Structural and Magnetochemical Properties of Mono-, Di-, and Trinuclear Manganese(III) Dithiolate Complexes

Aerial oxidation of Mn(II)/ptt(3)(-) (ptt(3)(-) = propane-1,2,3-trithiolate) mixtures gives [Mn(2)(pttd)(2)](2)(-), where pttd(4)(-) is the mono(disulfide) of ptt(3)(-). (NEt(3)Bz)(2)[Mn(2)(pttd)(2)] (2) crystallizes in space group P2(1)/c with (at -158 degrees C) a = 11.540(2) Å, b = 12.115(2) Å, c = 17.478(4) Å, beta = 101.78(1) degrees, and Z = 2. The anion contains a doubly-bridged [Mn(2)S(8)] core (Mn.Mn = 3.598(2) Å) with five-coordinate Mn(III) ions, very similar to previously reported [Mn(2)(edt)(4)](2)(-) (anion of 1; edt(2)(-) = ethane-1,2-dithiolate). Aerial oxidation of Mn(II)/pdt(2)(-) (pdt(2)(-) = propane-1,3-dithiolate) mixtures gives [Mn(3)(pdt)(5)](2)(-), which is mixed valent (Mn(II), 2Mn(III)). (PPh(4))(2)[Mn(3)(pdt)(5)] (3) crystallizes in space group P&onemacr; with (at -161 degrees C) a = 14.385(6) Å, b = 23.734(11) Å, and Z = 2. The anion contains a near-linear Mn(III)Mn(II)Mn(III) unit with five-coordinate Mn(III), six-coordinate Mn(II), and three thiolate bridges between each Mn(2) pair; Mn.Mn separations are 3.123(3) and 3.101(3) Å. Aerial oxidation of Mn(II)/edt(2)(-)/ImH (ImH = imidazole) mixtures gives [Mn(edt)(2)(ImH)](-). (NEt(4))[Mn(edt)(2)(ImH)] (4) crystallizes in space group P2(1)/n with (at -72 degrees C) a = 13.974(5) Å, b = 14.317(5) Å, c = 10.564(3) Å, beta = 90.13(2) degrees, and Z = 4. The anion is five-coordinate and square-pyramidal. Aerial oxidation of Mn(II)/edt(2)(-)/Im(-) mixtures gave [Mn(2)(Im)(edt)(4)](3)(-), which contains two Mn(III) ions. (NMe(4))(3)[Mn(2)(Im)(edt)(4)] (5) crystallizes in space group Pna2(1) with (at -160 degrees C) a = 17.965(5) Å, b = 16.094(4) Å, c = 14.789(3) Å, and Z = 4. The five-coordinate Mn(III) ions are bridged by the Im(-) group across a Mn.Mn separation of 6.487(2) Å. The anion of 4 contains high-spin Mn(III) (S = 2) and exhibits inter-anion antiferromagnetic exchange interactions (J = -0.15 cm(-)(1), g = 1.91) propagated by interanion NH.S hydrogen bonds. Complexes 1-3 and 5 all possess intraanion antiferromagnetic exchange interactions; the fitting parameters are as follows: 1, J = -19.0 cm(-)(1), g = 1.96, D = -0.22 cm(-)(1); 2, J = -16.4 cm(-)(1), g = 1.96, D = -0.22 cm(-)(1); 3, J = -18.8 cm(-)(1), g = 2.00; 5, J = -1.75 cm(-)(1), g = 1.84, D = -0.028 cm(-)(1) (H = -2JS(i)()S(j)() convention). Complexes 1, 2, and 5 have S = 0 ground states, while that of 3 is S = (3)/(2).