1 H and 13 C NMR spectra were recorded on a 200- and 50-MHz spectrometer (Bruker, F113V). The IR spec- tra were recorded on a Perkin–Elmer Spectrum GX spec-
trophotometer in KBr/nujol mull. Electronic spectra were
recorded in dichloromethane on a Hewlett–Packard diode array spectrophotometer (model 8452A). Microanalysis of the complex was done on a Perkin–Elmer CHNS analyzer (model 2400). An inductively coupled plasma spectrome- ter (Perkin–Elmer, USA; model ICP Optima 3300 RL) was used for Mn estimation. Powder X-ray diffraction patterns of the samples were recorded on a Philips X”pert MPD diffrac-
tometer with Cu-Kα (λ = 1.5405 Å) radiation with a step
size of 0.02◦ 2θ and a step time of 5 s and a curved Cu-Kα
monochromator under identical conditions. The BET sur-
face area was determined with the use of N2 sorption data measured at 77 K with a volumetric adsorption setup (Mi- cromeritics ASAP-2010, USA). The pore diameters of the samples were determined from the desorption branch of the N2 adsorption isotherm with the Barret, Joyner, and Halenda (BJH) method.