John McMeeking

Metallacycloalkanes: I. Preparation and characterisation of α,α′-bipyridyl-5-nickela-3,3,7,7-tetramethyl-trans-tricyclo[4.1.0.02,4]heptane

Abstract Oxidative addition of 2 molecules of 3,3-dimethylcyclopropene (I) to α,α′-bipyridyl(1,5-cyclooctadiene)nickel(0) (III) gave the title compound (IV) in over 90% yield. Complex IV was characterized by mass, 1 H NMR and 13 C NMR spectroscopy. Its structure was determined by X-ray diffraction ( a 13.7081(2), b 14.638(2), c 9.5139(1) A, β 110.82(1)°, C 2/ c , R = 0.05 for 1614 reflections).

Alkyl bridged complexes of the group 3A and lanthanoid metals as homogeneous ethylene polymerisation catalysts

The fully characterised group 3A and lanthanoid metal complexes [M(η-C5H4R)2Me]2(M;Y or Er, RH, Me, or SiMe3, and MYb, RH or Me) and [M(η-C5H4R)2Me2AlMe2](MY, Er, Ho, or Yb RH or Me, and MY, RSiMe3) are active homogenous ethylene polymerisation catalysts; they show an intramolecular deactivation process involving abstraction of a cyclopentadinyl hydrogen which is completely suppressed with peralkylated derivatives.

Neutral and anionic silylmethyl complexes of the Group 3a and lanthanoid metals; the X-ray crystal and molecular structure of [Li(thf)4][Yb{CH(SiMe3)2}3Cl](thf = tetrahydrofuran)

The neutral [M(CH2SiMe3)3(thf)2](M = Tb, Er, or Yb; thf = tetrahydrofuran) and the ionic [Li(L)4]-[MR4][R = Me3SiCH2; when M = Y, Er, or Yb, L2= Me2NCH2CH2NMe2(tmed); when M = Y, L = thf], [Li(thf)4][M(Cl)R3][M = Er or Yb, R =(Me3Si)2CH], and [LiL2][M(η-C5H4SiMe3)2Cl2][L = 0·5 tmed or thf) are reported; their structures are deduced from i.r. and 13C and 1H n.m.r. (M = Y) spectra, conductivity, and in the case of [Li(thf)4][Yb{CH(SiMe3)2}3Cl], by a single crystal X-ray analysis [l(Yb–C)(av.)= 2·38 A].

Alkylideneamido-derivatives of metals and metalloids. Part VI. The synthesis of alkylideneamido(carbene)rhodium(I) complexes and related chemistry; the crystal and molecular structure of trans-Rh[N:C(CF3)2][C(NMeCH2)2](PPh3)2

Two rhodium(I) complexes, trans-Rh[N:C(CF3)2][C(NRCH2)2](PPh3)2, (I; R =p-MeC6H4) and (II; R = Me), containing both alkylideneamido- and substituted carbene ligands have been prepared. Variable temperature 19F n.m.r. spectra suggest a low barrier to planar inversion at N. It did not prove possible to rearrange these to aza-allyl/allene isomers. As a contribution to the mechanism of formation of the latter, the synthesis of a C-alkylideneamidocarbene complex (V) is reported. A PtII imidoyl complex Pt–C(R)NR′, prepared by an oxidative addition reaction, did not isomerise to the alkylideneamide Pt–NCRR′; but with HCI the former gave a 1 : 1 adduct, presumed to be the carbene complex Pt–C(R)NHR′. A single crystal X-ray analysis of (II) has been carried out to R 0·067 for 2853 independent terms : the complex has an approximately square planar Rh environment with disorder about N:C and Rh–N, 2·02(3); NC, l·27(3); Rh–P, 2·290(4) and 2·291(4); and Rh–Ccarb, 2·006(15)A, and RhNC = 152°. Noteworthy are the significant departure from linearity at N and the exceptionally short mutually trans-Rh–P bond lengths; the M–NO/M–N:NR analogy is extended to M–N:CR2.

Nickelacyclopentane derivatives as intermediates in the nickel(0)-catalysed cyclodimerisation of strained-ring olefins

The syntheses of the bipyridylnickelacyclopentane derivatives (9)–(11) and their displacement reactions with activated olefins, e.g. maleic anhydride or the strained-ring olefins (1)–(3), are reported.