A novel asymmetrical phosphine tetracobalt complex ofo-Mercaptophenol: Synthesis,structure, and properties of Co4mp4(Hmp)(PBu 3 n )3 (H2mp=o-Mercaptophenol)

Complex Co₄mp₄(Hmp)(PBu ₃ ⁿ )₃ (1) (H₂mp=o-Mercaptophenol) was obtained from the reaction of CoCl₂ and H₂mp in the presence of PBu ⁿ ₃ and NaOMe with restricted oxidation. X-ray crystallographic data: triclinic, space group ,a=15.657(5) Å,b=20.469(8) Å,c=12.383(3) Å,=93.59(3)°, =112.45(2)°, =93.65(3)°,V=3648.7 ų,Z=2,D _c =1.33 g/cm³;R=0.065. The molecule consists of four cobalt atoms unsymmetrically bridged by S or S and O atoms from four of the five mp ligands. The fifth mp is terminally chelated to Co(4) which is in a distorted trigonal bipyramidal geometry, while Co(1)-Co(3) are square pyramidal. Atom Co(2) is bonded to Co(1) and Co(3) (average distance 2.632 Å) with strong interactions while Co(4) is only loosely connected to Co(1) (3.402 Å) and Co(3) (2.956 Å) through oxygen bridges and a hydrogen bond. The different coordination environments O₂S₂P, S₄P, and O₄S of the cobalt atoms make the molecule highly asymmetrical. XPS fitting data confirm the difference of the Co atoms. FABMS data indicate the possible fragmentation routes. The complex is paramagnetic with _eff=5.2 _B.