­Google has announced the completion of the delayed purchase of Motorola Mobility, and replaced the CEO.

Sanjay Jha has stepped down from his role as CEO and has been replaced by long-time Google employee, Dennis Woodside with immediate effect.

The company did not explain the reasons for the switch-over, although it had been rumoured earlier this year that Woodside would take over the top job. He oversaw the takeover of the company from Google's side.

Google has often struggled to retain executives from companies that it acquires with culture clashes between incumbent staff and the new entrants being regularly reported. Bringing in Google staff at the beginning may help to avoid the inevitable reports of Motorola execs having difficulties working within the Google structure.

When former Qualcomm executive Sanjay Jha joined the company in 2008, he was offered a salary comprising of some $35 million worth of stock and options, plus a 3% stake in the firm when it was split from the larger Motorola group.