there is no way to copy 

Inventory[{Slot:9b}]

from a player to

Items[{Slot:0b}]

of a chest, if you try to do this, slot: 9b copies to slot 9b only, and even if the data is incorrect if there is an item in that slot, it will give an error for that data already being there.

command used:

/data modify block -1 4 7 Items[{Slot:0b}] set from entity @p Inventory[{Slot:9b}]