The chemical inventory of pre/proto-stellar cores

Oral presentation given at the Terzo Workshop sull'Astronomia millimetrica e submillimetrica in Italia, held in Bologne (Italy) on January 20-21th, 2014.Cold dark clouds are the sites of low-mass star formation and future planetary systems. They exhibit a complex gas-phase ion-neutral chemistry leading to the formation of a large variety of molecules. The lack of internal heating sources and violent physical processes, like shocks, make these dense and quiescent cores the best sites to explore and to model interestellar gas-phase chemistry and molecular depletion into the dust grain surfaces. However, they have been found to be less chemically simple than previously thought. Using the IRAM 30m radiotelescope in Spain, we have performed a spectral line survey of the whole 3mm band (82.5-117.5 GHz) toward two prestellar cores, B1-b and TMC-1. Indeed spectral scans are the best tool to provide a complete view of the molecular complexity of dark clouds. Furthermore, unexpected species can provide new information about the physical and chemical evolution of molecular cores toward star formation and complement the usual tracers. In this talk I will present the results of the full 35 GHz scan in B1-b. So far we have detected 325 lines from 109 molecular species and isotopomers. These include unexpected discoveries such as the methoxy radical (CH3O) and other complex molecular species