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Reactions of CpWIr 3 (CO) 11 (1) with stoichiometric amounts of phosphines afford siteselective products CpWIr 3 (µ-CO) 3 (CO) 8-x (L) x (L ) PPh 3 , x ) 1 (2), 2 (3), or 3 (4); L ) PMe 3 , x ) 1 (5), 2 (6), or 3 (7)) in fair to excellent yields (38-63%). These products exhibit ligand fluxionality in solution, resolvable at low temperature into the constituent interconverting isomers. The structures of three of the species, namely 2a, 3a, and 5a, have been determined by X-ray diffraction studies. The single-crystal X-ray studies reveal that ligand substitution induces a rearrangement in the cluster coordination sphere from the all-terminal carbonyl ligand geometry of CpWIr 3 (CO) 11 to one in which the three edges of a WIr 2 face of the tetrahedral core contain bridging carbonyls (2a, 3a) or one in which the three edges of the triiridium face are bridged by carbonyl ligands (5a). The triphenylphosphine in 2a ligates radially to the carbonyl-bridged WIr 2 face; a similar site for one of the phosphines is found in 3a, with the second triphenylphosphine coordinated in an axial position with respect to this face. The trimethylphosphine ligand in 5a is located in an axial site with respect to the basal carbonyl-bridged triiridium plane. Information from the crystallographicallyverified isomers, the ligand substitution pattern in the related tetrairidium system, and chemical shifts of signals in the 31 P NMR spectra has been used to suggest coordination geometries for the isomeric forms of the complexes above and for other reported derivatives.

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Heating Cp 2 W 2 Ir 2 (CO) 10 with triphenylamine in refluxing tetrahydrofuran affords Cp 3 W 3 Ir 4 (µ-H)-(CO) 12 (1) in poor yield; an X-ray structural study reveals that the molecule consists of a trigonal bipyramidal CpW{Ir(CO) 2 } 4 unit bicapped by CpW(CO) 2 fragments.

Reaction of [WIr3(mu-CO)3(CO)8(eta-C5Me5)] (1c) with [W(C[triple bond]CPh)(CO)3(eta-C5H5)] afforded the edge-bridged tetrahedral cluster [W2Ir3(mu4-eta2-C2Ph)(mu-CO)(CO)9(eta-C5H5)(eta-C5Me5)] (3) and the edge-bridged trigonal-bipyramidal cluster [W3Ir3(mu4-eta2-C2Ph)(mu-eta2-C=CHPh)(Cl)(CO)8(eta-C5Me5)(eta-C5H5)2] (4) in poor to fair yield. Cluster 3 forms by insertion of [W(C[triple bond]CPh)(CO)3(eta-C5H5)] into Ir-Ir and W-Ir bonds, accompanied by a change in coordination mode from a terminally bonded alkynyl to a mu4-eta2 alkynyl ligand. Cluster 4 contains an alkynyl ligand interacting with two iridium atoms and two tungsten atoms in a mu4-eta2 fashion, as well as a vinylidene ligand bridging a W-W bond. Reaction of [WIr3(CO)11(eta-C5H5)] (1a) or 1c with [(eta-C5H5)(CO)2 Ru(C[triple bond]C)Ru(CO)2(eta-C5H5)] afforded [Ru2WIr3(mu5-eta2-C2)(mu-CO)3(CO)7(eta-C5H5)2(eta-C5R5)] [R = H (5a), Me (5c)] in low yield, a structural study of 5a revealing a WIr3 butterfly core capped and spiked by Ru atoms; the diruthenium ethyndiyl precursor has undergone Ru-C scission, with insertion of the C2 unit into a W-Ir bond of the cluster precursor. Reaction of [W2Ir2(CO)10(eta-C5H5)2] with the diruthenium ethyndiyl reagent gave [RuW2Ir2{mu4-eta2-(C2C[triple bond]C)Ru(CO)2(eta-C5H5)}(mu-CO)2(CO)6(eta-C5H5)3] (6) in low yield, a structural study of 6 revealing a butterfly W2Ir2 unit capped by a Ru(eta-C5H5) group resulting from Ru-C scission; the terminal C2 of a new ruthenium-bound butadiyndiyl ligand has been inserted into the W-Ir bond. Reaction between 1a, [WIr3(CO)11(eta-C5H4Me)] (1b), or 1c and [(eta-C5H5)(CO)3W(C[triple bond]CC[triple bond]C)W(CO)3(eta-C5H5)] afforded [W2Ir3{mu4-eta2-(C2C[triple bond]C)W(CO)3(eta-C5H5)}(mu-CO)2(CO)2(eta-C5H5)(eta-C5R5)] [R = H (7a), Me (7c); R5 = H4Me (7b)] in good yield, a structural study of 7c revealing it to be a metallaethynyl analogue of 3.