Cationic chelate phosphane substituted carbyne tungsten complexes

Reaction of W(CMes)Cl(CO)2(dppe) (1) and W(CMes)Cl(CO)(dppep) (8) (Mes=2,4,6-trimethylphenyl, dppe=Ph2PCH2CH2PPh2, dppep=(Ph2PCH2CH2)2PPh) with AgSbF6 or AgOTf (OTf=CF3SO3−) as halide abstraction reagents affords [W(CMes)(CO)n(Y)][X]; (2): Y=dppe, n=2; (9): Y=dppep, n=1; (a) X=SbF6−; (b): X=OTf. In solution, the metal moieties of compounds 2a, 9a and 9b exist as naked cations, which possess a square pyramidal coordination. The carbyne ligand occupies the apical position, and a free coordination site is located trans to the CMes group. The reaction of 2a with a variety of donor ligands leads to [W(CMes)(CO)2(dppe)L][SbF6] compounds, in which the ligand L binds trans to the carbyne unit (L=THF (4a), CH3CN (4b), PMe3 (5a), PEt3 (5b)). In the carbonyl adducts [W(CMes)(CO)n(Y)][SbF6]; Y=dppe, n=3, (3); Y=dppep, n=2, (10); the chelating ligands rearrange so that a phosphorus donor atom coordinates trans to the carbyne ligand. The reaction of 2a with P(OMe)3 and P(OEt)3 results in the phosphonate complexes [W(CMes)(CO)2(OPH(OR)2)(dppe)][SbF6]; R=Me (6a), Et (6b), which are formed in an Arbuzov dealkylation reaction. When 1 is reacted with a deficient amount of silver salt, the bimetallic complex [{W(CMes)(CO)2(dppe)}2Cl][SbF6] (7) is obtained. The unusual molecular geometries of 6a and 7 were confirmed by a crystal structure determination. A theoretical analysis reveals the importance of electrostatic interaction for ligand bonding with the cationic metal fragments.