Methoxo complexes

In another type of mixed ligand oxo-vanadium Schiff base complexes chloro-oxo-bis[N(4-bromophe-nyl) salicylideneiminato] vanadium (V) chelate, VOL2CI, and methoxo-oxobis[N(4-bromophenyl)sali-cylideneimine vanadium (V) chelate, VOL2OCH3 Aiiwi and Salih [43] show that these complexes are active pho-... 

The formation of the first osmium hydrido(alkoxo) complex, a yellow air-stable and thermally stable hydrido(methoxo)osmium(II) complex, trans-[OsH(OMe)(Cl) (NO) (P Pr3)2] (72), by the oxidative addition of MeOH to a 16-electron complex, trans-[OsCl(NO)(P Pr3)2] (71) was briefly reported (Eq. 6.22) [51]. 

The nitrosyl complexes of nickel(II) are scarce and less studied than those of nickel(0) (see Section 50.2.5.2) even though they have been known for nearly a century. Selected examples of nitrosyl nickel(U) complexes are reported in Table 58. As early as 1891 it was reported by Berthelot1117 that Ni(O0)4 reacts with gaseous NO giving a blue compound which was later characterized as a pseudotetrahedral complex of nickel(U) having the formula [Ni(OH)3(NO)].1118 This compound is paramagnetic and is formed only if traces of water are present in the reactants. Using a methanolic solution of Ni(CO)4 a methoxo derivative is formed. 

In the presence of trace amounts of water, the tetrameric p,2-oxo complex (182) in 1,2-dimethoxyethane is transformed into a p, -oxo tetrameric complex (183 equation 254), characterized by an X-ray structure.574 In contrast, (182) 572,575 is inactive towards the oxidation of phenols. The reaction of N,N,N, AT -tetramethyl-l,3-propanediamine (TMP) with CuCl, C02 and dioxygen results in the quantitative formation of the /z-carbonato complex (184 equation 255).s76 This compound acts as an initiator for the oxidative coupling of phenols by 02. 6 Such jz-carbonato complexes, also prepared from the reaction of Cu(BPI)CO with 02 [BPI = 1,3 bis(2-(4-methyl-pyridyl)imino)isoindoline],577 are presumably involved as reactive intermediates in the oxidative carbonylation of methanol to dimethyl carbonate (see below).578 Upon reaction with methanol, the tetrameric complex (182 L = Py X = Cl) produces the bis(/z-methoxo) complex (185 equation 256), which has been characterized by an X-ray structure,579 and is reactive for the oxidatiye cleavage of pyrocatechol to muconic acid derivatives.580,581... 

Mononuclear Hydroxo, Methoxo, and Hydrido Complexes of Platinum(ll)... 

Unexpectedly, the methoxo complex shows no tendency to decompose to a hydride by / -elimination, although it does react immediately with water to give the hydroxo complex. In contrast, cyclohexyne bis(triphenylphosphine)platinum(0) reacts with methanol to give a hydrido complex, presumably via an undetected intermediate methoxide (see Equation 3) ... 

Reaction of the methoxo complex 162 with PhSH gave the thiolate complex 168, while reaction with the weak carbon acid PhC = Cl I, gave the corresponding al-kynyl complex 169.74 Reaction of 114 with Tl(acac) gave the C-bonded acac complex 170, which exists as a mixture of tautomers. 

A novel peroxocopper complex with -coordination is formed when copper(II) perchlorate is reacted with the tridentate ligand 4-methyl-2,6-bis(pyrrol-idinomethyl)phenol (HL) in methanol solution, in the presence of air, triethyl-amine base, and 3,5-di-teri-butylcatechol [142], The four copper(II) ions in [Cu4L2(02)(0Me)2(C104)] (32) form a near-planar rectangle, with alternate methoxo (Cu... Cu = 3.03 A) and phenolato (Cu... Cu = 2.99 A) bridging ligands. 

A few alkoxo complexes are known with phosphine coligands, and the methoxo species trans-K2[0s02(0Me)4] is quite a useful synthetic reagent (see p. 584). 

As Eq. (h) illustrates, [MeO] can fail to generate a hydride ligand a stable methoxo complex is formed when MeOH is used in Eq. (i). Complications may occur with other primary alcohols as well EtOH, n-PrOH and n-BuOH are oxidized to carboxylato bridges when substituted for i-PrOH, e.g. ... 

It has been reported that the 1 1 reaction of [ Pt(C6F5)2( -OH) 2]2 with Hpz (Hpz = Hpz, Hdmpz, or Hmpz) represents a convenient route for the preparation of the complexes [ Pt(C6F5)2 2(/x-pz )(ft-OH)]2 (66). The latter compounds gave the corresponding mono(methoxo)-mono(pyrazolate) derivatives on treatment with methanol. Spectroscopic (IR, H, and l9F NMR) data were used for structural assignments, and an X-ray structure determination was carried out for [ Pt(C6F5)2 2( -dmpz)(/A-C)H)](NBu4)2, 158, which established the dinuclear nature of the anion (66). 

Special interest was focused on the photochemistry and redox properties of mononuclear ruthenium complexes.20 Examples show the nucleophilic attack of one of the N atoms of 1,8-naphthyridine on the coordinated CO in [Ru(bipy)2(napy)(CO)]2+ upon le reduction of the napy moiety (Scheme 2). Such a type of metallacyclization enables the reduction of the CO group, derived from the electrochemical reduction of C02 catalyzed by [Ru(bipy)(napy)2(CO)2](PF6)2, to produce acetone in the presence of Me4NBF4.21,22 An unusual result is the simultaneous formation of a carbene ligand and the addition of the methoxo group to the naphthyridine ring upon reaction of [Ru(bipy)2(napy)]2+ with propiolic acid in methanol (Scheme 2).23... 

The chloro methyl and the dimethyl diamido complexes TiXMe[( /(9)Si(NBut)2] have been prepared. Bulky substituents on the silylene bridge increase the kinetic stability of the spirosiladiazatitanacycle compound. These complexes react with dioxygen to give the binuclear methoxo-bridge derivatives [TiX ( /<9)Si(NBut)2 ]2(/ -OMe)2 through the insertion reaction of 02 into the Ti-Me bond (Scheme 23). The molecular structure has been determined by X-ray diffraction.70-72... 

CpTiCl3 reacts with lithium[3-(o-methoxy-phenyl)pentyl cyclopentadienide] to give the bis-Cp complex where the Cp ligands support methoxo functionalities (Scheme 471).815... 

Substituted bis-Cp dichloro complexes with a chiral alkoxo unit linked to the Cp ring by an ethylene spacer group have been prepared by conventional salt metathesis reactions (Scheme 472). The analogous achiral methoxo derivative has also been made.1101... 

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