Tetra(n-butyl)ammonium dicyanotetraphenylporphyrinatomanganate(III); Crystal structure and electronic resonance Raman and absorption spectra

The title complex salt has been isolated from a solution of chlorotetraphen ylporphyrinato-manganese(III) and tetra(n-butyl)ammonium cyanide in dichlor omethane. The complex salt crystallizes as a hydrate-dichloromethane solvat e in the orthorhombic space group Pbca (no. 61) with cell parameters as fol lows: a = 21.491(5) Angstrom b = 21.706(5) Angstrom, c = 28.489(5) Angstrom , V = 13290(5) Angstrom(3), Z = 8. The structure is that expected for a hex a-coordinated low-spin Mn(III) tetraphenylporphyrinate (magnetic moment: mu (eff) = 3.1 +/- 0.2 mu(B) at 273 K). The Mn atom is in the centre of the sl ightly ruffled porphyrinato core. The Mn-C-CN distance of 2.01(2)/2.02(2) A ngstrom and the Mn-N-p distance, varying between 1.972(13) and 2.016(14) A, are normal values. The Mn-C-CN-N group is bent (171(2)/174(2)degrees). At low temperatures, a molecular electronic resonance Raman effect is detected at 198 and 344 cm(-1). It is attributed to intraconfigurational transition s Gamma(1g) --> Gamma(4g) and Gamma(1g) --> Gamma(3g) Gamma(5g), respective ly, arising from the spin-orbit split T-3(1g) ground state of low-spin Mn(I II), assuming pseudooctahedral symmetry. Weak Q and intense B (Soret) trans itions at 17300 and 23200 cm(-1), respectively, as well as four weak trip-m ultiplet transitions are observed at 8650, 12000, 14900 and 19900 cm(-1). ( C) 1998 John Wiley & Sons, Ltd.