Pfizer Inc. is planning to give scientists up to a year and half to completely vacate the New London office complex it has agreed to sell to Electric Boat, the pharmaceutical giant's local site leader said Thursday.

Pfizer Senior Vice President Toni Hoover, site leader for the company's Groton and New London campuses, said the former global research-and-development headquarters off Pequot Avenue may not be emptied of Pfizer employees and equipment until the end of 2011, giving scientists time to complete some of the drug trials they are currently conducting all over the world.

"We're going to look at the work. If there's a clinical study that's close to completing or at a critical stage, that would not be an opportune time to move them," Hoover said.

The first group of EB employees has already moved into the former Pfizer complex.

EB designers and engineers who are working on the Navy's next generation of ballistic-missile submarines finished the work day in Groton last Friday, before the July 4 weekend, and reported to work in New London on Tuesday.

The company's facilities staff worked during the holiday weekend to get the offices set up so there would be "no disruption to the work routines," said Robert Hamilton, EB spokesman.

A "small number" of employees have moved, Hamilton said, but the number will grow. The Pfizer complex is designed for about 2,200 people, but the buildings could be modified to accommodate more. Of the 10,000 people employed by EB, about 4,000 are involved in design and engineering.

Hamilton said the company is still negotiating a final sales agreement with Pfizer, which it hopes to complete within the next two months. He added that Pfizer's phased exit from New London corresponds with EB's vision of gradually ramping up its presence in the city.

Officials have yet to disclose the actual sales price of the complex, but EB has said it plans to invest up to $99 million, including a $15 million state grant, in connection with its relocation of design and engineering workers to New London.

Hoover said plans are currently under way to renovate a total of five buildings on Pfizer's Groton campus to accommodate the 1,400 New London employees who will be moved there as part of a worldwide consolidation of the company's R&D footprint after its merger with Wyeth Pharmaceuticals.

One of the structures, a former administrative office known as Building 260, will be extensively renovated, she said, while others, including some on the west campus where the company's former manufacturing facilities were located, will be reconfigured or undergo more modest changes.

Hoover said no newly constructed buildings are planned on Pfizer's Groton campus. She declined to give an estimated cost for the move or renovations.

"My colleagues in New London and Groton are looking forward to having our colleagues from New London join us on the Groton campus," Hoover said.

The corporate services firm bkm Total Office of East Hartford will help accomplish the move, which is being coordinated by various local teams, including one headed by Hoover.

Hoover would like to vacate the former Pfizer Global Research and Development site tower by tower, but the company is still working out details with Electric Boat. Pfizer is hoping first to exit Tower C, the one closest to the water, she added, and already several groups have left their New London offices.

Hoover said the global operations, facilities and engineering groups have been moved temporarily into a Pfizer-leased office building on Howard Street that the company previously had vacated.

"We will continue to move small groups as space becomes available," she said.

The renovations and moves, dubbed the Back to the Future Project, are being accomplished with the aid of Pfizer's Global Operations department, Hoover said. Plans call for Pfizer employees to go right to work at their new stations as soon as they become available, she said.

Hoover said Pfizer is currently examining some of its support operations in Groton, such as the cafeteria, childcare facility and the fitness center, to determine whether any of the services need to be upgraded to accommodate 1,400 more people.

"I am absolutely confident we will be able to accommodate everyone from a services perspective," she said.

Hoover also was hopeful that by returning research and development to one site in Groton, more chances for direct collaboration would be available for employees - as well as fewer teleconferences and trips across the Gold Star Memorial Bridge. Having all its R&D personnel in one area also would allow for more flexibility in where people are stationed as different projects are developed, she added.

"People forget in the early 2000s or late 1990s, we had the same amount of people (on the Groton campus) ... prior to opening the New London facility," Hoover said. "I'm optimistic and excited about the consolidation."

Day staff writer Jennifer McDermott contributed to this report.