Synthesis and spectroscopic and magnetic characterization of tris(3,5-dimethylpyrazol-1-yl)borate iron tricyanide building blocks, a cluster, and a one-dimensional chain of squares

The synthesis and spectroscopic and magnetic characterization of several hydridotris(3,5-dimethylpyrazol-1yl)-borate (Tp*) iron(II) and iron(III) tricyanide complexes, a rectangular cluster, and a one-dimensional chain of squares are described. Treatment of [NEt4][(Tp*)Fe-III(CN)(3)] (3) with manganese(II) triflate in dimethylformamide (DMF) affords rectangular clusters (6, {[(Tp*)Fe(CN)(2)(mu-CN)Mn(DMF)(4)](2)[OTf](2)}(.)2DMF), while tosylate salts afford one-dimensional networks (5, {M-II(DMF)(2)(mu-OTs)(mu-NC)(2)(NC)Fe-III(Tp*)}(n)) containing embedded [(Tp*)(2)(Fe2Mn2II)-Mn-III(CN)(6)](2+) clusters via in situ trapping; the cluster and network crystallize in the monoclinic (6, P2(1)/n) and triclinic (5, P (1) over bar) space groups, respectively. The 1-D network (5) appears to be derived from {cis-(mu-O3SC6H4Me)(2)Mn-II(DMF)(4)}n (4, P-2/1n), which is obtained via crystallization of Mn(OTs)(2) from DMF/Et2O mixtures. For 4, magnetic studies indicate that the Mn-II centers are magnetically isolated, with calculated J, g, and theta constants of 6.7 x 10(-3) cm(-1), 2.03, and -0.52 K. Additional magnetic studies of 5 and 6 indicate that the [(Tp*)Fe-III(CN)(3)](-) centers are highly anisotropic (g = 2.9) and are antiferromagnetically coupled to adjacent Mn-II centers. For 5 and 6, fitting of the chi T vs T data via the Curie-Weiss expression affords Curie (6.25 and 10.8 cm(3) K mol(-1)) and Weiss (-14.37 and -8.80 K) constants that are consistent with antiferromagnetically coupled low-spin Fe-III and high-spin Mn-II centers; least-squares fitting of the chi T vs T data using molecular field theory affords g(avg)., J(1), J(2), and J' values of 2.25, -1.72, -0.58, and -0.12 cm(-1) for 5. Overall, bridging tosylates appear to be poor communicators of spin information. For 6, the g, J(1), and J(2) (2.15, -2.02, and -0.78 cm(-1)) values were obtained via least-squares fitting of the X T vs T data using an expression derived using the Kambe vector coupling method; simulations of the data via MAGPACK afford g(avg), and J(iso) values of 2.1 and -2.1 cm(-1).