Great question! One thing most students don't realize about carbon NMR is that in most instances, you run it in proton-decoupled mode and the software will decouple the protons for you. Hence why you get nice singlets that tells you the number of carbons in the molecule. However, if you think about it, protons couple with each other - why wouldn't they couple with carbons? The answer is that they do! So in proton-coupled mode, each carbon will actually be split by the protons attached to it! Cool, right?
