In a previous life I did advertising photography in NYC. Also taught a few college Photography courses. A couple of observations: first you're doing the right thing by bracketing your exposures. Sunsets [and sunrises] are difficult lighting situations & you'd rarely get one right with a single exposure.
Most camera metering &/or auto exposure systems measue light intensity at the center of the frame. In all the shots you provided the brightest part of the image is directly in the center so the darker parts of the frame are necessarily under exposed.
Since it's the sunset you're trying to capture there's a couple of things you can try. Lift the camera so that you aren't including so much of the dark ground-with such an extreme lighting contrast all that will ever be is a black void & it's really the sunset you're after anyway. Also, try not putting the brightest spot in the center of the frame. Since most metering systems a center weighted try focusing on a medium-lit portion of the frame. It will create a more dynamic image & perhaps one that shows a better colour balance.