On the street side of a corner lot in a C-2 district which abuts a key lot in any R district or in any other C district except a C-1 district, the width of the side yard shall be not less than one-half the depth of the front yard required on such key lot. Where the side lot line of a lot in a C-2 district abuts a lot in any R district, there shall be provided a side yard along that line having a width not less than that required on such abutting lot. Where the rear lot line of a lot in a C-2 district abuts a lot in any R district, then there shall be provided a rear yard having a depth not less than six feet. (Prior gen. code § 8-49.5)