Cobalt-mediated oligomerization reactions of amino-substituted acetylene derivatives

Bridging Rhodium–Iron Borataaminocarbyne Complexes Formed by Intramolecular Isonitrile–Borane Coordination

“…Consistent with the low C–N stretching frequencies for 2 – 4 (vide supra), the C–N bonds in 2 – 4 are notably long at 1.284(3), 1.298(7), and 1.294(6) Å, respectively. For comparison, the C–N distances in the μ-isonitrile complexes described above are 1.229(4) and 1.234(8) Å, whereas the C–N bonds in μ-aminocarbyne complexes D – G (Figure ) are 1.29(2), 1.296(6), 1.312(4), and 1.303(5) Å, respectively, and the C–N bond in borataaminocarbyne complex B (Figure ) is 1.34(2) Å . Taken together, these structural data point to a μ-borataaminocarbyne bonding description for the CNRBR 3 unit in 2 – 4 , one in which the carbyne carbon is doubly bound to iron and singly bound to rhodium.…”

“…The Lewis acid substituted aminocarbyne (CNR(LA)) complexes described above are related to aminocarbyne (CNR 2 ) complexes, in which an alkyl cation or a proton can be considered, conceptually, to play the role of the Lewis acid (see Figure for examples). − Naturally, aminocarbyne ligands represent just one of two possible canonical forms for a CNR 2 ligand. The other canonical form is that of an azavinylidene ligand, which is related to a borane-coordinated bent isonitrile ligand (a borataazavinylidene) in the same way that an aminocarbyne ligand is related to a borataaminocarbyne ligand (Figure ).…”

Chemistry of the highly stable hindered cobalt sandwich compound (η5-Cp)Co(η4-C4Ph4) and its derivatives

“…Compound 317 was obtained by reaction of CpCoCb derivative obtained from the alkyne (Me 3 SiC 2 ) 2 S with Co 2 (CO) 8 in 71 % yields [117]. Amino substituted derivatives 318 -320 were obtained by reaction of Cp * Co(C 2 H 4 ) 2 with 1-phenylthio-2-diethylaminoacetylene, 1-trimethylsilyl-2-diethylaminoacetylene and 1-diphenylphosphino-2-diethylaminoacetylene, respectively [118]. as a mixture of cis/trans isomers [128].…”

“…(η 5 -Cp)Co(η 4 -Cb) derivatives having hetero atoms bound to the cyclobutadiene ring[111][112][113][114][115][116][117][118] was of particular interest with both mono-and bis(catecholboryl)acetylenes (having two oxygen atoms attached to boron) resulting in the Co-catalyzed [2+2+2] cyclotrimerization to give benzene derivatives exclusively[119][120][121]. In contrast, reaction of CpCo(CO) 2 with 1-(dithiocatecholboryl)-2-phenylacetylene (having two sulfur atoms attached to boron) and 1-(1,3,2-benzothiaoxaborlolyl)-2-phenylacetylene (having one sulfur and one oxygen atoms attached to boron) resulted in the compounds 321 and 322, respectively, as a mixture of cis/trans isomers[120].…”

Cobalt-Catalysed Carbon-Carbon Bond-Formation Reactions

“…Siebert was the first to report the high-yielding cyclotrimerisation of an aminothioacetylene with CpCo(CO) 2 or Co 2 (CO) 8 as catalyst. 73 Concerning the development of new catalysts or catalyst systems, Eaton described an altered CpCoL-catalyst system for the cyclotrimerisation of various alkynes in aqueous solution under mild conditions. 74 Unprotected alcohols, amines and carboxylic acids can be used.…”