Synthesis, hydrogen-bonded 1D structure, and abrupt spin transition between high-spin (HS) and an ordered [HS–HS–HS–LS] of a mononuclear iron(III) complex [FeIII(Him)2(4-MeOhapen)]CF3SO3 (Him=imidazole, 4-MeOhapen=N,N′-bis(2-oxy-4-methoxyacetophenylidene)ethylenediamine)