PROVIDENCE, R.I. — The developers who hope to build a life-sciences complex on 5 acres of former highway land have taken a significant step forward by signing a purchase and sale agreement with the I-195 Redevelopment District Commission to buy the two largest parcels of vacant highway land, the 195 Commission told The Providence Journal Friday morning.

Wexford Science + Technology of Baltimore and CV Properties LLC, of Boston and Southport, Conn., are proposing in the agreement to subdivide the land and buy it in three phases, according to the agreement. The purchase price that's identified in the document is a calculation based on $15 per square feet of the real-estate term, Floor Area Ratio, for what would be built on the land in the first phase. Floor Area Ratio is the total square feet of a building divided by the total square feet of the lot where it's located.

That price equals $6.6 million, 195 Commission Spokeswoman Dyana Koelsch told The Journal.

In all, the developers have agreed to buy the 5 acres, in three phases, for approximately $13 million, Koelsch said.

The 195 Commission said construction is expected to begin on the first phase by early 2017.

Expected development costs for the first phase are approximately $250 million, she said.

State and city leaders hailed the agreement as an important step forward in realizing the state's goals for the highway land and Governor Raimondo's vision for "an innovation economy."

“Wexford and CV have created thriving life-science centers and leading research and development business environments around the country. Their decision to take this next step forward with Rhode Island is a big deal for our state and shows we have momentum,” Governor Raimondo said in a statement.

“This project has the potential to create many good-paying jobs for Rhode Islanders over the next few years. While there is still work to do, we remain relentless in our efforts to bring these jobs here and build an innovation economy in Rhode Island.”

The purchase and sale agreement is the result of months of negotiations between state leaders and the developers, who first announced intentions for the project in May. In December, the 195 Commission authorized Chairman Joseph F. Azrack and Executive Director Peter McNally to execute a draft purchase-and-sale agreement with CV and Wexford.

The development project would be the largest economic-development initiative in the state, and all parties acknowledge it will seek economic-development incentives created by the Raimondo administration. However, no details are immediately available Friday about how much the team might request from the state.

"Wexford and CV will apply for newly enacted state incentives designed to spark innovation and design development to create 21st century jobs," the commission's Friday statement said.

In the first phase of development, the CV-Wexford team expects to build about 500,000 square feet of mixed-use development that will encompass research and development, lab and office facilities, an innovation center, as well as restaurant and meeting facilities and a hotel and residential complex, the commission said in a statement.

The CV-Wexford team also intends to buy adjacent property, according to the purchase and sale agreement with the commission — One Ship Street, adjacent to Parcel 25 to the south, and 60 Clifford Street, now owned by Brown University and north of both Parcels 22 and 25. The 60 Clifford Street building has most recently been occupied by the former Nabsys life-sciences company.

The purchase and sale agreement includes a detailed development schedule for all three phases of the Project, beginning with a 90-day due-diligence period, followed by 180 days to obtain building permits leading to closing on Phase I, according to the 195 Commission.

Wexford Science + Technology is a real-estate investment and development company that partners with universities and hospitals across the country to build research parks. CV Properties is the lead developer of the shared nursing education center and Brown University administrative offices in the South Street Landing project, which is southeast and across Eddy Street from the 195 parcels the two now intend to buy.

The developers have been in talks with the Cambridge Innovation Center, Brown University and the University of Rhode Island as potential tenants for the life-sciences complex, but no tenants have yet been announced.

Richard A. Galvin, president and founder of CV Properties, issued a statement Friday about the purchase and sales agreement:

“We’re very pleased to have reached a purchase and sales agreement with the I-195 Commission. This is an exciting development and a critical step that will enable us to intensify the work of recruiting the tenants needed to make our proposed life sciences complex a reality. We’re hopeful that our work will be successful and allow us to realize the vision we share with the Governor and others in leveraging the former I-195 land to help spur growth in the innovation community, including the promising life sciences sector, while also creating new job opportunities for Rhode Islanders.”

Correction: An earlier version of this story mischaracterized the status of the developers' effort to buy additional land in the 195 area.