Money is great for getting trade agreements but for alliances I have found that offering techs sometimes works better. I tend to stay away from giving military/naval ones except to small nations I am trying to build up. Industrial ones are preferable to me since their lands will hopefully be richer when I take them.

I play on normal so I don't how diplomacy works on the harder difficulties but on normal I can usually come up with an agreement of some sort. It just takes some haggling and patience. If you can't get anywhere now, try a couple of turns later. I found this much much harder to do in 1.3. It takes work sometimes but that seems right to me.