ELSEVI ER InorganicaChimicaActa252 (1996) 307-374 One-step syntheses of Ph3P-substituted selenido carbonyl iron and ruthenium clusters Part 2. Crystal structures of Fe2(/~-Seg) (CO)6_~(PPh3)n (n= 1 or 2), Fe3(~3-Se) 2(CO) 8(PPh3) and Rua(/za-Se) 9(/z-CO) z(CO) 8(PPh3), and HPLC behaviour of the iron derivatives i Paolo Baistrocchi, Maria Cared, Daniele Cauzzi, Claudia Graiff, Maurizio Lanfranchi, Paola Martini, Giovanni Prcdicri *, Antonio Tiripicchio Dipartimento di Chimica Generale ed lnorganica. Chimica Analitica. Chimica Fisica, Universit~ di Parma. Centro di Studio per la StrurIuristica Diffrattometrica del CNR. Viale delle Scienze. 1-43100 Parma, Italy Received 31 May 1996 Abstract Ph3PSe reacts with Fe3(CO),2 giving six products (I-6) belonging to three different families of clusters: Fe2(/z-Se2) (CO)6_,~L,~ (two products, 3, 5, n= !, 2), Fe3(~3-Se)2(CO)9_nL n (three products, 1, 2, 4, n=0-2) and Fe3(/za-Se)(/t-CO) (CO)9_nl-~ (one product, 6, n = 2). Under tbe same conditions, Ru3(CO) 12 affords Ru3(/-t3-Se)2(CO)9- n(PPh3)n (three products7,8, lO, n = 1-3) and the tetrarmbenium clusters Ru4(/J.4-Se ) 2(IL-CO) 2(CO)9_n(PPh3)n (two products, 11, 9, n = 1,2). The structures of the clusters 2, 3, $ and 11-1/2CH2C]2 have been determined by X-ray diffraction methods. The mas3-spectral behaviour of iron .,.aono-and disubstituted phosphine derivatives (2--6) is characterised by the low abundance ( < 6% ) of polynuclear fragments, even under NiCI conditions. Gas-phase rearrangements are considered to take place in order to explain the presence of certain peaks. The six iron derivatives are effectively separated by HPLC, the elution ruder depending on the degree of phosphine substitution and the kind of cluster framework. Keywords: Iron complexes;Rutheniumcomplexes;Selenium complexes; Clustercomplexes; Crystalstructures 1. Introduction The combination ofchalcogen elements and transition met- als in discrete molecular clusters is of particular interest since it often results in new coordinations and geometries and could give rise to useful models and precursors for the synthesis of new materials [ 1-3]. Among the methods for the synthesis of transition-metal clusters containing bridging chalcogenido ligands [4], that involving tertiary pbosphine chalcogenide R3PE (E = S, Se, Te) has been proved to be one of the most effective [5-9]. This method takes advantage of the frailty of the P=E bond, which leads to the production of phosphine-substituted chal- cogenide clusters through oxidative transfer of chalcogen atoms to zero-valent metal complexes. s For PaR I see Ref. [8]. 0020-1693/96/$15.00 © 1996Elsevier ScienceS.A. All rightsreserved Pll S0020-1693 (96) 05362- 5 In the preceding paper [81, we reported on the reactions of Ph3PSe with Fe3(CO)l 2 and Ru3(CO)I 2. In the ca~ of iron the reaction afforded several dinuclear and trinuclear compounds, namely [Fe2(/~-Se2)(CO)6_,~L~ (n= 1, 2), [Fe3(/~3-Se)2(CO)9_nL~] (n=0-2) and [Fe3(/~3-Se)(/~- CO) (CO)9_~L~] (n = 2), whereas in the case of ruthenium the same reaction was found to be quite selective giving the disubstituted trinuclear cluster [Ru3(/z3-Se)2- (CO)7(PPh3)2] in very high yield, with minor amounts of other products, among which was the tetraruthenium cluster [Ru4(/.t4-Se)2(i.t*CO)2(CO)7(PPh3)2]. The crystal StrUCo tnres of Fe3(/z3-Se)(/.t=CO)(CO)7(PPh3)2, M3(~3-~)2- (CO)?(PPh3) 2 (M--Fe or Ru) and Ru4(p4-Se)2(p- CO)2(CO)7(PPh3)2 were determined by X-ray diffraction methods. Furthermore, we found [ 9 ] that the dipbosphiue diselenide CH2(Ph2PSe)2 and [Ru3(CO)t2] react in toluene to give (besides [Ru3(/z3-Se)2(CO)7(dppm)] arid [Ru4(iz4-