The commission shall negotiate with and purchase, on such terms as it deems to be in the best interest of the commonwealth and its employees, from one or more insurance companies, savings banks or non-profit hospital or medical service corporations, a policy or policies of group life and accidental death and dismemberment insurance covering persons in the service of the commonwealth, and group general or blanket insurance providing hospital, surgical, medical, dental and other health insurance benefits covering persons in the service of the commonwealth and their dependents, and shall execute all agreements or contracts pertaining to said policies or any amendments thereto for and on behalf and in the name of the commonwealth.