Double oxidative addition

Other sources of Ru(0) can also be used for this synthesis. For example, it was recently demonstrated that [Ru(arene)(diene)] complexes such as 39 undergo double oxidative addition of heterosubstituted dihalo compounds 40 in the presence of phosphine ligands (Eq. 5) [21]. 

The trimeric platinum(O) complex [Pt3(CNBu )6] undergoes a double oxidative addition reaction with 2,2-bis(disilanyl)dithiane to give tetrakis(organosilyl)bis(/-butylisocyanide)platinum(IV) complexes.53 The Si—Ge bonds in bis(silylgermyl)dithiane are also cleaved by [Pt3(CNBu )6] giving analogous platinum(IV) complexes with Pt—Si and Pt—Ge bonds.53... 

Double displacement of 1,3-propandiol ditosylate is obtained from the reaction with the strongly nucleophilic dianion Na2[Os(CO)4], a formal double oxidative addition reaction, providing osmacyclobutane complex 167 (Equation 87) <1992ICA57>. 

M. Olivan, and K. G. Caulton, The First Double Oxidative Addition of CH2Q2 to a Metal Complex Facile Synthesis of [Ru(CH2)CI2 P(C6I111)3(2], Chem. Common. 1997,1733-1734. 

Hexagonal macrocycle 50 is produced from a 120°-angle-tecton 33 and 120°-angle-linker 49 <19990L1921> (Scheme 8). Tecton 33 is prepared by double oxidative addition of 4,4 -diiodobenzenophenone 47 with tetrakis(triethylphosphine)platinum(ll) followed by treatment with AgOTf. Bis(4-pyridyl)ketone 49 combines spontaneously with 33 at room temperature to form metallocycle 50. 

Dichloromethane and chloroform add to Rh1 and Pd° compounds to give chlo-romethyl complexes.62 Double oxidative addition may, however, also be found,... 

A number of catalytic reactions involve CC bond cleavage, often driven by strain. For example, " biphenylene can be converted to tetraphenylene with Ni(cod)(PMe3)2 at 100 °C or Pt(PR3)3 at 120 °C (equation 14). In the Pt case, a series of intermediates could be isolated that suggest a pathway involving double oxidative addition of the biphenylene CC bond, as in the stoichiometric reactions previously discussed, followed by double reductive elimination to give the product. 

Double oxidative additions occur to generate hydrocarbyl-bridged complexes ... 

In contrast to the situation with Pt, there are few examples of addition of Sn-X or Sn-R bonds to Ni or Pd centers, although the Ni(0) complex [Ni(PPh3)3] has been reported to react with R3SnCl by a double oxidative addition to give stable, colorless Ni(IV) complexes of the type [NiCl2(SnR3)2(PPh3)2] . 

Complexes of the type [Pt(SePh)2(PR3)2] may be prepared by addition of excess PhSeH to the appropriate Pt(0) precursor, presumably by double oxidative addition followed by loss of H2. Addition of diphenyldiselenide to [Pt(C2H4)(PPh3)2], or to [PtCl2 (dppp)] in the presence of NaBH4, also generates species of the type [Pt(SePh)2L2]. The Pd and Pt complexes of the form [M(SePh)2(dppe)] may be prepared by reduction of the corresponding chloro complex with NaCioHg, followed by... 

Particular attention has been devoted to oxidative addition and reductive elimination reactions of [M2(PNNP)(/x-X)L2] with acyl and alkyl halides. Depending on the electron richness of the metals, a complete spectrum of possibilities was observed from reversible single oxidative addition on one of the metals to irreversible double oxidative addition on both metals (2) (Scheme 12). 

Reaction of bis(disilanyl)dithiane 32 with the corresponding palladium(O)-isonitrile complex affords a four-membered cyclic bis(silyl)palladium(II) complex 34 quantitatively together with the formation of a disilane (Eq. 15) [30]. The formal intramolecular metathesis of the two Si-Si bonds of 32 may proceed through initial formation of tetrakis(silyl)Pd(IV) complex, corresponding to the platinum complex 33. The double oxidative addition of the two Si-Si bonds may be followed by reductive elimination of the disilane with accompanying formation of four-membered bis(silyl)palladium complex 34, due to difficulty in reductive elimination leading to formation of a three-membered cyclic disilane. 

The complex, formally derived from a double oxidative addition of benzene to two Ir centers , is in contrast to the mononuclear product obtained with the pentamethylcyclopentadienyl derivative . In the absence of light there is no reaction presumably photolysis displaces one carbonyl ligand to give a coordinatively unsaturated precursor. An apparent intermediate in the photolysis has H NMR resonances in the aromatic, cyclopentadienyl and hydride regions and may be IrGp-j/ (GO)H(G6H5), but its nature remains uncertain. 

Scheme 2. Double oxidative addition of PhSeSePh to give bridging Ph and PhCO ligands.

Scheme 7. A double oxidative addition of ditnethylphenylphosphine to fonn a, ri complex.

The reaction of [(Ph3P)3Ni] with R3SnCl (R = Ph or Me) in toluene yields the colourless air-stable complexes [Ni Cl2(PPh3)2(SnR3)2]. The compounds are diamagnetic and can be considered as low-spin nickel(iv) products formed by a double oxidative addition. They are non-electrolytes, and preliminary n.m.r. and X-ray crystallographic evidence indicates the trans-trans-trans-structure (170). ... 

In the reaction of 2-pyridine-substituted imidazolium salts with Pd(dba)2 (Scheme 4), the formation of either cis or trans complexes having two carbenes per palladium center was observed [38]. No metal hydride was detected despite the fact that the ratio of metal to ligand was varied from 1 1 to 1 4. One of the proposed mechanisms for the formation of such complexes involves a double oxidative addition and elimination of H2 from a Pd(IV) center. The transient Pd-H species is then presumably too reactive toward the second molecule of the imidazolium salt and cannot be observed. A second possible mechanism involves two oxidative steps separated by a reductive elimination from the Pd(II) center. 

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