Ligands cobalt

Conventional Cobalt Cobalt Ligand Rhodium Ligand... 

In the case of the cobalt ligand process, alcohols rather than aldehydes are the main products. While the cobalt ligand catalyst overcomes the isomer ratio disadvantage, it has only one-fifth the activity of the conventional cobalt catalyst. 

Even at temperatures of 180-200°C, space time yields remain lower than in the conventional cobalt process. At the elevated temperatures the cobalt ligand catalyst is a highly active hydrogenation catalyst that converts a significant portion (10%) of the propylene to propane and most of the butyraldehyde to butanol. 

Stupperich, E., Eisinger, H. J., and Albracht, S. P. J., 1990, Evidence for a super-reduced cobamide as the major corrinoid fraction in vivo and a histidine residue as a cobalt ligand of the para-cresolyl cobamide in the acetogenic bacterium Sporomusa-ovata, Eur. J. Biochem. 193 1050109. 

There appear to be genuine examples of changes in the cobalt-ligand (NH3, Cl , and probably CN ) bond lengths caused by external effects. 

Saito M. A. and Moffett J. W. (2001b) Cobalt speciation in the equatorial Pacific and Peru upwelling region sources and chemical properties of natural cobalt ligands. Am. Soc. Limnol. Oceanogr. Meet. 

One difference between the aerobic and anaerobic corrinoid pathways in bacteria is in the formation of the benzimidazole moiety, the lower or a- cobalt ligand. It was known that in anaerobes the 5,6-dimethylbenzi-midazole is derived from a flavin, but the nature of the transformation and the enzyme involved was only... 

Co3(CO)5(SEt)4Co3(CO)0S (374). Using the Cotton-Haas (105) model as applied to Re3Cli2, Co3(CO)5(SEt)4 was oriented such that the cobalt-ligand cr bonding involved the d y, s, lj /2(py.+ Py), ll /2(p — Py), and Pz orbitals of each Co atom. Then the twenty valence electrons for the tricobalt system would occupy not only all five of the metal-bonding orbitals, d (a[) , dy (a[), dg.z y2(a )-, but also five antibonding... 

As an approximate method for the analyses of the relaxation data of Co systems without significant cobalt-ligand 7r-bonding, in Eq. (32) has... 

Cyclic and secondary amides, such as 2-pyrrolidinone, can be amidocarbony-lated only with formaldehyde (12). Lin and Knifton reported on the catalytic performance of various cobalt/ligand systems in the synthesis of iV-acetylglycine. Basic phosphines, such as PBus, allowed low pressure conditions (55 bar). The addition of Ph2SO or succinonitrile resulted in improved selectivity and facilitated the catalyst recovery (13-15). The addition of acid cocatalysts (plfa < 3 e.g., trifluoroacetic acid) allowed for low temperature conditions and the absence of hydrogen (16) (Scheme 3). 

CoOjCo bridges. The anion is dinuclear and contains a Co-O-N-Co nitrite bridge. Within their rather high standard deviations (0.05 A) the cobalt-ligand donor atom distances in (34) are normal. ... 

Ethyl 4-nitrophenyl phosphate coordinated to the pentaam-minecobalt(III) moiety liberates nitrophenolate in basic solution 10 -fold faster than the free phosphodiester. The reaction proceeds by attack of coordinated amido ion to give a four-membered N,0 chelate phosphoramidate ethyl ester (1) shown in Eq. (2). Interestingly, the four-membered chelate does not display the enhanced reactivity of the five-membered-ring cyclic ethylene phosphates but decays with cobalt-ligand... 

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