Li₄E₈ (E = P, As, Sb, Bi) Clusters: The ­Quest for Realgar‐Type [E₈]^4– Zintl Anions

Abstract

Keywords: Cluster compounds / Pnicogens / Zintl anions / Ab initio calculationsA systematic computational study focused on searching for the global minima and low-lying isomers of the Li 4 E 8 (E = P, As, Sb, Bi) series of clusters is reported. The global-minimum structures of Li 4 P 8 , Li 4 As 8 , and Li 4 Sb 8 as well as one of the lowest-lying Li 4 Bi 8 isomers were found to contain a realgar- IntroductionHigh-temperature reactions of s-block metals with pblock elements give intermetallic alloys known as Zintl phases, which contain polyatomic p-block anions, that is, Zintl anions. [1] The group 15 elements form soluble molecular Zintl polyanions having a great potential for the synthesis of novel functional materials, [2] including promising thermoelectric materials capable of converting heat to power. [3] Many [E x ] n-(E = P, As, Sb, Bi) structural motifs have been theoretically predicted [4][5][6][7] and synthesized to date. [1][2][3][8][9][10] One of the rarest Zintl anions is [E 8 ] 4-, which has been experimentally characterized in the case of E = P for several transition metal compounds ([(η 5 -C 5 H 4 Me) 4 -Fe 4 (CO) 6 P 8 ], [11] [(η 5 -C 5 H 4 Me) 4 Fe 6 (CO) 13 P 8 ], [11] and [{(η 5 -C 5 Me 5 )Ir(CO)} 2 {Cr(CO) 5 } 3 P 8 ] [12] ) and rare-earth metal complexes ([{(η 5 -C 5 Me 5 ) 2 Sm} 4 P 8 ] [13] and [{(NN fc )-Sc} 4 P 8 ], [14] where NN fc = 1,1Ј-fc(NSitBuMe 2 ) 2 , fc = ferrocenylene), formed by activation of white phosphorus (P 4 ).All species mentioned above have an unusual tricyclo-[3.3.0.0 3,7 ]octaphosphane core denoting α-P 8 (4), [15] which is structurally similar to realgar and to the carbon skeleton of cuneane (Figure 1). The α-P 8 (4) topology was initially reported in the series of seminal articles by Baudler and co-[a] Nikolaev 5801 type [E 8 ] 4unit, which is a rare Zintl anion. Increased stability of this skeleton allows its presence to be expected in more complex chemical compounds containing group 15 elements with appropriate stoichiometry.

Synthesis, Structure, and Reactivity of Ga‐Substituted Distibenes and Sb‐Analogues of Bicyclo[1.1.0]butane

“…All calculated bond lengths within the Ga 2 Sb 2 ( 1 , 2 ) and Ga 2 Sb 4 ( 3 ) cores (BP86‐D3/def2‐SVP level of theory, Tables S2–S4 in the Supporting Information) agree well with the corresponding experimental values (Δ r =0.02–0.08 Å). As predicted by atoms in molecules (AIM), electron localization function (ELF), and natural bond orbital (NBO) analyses, all Sb−Sb bonds in 1 , 2 , and 3 are covalent in nature (Tables S2–S4, Figures –), in accordance with recently reported computational data for these types of complexes …”

Samarium Polystibides Derived from Highly Activated Nanoscale Antimony

“…Noteworthy,the observed structural arrangement is in agreement with theoretical predictions published recently by Nizovtsev et al [21] These calculations show that ar ealgar-type E 8 unit forms with high probability. This was indeed the case,a sr ed single crystals were isolated, revealing an f-element realgar-type polystibide complex [(Cp* 2 Sm) 4 (m 4 ,h 2:2:2:2 -Sb 8 )] (4)( Scheme 1).…”

Samarium Polyarsenides Derived from Nanoscale Arsenic

“…The cage‐type polypnictide structure for Cp‐based metal complexes is in agreement with calculations published by Nizovtsev et al . Following their results, a realgar‐type E 8 unit will be very likely formed instead of other conceivable structural motifs.…”