W. Levason

Bidentate ligands containing very soft donor atoms. Nickel(II) complexes of arylarsines and arylstibines

Abstract Twenty nine nickel(II) complexes of o-phenylene-bis(diphenylphosphine), o-phenylenebis(diphenylarsine), o-diphenylphosphinophenyldiphenylstibine (sbp), o-diphenylarsinophenyldiphenylstibine, bisdiphenylarsinomethane (dam), 1,2-bisdiphenylarsinoethane, and cis-1,2-bisdiphenylarsinoethylene have been isolated. All ligands except dam form square pyramidal [NiL 2 X] + cations, as well as four coordinate NiLX 2 . The latter are planar complexes except when L = dam, sbp. The structures and magnetic behaviour of the anomalous tetracoordinate complexes are discussed. The factors influencing the formation of stable complexes of nickel(II) with very soft donors are considered; and it appears that the tendency for group VB donors to form diamagnetic square pyramidal nickel(II) complexes is Sb >As > P.

Bidentate group VB ligands. Part XVII. Palladium(II), platinum(II), and rhodium(III) complexes of o-phenylenebis(diphenylphosphine), (o-diphenylphosphinophenyl)diphenylstibine, and (o-diphenylarsinophenyl)diphenylstibine1

Sixty complexes of palladium(II), platinum(II), and rhodium(III) with the bidentate chelates o-phenylenebis(diphenylphosphine) (pp), (o-diphenylphosphinophenyl)diphenylstibine (sbp), and (o-diphenylarsinophenyl)diphenylstibine (sba), including MLX2, ML2X2, [ML2](ClO4)2 (M = Pd, Pt; L = pp, sbp; X = Cl, Br, I, CNS) and [M(sba)2X]Cl04 (M = Pd, Pt; X = Cl, Br, I), have been isolated. The planar thiocyanates, are formulated [M(pp)(NCS)(SCN)], [ML(SCN)2] (M = Pd, Pt, L = sba; M = Pt, L = sbp), whilst the palladium(II)-sbp complex exists as [Pd(sbp)(NCS) (SCN)] in the solid state but isomerises to [Pd(sbp) (SCN)2] in dichloromethane. The 2:1 species ML2X2 (M = Pd, Pt; L = pp, sbp; X = halide) and [M(sba)2X] ClO4 form some pentacoordinate ions in solution, whilst the corresponding thiocyanates are formulated [M(pp)2](NCS)2 and [Pd(sbp)2NCS]NCS; neither Pt(sbp)2(CNS)2 nor M(sba)2(CNS)2 could be prepared. The mode of thiocyanate coordination and the tendency to form pentacoordinate cations is discussed in terms of the metal ions and ligands. The [RhL2X2]X are readily prepared for L = pp; X = Cl, Br, I and L = sbp; X = Cl, Br. Some [RhLX3]2 were also isolated.

Bidentate group VB chelates : XVI. The preparation of o-phenylenebis(diphenylstibine) and attempts to prepare cis- and trans-1,2-bis(diphenylstibino)ethylene

Abstract o -Phenylenebis(diphenylstibine) (sbsb) has been obtained from sodium diphenylstibide and o -bromophenyldiphenylstibine. The failure of other routes to this compound, and of attempts to prepare ethylenic distibines, are discussed.

Coordination complexes containing multidentate ligands. Part X. The reaction of divalent cobalt, nickel, and palladium salts with open-chain tetrathioethers, α,ω-bis(methylthioalkylthio)alkanes. The effect of chelate chain length on donor and spectral properties

Abstract The aliphatic open-chain tetrathioethers, 1,2-bis(2-methylthioethylthio)ethane, 1,3-bis(2-methylthioethylthio)propane, 1,2-bis(3-methylthiopropylthio)ethane, and 1,3-bis(3-methylthiopropylthio)propane have been synthesised and reacted with divalent metal salts. They form complexes of the type [Co(ligand)I2], [Ni(ligand) X2] (X = Cl, Br, I), and [Pd2(ligand)X4] (X = Cl, Br, I), but not all ligands form each type of complex, and the donor properties of these tetrathioethers are discussed in terms of the chain lengths between the sulphur atoms. Calculation of in-plane ligand field in the trans- [Ni(ligand)X2] complexes indicates that the field strengths of the tetrathioethers changes from the solid state to solution and are also dependent on the nature of the coordinated halide.

Bidentate group VB chelates, Part VII. Some palladium(II) complexes with diphosphine, phosphine-arsine, and diarsine ligands, including some thiocyanate derivatives

Abstract Eighteen complexes of palladium(II) salts and the bidentate chelating ligands cis-1,2-bis(diphenylphosphino)ethylene (vpp). cis-1,2-bis(diphenylarsino)ethylene (vaa), cis-1-diphenylarsino-2-diphenylphosphinoethylene (vasp), and 9,10-bis(diphenylphosphino)phenanthrene (dpph) have been prepared and studied by infrared and electronic spectroscopic techniques. The thiocyanate complexes are formulated Pd(vpp)(SCN)2 Pd(vaa)(SCN)2 Pd(vasp)(SCN)2 and Pd(dpph)(NCS)(SCN), and the possible factors promoting the different types of coordination are discussed.

Bidentate group VB chelates Part V. Silver(I) complexes of some diphosphine and diarsine ligands

Abstract Silver(I) nitrate reacts with bisdiphenylphosphinomethane, 1,2-bisdiphenylphosphinoethane, 1,3-bisdiphenylphosphinopropane, cis-1,2-bisdiphenylphosphinoethylene, and o-phenylenebisdimethylarsine to form non-conducting complexes [(AgNO3)2.L]. The infrared spectra indicate monodentate nitrato groups, and the complexes are assigned a dimeric structure with single ligand bridges, a type of complex hitherto unknown to Ag1 with bidentate phosphines and arsines. Attempts to prepare silver(II) complexes were unsuccessful.

Bidentate group vb ligands. Part XIII. Divalent cobalt, nickel, and palladium complexes of 1,2-bis(methylphenylarsino)ethane and 1,3-bis(methylphenylarsino)propane. Stoichiometric and structural effects of chelate chain length

Abstract Thirtyfour complexes of 1,2-bis(methylphenylarisino)ethane (dase) and 1,3-bis(methylphenylarsino)propane (dasp) have been characterised. Interesting differences are observed in the complexing properties of these chelates. Thus, with cobalt(II) halides [Co(dase) 2 ][CoX 4 ], which contain planar cations, and pseudotetrahedral [Co(dasp)X 2 ] are obtained. Nickel (II) halides form planar [NiLX 2 ] complexes with dase, but with dasp form [Ni(dasp)X 2 ] n (X = Cl, Br) which are pseudooctahedral in the solid state and planar in solution, and the pseudotetrahedral [Ni(dasp)I 2 ]. The [Ni(dasp) 2 X] ClO 4 are trigonal bipyramidal in the solid state (X = Cl, Br, I, NCS), but in solution [Ni(dasp) 2 (NCS)] + appears to be square pyramidal, whilst the [Ni(dase) 2 X] ClO 4 are square pyramidal in both the solid state and solution. The planar [Ni(dasp)(NCS) 2 ] complex differs from the analogous dase species by losing ligand on recrystallisation to form the dimeric Ni 2 (dasp) 3 (NCS) 4 moiety. Planar [PdLX 2 ] (L = dase, dasp, X = Cl, Br, I) species are formed, but no [PdL 2 X] + complexescould be isolated. In the solid state [PdL(NCS)(SCN)] complexes are formed, and the dase species isomerises to [Pd(dase)(SCN) 2 ] in dichloromethane. An attempt is made to relate the structural differences in the complexes to the chain length of the chelates.

The coordination chemistry of molybdenum and tungsten. Part V. Open-chain tetrathioether complexes of molybdenum(IV) and (V) and tungsten(IV) and (V)

Abstract The tetrathioethers α, ω-bis(methylthioalkylthio)alkanes, CH 3 S(CH 2 ) n S(CH 2 ) m S(CH 2 ) n SCH 2 (n = m = 2; n = 2, m = 3; n = 3, m = 2, n = m = 3, ligand), yield seven-co-ordinate [MCl 4 (ligand) (M = Mo, W), seven-coordinate [WoCl 3 (ligand)] in which the thioethers act as tridentate ligands, and six-coordinate [MoOCl 3 ) 2 (ligand)] in which the ligand acts in a tetraligate bimetallic manner. 2-5-Dithiahexane (dth) similarly yielded [MCl 4 (dth)(RCN)] and [MoOCl 3 (dth)]. The electronic, infrared and electron paramagnetic resonance spectral properties of these complexes are reported and discussed.

The synthesis of some bidentate bismuth-containing ligands

Abstract The synthesis and properties including mass spectra of ( o -diphenylphosphinophenyl)diphenylbismuthine, o -C 6 H 4 (PPh 2 )(BiPh 2 ) and ( o -diphenylarsinophenyl)-diphenylbismuthine, o -C 6 H 4 (AsPh 2 )(BiPh 2 ) are described. The failure of attempts to prepare α, ω-bis(disphenylbismuthino)alkanes is discussed.

trans-Chelation of 1,12-bis(dimethylarsino)dodecane to palladium(II)

Abstract The diarsine ligand, 1,12-bis(dimethylarsino)dodecane, reacts with tetrachloropalladate(II) in ethanol/dichloromethane to form in highly yield the monomeric [Pd(ligand)Cl 2 ] complex containing the trans -chelating diarsine.