IRON(II) POLYAMINE CHEMISTRY - VARIATION OF SPIN-STATE AND COORDINATION-NUMBER IN SOLID-STATE AND SOLUTION WITH IRON(II) TRIS(2-PYRIDYLMETHYL)AMINE COMPLEXES

The synthetic system of Fe(SO3CF3)(2) and one or two TPA ligands (TPA = tris(2-pyridylmethyl)amine) affords a series of complexes that demon strate the complexities of the solid-state and solution coordination c hemistry of labile iron(II) even with a multidentate ligand. The low-s pin [Fe(TPA)(CH3CN)(2)](SO3CF3)(2) (1-OTf) complex forms in acetonitri le, but the high-spin complex Fe(TPA)(SO3CF)(2) (2) forms in chlorofor m. The methanol-bound complex [Fe(TPA)(CH3OH)(2)](BPh4)(2) (3) forms i n the presence of the noncoordinating anion, BPh4-, and six-coordinate [Fe(TPA)(2)](SO3CF3)(2) (4-OTf) and eight-coordinate [Fe(TPA)(2)](BPh 4)(2) (4-BPh4) form in the presence of excess ligand. Their behavior i n solution is explored by studying their magnetic properties and NMR s pectra, which indicate the presence of spin and coordination equilibri a. The crystal structures of these complexes are reported. Crystallogr aphic parameters are as follows. 1-OTf . CH3CN: C26H27F6FeN7O6S2, mono clinic, P2(1)/n, a = 12.418(2) Angstrom, b = 16.192(4) Angstrom, c = 1 5.855(2) Angstrom, beta = 92.09(2)degrees, Z = 4. 2: C20H18F6FeN4O6S2, monoclinic, P2(1)/c, a = 17.636(2) Angstrom, b = 9.659(1) Angstrom, c = 16.004(2) Angstrom, beta = 113.29 (1)degrees, Z = 4. 3 . CH3OH: C69 H70B2FeN4O3, monoclinic, P2(1)/n, a = 17.525(1) Angstrom, b = 19.150(2 ) Angstrom, c = 17.703(1) Angstrom, beta = 100.36(1)degrees, Z = 4. 4- OTf: C38H36F6FeN8O6S2, monoclinic, Pc, a = 10.236(1) Angstrom, b = 10. 129(1) Angstrom, c = 19.251(1) Angstrom, beta = 92.27(1)degrees, Z = 2 . 4-BPh4: C84H76B2FeN8, monoclinic, P2(1)/n, a = 12.489(1) Angstrom, b = 14.189(1) Angstrom, c = 19.843(1) Angstrom, beta = 102.84(1)degrees , Z = 2.