Polymerization carbonyl complexes

Organometallic Compounds. The predominant oxidation states of indium in organometalUcs are +1 and +3. Iridium forms mononuclear and polynuclear carbonyl complexes including [IrCl(P(C3H3)3)2(CO)2] [14871-41-1], [Ir2014(00)2] [12703-90-1], [Ir4(CO)22] [18827-81 -1], and the conducting, polymeric [IrCl(CO)3] [32594-40-4]. Isonitnle and carbene complexes are also known. 

A half-metallocene iron iodide carbonyl complex Fe(Cp)I(CO)2 was found to induce the living radical polymerization of methyl acrylate and f-bulyl acrylate with an iodide initiator (CH3)2C(C02Et)I and Al(Oi- Pr)3 to provide controlled molecular weights and rather low molecular weight distributions (Mw/Mn < 1.2) [79]. The living character of the polymerization was further tested with the synthesis of the PMA-fc-PS and PtBuA-fi-PS block copolymers. The procedure efficiently provided the desired block copolymers, albeit with low molecular weights. 

Sulfoxide adducts of chromium, molybdenum, and tungsten carbonyls have been studied as catalysts for the polymerization of monomers such as vinyl chloride (248). Simple adducts of the type [M(CO)5(Me2SO)] may be prepared by carbonyl displacement from the corresponding hexacarbonyl. Photochemical reactions are frequently necessary to cause carbonyl displacement in this manner, many carbonyl complexes of higher sulfoxides have been prepared (255, 256). Infrared (257) and mass spectral studies (154) of these complexes have appeared, and infrared data suggest that S-bonding may occur in Cr(0) sulfoxide complexes, although definitive studies have not been reported. 

Use of Co2(CO)8 in reactions involving 1,2-propadienes remains for the most part unexplored. It has been reported that terminal 1,2-propadienes react with Co2(CO)8 to form unidentified complexes, and that excess 1,2-propadiene is polymerized concurrently [30]. It has also been reported by Nakamura that a novel dimeric complex 54, in which a carbonyl ligand is connected to the central carbon of 1,2-propadiene, is produced by the reaction of 1,2-propadiene itself with Co2(CO)8 (Scheme 23) [31]. However, unlike the well-known chemistry of alkyne-Co2(CO)6 complexes, these 1,2-propadiene-cobalt carbonyl complexes have rarely been applied in synthetic reactions, probably due to their high activity in catalyzing the polymerization of 1,2-propadienes [32]. 

There remain the carbonyls of the second class. This includes all complexes containing carbonyls in chemically different environments for which, as shown above, A is necessarily repeated, as well as a few polymeric carbonyls, such as [Mn(CO)3SR]4 13) and [Ir(CO)3]4, in which the representation Tz of Ta is repeated 21, 22). 

Under mild conditions, hydroformylation of olefins with rhodium carbonyl complexes selectively produces aldehydes. A one-step synthesis of oxo alcohols is possible using monomeric or polymeric amines, such as dimethylbenzylamine or anion exchange resin analog to hydrogenate the aldehyde. The rate of aldehyde hydrogenation passes through a maximum as amine basicity and concentration increase. IR data of the reaction reveal that anionic rhodium carbonyl clusters, normally absent, are formed on addition of amine. Aldehyde hydrogenation is attributed to enhanced hydridic character of a Rh-H intermediate via amine coordination to rhodium. 

Alkene, Alkyne, Alkylidene,m and Carbonyl Complexes. While titanium al-kene complexes are unquestionably involved in polymerizations, relatively few have been isolated. Interactions of TiCL,(dmpe)2 and butadiene under reducing conditions give Ti(T7-C4H6)2(dmpe), which can be converted by CO and PF3 to Ti(CO)2(PF3)-(dmpe)2 and Ti(CO)3(dmpe)2. The latter reacts with K in the presence of biphenyl or naphthalene and then with CO to give Ti(CO) - species which are isolable as K(cryptate)+ salts 102... 

Monomeric complexes provided the earliest examples of Irn species in the red, square oxoaryl phosphines (18-G-VI) although IrBr3(NO)(PPh3)2 and polymeric carbonyl halides [Ir(CO)2X2] were known previously. 

Chloro- and other halo- containing carbonyl compounds of iridium may also be synthesized under mild conditions. Unlike [Rh(CO)2Cl]2, [Ir(CO)2Cl] is not obtainable by the direct reaction of an iridium chloride solution with CO. Instead, [Ir(CO)2Cl2]n (48) is obtained in low yields by reaction between IrCl3-H20 and carbon monoxide. The predominant mononuclear compound obtained upon carbonylation of iridium chloride salts is the tricarbonyl [Ir(CO)3Cl] (49), which appears in the sohd state to be a polymeric array consisting of stacking square-planar Ir(CO)3Cl units with short fr-Ir bonds. Even though [Ir(CO)3Cl] is polymeric, it is sublimable and is stiU a convenient source of iridium(I) containing carbon monoxide. (49) will react with a number of nucleophiles to form mononuclear iridium carbonyl complexes. 

Alkynols complexed to cobalt can be oxidized to alkynals without decomplexation. Propargyl aldehydes are protected from polymerization upon complexation with Co2(CO)6. These aldehydes smoothly undergo Wittig-type reactions. Carbonyl-ene reactions have been demonstrated (Scheme 194). Complexation to cobalt protected the enyne in complex (132) from Michael-type reactions (Scheme 195). Alkenyl-substituted complexes undergo [3 + 2]cycloadditions with nitrile A-oxides (Scheme 196). 

In terms of availability, number, and nature of surface groups, surface area, pore size, pore volume, and form and size of the particles, silica has been undoubtedly the most preferred inorganic support. Suitable modification is possible via the surface silanol groups, which can react either directly with an appropriate metal complex or with an intermediate ligand group. Direct surface bonding has often been practiced, e. g., for the anchoring of metal carbonyl complexes [14] (eq. (11)), carbonyl clusters [26], polymerization catalysts [21, 62], or other special systems, e. g., 7r-allyl complexes [63] or metalloporphyrins [64]. 

A bimetallic titanium complex of BINOL derivative can be used to catalyze the asymmetric carbonyl-ene reaction [46]. Insoluble polymeric catalyst 74 was prepared from a self-assembly of Ti(OiPr)4 and non-crosshnked copolymers with (R)-binaphthol pendant groups (Scheme 3.22) [47]. The self-assembled polymeric Ti complex is insoluble in organic solvent and catalyzed the carbonyl-ene reaction of glyoxylate 75 and a-methylstyrene 76. When the reaction of 75 and 76 was carried out with 20mol% of 74 in Gl pCf at room temperature, an 85% yield of the product with 88% ee was obtained. Following its recovery by filtration, this catalyst was reused five times with full retenhon of its activity and enantioselectivity, without further treatment... 

LMe, Pr2XiCI 2 has been used as a precursor to a nickel(II) amido complex, and to an unusual T-shaped nickel(I)-carbonyl complex.4 The analogous bromide complex has been used as an ethylene polymerization catalyst,5 and as a source of nickel(I) for group-transfer and bond activation reactions (described in more detail in Section 12). 

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