on to both samarium cations, forming a diamond core structure (Figure ) . The dibismuthide compound, [Cp* 2 Sm] 2 (μ‐ŋ 2 : ŋ 2 ‐Bi 2 ) was afforded by treating Cp* 2 Sm with BiPh 3 , a synthetic route different from that reported for the aforementioned isostructural distibide analogue . Notably, in this complex, the Bi—Bi bond length was found at 2.851 (1) Å, between that of typical Bi—Bi single bonds found in Ph 4 Bi 2 at 2.990(2) Å and [Bi 2 CoFe(CO)] 10 – at 3.092(2) Å and that of Bi=Bi double bonds found in [(MeC 5 H 4 )Mo(CO) 2 ] 2 Bi 2 and [K(2.2.2‐crypt)] 2 Bi 2 at 2.838 Å and W 3 (CO) 13 Bi 3 Me at 2.796(1) Å …”