Systematic structural studies on cobalt(II) complexes of tricyclohexylphosphine oxide and related ligands

The new cobalt(II) phosphine oxide complexes Co(Cy3PO)2Cl2 (1), Co(Cy3PO)2Br2 (2), Co(Cy3PO)2I2 (3), Co(Ph2CyPO)2Cl2 (4), Co(Ph2CyPO)2Br2 (5), Co(Ph2CyPO)2I2 (6), Co(Ph2EtPO)2Br2 (7), Co(Cy3PO)2(NCS)2 (8) and Co(Cy3PO)2(NO3)2 (9) have been prepared mainly by the reaction of anhydrous CoX2 (X = Cl, Br, I, NCS, NO3) with the appropriate phosphine oxide. The complexes were characterised by single-crystal X-ray crystallography supported by IR and UV–Vis absorption spectroscopy. The structural analyses show that the cobalt(II) centre adopts a distorted tetrahedral coordination geometry except for 9 which displays an octahedral geometry. Systematic structural features of these complexes are explained within this paper.

A series of 9 cobalt(II) phosphine oxide complexes, supported by halide, thiocyanate or nitrato groups have been prepared and structurally characterised. Trends in the molecular bond parameters have been analysed.Figure optionsDownload as PowerPoint slideHighlights
► Systematic structural study of cobalt phosphine oxide complexes.
► Structural changes reflect properties of the phosphine oxide ligands.
► Complexes characterised crystallographically and spectroscopically.