I can't create a second partition in Mac
Actually you have a CoreStorage Logical Volume Group on your physical disk named "Macintosh HD" containing a Logical Volume also named "Macintosh HD". The latter is the volume usually visible on your desktop (depending on your Finder settings). The Logical Volume Group already extends across your whole physical disk except an invisible EFI partition (200 MB) and an invisible Recovery HD (~650 MB).

The Logical Volume (499 GB with 456 GB free space) extends across your whole Logical Volume Group.

As a result you can't create a second partition (including the invisible partitions in fact a forth) because you have no unallocated space on your physical disk.

To create a second partition you have to resize the whole CoreStorage stack to create a non-CoreStorage volume or resize the Logical Volume to create a second CoreStorage Logical Volume first.