Effect of Methyl Substituent on the Spin State of Iron(II) Assembled Complex Using 1,4-Bis(4-pyridyl)benzene

• Published in: RADIOISOTOPES Vol. 66; no. 12; pp. 625 - 632
• Main Authors: Nakashima, Satoru, Yoshinami, Keisuke, Yasuhara, Hiroki, Kaneko, Masashi
• Format: Journal Article
• Language: English
• Published: Japan Radioisotope Association 15.12.2017
• Subjects: 1,4-bis(4-pyridyl)benzene; assembled complex; Mӧssbauer spectroscopy; spin crossover
• ISSN: 0033-8303; 1884-4111
• DOI: 10.3769/radioisotopes.66.625

Iron(II) assembled complexes [Fe(NCX)2(L)2] (X=S, Se and BH3; L=2,5-dimethyl-1,4-bis(4-pyridyl)benzene (dmbpb) and 2,3,5,6-tetramethyl-1,4-bis(4-pyridyl)benzene (tmbpb)) were synthesized to investigate the effect of substituent on the spin crossover (SCO) behavior. PXRD revealed that the structure is different between dmbpb and tmbpb complexes, while the structures are independent of anionic ligands. 57Fe Mӧssbauer spectroscopy and magnetic susceptibility measurement revealed that the SCO occurs in the case of [Fe(NCSe)2(dmbpb)2] and [Fe(NCBH3)2(dmbpb)2] but the SCO is not observed in other complexes. The quadrupole splitting (Q.S.) value in high-spin state decreased in the order of S>Se>BH3 for dmbpb complexes but S>BH3>Se for tmbpb complexes. It was suggested that electron distribution is different between dmbpb and tmbpb complexes. Transition temperature for [Fe(NCBH3)2(dmbpb)2] was 128 K, which is lower than that of the corresponding complex bridged with 1,4- bis(4-pyridyl)benzene.