Ge-X bonds

The broken bonds (boldface=dissociated atom or group), AfH (R), kcal/mol (kj/mol) BDEs (boldface = recommended data reference in parentheses) kcal/mol kJ/mol Methods (reference in parentheses) References 

l-Dimethyl-l- silaethyl)-3-germa- 2.2.4.4- tetramethyl- 2.4- disilapentane (Me3Si)3Ge-H 72.9 305.2 Correlation 2002DRO/DEN 

Phenylgermane, substituted (2,4,6-M63-C6H2) GeHz-H 80.7 337.5 Correlation 2002DRO/DEN 

2-Gema-l- phenylfromtane (PhCH3)(C2H5) GeH-H 81.6 341.6 Correlation 2002DRO/DEN 

2-Germa-l,3-diphenyl- 2-benzylpropane (PhCH2)3Ge-H 77.7 324.9 Correlation 2002DRO/DEN 

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As demonstrated above, the most stable singlet siUcon-centered monocyclic diradicals are the o-diradicals where the radicals interact with each other through the Si-Ge bonds, whereas the most stable triplet diradicals are jt-diradicals where the radicals interact with each other through the Ge-X bonds. However, for the bicyclic diradicals, 60 and 61, the conformations are fixed to exclude possibility of Jt-diradicals (Fig. 22). 

The transannular interaction in germatranes is explained by the model of hypervalency that assumes the formation of a three-center four-electron N Ge—X hypervalent bond . This model successfully explains the fraw -inhuence in such fragments, i.e. the inverse interdependence and the constancy of the sum of Ge—X and Ge—N bond orders. The calculated energies of the transannular bonds in some germatranes are higher than those in the corresponding silatranes . The three-center N Ge—X bond has a predominantly a-nature with a minor contribution from jt-interaction of the 4d-orbitals of the Ge atom. 

Halogermane reductions by complex hydrides are efficient, preferred methods for germane synthesis " . The complex hydrides used are MBH (M = Li, Na, K) and LiAlH.,. Reduction of Ge—X bonds by this method can be used for any molecule that otherwise is unsusceptible to complex hydride reduction or reaction. Lithium tetrahydroaluminate reduction of chiral halogermanes and alkoxygermanes results in inversion and retention of configuration, respectively. The LiBH., and LiAlH reactions require aprotic solvents, such as EtjO, THF, n-Bu O or glyme ethers. Sodium and K... 

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