V-Ray (Classic) Materials are not interchangeable or compatible with the V-Ray Node Materials.

 

V-Ray Materials Menu

By default, the V-Ray materials menu is visible next to the Create menu in the Material Manager.

If you want to access V-Ray materials from Cinema 4D's Create menu, go to Edit > Preferences > Renderer > V-Ray > Materials and disable the Separate menu for V-Ray materials option.

 

 

 

 

Then, restart Cinema 4D.

V-Ray materials now reside in the Material Manager's Create menu.