Atom‐Precise Organometallic Zinc Clusters

Abstract

The bottom-up synthesis of organometallic zinc clusters is described. The cation {[Zn10](Cp*)6 Me}(+) (1) is obtained by reacting [Zn2 Cp*2] with [FeCp2][BAr4 (F)] in the presence of ZnMe2. In the presence of suitable ligands, the high reactivity of 1 enables the controlled abstraction of single Zn units, providing access to the lower-nuclearity clusters {[Zn9 ](Cp*)6} (2) and {[Zn8 ](Cp*)5 ((t) BuNC)3}(+) (3). According to DFT calculations, 1 and 2 can be described as closed-shell species that are electron-deficient in terms of the Wade-Mingos rules because the apical ZnCp* units that constitute the cluster cage do not have three, but only one, frontier orbitals available for cluster bonding. Zinc behaves flexibly in building the skeletal metal-metal bonds, sometimes providing one major frontier orbital (like Group 11 metals) and sometimes providing three frontier orbitals (like Group 13 elements).

Intermetalloid Clusters: Molecules and Solids in a Dialogue

“…Magnetic measurements reveal ad iamagnetic compound, and the 119 Sn NMR spectrum exhibits as ingle resonance signal at À1440 ppm splitted by CuÀSn coupling.T hus,a ll Sn atoms are time averaged in solution indicating the structural flexibility of the cage anion. [127] Even more surprising seems the at first sight strong resemblance of the earlier introduced polyhedral structures of homoleptic zincrich coordination compounds [M(ZnR) n ]( M = Mo,R u, Rh, Ni, Pd, Pt; n = 8-12) with endohedrally filled Zintl ions,asin the preceding example.A ccordingly performed quantum chemical investigations revealed the exceptional standing of these 18 valence electron (VE) compounds on the verge between classical coordination compounds and clusters with strong radial M-Zn bonding involving multiple 2e3c bonds, and weak tangential ZnÀZn interactions. [69] Ab order case between coordination and cluster compounds in the field of ligand-stabilized clusters is represented through the homo-and heterometallic Zn clusters.D espite the diversity of zinc-rich intermetallic phases featuring homometallic Zn building blocks,t he closed-shell s 2 configuration of Zn and the large valence s/p separation strongly disadvantage delocalized bonding.Consequently,only ahandful of homometallic zinc clusters are known.…”

“…[69] Ab order case between coordination and cluster compounds in the field of ligand-stabilized clusters is represented through the homo-and heterometallic Zn clusters.D espite the diversity of zinc-rich intermetallic phases featuring homometallic Zn building blocks,t he closed-shell s 2 configuration of Zn and the large valence s/p separation strongly disadvantage delocalized bonding.Consequently,only ahandful of homometallic zinc clusters are known. [127] Even more surprising seems the at first sight strong resemblance of the earlier introduced polyhedral structures of homoleptic zincrich coordination compounds [M(ZnR) n ]( M = Mo,R u, Rh, Ni, Pd, Pt; n = 8-12) with endohedrally filled Zintl ions,asin the preceding example.A ccordingly performed quantum chemical investigations revealed the exceptional standing of these 18 valence electron (VE) compounds on the verge between classical coordination compounds and clusters with strong radial M-Zn bonding involving multiple 2e3c bonds, and weak tangential ZnÀZn interactions. [111, 113a] Fort he exemplary [Mo(ZnR) 12 ], this bonding situation was described as as d 5 -hybridized molybdenum in which all 12 lobes of the hybrid orbitals are engaged in strong covalent chemical bonding,w hereas the remaining six electrons stay available for weak delocalized Zn-Zn bonding (Figure 20).…”

(Multi‐)Metallic Cluster Growth

“…[53] In 2016, the formation of metalloid clusters of the type [Zn n Cp* m ] was achieved with [Zn 10 Cp* 6 Me] + ,[ Zn 9 Cp* 6 ], and [Zn 8 Cp* 5 (tBuNC) 3 ]. [54] In 2016, Schnçckel and co-workersr eported the first metalloid magnesiumc luster, which represents ap otentials napshot intermediate from the bulk metal to aG rignard reagent. [55] A magnesium(I) halide was produced at higher temperature and stabilized in am etastable solution at À40 8C.…”

Intermetalloide Cluster: Moleküle und Festkörper im Dialog

“…Am verblüffendsten ist das 63 Cu-NMR-Spektrum mit einem scharfen Signal bei À330 ppm, das gut mit anderen Cu + -Verbindungen vergleichbar ist. [127] Noch überraschender scheint auf den ersten Blick die starke ¾hnlichkeit der bereits vorgestellten polyedrischen Strukturen der homoleptischen zinkreichen Koordinationsverbindungen [M(ZnR) n ]( M = Mo,R u, Rh, Ni, Pd, Pt; n = 8-12) mit endohedral gefüllten Zintl-Ionen, wie im vorhergehenden Beispiel. [69] Ein Grenzfall zwischen Koordinations-und Clusterverbindung im Bereich der ligandenstabilisierten Cluster sind die homo-und heterometallischen Zn-Cluster.…”

“…Konsequenterweise ist nur eine Handvoll homometallischer Zinkcluster bekannt. [127] Noch überraschender scheint auf den ersten Blick die starke ¾hnlichkeit der bereits vorgestellten polyedrischen Strukturen der homoleptischen zinkreichen Koordinationsverbindungen [M(ZnR) n ]( M = Mo,R u, Rh, Ni, Pd, Pt; n = 8-12) Angewandte Chemie Aufsätze mit endohedral gefüllten Zintl-Ionen, wie im vorhergehenden Beispiel. Quantenchemische Untersuchungen offenbarten die Ausnahmestellung dieser 18-Valenzelektronen-Verbindungen am Übergang von klassischer Koordinationsverbindung und Cluster,mit starken radialen M-Zn-Bindungen, die mehrere 2e3c-Bindungen und schwache tangentiale Zn-Zn-Wechselwirkungen mit einbeziehen.…”