Ask HN: How do you Contact Large Corporations?

I would love to get some advice around this. We are a 4 people company, rather small and we want to acquire a defunct business unit for a large corporation (think IBM, GE, etc).

I've thought about a few options:

1) Write a letter to their corporate address

2) Call their corporate office

3) Get an M&A attorney and have them contact their legal councel.

4) Find someone from the executive office or VP on LinkedIn, stalk them and get their attention.

We want buy the rights to their IP which is no longer been used for over 20 years. We'd first like to investigate if they possess documentation and the relevant code/diagrams/drawings/blueprints for the IP and then put an offer on the table.

Thank you very much and I hope it also helps others who are in the similar situation.