Mononoble metal dithiolates, preparations containing them and their use

A mononoble metal dithiolate of the formula (A):

• ##STR9## in which Em is a noble metal selected from the group consisting of Au(I), Ag(I), Pd(II), Pt(II) and Rh(III),
• Q is a tetravalent organic radical containing 2 to 10 carbon atoms,
• Y is a hydrophilic group selected from the group consisting of (1) --COOH, (2) --COO.sup.- cat.sup.+, where cat.sup.+ is Li.sup.+, Na.sup.+, K.sup.+, NH.sub.4.sup.+, (C.sub.1-3 alkyl).sub.n N.sup.+ H.sub.(4-n) or (hydroxy-(C.sub.1-3)-alkyl).sub.n N.sup.+ H.sub.(4-n) and n is an integer of 1 to 4, and (3) ##STR10## where R.sup.1, R.sup.2 and R.sup.3 may be the same or different and represent H or methyl and m is an integer of 1 to 12,
• Z has the same meaning as Y or represents --H or a member selected from the group consisting of --OR', --SR', --SO.sub.3 R', --NR'.sub.2, NR'.sub.3.sup.+ X.sup.-, where X.sup.- is a mineral acid or carboxylic acid anion and R' is hydrogen or the group ##STR11## wherein R.sup.1 is H or methyl and
• m is an integer of 1 to 12.