Iron(III) chelates with hexadentate ligands from triethylenetetramine and .beta.-diketones or salicylaldehyde. Spin state dependent crystal and molecular structures of Fe(acac)2trienPF6(S = 5/2), Fe(acacCl)2trienPF6(S = 5/2), Fe(sal)2trienCl.2H2O(S = 1/2), and Fe(sal)2trienNO3.H2O(S = 1/2)