Chalcogen-capped ruthenium carbonyl clusters derived from diphosphazane mono- and dichalcogenides of the type X2P(E)N(R)PX2 and X2P(E)N(R)P(E)X2 (E = S or Se)

Reactions of Ru3(CO)12 with diphosphazane monoselenides Ph2PN(R)P(Se)Ph2 [R = (S)-∗CHMePh (L4), R = CHMe2 (L5)] yield mainly the selenium bicapped tetraruthenium clusters [Ru4(μ4-Se)2(μ-CO)(CO)8{μ-P,P-Ph2PN(R)PPh2}] (1, 3). The selenium monocapped triruthenium cluster [Ru3(μ3-Se)(μsb-CO)(CO)7{κ2-P,P-Ph2PN((S)-∗CHMePh)PPh2}] (2) is obtained only in the case of L4. An analogous reaction of the diphosphazane monosulfide (PhO)2PN(Me)P(S)(OPh)2 (L6) that bears a strong π-acceptor phosphorus shows a different reactivity pattern to yield the triruthenium clusters, [Ru3(μ3-S)(μ3-CO)(CO)7{μ-P,P-(PhO)2PN(Me)P(OPh)2}] (9) (single sulfur transfer product) and [Ru3(μ3-S)2(CO)5{κ2-P,P-(PhO)2PN(Me)P(OPh)2}{μ-P,P-(PhO)2PN(Me)P(OPh)2}] (10) (double sulfur transfer product). The reactions of diphosphazane dichalcogenides with Ru3(CO)12 yield the chalcogen bicapped tetraruthenium clusters [Ru4(μ4-E)2(μ-CO)(CO)8{μ-P,P-Ph2PN(R)PPh2}] [R = (S)-∗CHMePh, E = S (6); R = CHMe2, E = S (7); R = CHMe2, E = Se (3)]. Such a tetraruthenium cluster [Ru4(μ4-S)2(μ- CO)(CO)8{μ-P,P-(PhO)2PN(Me)P(OPh)2}] (11) is also obtained in small quantities during crystallization of cluster 9. The dynamic behavior of cluster 10 in solution is probed by NMR studies. The structural data for clusters 7, 9, 10 and 11 are compared and discussed.