Unable to use datetime2(0) in Partition Function
Removing the NULL as the first partition value should get you past the error.
(UPDATE - Read the comments further down from Dan's post - he actually DOES recommend the action of the OP - you just need to use convert(datetime2(0),null)

Also - check out Dan Guzman's Table Partitioning Best Practices.

Well - after re-reading Dan's post, he actually DOES recommend creating the first partition with a NULL boundary for RANGE RIGHT, 


  I suggest specifying a NULL value for the first boundary of a RANGE
  RIGHT partition function.  This NULL boundary serves as the upper
  boundary of the permanent first partition as well as the lower
  boundary for the second partition containing data outside the expected
  range.  No rows are less than NULL so the first partition will always
  be empty.  It is therefore safe to map the first partition to the
  previously mentioned dummy filegroup even if you need to house data
  outside the expected range.  That being said, there is no harm in
  mapping the first partition to another filegroup other than lack of
  clarity.