The Maven Help plugin might help you get where you want to go. The ${reactorProjects} variable holds what you are looking for, but perhaps not in precisely the format you are looking to reuse it.
You can view all the expressions available to you via:
mvn help:expressions
and then you can test one of them without the tedium of a pom via evaluation:
mvn help:evaluate
which takes you to a prompt you can use to try expressions.
If I use the help:evaluate and type ${reactorProjects}, I'll get a lot of output, but part of which includes the data you are after:
<plugins>
<plugin>
<inheritanceApplied>true</inheritanceApplied>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-help-plugin</artifactId>
<version>2.1</version>
<extensions>false</extensions>
<dependencies/>
</plugin>
</plugins>
<pluginMap class="linked-hash-map">
<entry>
<string>org.apache.maven.plugins:maven-help-plugin</string>
<plugin reference="../../../plugins/plugin"/>
</entry>
</pluginMap>