Abstract: New complexes of general formula (I) in whichR.sub.1 and R.sub.2 together form a saturated or unsaturated polycyclic carbocyclic radical containing 7 to 12 carbon atoms, or a saturated or partially saturated mono-, bi- or tricyclic heterocyclic radical containing 5 to 11 chain members and a hetero-atom chosen from oxygen, sulphur or nitrogen, which latter atom can optionally be substituted by an alkoxycarbonyl radical, and,X.sub.1 and X.sub.2 represent chlorine atoms or together formeither a radical of structure: ##STR1## in which n is 0 to 2 and R.sub.6 and R.sub.7, which are identical or different, are hydrogen atoms or, when n=1, can be alkyl radicals or form, together with the carbon atom to which they are attached, a cyclobutyl radical,or a radical of structure: ##STR2## in which n, R.sub.6 and R.sub.7 are defined as above, or their salts where such exist, and their hydrates, their preparation and the pharmaceutical compositions which contain them.