At this time, your question has three close votes as "too broad". This is probably because you've asked about more than one topic (pi bonding in coordination compounds and synergic bonds), and possibly also because either one of these topics by itself may require an extremely long answer.
First, I would ask about pi bonds and synergic bonds in separate questions.
Second, I would ask about specific aspects of each of the types of bonds, that you are confused about, or would like to learn more about.
More generally, read through the tour page and browse the help center for the site -- they both have a lot of information on the site policies and expectations.