Don't worry, I had the same problem! You won't be able to fix your split leaps overnight, but if you practice regulary you'll soon see improvment!
First off, you have to be able to do the splits, to be able to do a 180 degree split leap, like the gymnasts in your photos.
I stretch for 30 minutes nearly every day, then hold splits for a few minutes. You can put your leg on a chair to practice hyper-splits too.
Next, make sure you have a good run before you do the split leap(s). My coach says, you should only take 2-3 steps.
Also, one leg is usually more flexible than the other, called the good/bad leg. Check that your doing your split leaps with your 'good' leg in front!
If you practice and stretch properly, I'm sure you'll have a fantastic split leap sooner or later! Don't forget, nothing can beat the advice of a good gymnastics coach, so if you haven't already, ask your coach on some tips!
I hope everything goes well!
(P.S. if the tips I gave you don't make sense, please tell me!)