- AMER CHEMICAL SOC
Two kinds of 1:1 manganese complexes a and b of bis(hexafluoroacetylacetonato)manganese(II) coordinated with diazodi(4-pyridyl)methane (1) were prepared. Complexes a and b crystallize in the orthorhombic space group Pbca and in monoclinic Cu,lc, respectively. Two pyridyl nitrogen atoms from two different molecules of 1 are coordinated in the cis and trans configurations to the manganese ion to form helical and zigzag infinite chains of octahedral manganese complexes in complexes a and b, respectively. The magnetic susceptibilities (chi(mol)) Of both crystals before and after irradiation were measured on a SQUID susceptometer and revealed chi(mol)T vs T plots characteristic of ferrimagnetic chains after irradiation for 97 h; interaction between the manganese(II) ion and the photogenerated carbene is antiferromagnetic in both complexes. The antiferromagnetic exchange coupling parameters (J) in the photolyzate of complex a and b were estimated by a theoretical treatment through a procedure of extrapolation by using small rings to be J/k(B) = -34.8 +/- 0.8 and -24.4 +/- 0.5 K, respectively. Maximum chi(mol)T values of 210 at 5 K for cis- and 246 emu . K . mol(-1) at 1.9 K for trans complexes correspond to correlation lengths of 186 and 218 manganese-carbene S = 3/2 units, respectively.
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