Nickel amides bonding

Reduction of nitro compound 31 with hydrazine hydrate/Raney nickel affords an amine, which produces pyrrolo-benzazepine 32 under intramolecular amide bond coupling (Equation (5) (1996BCF251). 

Bis(pyrrole-2-aldiminato)nickel(II) complexes (125) are diamagnetic in the solid state when R = H, Pr, Pr and Et, and paramagnetic pseudotetrahedral when R = Bu. 1001-1003 In solution there exists an equilibrium between square planar and tetrahedral species when R = Pr1, Bus and Bu Such equilibria were also investigated for complexes of the type (126) obtained from the condensation reaction in basic media of o-aminobenzaldehyde and a number of diamines in the presence of nickel(II).1004-1007 Square planar complexes (127)1008,1009 and (128)1010 were obtained with deprotonated pyridinecarboxamide ligands. In these complexes the Ni—N (amide) bond distance (184-187 pm) is shorter than the Ni—N (pyridine) distance (192-195 pm). 

Unlike two previous theories of life origin, only a few pieces of experimental evidence exist at present to prove the theoretical speculations. However, we have to notice the verification of the basic mechanism of molecular hydrogen generation as a reducing power, furthermore, the amide bond synthesis has been also demonstrated, both at temperatures within the range of hydrothermal vents (100 °C). In addition, the evidence for at least sulfide-based amino acid synthesis and polymerization from simple precursors has been shown. The formation of acetic acid and an activated thioester from carbon monoxide, methanethiol and various combinations of ferrous and nickel sulfides has been experimentally proved as well. However, further verification is necessary for the modes and rates of organic synthesis. 

H2L435 and diamines. Attempts to carry out non-template macrocyclisation under conditions of high dilution were also unsuccessful only starting materials and small amounts of insoluble polymeric materials were isolated from the reaction mixture. It proved to be impossible to demetallate the oxamide macrocyclic nickel(II) complexes using cyanide because of the high stability of the metal-amide bonds 382]. 

As already mentioned, reactive nickel amide, hydroxo, or alkoxo complexes can experience insertion reactions giving rise to new Ni-G bonds. The mononuclear anilido complex 114 reacts with dimethyl acetylenedicarboxylate, resulting in the formation of the alkenyl complex 151 (Equation (74)). The insertion of GO into the Ni-N bond of an unusual tricoordinated Ni(ii) amido complex yields a carbamoyl ligand that features an unprecedented rf -C,0... 

Functionalization of Ni(MeCOCHCOMe)2 occurs in reactions with isocyanates, diethyl azodi-carboxylate and dimethyl acetylenedicarboxylate, which proceed by formal insertion of the methine C—H unit into the substrate multiple bonds to form respectively amides and ester-substituted hydrazines and alkenes. Similar additions of acetylacetone to these electrophiles is catalyzed by nickel acetylacetonate.217,218... 

A new method of synthesis162 of the imidazole ring by the use of A-cyaniminodithiocarbonic esters (41) involves formation of the 4 5-bond. Reaction of (42) with KNCO in acetic acid yielded the corresponding amide (43) which was cyclized by sodium hydroxide to the substituted purine (44). Treatment of (42) with Raney nickel and hydrogen produced 4-amino-5-carbethoxy-l-methyl-4-imidazo-line (45), which could also be cyclized to a purine (46).162... 

---