Syntheses and Reactivity of Heterometallic Oxo−Acetylide Cluster Compounds. Skeletal Rearrangement and Conversion of Acetylide to Alkenyl, Alkylidene, and Allenyl Ligands on a WRe₂ Framework

Abstract

Oxidation of the mixed-metal cluster Cp*WRe 2 (CCR)(CO) 9 (1, Cp* ) C 5 Me 5 ; R ) Ph and C(Me)dCH 2 ) with dioxygen in solution at 100 °C affords the oxo clusters Cp*W(O)Re 2 (CCR)-(CO) 8 , (2a, R ) Ph; and 2b, R ) C(Me)dCH 2 . Treatment of 2 with CO at 110 °C provides the clusters Cp*W(O)Re 2 (CCR)(CO) 9 (4), which revert back to 2 by removal of one CO upon thermolysis. Both compounds 2 and 4 contain an open triangular skeletal arrangement, a multisite bound acetylide ligand, and a terminal oxo ligand attached to the W atom. Complex 2a reacts with dihydrogen to form a mixture of three cluster complexes: the acetylide cluster Cp*WRe 2 (µ-O)(µ-H) 2 (CCPh)(CO) 6 (5a), alkenyl cluster Cp*W(O)Re 2 (CHCHPh)(CO) 8 (6a), and the alkylidene cluster Cp*W(O)Re 2 (µ-H)(CHCH 2 Ph)(CO) 8 ( 7a), which are formally produced by addition of two H 2 and elimination of two CO molecules, transferring one H 2 to the acetylide ligand and incorporation of one H 2 molecule to 6a, respectively. For the vinylacetylide compound 2b, it reacts with dihydrogen under similar conditions to furnish a mixture of the above mentioned clusters 5b, 6b, and 7b, together with a fourth allenyl cluster Cp*WRe 2 (µ-O)(CHCCMe 2 )(CO) 7 ( 8), which is probably produced through a 1,3-Hmigration on the alkenyl ligand CHdCHC(Me)dCH 2 in 6b. The X-ray structural analysis of these oxo cluster compounds, their spectroscopic data, and the mechanistic studies of the conversion from acetylide clusters 2, 4, and 5 to alkenyl clusters 6, alkylidene clusters 7, and allenyl cluster 8 are presented.

Acceptor Behavior and E–H Bond Activation Processes of the Unsaturated Heterometallic Anion [MoReCp(μ-PCy2)(CO)5]−(Mo═Re)

“…Unfortunately, no oxide-bridged MoRe binuclear complexes appear to have been structurally characterized so far, to be used for comparative purposes. However, a few WRe 2 organometallic clusters have been reported with oxide ligands bridging over WRe edges . Even if the coordination spheres in these clusters are not strictly comparable to those in 4 , it is interesting to note that all of them also display strongly asymmetric oxide ligands (W–O = 1.77–1.80 Å; Re–O = 2.14–2.29 Å) bridging over short W–Re edges (2.79–2.87 Å), as found in 4 .…”

Mixed-Metal Cluster Chemistry. 31. Reactions of Dimolybdenum–Diiridium Clusters with Alkylidyne Complexes

“…The edge-bridging oxo ligand is somewhat unsymmetrically disposed (Mo3–O34 = 1.881(8) Å, Mo4–O34 = 1.998(8) Å). This specific ligand coordination mode is not unusualreactions of monometallic oxo complexes, μ-acyl clusters, and terminal oxo-ligand-containing clusters have all afforded edge-bridging oxo-ligand-containing clusters, as have reactions of clusters with water and trimethylamine N -oxide, and indeed derivatization of pre-existing μ-oxo-containing clusters has been successfully effected. The formation of coordinated carbide and oxo ligands by cleavage of a coordinated carbonyl ligand, as in the present case, is comparatively rare, although there are mixed-metal precedents .…”

Synthesis, Structure, and Electrochemistry of Acetylide and Oxo Incorporated Mixed Fe/Mo and Fe/W Chalcogen-Bridged Clusters

“…Oxidation of [(η 5 -C 5 Me 5 )MCl 4 (M = Mo or W) with hydrogen peroxide provides a high yield synthesis of the oxo-peroxo complexes [(η 5 -C 5 Me 5 )M(O)(O 2 )Cl] . Several oxo-containing cluster complexes have also been reported. − At least in some cases, the formation and type of metal-oxo complex have been found to be highly sensitive to the reaction conditions used. For instance, [(η 5 -C 5 Me 5 ) 2 V] reacts with different concentrations of oxygen to form three types of complexes: 1:2 molar excess of oxygen gives [(μ-η 3 -C 5 Me 5 O 3 )V(O)] 2 ; in the presence of trace amounts of oxygen, [(η 5 -C 5 Me 5 )V] 4 (μ-O) 6 is formed; and when a large excess of oxygen is used, [(η 5 -C 5 Me 5 ) 6 V 8 (O) 17 ] is obtained …”