Tetra(n-butyl)ammonium Dicyanotetraphenyl-porphyrinatomanganate(III); Crystal Structure and Electronic Resonance Raman and Absorption Spectra

Abstract

<jats:p> The title complex salt has been isolated from a solution of chlorotetraphenylporphyrinatomanganese(III) and tetra(n-butyl)ammonium cyanide in dichloromethane. The complex salt crystallizes as a hydrate-dichloromethane solvate in the orthorhombic space group Pbca (no. 61) with cell parameters as follows: a = 21.491(5) Å, b = 21.706(5) Å, c = 28.489(5) Å, V = 13 290(5) Å<jats:sup>3</jats:sup>, Z = 8. The structure is that expected for a hexa-coordinated low-spin Mn ( III ) tetraphenylporphyrinate (magnetic moment: μ<jats:sub> eff </jats:sub> = 3.1 ± 0.2 μ<jats:sub> B </jats:sub> at 273 K). The Mn atom is in the centre of the slightly ruffled porphyrinato core. The Mn - C <jats:sub> CN </jats:sub> distance of 2.01(2)/2.02(2) Å and the Mn - N <jats:sub> p </jats:sub> distance, varying between 1.972(13) and 2.016(14) Å, are normal values. The Mn - C <jats:sub> CN </jats:sub>- N group is bent (171(2)/174(2) °). At low temperatures, a molecular electronic resonance Raman effect is detected at 198 and 344 cm<jats:sup>−1</jats:sup>. It is attributed to intraconfigurational transitions Γ<jats:sub> 1g </jats:sub> → Γ<jats:sub> 4g </jats:sub> and Γ<jats:sub> 1g </jats:sub> → Γ<jats:sub> 3g </jats:sub> Γ<jats:sub> 5g </jats:sub>, respectively, arising from the spin-orbit split <jats:sup>3</jats:sup> T <jats:sub> 1g </jats:sub> ground state of low-spin Mn ( III ), assuming pseudo-octahedral symmetry. Weak Q and intense B (Soret) transitions at 17 300 and 23 200 cm<jats:sup>−1</jats:sup>, respectively, as well as four weak trip–multiplet transitions are observed at 8650, 12 000, 14 900 and 19 900 cm<jats:sup>−1</jats:sup>. </jats:p>

Synthesis, characterization and solid state molecular structures of five- and six-coordinate primary amide manganese porphyrin complexes

“…The similar bond lengths and resulting tetragonal elongation geometry around the Mn center have been observed in other highspin d 4 six-coordinate Mn(III) porphyrin complexes [16,26,27]. It is worth noting that most of the d 4 Mn(III) porphyrin complexes reported have a high-spin Mn(III) ion, with only a couple of exceptions [28,29].…”

Drastic Redox Shift and Electronic Structural Changes of a Manganese(III)-Salen Oxidation Catalyst upon Reaction with Hydroxide and Cyanide Ion

“…A [Mn III (CN) 6 ] 3– ion is a classic example . A macrocyclic porphyrin ligand having a planar N 4 coordination site is another example to accommodate low-spin S = 1 manganese­(III) upon binding of two cyanide or imidazolate anions as external axial ligands. , The latest example is manganese­(III)–poly­(pyrazolyl)­borate complexes, in which two tridentate poly­(pyrazoly)­borate monoanionic ligands bind to manganese­(III), as reported by Schultz and co-workers. , Schultz, Baik, and co-workers investigated the role of a low-spin S = 1 configuration in a stepwise Mn­(II)/Mn­(III)/Mn­(IV) electron transfer . But the Mn­(III)/Mn­(IV) redox potentials are seemingly not significantly altered for their low-spin S = 1 manganese­(III) complexes (0.96–1.30 V vs Fc–Fc + ).…”

A cyano-bridged single-chain magnet featuring alternate high- and low-spin manganese(iii) porphyrins

“…The bridging cyanides and the Mn atoms of [Mn(TPP)] + and [Mn(TPP)(CN) 2 ] À are crystallographically disordered, and the presence of two kinds of Mn(III) ions is proved by the magnetic characterisation. The Mn-C bond distances for [Mn III (TPP)(CN) 2 ] À are 2.00(2)/2.03(2) Å, 13 Fig. 1 The 1D chain structure of complex 1.…”