183 Mnx edt full IC

183 Mnx edt full IC - Inorg. Chem. 1998, 37, 516-525 516...

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Structural and Magnetochemical Properties of Mono-, Di-, and Trinuclear Manganese(III) Dithiolate Complexes Jeffrey L. Seela, 1a Michael J. Knapp, 1b Kevin S. Kolack, 1a Hsiu-Rong Chang, 1b John C. Huffman, 1a David N. Hendrickson,* ,1b and George Christou* ,1a Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405-4001, and Department of Chemistry-0358, University of California at San Diego, La Jolla, California 92093-0358 Recei V ed May 15, 1997 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 - .(N E t 3 Bz) 2 [Mn 2 (pttd) 2 ]( 2 ) crystallizes in space group P 2 1 / c with (at - 158 ° C) a ) 11.540(2) Å, b ) 12.115(2) Å, c ) 17.478(4) Å, ± ) 101.78(1) ° ,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 ;ed t 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 1 h with (at - 161 ° 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)] - E t 4 )[Mn(edt) 2 (ImH)] ( 4 ) crystallizes in space group P 2 1 / n with (at - 72 ° C) a ) 13.974(5) Å, b ) 14.317(5) Å, c ) 10.564(3) Å, ± ) 90.13(2) ° 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 Pna 2 1 with (at - 160 ° 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 ˆ) - 2 JS i S j convention). Complexes 1 , 2 5 have S ) 0 ground states, while that of 3 is S ) 3 / 2 . Introduction Manganese(III) chemistry is proving to be a rich source of polynuclear complexes with a variety of interesting structural and physical properties. One such property is an unusually large value of spin ( S ) in the ground state, 2 - 7 a result of the presence of (at least some) ferromagnetic exchange interactions between the constituent paramagnetic metal ions and/or the presence of spin frustration 8,9 effects arising in certain topological arrange- ments of metal ions possessing competing pairwise exchange interactions of comparable magnitude. More recently, a subset of high-spin molecules has emerged that has been termed
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183 Mnx edt full IC - Inorg. Chem. 1998, 37, 516-525 516...

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