Synthesis and crystal structure of the germatrane E-N(CH) 2CH2O3GeC(Br)=C(Br)Ph

The reaction of (phenylacetylenyl)triethoxygermane, (EtO)₃GeC≡CPh (3), with bromine in CHCl₃/CCl₄ solution leads to a mixture of Z- and E- (EtO)₃GeC(Br)=C(Br)Ph (4) in the ratio Z/E = 3/1. Treatment of this product with N(CH₂CH₂OH)3 affords a mixture of Z- and EN(CH₂CH₂O)₃GeC(Br)=C(Br)Ph (2) in high yield. Compound E-2 was isolated in 16% yield. The molecular composition and the structure of all new compounds have been established by elemental analyses, ¹H and ¹³C NMR spectroscopy. The crystal structure of E-2 is reported. The possible reasons for the different Z/E ratios in the products of the bromination of 3 and N(CH₂CH₂O)₃GeC≡CPh (1) are discussed using DFT calculations.