Cluster bridging alkylidyne ligand

Reactions of alkynes with trinuclear group 6-group 9 clusters incorporating bridging alkylidyne ligands proceeded by coupling the C-donor ligands. 

The structure of 11a has been established by X-ray diffraction. The compounds 11 are 30-cluster valence-electron (CVE) dimetal species, and are therefore electronically unsaturated. The electron distribution within the W(fi-C)fth rings may be represented by various canonical forms. However, that shown, which implies that the W=C bond in the ( 5-C2B9H9R 2)(OC)2-W=CC6H4Me-4 moiety formally contributes three electrons to the rhodium center (16-electron valence shell), accords with other results from our laboratory involving electronically unsaturated dimetal compounds with bridging alkylidyne ligands 18). 

Scheme 82. Formation of tetranuclear WRU3 cluster containing a triply bridging alkylidyne ligand...

One hexanuclear structure [W6(M-H)4(M-OPr )7(ju,-CPr )(OPr )5(H)] has been reported. This is based on the familiar octahedral We cluster configuration with 12 bridging (4 hydride, 7 isopropoxide, 1 alkylidyne) ligands and 6 terminal (5... 

A series of recent reports have shown that reacting nickelocene with various hydrocarbons in a reducing environment results in the formation of a family of novel complexes, as shown in Scheme 37. For instance, the reaction of nickelocene with 1-pentene or 1-hexene in the presence of metallic sodium gave the red, paramagnetic alkylidyne-hydrido clusters (NiCp)3(/W3-CR)(/U3-H), 133 (R = Bu, (CH2)4Me) in addition to the known (NiCp)3(/X3-GR), 134, and (NiCp)4(ju-H) (135, Scheme 37). The solid-state structure of 133 shows that the bridging hydride ligand caps one face of the Ni3 moiety. The solid-state structure of 135 has also been described. Closely related trinickel /X3-alkylidynes have been obtained from very different routes, by reaction of Ni(acac)Gp or NiCp2 with LiMe vide infra). 

The CC triple bond of the bridging alkyne of cluster (30) is cleaved in a reversible decarbonylation to form the bis-alkylidyne (31). Two molecules of HCCH are incorporated into a ligand in a photochemical reaction of Cp(0C)2Mo( rPPh2)( U"H)Mn(CO)4. A rare U3 ri roethylenearsanediyl complex is formed in the reaction of PPh3=CH2 with the M3-AS cluster As[Mo(CO)2Cp]3. 

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