A compound of the general formula R′MR4R5R6 where R1 is an aryl, alkyl, alkenyl, epoxy or alkynyl group, and where R1 is fully or partially fluorinated, wherein M is selected from group 14 of the periodic table, wherein R4, R5 and R6 are independently an alkoxy group, OR3, or a halogen group X, except,
- a) where R4, R5 and R6 are each ethoxy, M is Si and R1 is perfluorinated phenyl or perfluorinated vinyl;
- b) where R4 is ethoxy, R5 and R6 are chlorine, M is Si, and R1 is perfluorinated phenyl;
- or
- c) where R4, R5 and R6 are chlorine, M is Si, and R1 is perfluorinated phenyl, perfluorinated methyl or perfluorinated vinyl.