Cluster Chemistry with ( Pseudo -)Tetrahedra Involving Group 13–15 (Semi-)Metal Atoms

Abstract

Compounds containing (pseudo-)tetrahedral main group (semi-)metal units are fundamentally important in three regards. Firstly, they provide us with new strategies for the stabilization of tetrahedral units, such as Pn 4 (Pn = P, As) and their isoelectronic analogs, in the coordination sphere of d-/f-block metal atoms. Secondly, they serve as first-step models for the activation of tetrahedral molecules. Thirdly, they are starting materials for subsequent transformations towards larger clusters or materials. Partial or full isoelectronic replacement of the pnictogen atoms in P 4 or As 4 results in a variety of (pseudo-)tetrahedral anions, Tt 4 4− (Tt = Si, Ge, Sn, Si/Ge), (Ge3Pn) 3− (Pn = P, As; formed in situ), (Tt2Pn2) 2− (Tt/Pn = Ge/P, Ge/As, Sn/Sb, Sn/Bi, Pb/Sb, Pb/Bi), or (TrBi3) 2− (Tr = Ga, In, Tl), and also cations, (P3Ch) + (Ch = S, Se, Te). The anions proved to be excellent starting materials and building blocks for multinary clusters in the context of Zintl chemistry. Such compounds, which push forward the boundary of the intriguing P 4 chemistry, have never been thoroughly summarized before. In this mini review, we introduce all known intact (pseudo-)tetrahedral group 13−15 units, as well as the coordination compounds based on them, along with two new missing links, [Au(η 2 -Tt2Bi2)2] 3− (Tt = Sn, Pb).

Capture the missing: formation of (PbBi3)− and {[AuPb5Bi3]2}4− via atom exchange or reorganization of the pseudo‐tetrahedral Zintl anion (Pb2Bi2)2−

“…In addition to the reported [Au{η 2 ‐(Pb 2 Bi 2 )} 2 ] 3− anion in [K(crypt‐222)] 3 [Au{η 2 ‐(Pb 2 Bi 2 )} 2 ] ( A ), 1 which was isolated upon reaction of (Pb 2 Bi 2 ) 2− and [AuMePPh 3 ] in en/tol (tol = toluene) solution, we introduced the same reactants into py/THF (THF = tetrahydrofuran) or py/tol respectively. As a result, we were able to isolate two new anions, (PbBi 3 ) − and {[AuPb 5 Bi 3 ] 2 } 4− , which crystallized as [K(crypt‐222)] 4 [(PbBi 3 )(Pb 2 Bi 2 )(AuMe 2 )]·6py ( 1 ) and [K(crypt‐222)] 4 {[AuPb 5 Bi 3 ] 2 }·2py ( 2 ).…”

“…Remarkably, (PbBi 3 ) − represents the first ( pseudo ‐)tetrahedral anion featuring a single negative charge (−1) that was obtained in condensed phase (Figure 1, left). All other analogous species that were found in crystalline compounds possess different charges, such as Tl 4 8− , (TlSn 3 ) 5− , Pb 4 4− , (Ge 3 As) 3− , (Pb 2 Bi 2 ) 2− , (TlBi 3 ) 2− , P 4 , and (P 3 S) + 1 . Thus, the new anion fills a gap in an otherwise seamless series running from charges of +1 to −5.…”

“…[9][10][11][12] Among them, the solution chemistry of Tt 4 4− (Tt = Si, Ge, Sn, and Pb), (Tt 2 Pn 2 ) 2− (Tt/Pn = Ge/P, Ge/As, Sn/Sb, Sn/Bi, Pb/Sb, and Pb/Bi), and (TrBi 3 ) 2− (Tr = Ga, In, and Tl) in liquid ammonia, ethane-1,2-diamine (en), or pyridine (py) has attracted particular attention. 1 Upon introducing d-block metal atoms, Tt 4 4− anions usually maintain their overall intact tetrahedral form in the resulting complexes, such as in [(MesCu) 2 (η 3 :η 3 -Tt 4 )] 4− (Tt = Si, Ge), [(EtZn) 2 (η 3 :η 3 -Ge 4 )] 2− , and [(η 2 -Sn 4 )Zn(η 3 -Sn 4 )] 6− . [13][14][15][16] This concept can also be extended to p-block element atoms linking the tetrahedral units, which is exemplified by [In(η 3 -Pb 4 ) 2 ] 5− in the A 5 InPb 8 (A = K, Rb) alloy.…”

“…Consequently, a series of intermetalloid or heterometallic clusters were reported, such as [U@Pb 7 Bi 7 ] 3− , [Th@Bi 12 ] 4− , [Bi@Ga 8 (Bi 2 ) 6 ] q − ( q = 3, 5), and [(Bi 6 )Zn 3 (TlBi 5 )] 4− 22–25 . On the other hand, reactions with softer Lewis acids like the Au(I) cation, (Tt 2 Pn 2 ) 2− anions can also stay intact in the resulting complexes [Au{η 2 ‐(Tt 2 Pn 2 )} 2 ] 3− (Tt/Pn = Sn/Sb, Sn/Bi, and Pb/Bi) 1,26,27 …”

“…( Pseudo ‐)tetrahedral Zintl‐type anions derived from partial or full isoelectronic replacement of vertexes of P 4 by group 13–15 element (semi‐)metal atoms paved way to a series of main group ( pseudo ‐)tetrahedral anions with overall charges of −8, −5, −4, −3, or −2, which were used as starting materials for the formation of a multitude of binary or ternary (semi‐)metal complexes and clusters 9–12 . Among them, the solution chemistry of Tt 4 4− (Tt = Si, Ge, Sn, and Pb), (Tt 2 Pn 2 ) 2− (Tt/Pn = Ge/P, Ge/As, Sn/Sb, Sn/Bi, Pb/Sb, and Pb/Bi), and (TrBi 3 ) 2− (Tr = Ga, In, and Tl) in liquid ammonia, ethane‐1,2‐diamine (en), or pyridine (py) has attracted particular attention 1 …”