Preparation and Oxygenation of Cobalt N‐Confused Porphyrin Nitrosyl Complexes

Abstract

The nitrosylation of Co(HCTPP) (1) in CH2Cl2 afforded [Co(CTPPC2H2Cl)(NO)] (2) with a chlorovinyl group substituent on the inner carbon atom of the N‐confused porphyrin ring. The spectroscopic data suggest that 1 exhibits an {Co(NO)}8 electronic structure. The nitrosylation of 1 in the presence of oxygen leads to [Co(CTPPO)(NO)] (3), which is a {Co(NO)}7 cobalt nitrosyl complex. A bent axial Co–N–O conformation was observed in both nitric oxide complexes with an angle of 128.5(7)° for 2 and 146.9(11)° for 3. An sp3 hydride carbon atom was evidenced in the crystal structure of 2, and an η2 interaction between the cobalt center and the inner carbonyl group was observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A Rhodium‐Mediated Contraction of Benzene to Cyclopentadiene: Transformations of Rhodium(III) m‐Benziporphyrin

“…First, the CO ligand could have been transformed over the course of the redox processes,triggered by the provided reducing reagent, to eventually afford af ragment containing two carbon atoms. [26] The presence of the 2-chlorovinyl fragment has been undoubtedly proven by 1 Even deeper structural modifications were observed when 3-CO was placed on ab asic alumina, as this species immediately converts into am ixture of reddish-brown compounds (6, 7-1, 7-2;S cheme 5). Reported carboncarbon or carbon-hydrogen bond activation triggered by rhodium(III) or iridium(III) porphyrins provided grounds for this hypothesis.…”

Factors That Regulate the Conformation of m‐Benziporphodimethene Complexes: Agostic Metal–Arene Interaction, Hydrogen Bonding, and η2,π Coordination

“…[8][9][10] Facilitated by macrocyclic constraint, the complexes of carbaporphyrinoids can readily form agostic intramolecular interactions, [9,[11][12][13] which may result in the formation of a metalcarbon bond through CÀH bond activation. [9,[14][15][16][17] Weak metal-arene interactions in cadmium and nickel complexes of m-benziporphyrin, with distances shorter than the sum of van der Waals radii, have been observed through X-ray structure analyses. The unusually large intramolecular through-space scalar couplings between the cadmium nucleus and the arene protons in m-benziporphyrin Cd II complexes as well as the downfield chemical shifts as a result of spin transfer from nickel center to an agostic proton in the paramagnetic m-benziporphyrin Ni II complexes provide solid supporting evidence for the presence of the metalarene interaction.…”

Conversion of Nitric Oxide into Nitrous Oxide as Triggered by the Polarization of Coordinated NO by Hydrogen Bonding

“…Thecobalt-nitrosyl complex [Co(CTPPMe)(NO)] (1)was produced from the reaction of [Co(HCTPP)] [11] and excess CH 3 Ii nC H 2 Cl 2 ,f ollowed by nitrosylation in aT HF/MeOH mixed-solvent system under anaerobic conditions in the presence of NaOMe as ab ase and NO gas (1 %) as the NO source. [12] Thes tructure of complex 1 was corroborated by single-crystal X-ray structure determination ( Figure 1a), and the complex was characterized by spectroscopic methods.The key structural parameters of 1 include ab ent Co-N-O unit with an angle of 125.62(14)8 8 and CoÀNO and CoNÀOb ond lengths of 1.7886(16) and 1.187(2) , respectively.T he severely bent angle of Co-N-O in 1 is consistent with the structural characteristics of the {Co(NO)} 8 cobalt-nitrosyl group.The IR spectrum of 1 (KBr) revealed a n NO vibration at 1620 cm À1 (n( 15 NO) = 1592 cm À1 ; Dn NO = 28 cm À1 ); this value is in the regular range for a{Co(NO)} 8 complex.…”