timestamp range partition boundary to max 6 decimal places

> DROP TABLE ts
TABLE TS dropped.
> CREATE TABLE ts ( ts TIMESTAMP, n NUMBER )
PARTITION BY RANGE ( ts)
( PARTITION p1 VALUES less than  (
TO_TIMESTAMP(' 2015-03-01 00:00:00.123456789', 'SYYYY-MM-DD HH24:MI:SS.ff9', 'NLS_CALENDAR=GREGORIAN')
)  )
TABLE TS created.
> INSERT INTO ts ( ts ) VALUES (
TO_TIMESTAMP(' 2015-03-01 00:00:00.123456000', 'SYYYY-MM-DD HH24:MI:SS.ff9', 'NLS_CALENDAR=GREGORIAN')
)
1 ROWS inserted.
> INSERT INTO ts ( ts ) VALUES (
TO_TIMESTAMP(' 2015-03-01 00:00:00.123456700', 'SYYYY-MM-DD HH24:MI:SS.ff9', 'NLS_CALENDAR=GREGORIAN')
)

Error starting AT line 13 IN command:
INSERT INTO ts ( ts ) VALUES (
TO_TIMESTAMP(' 2015-03-01 00:00:00.123456700', 'SYYYY-MM-DD HH24:MI:SS.ff9', 'NLS_CALENDAR=GREGORIAN')
)
Error report:
SQL Error: ORA-14400: inserted PARTITION KEY does NOT map TO ANY PARTITION
14400. 00000 -  "inserted partition key does not map to any partition"
*Cause:    An attempt was made TO INSERT a RECORD INTO, a RANGE OR Composite
           RANGE object, WITH a concatenated PARTITION KEY that IS beyond
           the concatenated PARTITION bound list OF the LAST PARTITION -OR-
           An attempt was made TO INSERT a RECORD INTO a List object WITH
           a PARTITION KEY that did NOT match the literal VALUES specified
           FOR ANY OF the partitions.
*Action:   DO NOT INSERT the KEY. OR, ADD a PARTITION capable OF accepting
           the KEY, OR ADD VALUES matching the KEY TO a PARTITION specification