Reaction of a tetraaza[14]annulene cobalt(III) complex with acetylene. Synthesis and structural characterization of a novel cobalt(III) complex containing a pentadentate macrocyclic ligand with a carbon .sigma.-donor atom

Weiss, Marvin C.; Gordon, Guy C.; Goedken, Virgil L.

doi:10.1021/ja00498a013

Cited by 36 publications

(11 citation statements)

References 4 publications

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“…This result might indicate that the bridging methylene group has a smaller trans influence than a normal alkyl group or that the distorted equatorial ligand has a smaller steric cis influence. In addition, the Co−C bond length of 1.927(5) Å is not only shorter than in normal imine/oxime-type structures, but shorter than almost all examples of organocobalt(III) compounds in which the coordinated alkyl is part of a polydentate ligand. ,− …”

Section: Resultsmentioning

confidence: 91%

“…In addition, the Co-C bond length of 1.927(5) Å is not only shorter than in normal imine/oximetype structures, but shorter than almost all examples of organocobalt(III) compounds in which the coordinated alkyl is part of a polydentate ligand. 7, [14][15][16][17][18] The two reported structures of compounds with the η 2aminomethylene-Co(III) ring were not well refined. 7,8 In one case, [η 2 -NH 2 CH 2 Co(bpy) 2 ] 2+ (R ) 0.128), 8 the η 2 -aminomethylene moiety is a simple chelate ligand approximately coplanar with two bpy nitrogen atoms.…”

Section: Resultsmentioning

confidence: 99%

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Novel Chemistry of Carbon Bound to Cobalt in Organocobalt Complexes Related to B12

1996

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A rare Co−N−C three-membered ring has been formed by a novel pathway involving a facile interligand nucleophilic addition of an equatorial nitrogen donor to a ligated axial carbon in some organocobalt complexes. The highly distorted structure of a typical resulting complex provides clear experimental evidence useful in assessing hypotheses and computations concerning Co−C bond activation in B12 chemistry. Treatment of R = −CH2X (X = halogen) derivatives of imine/oxime B12 models of the type [LCo((DO)(DOH)pn)R]+ with base afforded major products with striking NMR spectral features in common, e.g., two one-proton olefinic doublets (J ≈ 3 Hz) and two one-proton singlets. The X-ray structure for the pyridine (py) derivative [pyCo(N-CH2-CHEL)]+ (1) reveals two unexpected features: a three-membered metallocycle containing an η2-aminomethylene group, and an enamine (N−CCH2) in place of one imine moiety (NC−CH3). The C−Co−N ring angle is acute (43.7°) with the distortion of the coordination sphere concentrated in the Co−C and the Co−N ring linkages, which move away from the normal pseudooctahedral positions. Studies of the formation of the aqua analog of 1, [H2OCo(N-CH2-CHEL)]+ (3), in aqueous solution suggest that the initial intermediate formed is deprotonated at one imine methyl. Ring closure in the short-lived deprotonated intermediate is facile. Published calculations predict that such ring closure could occur and that, of two processes which could facilitate Co−C bond cleavage (θ-bending of the N−Co−C angle and φ-bending of the Co−C−C angle), the latter factor should be more significant in weakening the Co−C bond. There is large θ-bending in 1; thus, the new metallocyclic B12 analogs afford the first experimental test of these calculations. Our findings that the Co−C bond in 1 is short and that the bond did not readily cleave support the predictions of the calculations.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Novel Chemistry of Carbon Bound to Cobalt in Organocobalt Complexes Related to B12

1996

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“…In another recent example involving a main-group-element cycloaddition of acetylene and phenylacetylene to a dianionic diiminate based germylene complex was reported by Driess and co-workers . Iron, titanium, and copper nacnac complexes have been reported to add oxygen- and nitrogen-containing unsaturated molecules across the metal and ligand CH. − Acetylacetonate complexes of Pd(II), Rh(I), and Ir(I) added the activated alkyne hexafluoro-2-butyne across the M and central CH as well, but unactivated alkynes did not react, and unlike our system, these are all d 8 metal reagents. , A number of macrocyclic compounds of Co, Rh, Fe, and Ru with ligands based on multiple β-diiminate units have been reported to undergo cycloadditions. − …”

Section: Resultsmentioning

confidence: 99%

Cycloaddition Reactions of Terminal Alkynes and Phosphaalkynes with an Isolable 5-Coordinate β-Diiminate Platinum(IV) Dihydrosilyl Complex

et al. 2009

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Combining (Cl-nacnac)Pt(H)(1-pentene) (Cl-nacnac = N-p-Cl-phenyl-β-diiminate) and HSiR3 (SiR3 = SiPh3, SiEt3, SiHPh2) leads to rapid displacement of 1-pentene; oxidative addition of the Si−H bond produces a stable 5-coordinate Pt(IV) silyl dihydride complex which has been isolated and characterized crystallographically. The 5-coordinate silyl dihydride platinum(IV) complex undergoes a cycloaddition reaction with either acetylene or phosphaalkyne to form a vinyl or phosphaalkenyl Pt(IV) product, respectively. One acetylenic carbon adds to the central methine carbon of the Cl-nacnac ligand and the other alkyne carbon or phosphorus coordinates to the vacant site of the d6 metal. Phosphaalkynes are polarized such that the carbon is at the negative end of the dipole; however we observe a final product that reflects a reversal of this normal polarity. The phosphorus is nucleophilic even after the cycloaddition reaction is complete, and its lone pair can be methylated by MeOTf (OTf = trifluoromethanesulfonate) or protonated by addition of HBF4·Et2O.

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“…In addition to commonly explored porphyrins and phthalocyanines, also well known but less studied (in the context of carbon nanohybrid materials) are tetraazamacrocyclic compounds exhibiting rather similar optical and electronic properties, which belong to the family of tetraaza [14]annulenes including both free ligands and their transition metal complexes [17][18][19][20][21][22][23][24][25][26]. As considered per se, these compounds exhibit a wide spectrum of interesting and potentially useful properties [27][28][29], being able to act as DNA/RNA binding agents [30][31][32], catalase mimics [33], conducting materials [34][35][36][37][38][39], chiral receptors [40], gas sensors [41][42][43], and electrocatalysts [44][45][46].…”

Section: Introductionmentioning

confidence: 99%

Interaction of a Ni(II) tetraazaannulene complex with elongated fullerenes as simple models for carbon nanotubes

Henao-Holguín

Basiuk

2015

J Mol Model

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Nickel(II) complex of 5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine (NiTMTAA), which can be employed for noncovalent functionalization of carbon nanotubes (CNTs), represents a more complex and interesting case in terms of structure of the resulting nanohybrids, as compared to the related materials functionalized with porphyrins and phthalocyanines. Due to its saddle shape, the NiTMTAA molecule adsorbed can adopt different, energetically non-equivalent orientations with respect to CNT, depending on whether CH3 or C6H4 groups contact the latter. The main goal of the present work was to provide information on the interactions of NiTMTAA with simple single-walled CNT (SWNT) models accessible for dispersion-corrected DFT calculations. For reasons of comparison, we employed three such functionals: M06-2X and LC-BLYP as implemented in Gaussian 09 package, and PBE-G as implemented in Materials Studio 6.0. In order to roughly estimate the effect of nanotube chirality on the interaction strenght, we considered two short closed-end SWNT models (also referred to as 'elongated fullerenes'), one armchair and one zigzag, derived from C60 and C80 hemispheres. In addition, we calculated similar complexes with C60, as well as I h and D 5h isomers of C80. The results were analyzed in terms of optimized geometries, formation energies, HOMO-LUMO gap energies, and intermolecular separations. Graphical Abstract Interaction of Ni(II) tetraazaannulene complex with elongated fullerenes.

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Reaction of a tetraaza[14]annulene cobalt(III) complex with acetylene. Synthesis and structural characterization of a novel cobalt(III) complex containing a pentadentate macrocyclic ligand with a carbon .sigma.-donor atom

Cited by 36 publications

References 4 publications

Novel Chemistry of Carbon Bound to Cobalt in Organocobalt Complexes Related to B12

Novel Chemistry of Carbon Bound to Cobalt in Organocobalt Complexes Related to B12

Cycloaddition Reactions of Terminal Alkynes and Phosphaalkynes with an Isolable 5-Coordinate β-Diiminate Platinum(IV) Dihydrosilyl Complex

Interaction of a Ni(II) tetraazaannulene complex with elongated fullerenes as simple models for carbon nanotubes

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