Yeah, you must use colons instead of dots in the time. I'm used to seeing either one ... but SQL isn't.
SELECT CAST('20180326 05:00:00' as datetime2)
SQL DBA,SQL Server MVP(07, 08, 09) Prosecutor James Blackburn, in closing argument in the Fatal Vision murders trial:
If in the future, you should cry a tear, cry one for them [the murder victims]. If in the future, you should say a prayer, say one for them. And if in the future, you should light a candle, light one for them.