Uses of carbenes in solution as organopolysiloxane polycondensation catalysts

A silicone-based elastomer precursor composition X comprising:

• a silicone base B comprising at least one polyorganosiloxane oil or gum C, said oil or gum C being (i) polymerizable or crosslinkable via a polycondensation reaction and having (ii) a dynamic viscosity of from 10 mPa·s to 1.5×106 mPa·s at 25° C.;
• and
• a catalytic composition Y′ comprising:
• a) a catalytically effective amount of at least one polycondensation catalyst A which is a carbene of formula (I) below:
• with:
• the symbol X being selected from the group consisting of the following atoms or groups:
• —O—, —S—, —N(R)— and —P(R)— with R being a C1-C30 group,
• R1, R2 and R3 being identical or different, optionally substituted, C1-C30 groups optionally comprising one or more atoms selected from the group consisting of:
• S, P, Si, N and O, and
• the symbols X, R1, R2 and R3 taken in pairs can form a 5-, 6- or 7-membered ring, and
• b) at least one solvent comprising at least one alcohol G.