Semitopological diagrams

There is another way to represent the electron distribution in diborane and its heavier relatives. These are Lipscomb s semitopological diagrams, which involve the four structure-bonding elements depicted in Table 14.5. We have already seen two of these elements, the 2c-2e B-H bond and the 3c-2e B-H-B bond, in diborane. Using... 

Tlie B3H cation is not known, but it is possible to speculate on its structure. Draw a semitopological diagram representing a reasonable structure for this cation. Indicate the hybridization of each boron in your structure. 

The B5H anion can be prepared by extracting a proton from pentaborane(9).The proton is removed from a bridging position, leaving this anion with three B—H-B 3c-2e bonds. Draw a semitopological diagram for this anion. Indicate the number of resonance structures, if any, that are necessary to characterize the anion fully. 

A common borane anion is B3H8. Keeping the three boron atoms in a triangle, draw a semitopological diagram of this anion. Include an analysis of the number of electrons available and the distribution of these electrons into bond types. 

Draw a semitopological diagram of the trimethylaluminum dimer, Al2(CH3)g. With the aid of a separate diagram, briefly describe the bonding in this molecule including the hybridization of the aluminum and carbon atoms. 

Given the structure of AI4H6 shown in Rgure 14.26a, write a semitopological diagram for this alane. 

The structure of AI4H7 is shown below. Write a semitopological diagram for this aluminum cluster anion. 

New problems on explaining trends in electron affinities on the basis of radial distribution functions, the reaction between aqueous copper chloride solution and aluminum metal, assigning structural classes to simple boranes, isomers of carboranes, and semitopological diagrams for alanes... 

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