In Russia, there is a presumption that marital property be shared equally.
You may recall that in 2014, Russian oligarch Dmitry Rybolovlev was ordered to pay his wife one-half of his $8.8 Billion fortune. Therefore, unless special circumstances apply, Vladimir Potanin can expect to pay his wife one-half of his $15 Billion fortune.
While that may seem "unfair" to some, perspective is important. If Russian law provides that marital property is essentially equally owned by each, then Mr. Rybolovlev didn't give his wife anything that didn't already belong to her and the same will be true of whatever Mr. Potanin's wife receives, unless they reach an agreement on their own terms.
The law is a blunt object, but people may agree to anything they want that is not illegal or otherwise in violation of public policy. I much prefer helping people resolve their issues in accordance with their needs and interests than through the application of blunt objects, which is one reason why I favor mediation.