1. What kind of bonds exist between the metal and the carbyne moiety in the Schrock type carbyne complexes? 

Three normal covalent interaction.

2. What kind of metal centers prefer the formation of the Fischer type carbyne complexes? 

The late−transition metals having low valent oxidation state.

3. How does reactivity of the Fischer type and the Schrock type carbyne complexes differ with regard to the attacks by electrophiles and nucleophiles?

Nucleophilic attack at the carbyne−C center of the Fischer type complex and the electrophilic attack at the carbyne−C center of the Schrock type complex.