Facebook's new enterprise tool has taken an early knock as its key architect has decided to leave the company. Engineering director Lars Rasmussen is leaving to set up a music startup with his partner.

Rasmussen, who helped create Facebook's search engine, has been building Facebook At Work, the company's effort to turn the world's most popular social network into an enterprise tool.

Rasmussen and Facebook told Techcrunch that he will leave the company in June. "Leaving Facebook was an incredibly difficult decision," Rasmussen said in a statement. "Working there has never been more exciting for me, in particular given the incredible momentum behind Facebook at Work, and the ridiculously talented people I work with on that project and at Facebook in general. But over the past year my fiancé, Elomida, has built what I think is a new and exciting way to compose and experience music. And trying to turn that into a successful startup together will be way too much fun to postpone any longer."

The Dane has not released any details about his music venture except that it will be based in London, where he lives with his partner Elomida Visviki. It will be interesting what the couple come up with at what feels like a key time for the music industry. Apple's streaming service due to be launched later this year following its acquisition of Beats Music could transform the market. Jay-Z recently launched his streaming service, Tidal, to great acclaim from some of his A-list friends, but it has failed to gain much traction yet, so much so that the artist has taken to Twitter to defend his brand.

You would imagine that Rasmussen and Visviki have something a little different from the current models in mind when they mention "a new and exciting way to compose and experience music."

It's not Rasmussen's first tilt at entrepreneurship. He was the co-founder of an Australian company called Where2 Technologies, which was acquired by Google in 2004. Using his technology he became the co-creator of Google Maps and then the less-successful Google Wave. Rasmussen moved to Facebook in 2010 where he developed Facebook's search engine Graph Search before working on Facebook@Work.

The enterprise tool has been in closed beta since its launch in January. Chaitanya Mishra, who had been working under Rasmussen in London, will take over the running of the engineering team. Julien Codorniou, Facebook's global partnerships head also based in London, will lead on partnership support. It will be a blow to Facebook to lose the man who imagined Google Maps, but will be interesting to see what designs he has for the music industry.