Nucleophilic Attack of Carbonyl-Stabilized Phosphorus Ylides on 1,5-Cyclooctadiene Complexes of Palladium and Platinum

Abstract

Carbonyl-stabilized phosphorus ylides R3PCHC(O)R‘ (R = Ph, Tol-p; R‘ = OEt, OMe, NMe2) react with the 1,5-cyclooctadiene complexes [MCl2(cod)] (M = Pt, Pd; cod = C8H12 = 1,5-cyclooctadiene) to give the monomeric cyclooctenyl complexes [MCl2{C8H12{CH(PR3)C(O)R‘}}]. The ylides attack in an exo fashion to give complexes which can be regarded as metalated phosphonium salts. Reactions involving the replacement of one or both chloro ligands with a neutral ligand are discussed. The crystal structures of complexes [PtCl2{C8H12{CH(PPh3)CO2Me}}] and [Pt{C8H12{CH(PPh3)CO2Me}}(py)2](CF3SO3)2 are reported.

A Novel Alkene(alkyl)(aqua)(aryl)platinum(II) Complex - [Pt{CH(CH2C6F5)CH2CH2CH=CH2}(C6F5)(OH2)]

“…2, respectively. The Pt±C(alkyl) distance (Table 1) is comparable with those observed for analogous bonds (2.051(9), 2.057(7) A Ê ) formed by nucleophilic addition to a coordinated double bond [2]. Platinum is coordinated by an alkene group, an alkylcarbon, a pentafluorophenyl carbon, and an oxygen atom, considered (below) to be from a water ligand though the hydrogen atoms were not located, in a near square planar arrangement.…”

Zwitterionic Organometallates

“…They were obtained through an unusual vinylogous nucleophilic attack of stabilized α-phosphonium ylides at a cyclooctadiene ligand in an exo fashion (Scheme 7). [35] Although the chloride ligands may be displaced by non-coordinating anions, the Pt-Cl 8distances in the crystal (2.3 or 2.4 Å depending on the …”

Ylide Ligands

“…The COD ligand is easily removable from the coordination sphere of the Pd(II) or Pt(II) centers, and therefore the expected reactivity would be the displacement of the alkene by a more powerful ylidic nucleophile. However, the observed process is the addition of the ylide to the alkene giving -bonded alkyl derivatives (40) as those presented in Scheme 12 [99,100]. In the same way, platinum coordinated nitriles NCR' react with stabilized ylides to give iminophosphoranes (41) [101], imidoyl-ylides (42) [102], iminoylides (43) [103], while coordinated isonitriles CNR' (where R' is a functional group containing the ylide moiety) react also with ylides giving interesting carbenes (44) [104,105].…”

“…Complexes (101) are shown in Scheme 30 as trans-trans, but they could also be obtained in other isomeric forms [206]. Although no formal gold-gold bonds are present in (99) or (101), short metal-metal separations are found (numismophilicity) and, in the case of (101), very unusual structures have been obtained [207]. The oxidative additions to (99) always occurs in the same way, giving complexes (100), which are very stable.…”

“…Complexes (100) can also be obtained by comproportionation of (99) and (101). However, the 2eoxidation of a single center in dimer (99) to give the mixed derivative [Au I Au III ] (102) is not possible at all but, curiously, the 2ereduction of (101) (for instance, with AgCN) affords (102) in a clean way [208]. Complexes (102) can also be obtained by disproportionation of (100), induced by strong -donors as lithium derivatives [205,209,210] or R 3 P=CH 2 [211].…”