| 556 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
| * | DD | ORGANIC COMPOUNDS (Class 532, Subclass 1) {3} |
| 1 | DF | .~ HEAVY METAL CONTAINING (e.g., Ga, In or T1, etc.) {19} |
| 42 | | .~.~ Vanadium, niobium, or tantalum containing (V, Nb, or Ta) {2} |
| 43 | DF | .~.~.~> Carbon bonded directly to the metal (e.g., cyclopentadienyl vanadium tetracarbonyl, etc.) |
| 44 | DF | .~.~.~> The metal is bonded directly to X of a -C(=X)X- group, wherein the X's are the same or diverse chalcogens (e.g., vanadyl xanthate, etc.) |