Above articles refer to this article here (dated January 2nd, 2015), according to which Vladimir Chizhov (Russian Ambassador to the EU) has "urged Brussels to launch talks with the newly born Eurasian Economic Union (EAEU)".
The article quotes him as saying that "I think that common sense advises us to explore the possibility of establishing a common economic space in the Eurasian region...We might think of a free trade zone encompassing all of the interested parties in Eurasia".
However the article is now several months old and nothing much has been mentioned about this elsewhere.
Also to me the expression "urged Brussels" can mean both an "urging" that is actually meant for the public to hear (through e.g. news media) or a reference to a formal request through e.g. the diplomatic channels.
So the question I wanted to ask is: has Russia actually asked EU to join the Eurasian Economic Union?
Note: There is also this article (dated January 3rd, 2015) but it is in German and my German is not good enough to interpret it properly.