Synthesis, Structures, and Solution Dynamics of Tetrasubstituted Nine-Atom Germanium Deltahedral Clusters

Abstract

Reported are the rational synthesis, structures, and solution dynamics of three tetrasubstituted and neutral Ge9-based deltahedral clusters [Ge9R3R'](0), where R = Si(SiMe3)3 and R' = Et (1), Sn(n)Bu3 (2), or Tl (3). The first step of the synthesis is a reaction of an acetonitrile suspension of the intermetallic precursor compound K4Ge9 with {Si(SiMe3)3}Cl which produces the trisubstituted monoanions [Ge9{Si(SiMe3)3}](-). A benzene suspension of the latter is then reacted with Sn(n)Bu3Cl or TlCp to produce 2 and 3, respectively, while the same acetonitrile solution is reacted with EtBr in order to produce 1. All three structures can be viewed as tricapped trigonal prisms of Ge9 with the three "hypersilyl" substituents, Si(SiMe3)3, exo-bonded to the capping atoms. The fourth substituent in 1, the ethyl group, is exo-bonded to one of the six available Ge atoms with the Ge-C bond positioned radially to the Ge9 core. In the case of 2, on the other hand, the tin fragment is found above one of the triangular bases of the prism interacting with one or more Ge atoms in three crystallographically different molecules in the structure. Lastly, the Tl atom in the structure of 3 is found capping a pseudosquare face between two hypersilyl substituents. NMR spectroscopy indicates that all three compounds are dynamic at room temperature. Variable-temperature studies suggest that the process in 1 and 2 is intramolecular while the process in 3 involves dissociation of the Tl(+) ion from the molecule followed by association at the same or another equivalent pseudosquare face of the molecule. Thus, the latter compound may be considered to a large extent to be ionic as it is made of a thallium cation and a trisubstituted cluster anion.

Reactivity of [Ge9{Si(SiMe3)3}3]− Towards Transition‐Metal M2+ Cations: Coordination and Redox Chemistry

“…The reaction of 1 with different transition metal compounds like MnCl 2 (d 5 ), FeCl 2 (d 6 ), CoCl 2 (d 7 ), and NiCl 2 (d 8 )w ere initially done to enlarge the group of [Hyp 3 Ge 9 -M-Ge 9 Hyp 3 ]c lusters to examinet he influence of the connecting atom Mo nt he bonding and property of the resulting cluster. [12] However,t he expected product is only obtained in the case of MnCl 2 .I na ll the other cases an additional redox chemistry takes place, leading to TM + (TM = Fe, Co, Ni)c omplexes which will be discussed below.…”

“…The molecular structure of 2 (Figure 1) might be described as ac entral manganese atom that is bound h 3 to two Ge 9 Hyp 3 units;t hat is, 2 is isostructural to all other known [Hyp 3 Ge 9 -M-Ge 9 Hyp 3 ]c lusters. [15] [Fe(dppe) 2 ][Ge 9 Hyp 3 ]and [Co(dppe) 2 ][Ge 9 Hyp 3 ] In contrastt ot he reaction with MnCl 2 (d 5 ), the reaction of 1 with the more electron-richt ransition-metal sources like FeCl 2 (d 6 ), CoCl 2 (d 7 )a nd [NiCl 2 (dppe)] (d 8 )( dppe = 1,2-bis(diphenylphosphino)ethane) went in ac ompletely different direction. The arrangement is symmetric, which might be due to the d 5 configuration of the transition-metala tom.…”

“…The arrangement is symmetric, which might be due to the d 5 configuration of the transition-metala tom. [18] The Fe + and Co + compounds [Fe(dppe) 2 ][Ge 9 Hyp 3 ]( 3)a nd [Co(dppe) 2 ][Ge 9 Hyp 3 ]( 4)a re isostructural and show an unusual arrangement of the [M(dppe) 2 ] + cations (M = Fe, Co) and [Ge 9 Hyp 3 ] À anionsi nt he solid state (see the Supporting Informationf or furtheri nformation). [14] The presence of unpaired electrons within 2 was provenb y EPR measurements, which give only one signal without hyperfine splitting with a g value of 1.995 ( Figure S7, Supporting Information),which is in line with other Mn 2 + complexes.…”

“…[1] In addition to naked Zintl anionslike E 9 4À ,the metalloid germanium cluster [Ge 9 Hyp 3 ] À 1 (Hyp = Si(SiMe 3 ) 3 ) [2] is becoming am ajor focus of actual research, not only due to its good solubility in different solvents, but also due to its high yield synthesis from the Zintl anion Ge 9 4À as introduced by Sevov et al [3] Compound 1 exhibits an incompletely shielded clusterc ore, giving accesst oavariety of furtheri nvestigations.T hereby build-up reactions were possible to give clusters of the composition [Hyp 3 Ge 9 -M-Ge 9 Hyp 3 ] x (x = À1: M = Cu, Ag, Au; x = 0: M= Zn, Cd, Hg) [4] and recently ac ompound exhibiting al inear chain build-up of two coppera toms and two Ge 9 Hyp 3 units: [Ge 9 Hyp 3 -Cu-Ge 9 Hyp 3 -Cu-PPh 3 ]w as synthesized,s howing the potentialof1 for the synthesis of novel materials. [1] In addition to naked Zintl anionslike E 9 4À ,the metalloid germanium cluster [Ge 9 Hyp 3 ] À 1 (Hyp = Si(SiMe 3 ) 3 ) [2] is becoming am ajor focus of actual research, not only due to its good solubility in different solvents, but also due to its high yield synthesis from the Zintl anion Ge 9 4À as introduced by Sevov et al [3] Compound 1 exhibits an incompletely shielded clusterc ore, giving accesst oavariety of furtheri nvestigations.T hereby build-up reactions were possible to give clusters of the composition [Hyp 3 Ge 9 -M-Ge 9 Hyp 3 ] x (x = À1: M = Cu, Ag, Au; x = 0: M= Zn, Cd, Hg) [4] and recently ac ompound exhibiting al inear chain build-up of two coppera toms and two Ge 9 Hyp 3 units: [Ge 9 Hyp 3 -Cu-Ge 9 Hyp 3 -Cu-PPh 3 ]w as synthesized,s howing the potentialof1 for the synthesis of novel materials.…”

“…[1] In addition to naked Zintl anionslike E 9 4À ,the metalloid germanium cluster [Ge 9 Hyp 3 ] À 1 (Hyp = Si(SiMe 3 ) 3 ) [2] is becoming am ajor focus of actual research, not only due to its good solubility in different solvents, but also due to its high yield synthesis from the Zintl anion Ge 9 4À as introduced by Sevov et al [3] Compound 1 exhibits an incompletely shielded clusterc ore, giving accesst oavariety of furtheri nvestigations.T hereby build-up reactions were possible to give clusters of the composition [Hyp 3 Ge 9 -M-Ge 9 Hyp 3 ] x (x = À1: M = Cu, Ag, Au; x = 0: M= Zn, Cd, Hg) [4] and recently ac ompound exhibiting al inear chain build-up of two coppera toms and two Ge 9 Hyp 3 units: [Ge 9 Hyp 3 -Cu-Ge 9 Hyp 3 -Cu-PPh 3 ]w as synthesized,s howing the potentialof1 for the synthesis of novel materials. [6,7] The addition of af ourth ligand to 1 gives neutralc ompounds of the composition R-(Ge 9 Hyp 3 )( R= SnPh 3 ,E t) [8,9] and recently we could show that 1 can be coupled, by means of oxidation, to give the largest metalloid Group 14 cluster Ge 18 Hyp 6, in which the germani-um atoms are arranged in au nique way, giving insighti nto the formation processo ft he new solid-state structure of ger-maniumG e(cF136) [10] on an atomics cale. [6,7] The addition of af ourth ligand to 1 gives neutralc ompounds of the composition R-(Ge 9 Hyp 3 )( R= SnPh 3 ,E t) [8,9] and recently we could show that 1 can be coupled, by means of oxidation, to give the largest metalloid Group 14 cluster Ge 18 Hyp 6, in which the germani-um atoms are arranged in au nique way, giving insighti nto the formation processo ft he new solid-state structure of ger-maniumG e(cF136) [10] on an atomics cale.…”