Fredric R. Askham

The synthesis of heterobimetallic systems based on a hexatertiaryphosphine ligand system: cobalt-nickel and nickel-platinum complexes

Abstract Heterobimetallic complexes can be prepared in an extremely straightforward fashion by the use of the binucleating hexatertiaryphosphine ligand (Et 2

Reaction of oxygen with a binuclear cobalt (II) hexaphosphine complex. Single-crystal X-ray structure of an extended chain cobalt (II) hexaphosphine oxide system

Abstract Molecular oxygen reacts rapidly with Co 2 Cl 4- x ,(eHTP) x + [ x = 0 or 2; eHTP = (Et 2 PCH 2 CH 2 ) 2 PCH 2 P(CH 2 CH 2 PEt 2 ) 2 ] in dry acetonitrile to produce in approximately 66% yield the fully-oxygenated phosphine oxide eHTP (eHTPO) Co(II) complex [Co(eHTPO) 2+ ][CoCl 4 2− . The X-ray structure on this novel system shows an extended chain system in which the monomeric repeating unit has an octahedral Co(II) centre. The eHTPO ligand is adopting an unusual conformation with the phosphine oxide groups P(2)P(1)P(3) (P(1) is one of the internal phosphorus atoms) forming a P(1)P(2) chelate to the metal atom while P(3) bridges to another Co(eHTPO) 2+ monomer unit making up the extended chain, instead of acting as an independent bis chelating group. The third unique coordination site on the cobalt centre is occupied by a phosphine oxide group from the other half of the eHTPO ligand which bridges over to the cobalt centre forming a facial set of three PO donor ligands. This mixed bridging/chelating conformation gives rise to fused seven- and nine-membered ring systems with a CoCo separation of 7.613(0) A between symmetry related cobalt sites on the extended chain. This structure is the first reported for a Co(R 3 PO) 6 n + (R = alkyl, phenyl) system.