Manganese, technetium and rhenium

Abstract

This Chapter reviews the literature reported during 2007 on manganese, technetium and rhenium. The synthesis of novel compounds and complexes of these metals is reviewed and new observations and inferences are reported. Research highlights for each of the metals during the year are also given. HighlightsA rare example of a manganese tetranuclear star-shaped complex has been synthesised and characterised. 27 TcO 3 F has been prepared for the first time and found to dimerise in the solid state via fluoride bridges. 70 The first tetrazolate hexanuclear rhenium cluster complexes have been prepared and studied. 99 ManganeseA facile route to the molecular compound [Mn 3 Ti(m , containing a chiral Mn 3 Ti centre, has been reported for the first time. 1 Oxidation of a manganese(III) corrole with molecular iodine has led to the synthesis of the first compound containing a Mn IV -I bond. 2 Using structural, magnetic and theoretical studies, [Mn 2 (1,4-(Si i Pr 3 ) 2 C 8 H 4 ) 2 ] has been found to contain both high and low spin manganese(II) in two very different sites, 3 while using magnetisation measurements and multifrequency high-field EPR, the largest zero-field splitting for any individual isolated manganese(II) ion has been found in a polyoxometalate complex. 4 A large [Mn 10 Na] 4 loop-of-loops aggregate has been prepared, constructed of four [Mn 10 (m 3 -O) 2 (O 2 CMe) 13 (pd) 6 (py) 2 ] À (pdH 2 = 1,3-propanediol) loops linked through Na + ions. 5 Magnetic characterisation reveals that the Mn 10 loop has an S B 4 ground state. Without the use of a surfactant as a template, single crystalline Li 4 Mn 5 O 12 nanowires have been prepared on a large scale. 6 Icosa-and hexadeca-nuclear mixed-metal clusters in which dinuclear copper(II) complexes trap oxo-bridged [Mn III 8 Mn IV 4 O 12 ] and [Mn III 6 O 6 ] cores respectively have been prepared using quinquedentate Schiff base ligands. 7 The 2D molecular magnet K 2 [Mn(H 2 O) 2 ] 3 [Mo(CN) 7 ] 2 Á 6H 2 O has been probed by a combination of neutron diffraction studies and theoretical DFT calculations. 8 Meanwhile, mechanistic studies have been carried out on the oxidation of nitrite by a {Mn 3 O 4 } 4+ core in aqueous acidic media. 9 [Mn 3 (m-O) 4 (phen) 4 (H 2 O) 2 ] 4+ (I) quantitatively oxidises HNO 2 and NO 2 À to NO 3 À , and a rate-determining 1e, 1H + electroprotic mechanism is proposed. The new Zintl phases Ca 21 Mn 4 Bi 18 and Ca 21 Mn 4 Sb 18 have been synthesised by high temperature reactions and crystallise in the space groups C2/c and C2/m, respectively. 10 Electronic band structure calculations suggest narrow-gap semiconducting behaviour for both compounds.