Synthesis and Structure of Novel Complexes of Gallium

Abstract

[Cp*GaCl2] (Cp* = 1-C5Me5) reacts with K[Co(CO)4] with elimination of KCp* and KCl to form the novel ionic complexes [K(toluene)2][Ga{Co2(CO)6(-CO)}2] (1) and K[GaCl{Co2(CO)6(-CO)}{Co(CO)4}] (2), where the gallium atoms possess the coordination number four. The reaction of [{Co(CO)4}2GaCl(THF)] with LiCp* leads to the ionic product [Li(THF)][Ga{Co2(CO)6(-CO)}2] (3). The [Ga{Co2(CO)6(-CO)}2]- anions of 1 and 3 represent the first homoleptic spirocyclic coordination mode of gallium. The reaction of GaCl3 with Na2[Fe(CO)4] leads to the ionic compound [Na(OEt2)2][Fe(CO)4(GaCl3)2] (4). Complexes 1, 2, 3 and 4 were characterised by X-ray structure analysis and IR spectroscopy. Additionally, ESI mass spectra of 1 were recorded at different cone voltages, where the molecular ion peak of the anion [Ga{Co2(CO)6(-CO)}2]- as well as the peaks resulting from sequential loss of CO ligands until the formation of the naked [Co4Ga]- cluster are observed. The ionic complexes 1, 2, 3 and 4 form polymeric networks through coordination of their cations. In 2 a three-dimensional polymeric network is formed by coordination of the Co3Ga units and their K counterions, whereas in 1 the K ions are additionally coordinated by toluene molecules to form dimeric macrocyclic motifs by coordination of two of the anionic Co4Ga units. In 3 a zigzag chain is formed by coordination of the Co4Ga units through their Li cations. In the crystal packing of complex 4 the FeGa2 moieties form zigzag chains, coordinating through their Na counterions.