jq rename nested json key and place under same key

I want to rename nested json key and keep under same schema.

Input:"properties": {"name": "Ram","age": "17","department": "Sony" }Code : jq '[.["properties.company"] = .properties.department| del(.properties.department)]'  file

Output:

"properties": {"name": "Ram","age": "17"   }"properties.company" = "Sony"

Expected Output should be :

"properties": {"name": "Ram","age": "17","company": "Sony"   }

What I am doing wrong ?