Self-assembled supramolecular M9 (Mn(II), Fe(III), Zn(II)), M5 (Fe(III)), and [M3]2 (Pb(II)) complexes: structural, magnetic, and Mössbauer properties.

Abstract

The tritopic ligand 2poap self-assembles in the presence of Zn(NO(3))(2) and Fe(NO(3))(3) to form homoleptic [3 x 3] nonanuclear M(9) (M = Zn(II), Fe(III)) square grid structures and with Pb(ClO(4))(2) to form a dimerized linear trinuclear [Pb(3)](2) structure. Cl2poap and Cl2poapz form self-assembled homoleptic [3 x 3] Mn(II)(9) square grids with Mn(ClO(4))(2) and Mn(NO(3))(2), respectively, but an unusual incompletely metalated Fe(III)(5) square grid is formed on reaction of Cl2poap with Fe(ClO(4))(3). X-ray structures are reported for [Mn(9)(Cl2poap-2H)(6)](ClO(4))(6).10H(2)O (3), [Mn(9)(Cl2poapz-2H)(6)] (NO(3))(6).22H(2)O (4), [Zn(9)(2poap-2H)(3)(2poap-H)(3)](NO(3))(9).24H(2)O (5), [Pb(3)(2poap-2H) (ClO(4))(4)](2).8H(2)O (6), and [Fe(5)(Cl2poap-H)(6)](ClO(4))(9).34.5H(2)O (7). Compound 3 crystallized in the monoclinic system, space group P(-)1, with a = 18.179(1) A, b = 18.857(1) A, c = 25.871(2) A, alpha = 70.506(2) degrees, beta = 86.440(1) degrees, gamma = 75.175(2) degrees, and z = 2. Compound 4 crystallized in the monoclinic system, space group P(-)1, with a = 16.900(2) A, b = 20.02393) A, c = 25.663() A, alpha = 84.743(3) degrees, beta = 84.885(2) degrees, gamma = 67.081(2) degrees, and z = 2. Compound 5 crystallized in the monoclinic system, space group P(-)1, with a = 18.482(1) A, b = 18.774(1) A, c = 28.112(2) A, alpha = 104.020(1) degrees, beta = 97.791(1) degrees, gamma = 117.036(1) degrees, and z = 2. Compound 6 crystallized in the monoclinic system, space group P(-)1, with a = 10.0513(6) A, b = 11.0958(6) A, c = 17.334(1) A, alpha = 100.932(1) degrees, beta = 100.387(1) degrees, gamma = 94.565(1) degrees, and z = 2. Compound 7 crystallized in the monoclinic system, space group P(-)1, with a = 19.164(1) A, b = 19.587(2) A, c = 26.673(2) A, alpha = 76.430(2) degrees, beta = 78.834(2) degrees, gamma = 64.973(1) degrees, and z = 2. Compound 3 exhibits intramolecular antiferromagnetic exchange within the nonanuclear [Mn(9)(mu-O)(12)] grid structure (J = -4.6 cm(-1)), while the analogous nonanuclear complex [Fe(9)(2poap-2H)(6)](NO(3))(15).18H(2)O (8) is dominated by intramolecular antiferromagnetic coupling at high temperatures but exhibits a low-temperature feature indicative of additional ferromagnetic interactions. The isolated pentanuclear Fe(5) [4 + 1] square grid in 7, with distant Fe-Fe bridging, exhibits very weak antiferromagnetic coupling (J = -0.2 cm(-1)). Mössbauer spectroscopy data are consistent with high-spin Fe(III)(9) and Fe(III)(5) structures.