Abstract: A novel compound which can be used in the field of separation and purification of gases is disclosed. The compound can be incorporated into a silica gel incorporating polyazacycloalkane structural units for separating a predetermined gas from a mixture of gases. The mixture of gases is brought into contact with a metallated hybrid gel under conditions which make possible the absorption of the gas to be separated, followed by a phase of desorption of the attached gas, and the recovery of the gas.

Abstract: Organgomagnesium complexes which correspond to the formula (I): ps(RMgX).sub.m /N[--CHR.sub.1 --CHR.sub.2 --O--(CHR.sub.3 --CHR.sub.4 --O).sub.n --R.sub.5 ].sub.3 (I)wherein:m is 1, 2, or 3;R denotes a substituted or unsubstituted group which is:linear or branched alkyl containing from 1 to 18 carbon atoms,alkenyl or alkynyl containing from 2 to 18 carbon atoms,cycloalkyl or cycloalkenyl containing from 3 to 12 carbon atoms,alkoxyalkyl, dialkoxyalkyl or alkylthiocarbonyl, aryl (which aryl may particularly be position-substituted by at least a halogen or an alkoxy, trifluoroemethyl, trifluoromethoxy or trifluromethoylthio group), oralkoxyaryl or alkylthioaryl;X denotes a chlorine, iodine or bromine atom;n is an integer ranging from 0 to about 10;R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which are identical or di fferent, denote a hydrogen atom or an alkyl or cycloalkyl radical containing from 1 to 4 carbon atoms; andR.sub.5, which is identical or different in each of the three [--CHR.sub.1 --CHR.sub.2 --O--(CHR.