Dinuclear oxidative-addition reactions

Oxidative-Addition Reactions to the Dinuclear Gold(l) Amidinate Complex 9... 

Oxidative-addition reactions have been widely studied with bridged dinuclear metal complexes [1,2,5, 32]. Earlier work with the ylides and sulfur bonded ligands... 

Oxidative addition reactions to nickel(O) complexes are another well-developed synthetic method which affords mono and bis alkyl and aryl compounds (equation 148).1232-1239 The oxidative addition of a, ar -dichloro-p-xylene to [Ni(QjH4)(PPh3)2] gives the dinuclear nickel(II) complex t(PPh3)2ClNi(CH2C6H4CH2)NiCl(PPh3)2].124 ... 

A natural extension of oxidative addition reactions of Os3 clusters with C—H bond cleavage is that with Si—H, Ge—H, or Sn—H bond cleavage. Os3(CO)12 reacts at high temperatures (e.g., 140°C) or under uv photolysis with Me3SiH to give mono- and dinuclear compounds, exem-... 

The gold(II) compounds without Au-Au bonds are in general prepared by reduction of Au . There are several dinuclear gold(II) complexes with Au-Au bonds. They are obtained from the corresponding gold(I) complexes by oxidative addition reactions as shown in Scheme (2). In a special case, both the Au -Au and Au products were isolated. ... 

These complexes were fully characterized and the X-ray crystal structure of 89 was also reported. The reactivity of these dinuclear complexes toward a variety of nitrogen- and phosphorus-donor ligands was described (104-106) as well as oxidative-addition reaction with iodine (104). 

Scheme 6. Oxidative-addition reactions of the Ir(l) dinuclear pyrazolate complex [Ir2(p-pz)(/r-S-t-Bu)(CO)2L2), 114 [L = P(OMe),] (see text for references).

Scheme 1.2 General scheme for the oxidative addition reaction of an A-B molecule to a mononuclear (Eq. 1) and dinuclear (Eq. 2) metal complexes...

Complex [(CXI )Ir(/j,-pz)(/i,-SBu )(/j,-Ph2PCH2PPh2)Ir(CO)] reacts with iodine to form 202 (X = I) as the typical iridium(II)-iridium(II) symmetrical species [90ICA(178)179]. The terminal iodide ligands can be readily displaced in reactions with silversalts. Thus, 202 (X = I), upon reaction with silver nitrate, produces 202 (X = ONO2). Complex [(OC)Ir(/i,-pz )(/z-SBu )(/i-Ph2PCH2PPh2)Ir(CO)] reacts with mercury dichloride to form 203, traditionally interpreted as the product of oxidative addition to one iridium atom and simultaneous Lewis acid-base interaction with the other. The rhodium /i-pyrazolato derivative is prepared in a similar way. Unexpectedly, the iridium /z-pyrazolato analog in similar conditions produces mercury(I) chloride and forms the dinuclear complex 204. 

A related dinuclear species 77, recently described, constitutes the first dinuclear gold(I) complex with heterobridged phosphor-1,1 -dithiolato moieties and bis(ylide) bridging ligands [ 102]. It is obtained by reaction between [ AuS2PPh2] and the diylide gold complex 74 (R=Me). No intermolecular Au-Au interaction is observed in 77 but the oxidative addition of chlorine to the product leads to a new complex 78 in which a single bond is formed between the two Au(II) centers (Scheme 26). 

Square-planar complexes Pt(CO)(PR3)Cl2 (R = Ph or Bu) are transformed to the dinuclear [R COPt(PR3)Cl]2 by the action of HgRj (R = Me or Ph) under mild conditions 82). These reactions are thought to proceed through the oxidative addition to Pt(II) of HgRj, migration of R onto CO, and elimination of R HgCl. 

The reaction of the dinuclear gold(I) amidinate complex, [Au2(2,6-Me2Ph-form)2], with Hg(CN)2 (1 2 stoichiometry) in THF forms a 2D coordination polymer, [Au2(2,6-Me2Ph-form)2]-2Hg(CN)2 2THF, not the expected oxidative-addition product of the type formed vdth the ylides. White crystals and a yellow powder are formed. 

Abdou, H.E., Mohamed, A.A. and Fackler, J.P. Jr (2004) Oxidative addition of methyl iodide to dinuclear Gold(I) amidinate complex schmidbaur s breakthrough reaction revisited with amidinates. ZeitschriJiJurNaturforschungB. A Journal of Chemical Sciences, 59, 1480-1482. 

The key features of both catalytic cycles are similar. Alkene coordination to the metal followed by insertion to yield an alkyl-metal complex and CO insertion to yield an acyl-metal complex are common to both catalytic cycles. The oxidative addition of hydrogen followed by reductive elimination of the aldehyde regenerates the catalyst (Scheme 2 and middle section of Scheme 1). The most distinct departure in the catalytic cycle for cobalt is the alternate possibility of a dinuclear elimination occurring by the in-termolecular reaction of the acylcobalt intermediate with hydridotetracarbonylcobalt to generate the aldehyde and the cobalt(0) dimer.11,12 In the cobalt catalytic cycle, therefore, the valence charges can be from +1 to 0 or +1 to +3, while the valence charges in the rhodium cycles are from +1 to +3. 

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