Carbamato complexes

Organic carbamates (RNHCOO-) commonly display monodentate coordination, as exemplified in the structurally characterized tetrahedral Co(bmc)2Cl2,438 (bmc = lV-(benzimidazoyl-2-yl)-O-methylcarbamate). An unusual route to a carbamato complex involves the reaction of Co2(CO)8 in the presence of a fourfold excess of the stable radical species tmpo, which yields the blue Co40(OOCNC9H18)6 cluster, presumably via a Co(CO)2(tmpo) intermediate, with the nitroxyl radical serving as oxidant.439... 

Reactions of Cr(NEt2)4, some examples of which have been discussed elsewhere, are presented in Scheme 119. The unusual reactions with C02, which produce the chromium(III) and chromium(II) carbamato complexes (287) and (288), are believed163 to proceed by C02 insertion into a Cr—N bond, which promotes /3-hydrogen elimination from a coordinated diethylamido ligand, and then reductive elimination of Et2NH produces a reactive chromium(II) species Crn(02CNEt2)(NEt2). The subsequent reaction is dependent upon the relative concentration of C02. 

Ureato and Carbamato Complexes. These can be made in a variety of ways such as the interaction of metal carbonyls with RNCO or RN3. A more general method involves the sequence218 ... 

The alkyne complex, (77s—C5H5X775—C5Me5)Ti(diphenylacetylene) reacted with C02 to give a five-membered metallacycle.53 Similarly, nickel complexes reacted with alkynes and C02 to yield the same type of metallacycles.54 The oxidative coupling of C02 with imines (Schiff bases) at electron-rich nickel(O) centers leads to cyclic carbamato complexes.55... 

Reaction of the Cp-amidinato imido titanium complexes Cp Ti[MeC(NPr1)2](NR) (R = But, 2,6-C6H3Me2) with C02 proceed via initial cycloaddition reactions to give N-O-carbamato complexes. The Buc derivative does not react with an excess of C02 and it undergoes a retrocyclization process with the formation of BuNCO and the binuclear fi-oxo compound Cp Ti[MeC(NPr1)2] 2(/i-0). The aryl derivatives exhibit a double CO2 insertion process to give Cp Ti[MeC(NPri)2][0(C0)N(Ar)(C0)0] (Scheme 248).661... 

Differential scanning calorimetry has been employed in studies of the solid-state decarbonylation of carbamato-complexes [Mn(CO)4(L)] (8a) [L = XYCOSlMca),... 

The Ti- and Zr-carbamato complexes can also undergo exchange according to (4.27) and (4.28) [87]. The latter exchange processes ((4.27) and (4.28)) were also found to be catalyzed by trace amount of fortuitous amine [86, 87]. 

McGowan CS, Groy TL, Caudle MT (2002) Synthesis, structure, and preparative transamination of tetrazinc carbamato complexes having the basic zinc carboxylate structure. Inorg Chem 41 1120-1127... 

Tang Y, Kassel WS, Zakharov LN, Rheingold AL, Kemp RA (2005) Insertion of carbon dioxide into Zn-N bonds. Syntheses and structure of tetrameric and dimeric alkylzinc carbamato complexes, htorg Chem 44 359-364... 

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