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)

Abstract

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)(μ_sb-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 p-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(λ₃-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-Ph ₂PN(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.