Faz
SELECT CAST('2009-12-07 10:40:21.893' AS DATETIME2(0)),
CAST('2009-12-07 10:42:18.173' AS DATETIME2(0))
Faça o que você precisa?
SELECT CAST('2009-12-07 10:40:21.893' AS DATETIME2(0)),
CAST('2009-12-07 10:42:18.173' AS DATETIME2(0))