Page 141 - Arrow Pushing in Inorganic Chemistry A Logical Approach to the Chemistry of the Main Group Elements

4.9 ALKYNE ANALOGS 121

Ari-Pr 4
Ge Ge
i-Pr 4 Ar

Like a diarylgermylene, the digermyne reacts readily with dihydrogen, yielding multiple
products:

Ari-Pr i-Pr 4 Ar H i-Pr Ar
Ari-Pr 4
4 4
H 2
Ge Ge Ge Ge Ge Ge 2 Ge
H
i
i-Pr Ar Ar Pr H H Ari-Pr 4 H
4
4
H
2 H
2
H Ari-Pr 4
H
Ge Ge
i-Pr Ar GeH
H 4 3
Ar H
i-Pr 4
(4.54)
The Ge and Sn alkyne analogs also undergo cycloaddition reactions with carbon–carbon
double bonds. The following reactions are common to both the digermyne and distannyne
derivatives:
Ari-Pr 4
C CH
2 H 2 2
(a) M M i-Pr 4 Ar M M Ari-Pr 4
i-Pr Ar
4
M = Ge, Sn
(4.55)

Ari-Pr
Ari-Pr 4 4
M
(b) M M M
i-Pr Ar i-Pr Ar
4
4
M = Ge, Sn

REVIEW PROBLEM 4.18
Write simple concerted mechanisms for reaction 4.55a and 4.55b.