ONE-STEP SYNTHESES OF PH(3)P-SUBSTITUTED SELENIDO CARBONYL IRON AND RUTHENIUM CLUSTERS .2. CRYSTALS STRUCTURES FE-2(MU(2)-SE-2)(CO)(6-N)(PPH(3))N (N=1 OR N=2), FE-3(MU(3)-SE)(2)(CO)(8)(PPH(3)) AND RU-4(MU(4)-SE)(2)(MU-CO)(2)(CO)(8)(PPH(3)), AND HPLC BEHAVIOR OF THE IRON DERIVATIVES

Ph(3)PSe reacts with Fe-3(CO)(12) giving six products (1-6) belonging to three different families of clusters: Fe-2(mu-Se-2)(CO)(6-n)L(n) (t wo products, 3, 5, n=1, 2), Fe-3(mu(3)-Se)(2)(CO)(9-n)L(n) (three prod ucts, 1, 2, 4, n=0-2) and Fe-3(mu(3)-Se) (mu-CO)(CO)(9-n)L(n) (one pro duct, 6, n=2). Under the same conditions Ru-3(CO)(12) affords Ru-3(mu( 3)-Se)(2)(CO)(9-n)(PPh(3))(n) (three products 7,8, 10,n = 1-3) and the tetraruthenium clusters Ru-4(mu(4)-Se)(2)(mu-CO)(2)(CO)(9-n)(PPh(3))( n) (two products, 11, 9, n = 1, 2). The structures of the clusters 2, 3, 5 and 11 . 1/2CH(2)Cl(2) have been determined by X-ray diffraction methods. The mass-spectral behaviour of iron mono- and disubstituted p hosphine derivatives (2-6) is characterised by the low abundance (< 6% ) of polynuclear fragments, even under NICI conditions. Gas-phase rear rangements are considered to take place in order to explain the presen ce of certain peaks. The six iron derivatives are effectively separate d by HPLC, the elution order depending on the degree of phosphine subs titution and the kind of cluster framework.