Bridging nitrate groups in [Mn4O3(NO3)(O2CMe)3(R2dbm)3] (R = H, Et) and [Mn4O2(NO3)(O2CEt)6(bpy)2](ClO4):: Acidolysis routes to tetranuclear manganese carboxylate complexes

New synthesis procedures are described to tetranuclear manganese carboxylate complexes containing the [Mn4O2](8+) or [Mn4O3X](6+) (X- = MeCO2-, F-, Cl-, Br-, NO3-) core. These involve acidolysis reactions of [Mn4O3(O2CMe)(4)(dbM)(3)] (1; dbm is the anion of dibenzoylmethane) or [Mn4O2(O2CEt)(6)(dbm)(2)] (8) with HX (X- = F-, Cl-, Br-, NO3-; high-yield routes to 1 and 8 are also described, The X- NO3- complexes [Mn4O3(NO3)(O2CR)(3)(R'(2)-dbm)(3)] (R = Me, R' = H (6); R = Me, R' = Et (7); R = Et, R' = H (12)) represent the first synthesis of the [Mn4O3(NO3)](6+) core, which contains an unusual eta(1):mu(3)-NO3- group. Treatment of known [Mn4O2(O2CEt)(7)(bpy)(2)](ClO4) with HNO3 gives [Mn4O2(NO3)(O2CEt)(6)(bpy)(2)](ClO4) (15) containing a eta(1):eta(1):mu-NO3- group bridging the two body Mn-III ions of the [Mn4O2](8+) butterfly core. Complex 7.4CH(2)Cl(2) crystallizes in space group P2(1)2(1)2(1) with (at -168 degreesC) a = 21.110(3) Angstrom, b = 22.183(3) Angstrom, c = 15.958(2) Angstrom, Z = 4, and V = 7472.4(3) Angstrom(3). Complex 15.3/2CH(2)Cl(2) crystallizes in space group P2(1)/c with (at -165 degreesC) a = 26.025(4) Angstrom, b = 13.488(2) Angstrom, c = 32.102(6) Angstrom,beta = 97.27(1)degrees, Z = 8, and V = 11178(5) Angstrom(3). Complex 7 contains a [Mn-4(mu(3)-O)(3)(mu(3)-NO3)](6+) core (3Mn(III), Mn-IV) as seen for previous [Mn4O3X](6+). complexes. Complex 15 contains a butterfly [Mn-4(mu(3)-O)(2)](8+) core. H-1 NMR spectra have been recorded for all complexes reported in this work and the various resonances assigned. All complexes retain their structural integrity on dissolution in chloroform and dichloromethane. Magnetic susceptibility (chi(M)) data were collected on 12 in the 5-300 K range in a 10.0 kG (1 T) field. Fitting of the data to the theoretical chi(M) vs T expression appropriate for a [Mn4O3X](6+) Complex of C-3v symmetry gave J(34) = -23.9 cm(-1), J(33) = 4.9 cm(-1), and g = 1.98, where J(34) and J(33) refer to the (MnMnIV)-Mn-III and (MnMnIII)-Mn-III pairwise exchange interactions, respectively. The ground state of the molecule is S = 9/2, as found previously for other [Mn4O3X](6+) complexes. This was confirmed by magnetization data collected at various fields and temperatures. Fitting of the data gave S = 9/2, D = -0.45 cm(-1), and g = 1.96, where D is the axial zero-field splitting parameter.