Passing mongodb ISODate in R

ISOdate(year=2008, month=1, day=1, hour=0)

$orig_date = new DateTime('2016-01-22  14:00:00');
# or you can use any other way to construct with (int timestamp)
$mongo_date = new MongoDB\BSON\UTCDateTime($orig_date->getTimestamp());
$filter = [
          ....
           ....
            ['timestamp' => ['$gte' =>  $mongo_date]],
           ....
          ....
]
# create command (for example aggregation)
$cmd = new MongoDB\Driver\Command( $filter );
# execute command
$cursor = $manager->executeCommand('my_mongo_db_name', $cmd);

$stringtime = "2016-04-09 00:00:00"

$inputdate = strtotime($stringtime)

new MongoDate($inputdate)