Connecting to MongoDB using PDO driver
MongoDB requires its own driver.
In your case, the PHP driver is located here:http://php.net/manual/en/book.mongo.php
The instructions for installing it are on that page. There is also some sample code.
There is list of databases which you can use with the PDO driver: http://php.net/manual/en/pdo.drivers.php. MongoDB is not among them.