Split paper into two, one was accepted, is it fine to negotiate the rejected paper to be accepted?
Now, can I write to the conference and tell them to review the paper or argue with them that the paper could be accepted based on points made by the two reviewers?

You can try, but what do you have to tell them that they do not already know? They have already read the reviews, thought about them and reached a decision. Unless you can think of a compelling argument that invalidates or rebuts the criticism of the unfavorable review, your chances of success are essentially zero.