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)(2)PPh) 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)}(2)Cl][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. (C) 2001 Elsevier Science B.V. All rights reserved.