node_delete() does not trigger the "deleting content" Rule?
Short inspection of rules code showed that it should be triggered after node delete:

function rules_entity_delete($entity, $type) {
  switch ($type) {
  ...
    case 'node':
      rules_invoke_event('node_delete--' . $entity-&gt;type, $entity);
      rules_invoke_event('node_delete', $entity);
      break;
  ...


(from events.inc)

Have you tried turning on rules debug to see what is happening? Go to admin/config/workflow/rules/settings and turn on Show debug information to Always.

Maybe the event is being invoked, but some of your condition is incorrect and it appears that nothing is happening.