Draw resonance eliminator

DMC-12 DeLorean motor car (plastic body) DRE Draw resonance eliminator... 

The 18-electron complex CpCo(CO)2 must lose at least one CO ligand before it is able to coordinate to PhC=CPh, another two-electron donor. One can draw two resonance structures for this complex, one of which is a cobaltacyclopropene, with Co(III). Loss of a second CO ligand (before or after coordination of PhC=CPh) and coordination of another equivalent of PhC=CPh is followed by an insertion reaction to give a cobaltacyclopentadiene. Coordination and insertion of another equivalent of PhC=CPh gives a cobaltacycloheptatriene, and reductive elimination gives the product and the 14-electron complex CpCo(I), which recoordinates PhC=CPh to reenter the catalytic cycle. 

Draw all possible contributing structures for the molecules shown.Then discuss which of these contributing structures would not contribute significantly to the resonance hybrid. Provide good reasons for the structures you eliminate. 

The small amounts of cyanide ion contained in the seeds of some fruits are eliminated from the body as SCN. Draw two possible resonance forms for the ion. Which atom has the formal negative charge in each form ... 

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