Oliver Seewald

Di-μ-oxido-bis{[1,3-bis(tetramethylguanidino)propane-κ2N,N′]bromidomanganese(III)}

The title compound, [Mn2Br2O2(C13H30N6)2], is the first crystallographically characterized MnIII2(μ-O)2 complex with a bidentate imine ligand . The molecule lies on a crystallographic inversion centre and shows distorted square-pyramidal coordination of the Mn atoms by two guanidine N atoms, the two bridging O atoms and a terminal Br ligand. The crystal structure involves an intermolecular C—H⋯Br hydrogen bond.

The diprotonated 2,2-(propane-1,3-diyl)bis(1,1,3,3-tetramethylguanidinium) cation: packing and conformational changes.

Subject to packing with different anions, the title cation undergoes various conformational changes with significantly different N-C-C-C torsion angles, as well as different angles between the NCN2 guanidine planes. The 2,2-(propane-1,3-diyl)bis(1,1,3,3-tetramethylguanidinium) salts reported here, viz. the dibromide, C13H32N6(2+).2Br-, the tetraphenylborate chloride, C13H32N62+.C24H20B-.Cl-, the tetrachloromercurate, (C13H32N6)[HgCl4], and the bis(trifluoromethanesulfonate), C13H32N6(2+).2CF3SO3-, are dominated by strong intermolecular N-H...X hydrogen bonds, which form different packing patterns.

Diastereomeric metallatetrahedron complexes of the type Re2(MPPh3)(M′PPh3)(μ-PCy2)(CO)7(−)-thiocamphanate (M = Ag, Au, M′ = Cu, Ag, Au): synthesis, structure and CD data

Four pairs of diastereomeric metallatetrahedron complexes of the type Re2(MPPh3)(M′PPh3) (μ-PCy2)(CO)7(−)-thiocamphanate have been synthesized, with identical (M = M′ = Au (5a, 5b) and Ag (6a, 6b)) and with mixed coinage metals (M = Au, M′ = Ag (8a, 8b) and Cu (9a, 9b)). After separation, the absolute configuration was determined by single crystal X-ray crystallography for 6a, 8a and 9a. In agreement with solution (31P and 1H NMR) spectral data, the thiocamphanate acts as a μ-S bridging bidentate ligand along the Re-coinage metal edge; in the mixed coinage metal complexes coordination involves the lower homologue of the coinage metals. Signs of the long wavelength absorption bands in the CD spectra were found to correlate with the counter (A) or clockwise (C) configuration of the chiral transition metal core.