Is it possible to connect an Xbox 360 wireless controller to the Xbox One's wireless receiver for PC?
No, Xbox 360 wireless controllers need a compatible Xbox 360 Wireless Gaming Receiver. They aren't compatible with any Xbox One receivers.
https://en.wikipedia.org/wiki/List_of_Xbox_360_accessories#Wireless_Gaming_Receiver
See Set up a wireless controller on a Windows PC on this page:
https://support.xbox.com/en-US/help/xbox-360/xbox-on-windows/accessories/xbox-controller-for-windows-setup