B.O. West

Platinum derivatives of decafluorophosphorobenzene and decafluoroarsenobenzene. The crystal structure of Pt(PPh3)2 (PC6F5)2

Abstract The platinum complexes Pt(PPh3)2 (PC6F5)2 and Pt(PPh3)2(AsC6F5)2 have been isolated from reactions of Pt(PPh3)3 with (PC6F5)4 and (AsC6F5)4 respectively. A single-crystal X-ray analysis of Pt(PPh3)2(PC6F5)2 has shown that the compound crystallizes in space group P21 with a = 9.286(5), b = 20.95(1), c = 11.226(5) A, β = 90.7(1)°, Z = 2. The structure has been solved by Patterson and Fourier methods and refined to R = 0.043 from three-dimensional diffractometer data. The complex contains the decafluorophosphorobenzene unit C6F5PPC6F5 bound through each P atom to the platinum. Coordination around the platinum is distorted square planar; the dihedral angle between the two PtP2 planes is 20.4°.

The reaction of iron carboxylates with titanium alkoxides. Isolation and structural characterisation of [Ti6(μ3-O)6(O2CPh)6(OCH2C(CH3)3)6]

Abstract The reaction of [Fe4(μ3-O)2(O2CPh)8(py)2] (1) with Ti(OPrn)4 in toluene yields separate Fe and Ti species each containing both carboxylate and alkoxide groups rather than a bimetallic FeTi complex. The addition of neopentanol to the reaction mixture has enabled [Ti6(μ3-O)6(O2CPh)6(OCH2C(CH3)3)6] (3) to be isolated and structurally identified. The compound [Ti6(μ3-O)4(O2CPh)8(OPrn)8] (4) has also been characterised and shown not to convert to a {Ti6(μ3-O)6}12+ core compound under the same temperature conditions used in the FeTi reactions.

The synthesis and the magnetic properties of perfluoroalkyl organometallic chromium(III) complexes containing n-substituted salicylaldimines and other ligands

Abstract Perfluoroalkyl derivatives of CrIII containing tetradentate or bidentate ligands derived from N-substituted salicylaldimines have been prepared by the reaction between the ligands and dihaloperfluoroalkylchromium acetonitrile complexes. The compounds show considerable solid-state and solution stability. Their magnetic moments are all greater than the spin-only value for a d3 system, and a molecular orbital bonding scheme is suggested to explain this observation.

Synthesis, molecular structure and magnetic properties of [Fe6(μ3-O)2(OPri)2(μ-OPri)6(O2CPh)2(μ-O2CPh)4]

Abstract The reaction of an Fe(III) oxo-benzoate species (1) with Al(OR)3 (R=Pri, Busec) yields the hexanuclear derivatives [Fe6(μ3-O)2(OR)8(O2CPh)6] (R=Pri (2); R=Busec (3)) which consist of planar Fe4(μ3-O)2 units, formed by two Fe3(μ3-O) groupings having common Fe(III) atoms, with further Fe(OR)4 entities, each attached by three bridging OR groups to Fe3(μ3-O) units, above and below the Fe4 plane. The OPri complex has an S=3 magnetic ground state and shows unusual temperature dependence of μeff below 60 K because of the complex series of low lying spin states generated by six high-spin Fe(III) centres undergoing antiferro- and ferromagnetic intracluster coupling. The Mossbauer spectrum at 81 K supports the presence of three inequivalent Fe sites in the molecule, as noted in the crystal structure.

Perfluoroalkyl derivatives of chromium and cobalt containing sulphur donor ligands

Perfluoroalkyl derivates of chromium (III) have been prepared containing dithiocarbamate ligands, e.g. RfCr(DTC)2py. The complexes have a cis arrangement of pyridine and Rf groups as determined by the X-ray crystal structure determination of C3F7Cr(Me2NCS2)2py. An analogous cobalt(III) complex C3F7Co(Et2NCS2)2py has also been prepared in small yield and 19F NMR measurements indicate a similar structure.

The synthesis and properties of dichloroheptafluoropropyltripyridinechromium(III) and some related compounds

Abstract The reaction between C 3 F 7 I and CrCl 2 (CH 3 CN) 2 in the presence of pyridine allows the isolation of C 3 F 7 CrCl 2 py 3 together with a CrICl 2 -pyridine complex. Similar complexes can be prepared using 2,2′-bipyridyl, 2,2′,2″-terpyridyl and 1,10-phenanthroline. The latter complexes are resistant to hydrolysis whereas C 3 F 7 CrCl 2 py 2 is rapidly hydrolysed to a pentafluoroalkyl aquo species.

Ligand substitution by fluoroalkyl groups in the reaction of perfluoroalkyl iodides with a Co1 complex

Abstract The perfluoroalkyl iodide C 3 F 7 I reacts with [Co 1 Salphen] −1 at −78°C to yield a mixture of ICo III Salphen and Co II Salphen accounting for ca. 95% of the original Co I complex, together with the organometallic compound C 3 F 7 Co III Salphen (2%). Other Co III and Co II complexes were identified in very low yields containing C 3 F 7 groups substituted in the ligand, one organometallic derivative being shown to have a C 3 F 7 group substituted in the 4-position of the phenylene ring.

Bis-aryl chromium complexes containing the dimethyldithiocarbamate anion and other chelate ligands

The complex CrC12(Me2dtc)bipy reacts with aryl Grignard reagents to yield R2Cr(Me2dtc)bipy (R = C6H5, CH3C6H4) as orange, air and moisture stable compounds. Other complexes CrC12(L)py2, L = Me2dtc−, sal−, acac− react with aryl Grignards to give related organo derivatives which are air and moisture sensitive.

Electron-transfer reactions between neutral cobalt complexes

Electron transfer occurs between the acetylacetone complexes of cobalt(II) and cobalt(III) in toluene at 98 °C. The slow reaction follows second-order kinetics with k= 2·36 l mol–1 h–1. A mechanism involving an acetylacetonate ion bridge is suggested for the transfer of ligand which accompanies the electron-transfer process. A similar mechanism is believed to account for electron transfer between N-arylsalicylideneimine complexes of cobalt although these reactions show only first-order dependence on the concentrations of the cobalt(III) complexes.