Enhancing the Variability of [Ge9 ] Cluster Chemistry through Phosphine Functionalization.

The synthetic approach towards molecules that contain Ge atoms with oxidation state 0, and which are exclusively connected to other Ge atoms, is explored by using anionic clusters extracted from binary solids. Besides providing a novel variable method for the introduction of alkenyl moieties to [Ge9 ] cluster compounds, this work expands the spectrum of mixed-functionalized [Ge9 ] cluster anions, which are suitable for the straightforward synthesis of zwitterionic compounds upon coordination to metal cations. In detail, the synthesis of a series of mixed-functionalized [Ge9 ] clusters is reported, including [Ge9 {Si(TMS)3 }3 PRRI ] (R=tBu, RI =(CH2 )3 CH=CH2 ; 2) and [Ge9 {Si(TMS)3 }2 PRRI ]- (R and RI : alkyl, alkenyl, aryl, aminoalkyl; 3 a to 11 a, TMS: (trimethyl)silyl). In 2 and 3 a, pentenyl functionalization of the [Ge9 ] clusters was achieved by reaction of the novel chlorophosphine tBu{(CH2 )3 CH=CH2 }PCl (1) with silylated [Ge9 ] clusters. Furthermore, the reactivity of the cluster anions 3 a to 11 a towards NHCDipp MCl (NHCDipp =1,3-di(2,6-diisopropylphenyl)imidazolylidine; M=Cu, Ag) showed a dependency on the steric demand of the phosphine either zwitterions (3-MNHCDipp to 7-MNHCDipp ) featuring P-M interactions are formed, or Ge-M coordination (8-MNHCDipp to 11-MNHCDipp ) occurs. For M=Ag, the formation of zwitterionic complexes was unequivocally proven by NMR investigations showing 1 J(31 P-107 Ag/109 Ag) spin-spin coupling.