my %isis_adjacencies;
for my $R2 (@array) {
    push @{ $isis_adjacencies{$R2} }, $R2;
}
[download]

See Why it's stupid to `use a variable as a variable name' for reasons not to do it the way you originally asked for.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]

Is it possible

It is possible but it is also unwise. Use a HoA instead:

#!/usr/bin/env perl 
use strict;
use warnings;
use Data::Dumper;

my @array = qw/x y z/;
my %HoA;
foreach my $R2 (@array) {
    push @{$HoA{$R2}}, $R2
}
print Dumper (\%HoA);
[download]

See perldsc for how to work with deep structures.

"Is it possible"

While it's possible, it's almost certainly a really bad move.

You really need to show the context of what you're hoping to achieve. If you do that, you can probably get a much better answer. Perhaps consider writing something like this:

my %isis_adjacencies;

for my $R2 (@array) {
    push @{$isis_adjacencies{$R2}}, $R2;
}
[download]

Here's the net effect of doing something like that:

$ perl -MData::Dump -e 'my %x; my @y = qw{a b c}; push @{$x{$_}}, $_ f
+or @y; dd \%x'
{ a => ["a"], b => ["b"], c => ["c"] }
[download]

It seems unlikely that's what you want; however, in the absence of more information, I can but guess.

See "perlref: Symbolic references" for more on what you're currently trying to do, why not to, and how to avoid doing it accidently by using the strict pragma (which you should be using anyway).