On the Reactivity of Silylated Ge₉ Clusters: Synthesis and Characterization of [ZnCp*(Ge₉{Si(SiMe₃)₃}₃)], [CuPiPr₃(Ge₉{Si(SiMe₃)₃}₃)], and [(CuPiPr₃)₄{Ge₉(SiPh₃)₂}₂]

Abstract

We report on the synthesis of new derivatives of silylated clusters of the type [Ge (SiR ) ] (R = SiMe , Me = CH ; R = Ph, Ph = C H ) as well as on their reactivity towards copper and zinc compounds. The silylated cluster compounds were synthesized by heterogeneous reactions starting from the Zintl phase K Ge . Reaction of K[Ge {Si(SiMe ) } ] with ZnCl leads to the already known dimeric compound [Zn(Ge {Si(SiMe ) } ) ] (1), whereas upon the reaction with [ZnCp* ] the coordination of [ZnCp*] to the cluster takes place (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) under the formation of [ZnCp*(Ge {Si(SiMe ) } )] (2). A similar reaction leads to [CuPiPr (Ge {Si(SiMe ) } )] (3) from [CuPiPr Cl] (iPr=isopropyl). Further we investigated the novel silylated cluster units [Ge (SiPh ) ] (4) and [Ge (SiPh ) ] (5), which could be identified by mass spectroscopy. Bis- and tris-silylated species can be synthesized by the respective stoichiometric reactions, and the products were characterized by ESI-MS and NMR experiments. These clusters show rather different reactivity. The reaction of the tris-silylated anion 4 with [CuPiPr Cl] leads to [(CuPiPr ) Ge (SiPh ) ] as shown from NMR experiments and to [(CuPiPr ) {Ge (SiPh ) } ] (6), which was characterized by single-crystal X-ray diffraction. Compound 6 shows a new type of coordination of the Cu atoms to the silylated Zintl clusters.

N-Heterocyclic Carbene Coinage Metal Complexes of the Germanium-Rich Metalloid Clusters [Ge9R3]− and [Ge9RI2]2− with R = Si(iPr)3 and RI = Si(TMS)3

“…The resulting bis- and tris-silylated cluster species [Ge 9 R 2 ] 2− (R = Si(TMS) 3 ) [14] and [Ge 9 R 3 ] − (R: various silyl groups) [15,16,17,18,19,20] are, due to their lower charge, soluble in common solvents (acetonitrile, thf, toluene). Subsequent reactions of the tris-silylated cluster [Ge 9 R 3 ] − (R: Si(TMS) 3 ) with coinage metal complexes, in most cases coinage metal phosphine complexes, commonly yield coinage metal-bridged cluster dimers, under the loss of the original ligand sphere of the transition metal [19,21,22].…”

“…Subsequent reactions of the tris-silylated cluster [Ge 9 R 3 ] − (R: Si(TMS) 3 ) with coinage metal complexes, in most cases coinage metal phosphine complexes, commonly yield coinage metal-bridged cluster dimers, under the loss of the original ligand sphere of the transition metal [19,21,22]. However, there are also a few reports in which the Cu-phosphine bond is retained [18,23]. The reaction of coinage metal NHC complexes such as NHC Dipp M Cl ( M = Cu, Ag, Au) with tris-silylated clusters [Ge 9 R 3 ] − (R = Si(TMS) 3 , Si( i Bu) 3 ) leads to NHC Dipp M {η 3 -Ge 9 (Si(TMS) 3 ) 3 } ( M = Cu, Ag, Au) [24] or NHC Dipp Cu{η 3 -Ge 9 (Si( i Bu) 3 ) 3 } [19].…”

(Multi‐)Metallic Cluster Growth

“…By adding chlorosilanes, Ge 9 clusters can be silylated to yield tri‐silylated mono‐anionic clusters. These were proven to be excellent starting materials for subsequent reactions with (phosphine‐stabilized) metal halides and metal NHC ( N ‐heterocyclic carbene) complexes . Some cases, in which such reactions came along with cluster re‐organization, were already mentioned above .…”

“…These range from simple capping processes to the dimerization of metal‐capped fragments. Even larger assemblies are observed where [CuP i Pr 3 ] fragments are coordinated by the Ge 9 cluster and serve as bridging units between them . Some examples for such clusters are shown in Figure with Zn atoms (top) or Cu atoms (bottom) integrated.…”

“… Molecular structures of Zn complexes (top) and Cu complexes (bottom) with silylated Ge 9 units as ligands: [Zn{Ge 9 (Hyp) 3 } 2 ] (Hyp=hypersilyl Si(SiMe 3 ) 3 ; top left), [ZnCp*{Ge 9 (Hyp) 3 }] (Cp*=pentamethylcyclopentadienide, top right), [CuNHC Dipp {Ge 9 (Hyp) 3 }] (NHC Dipp =1,3‐bis(2,6‐diisopropylphenyl)‐2,3‐dihydroimidazol‐2‐ide, center left), [Cu i Pr{Ge 9 (Hyp) 3 }] (center right), [(CuP i Pr) 4 {Ge 9 (SiPh 3 ) 2 } 2 ] (bottom) . Ge: red, Zn, Cu, or Au: grey, N: blue, P: pink, Si: bordeaux, organic groups drawn as wires.…”