There is no "standalone material format" that you can export to or import from, so it is not possible at present to load Corona Materials from 3ds Max into Cinema 4D (or vice versa). Unfortunately, you'd either have to load the scene into Max (or C4D) and manually copy the material settings into C4D (or Max), or recreate the material by eye. The second might be made easier by using the Corona Material Library, e.g. if you have a wood material, you can start from a similar one in the Corona Material Library.