Are you removing the { }'s e.g., with a server called ALPHA that is a domain controller you would put:
ldifde -f groups.ldf -s ALPHA -r "(&(objectcategory=group)(objectclass=group))"
This will dump all groups - not sure if you can just pick the Distribution Group unless they are in a particular container.
It also helps if I get the syntax correct - sorry.groups.ldf
This will give you the groups on the server and the members of those groups. Not sure if you can export all that you want in one go.
To export the members details of a specific Distribution group you can use this:
ldifde -f members.ldf -r "memberOf=cn=group name,ou=ou name,dc=domain,dc=name" -l mail