This is not a partnership. It is a limited company and you are shareholders in that limited company. You are presumably both directors.
In this scenario there are two applicable agreements albeit that neither of them have been formalised. Nonetheless, they are both legally enforceable provided there is no dispute over the content.
The two agreements are a directors service agreement and a shareholders agreement.
The directors service agreement is basically an employment contract because the directors (the two of you) are employed by the limited company and the directors service agreement dictates what you do, what you don’t do, what you get paid et cetera in exactly the same way that a contract of employment would. It may also include an arrangement for the directors to purchase shares.
The other document which you would normally have is a shareholders agreement which says what share holders are going to invest, who the shares can be sold to, what happens if one person dies, what happens if one person wants to sell, and what each person is going to invest.
Money which goes into a business can invested by way of share purchase or as a loan to the company (directors loan).
In this particular case it would appear that the investment money is going to be a directors loan and it would appear in the accounts in the directors loan account to be repaid at some stage in the future.
There is an agreement that he would put a certain amount of money into the company and he has failed to do so and hence, he is in breach of the directors service agreement albeit a verbal one
On the other hand, you appear to have done everything which you said that you were going to do.
You are both under a duty to act in the best interest of the shareholders and the delay is prejudicing that.
It would be possible for you to take him to court for breach of the agreement but it’s going to be lengthy and costly litigation with no guaranteed outcome. It’s not something that I would encourage you to undertake.
Any work you have done on this or that he has done on it belong to the limited company and hence, neither of you could leave and take that with you. There is no intellectual property or copyright in an idea and hence, if either of you left and set up the same business idea using your own resource, there is nothing either of you could do against the other. It would be different if there was a restriction in either of your contracts (you don’t have them) preventing that within a particular radius or period of time.
Hence, the practicalities of suing the director for failing to put the money in really make it not worthwhile but if you wanted to go off, either of you, and do your own thing, you would be at liberty to do so.
I am not certain whether that answers the question for you or not but I am happy to answer any specific points arising from this. Kind regards