Inorganic Chemistry, Vol.37, No.3, 516-525, 1998
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) <(A)Angstrom>, b = 12.115(2) (A) over circle, c = 17.478(4) <(A)Angstrom, beta = 101.78(1)degrees, and Z = 2. The anion contains a doubly-bridged [Mn2S8] core (Mn...Mn = 3.598(2) <(A)r Angstrom with five-coordinate Mn-III ions, very similar to previously reported [Mn-2(edt)(4)](2-) (anion of 1; edt(2-)= ethane-l,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)). (PPh4)(2)[Mn-3(pdt)(5)] (3) crystallizes in space group P (1) over bar with (at-161 degrees C) a=14.385(6) (A) over circle, b = 23.734(11) (A)Angstrom>, and Z = 2. The anion contains a near-linear (MnMnMnIII)-Mn-III-Mn-II 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) (A) over circle. 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) (A) over circle, b = 14.317(5) (A)Angstrom c = 10.564(3) (A) over circle, 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. (NMe4)(3)[Mn-2(Im)(edt)(4)] (5) crystallizes in space group Pna(1) with (at -160 degrees C) a 17.965(5) (A) over circle, b = 16.094(4) (A)Angstrom, c = 14.789(3) (A) over circle, and Z = 4. The five-coordinate Mn-III ions are bridged by the Im(-) group across a Mn...Mn separation of 6.487(2) (A) over circle. 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.
Keywords:IMIDAZOLATE-BRIDGED COMPLEXES;ZN SUPEROXIDE-DISMUTASE;HIGH-SPIN MOLECULES;COPPER(II) COMPLEXES;MAGNETIC-PROPERTIES;CRYSTAL-STRUCTURE;MONONUCLEAR;BINUCLEAR;DICOPPER(II);CHEMISTRY