Metal-Centered Deltahedral Zintl Ions: Synthesis of [Ni@Sn₉]^4– by Direct Extraction from Intermetallic Precursors and of the Vertex-Fused Dimer [{Ni@Sn₈(μ-Ge)_1/2}₂]^4–

Abstract

Ni-centered deltahedral Sn(9) clusters with a charge of 4-, i.e., [Ni@Sn(9)](4-), were extracted in ethylenediamine in high yield directly from intermetallic precursors with the nominal composition "K(4)Sn(9)Ni(3)". The new endohedral clusters were crystallized and structurally characterized in K[K(18-crown-6)](3)[Ni@Sn(9)]·3benzene (1a, triclinic, P1̅, a = 10.2754(5) Å, b = 19.5442(9) Å, and c = 20.5576(13) Å, α = 73.927(3)°, β = 79.838(4)°, and γ = 84.389(3)°, V = 3899.6(4) Å(3), Z = 2) and K[K(2,2,2-crypt)](3)[Ni@Sn(9)] (1b, triclinic, P1, a = 15.8028(8) Å, b = 16.21350(9) Å, and c = 20.1760(12) Å, α = 98.71040(10)°, β = 104.4690(10)°, and γ = 118.3890(10)°, V = 4181.5(4) Å(3), Z = 2). The alternative method of a post-synthetic insertion of a Ni atom in empty Sn(9) clusters by a reaction with Ni(cod)(2) predominantly produces the more-oxidized clusters with a charge of 3-, i.e., the recently reported [Ni@Sn(9)](3-). Nonetheless, using substoichiometric amounts of 18-crown-6 as a cation sequestering agent, we also have been able to isolate the 4- clusters as a minor phase from such reactions. They were structurally characterized in K[K(en)][K(18-crown-6)](2)[Ni@Sn(9)]·0.5en (2, monoclinic, P2(1)/n, a = 10.4153(5) Å, b = 25.6788(11) Å, and c = 20.6630(9) Å, β = 102.530(2)°, V = 5394.7(4) Å(3), Z = 2). The ability of the Ni-centered clusters to exist with both 3- and 4- charges parallels the same ability of the empty clusters and is very promising for similarly rich chemistry involving electron transfer and flexible "oxidation states". We also report the synthesis and characterization of the endohedral heteroatomic dimer [{Ni@Sn(8)(μ-Ge)(1/2)}(2)](4-) composed of two [Ni@(Sn(8)Ge)]-clusters fused at the Ge-vertex. The dimer was synthesized by reacting an ethylenediamine solution of a ternary precursor with the nominal composition "K(4)Ge(4.5)Sn(4.5)", which is known to produce heteroatomic Ge(9-x)Sn(x) clusters, with Ni(cod)(2). It is isostructural with the reported [{Ni@Sn(8)(μ-Sn)(1/2)}(2)](4-) and is structurally characterized in [K-(2,2,2-crypt)](4)[{Ni@Sn(8)(μ-Ge)(1/2)}(2)]·2en (3, monoclinic, C2/c, a = 30.636(2) Å, b = 16.5548(12) Å, and c = 28.872(2) Å, β = 121.2140(10)°, V = 12523.5(15) Å(3), Z = 4).

[Bi12Ni7(CO)4]4–: Aggregation of Intermetalloid Clusters by Their Thermal Deligation and Oxidation

“…We already reported that ethylenediamine solutions of the intermetallic compound K 5 Bi 4 react with Ni(PPh 3 ) 2 (CO) 2 to form a number of small intermetalloid clusters such as Bi 3 Ni 4 (CO) 6 3− , Bi 3 Ni 6 (CO) 9 3− , and Ni@ Bi 6 Ni 6 (CO) 8 4− . 17 Of these, the first two anions exhibit bent bismuth trimers with an overall charge of 3−, i.e., each bismuth is formally Bi − .…”

“…One approach is to aggregate the known smaller Bi/Ni/CO clusters Bi 3 Ni 4 (CO) 6 3− , Bi 3 Ni 6 (CO) 9 3− , and Ni@Bi 6 Ni 6 (CO) 8 4− by applying oxidation and deligation. Both processes can be accomplished by simply elevating the temperature of the reaction mixture.…”

Metal‐Centered Zintl Ions Isolated by Direct Extraction from Endohedral Intermetallic Precursor: [Co1–x@Sn9]4– (x ≈ 0.32) and [Co2@Sn17]5–

“…Thus the clusters are linked by potassium cations to infinite 4-clusters are drawn as polyhedra, hydrogen atoms are omitted for clarity. [7] including empty as well as completely Ni-filled Sn 9 clusters, respectively. Comparison with these two crystal structures reveals that all relevant structural parameters of the new compound are intermediate between the known examples of this structure type (see Supporting Information).…”

“…anions. [7,10] The formation of such dimeric units seems to depend on the presence of a suitable transition metal stabilizing these partially oxidized fused cluster dimers. This assumption is also supported by the lack of observations of unfilled [E 17 ] 5-clusters residing in the center ( Figure 5).…”

“…[3,4] The functionalization of transition metal-introduced E 9 clusters includes direct atom insertion, capping by various metal-organic ligands, linkage with naked metal atoms, increasing nuclearity by fusion of two original clusters, or losing the deltahedral shape to form non-deltahedral clusters. [5] * Prof. Dr. T. F. [6] [Ni@Sn 9 ] 4-, [7] [Ni@Sn 9 Tl] 3-, [6a] [Ni@Pb 10 ] 2-, [8] [Ni@Pb 12 ] 2-, [9] [Ni 2 @Sn 17 ] 4-, [10] [Ni 2 @Sn 16 Ge] 4-, [7] [Ni 3 @Ge 18 ] 4- [11] ), Pd-centered clusters ([Pd@Pb 12 ] 2-, [9] [Pd 2 @Ge 18 ] 4-, [12] [Pd 2 @Sn 18 ] 4-, [13] [Pd@Sn 9 (SnCy 3 )] [19] [Ni@Ge 9 (PdPPh 3 )] 2-, [17] [Pd@Sn 9 (PdSnCy 3 )] 3-, [14,20] [Ni@Sn 9 Ni(CO)] 3-, [21] [Pt@Sn 9 Pt(PPh 3 )] 2- [21] 4-clusters with involved transition metal. [22] Clusters including elements of groups 8 and 9 are less frequent and also the number of observed arrangements decreases: [Ge 8 Fe (CO) 3 ] 3-, [23] heavily disordered deltahedra [Fe@Sn 10 ] 3-, [24] [Ru@Ge 12 ] 3-with D 2h symmetry, [25] two analogues of pentagonal prismatic cage [Fe@Ge 10 ] 3- [26] and [Co@Ge 10 ] 3-, [5] more compounds such as monomer [Co@Sn 9 ] 5-, [27] cluster dimers [Co 2 @Sn 17 ] 5-, [27] as well as [Ir@Sn 12 ] 3-, [28] which is made from coordinated heteroatoms [Sn 9 Ir(cod)] 3-.…”