Trimethylaluminum reacts with [CPh3][B(C6F5)4] at elevated temperatures to give a mixture of AlMe3-x(C6F5)x compounds, depending on the Al/B ratio. AlBui 3 reacts significantly faster under β-hydride abstraction. The Al−C6F5 species rapidly react with Cp2ZrMe2 or [Cp2ZrMe]+ under C6F5 transfer to give poorly active Cp2ZrMe(C6F5); this reaction may have implications for the deactivation of Cp2ZrMe2/AlR3/[CPh3][B(C6F5)4] olefin polymerization catalysts.

Treatment of the thf adduct UO2(NCN)thf (NCN = [(Me3SiN)CPh(NSiMe3)]) (1) with 2 equiv of B(C6F5)3 provides UO{OB(C6F5)3}(NCN)2 (2) the first example of a neutral uranyl complex exhibiting Lewis basic behavior. The crystal structure of 2 shows a U=O-B interaction with an elongated U=O bond (1.898(3) A). Raman spectroscopy suggests weakening of the O=U=O bonding, giving the lowest reported symmetric stretching frequency for a monomeric uranyl complex, nu1 = 780 cm-1. The borane can be selectively removed using PMe3 to give the coordinatively unsaturated UO2(NCN)2 (3) or using tBuNC to provide UO2(CNBut)(NCN)2 (4), the first example of an isonitrile coordinated to uranium.

Bis(aryliminophosphoranyl)alkanes L 1 = (CH 2 ) n (R 1 2 P᎐ ᎐ NR 2 ) 2 (n = 1 or 2, R 1 = Ph or Me, R 2 = Ph, C 6 H 2 Me 3 -2,4,6 or C 6 H 3 Pr i 2 -2,6) reacted with cobalt and nickel dihalides to give chelate complexes of the type MX 2 (L 1 ). The reaction of Li[HC(Ph 2 P᎐ ᎐ NR 2 ) 2 ] with MX 2 afforded the compounds MX{HC(Ph 2 P᎐ ᎐ NR 2 ) 2 } (M = Co, X = Cl; M = Ni, X = Br). The crystal and molecular structures of CoCl 2 {CH 2 (Ph 2 P᎐ ᎐ NPh) 2 } and NiBr{HC(Ph 2 P᎐ ᎐ NC 6 H 3 Pr i 2 ) 2 } were determined. While the former has the expected tetrahedral structure, the latter is square planar. Ab initio calculations on the latter show that the bonding of the bis(iminophosphoranyl)methanide ligand to nickel involves π delocalisation over the N 2 P 2 C framework as well as σ bonding between nickel and the P 2 CH carbon atom. Bis(iminophosphoranyl)pyridines C 5 H 3 N(R 2 P᎐ ᎐ NRЈ) 2 -2,6 (R = Ph or cyclohexyl, RЈ = C 6 H 2 Me 3 -2,4,6, C 6 H 3 Pr i 2 -2,6 or SiMe 3 ) reacted with VCl 3 (thf) 3 , FeX 2 (X = Cl or Br) or CoCl 2 to give the corresponding octahedral (V) or five-coordinate (Fe, Co) complexes. The crystal structure of FeBr 2 {C 5 H 3 N(Ph 2 P᎐ ᎐ NSiMe 3 ) 2 -2,6} has been determined; the complex is trigonal bipyramidal. In the presence of methylaluminoxane [MeAlO] n , cobalt complexes of bis(aryliminophosphoranyl)methane are moderately active in ethene polymerisation, while bis(iminophosphoranyl)pyridine iron complexes show only low activity. The vanadium complexes polymerise ethene under ambient conditions and give polymers of very high molecular weight.

Treatment of [UO(2)Cl(2)(thf)(3)] in thf with 2 equiv of Na[PhC(NSiMe(3))(2)] (Na[NCN]) or Na[Ph(2)P(NSiMe(3))(2)] (Na[NPN]) gives uranyl complex [UO(2)(NCN)(2)(thf)] (1) or [UO(2)(NPN)(2)] (3), respectively. Each complex is a rare example of out-of-plane equatorial nitrogen ligand coordination; the latter contains a significantly bent O=U=O unit and represents the first example of a uranyl ion within a quadrilateral-faced monocapped trigonal prismatic geometry. Removal of the thf in 1 gives [UO(2)(NCN)(2)] (2) with in-plane N donor ligands. Addition of 3 equiv of Na[NCN] gives the tris complex [Na(thf)(2)PhCN][[UO(2)(NCN)(3)] (4.PhCN) with elongation and weakening of one U=O bond through coordination to Na(+). Hydrolysis of 4 provides the oxo-bridged dimer [Na(thf)UO(2)(NCN)(2)](2)(micro(2)-O) (6), a complex with the lowest reported O=U=O symmetrical stretching frequency (nu(1) = 757 cm(-)(1)) for a dinuclear uranyl complex. The anion in complex 4 is unstable in solution but can be stabilized by the introduction of 18-crown-6 to give [Na(18-crown-6)][UO(2)(NCN)(3)] (5). The structures of 1-4 and 6 have been determined by crystallography, and all except 2 show significant deviations of the N ligand atoms from the equatorial plane, driven by the steric bulk of the NCN and NPN ligands. Despite the unusual geometries, these distortions in structure do not appear to have any direct effect on the bonding and electronic structure of the uranyl ion. The main influences toward lowering the U=O bond stretching frequency (nu(1)) are the donating ability of the equatorial ligands, overall charge of the complex, and U=O.Na-type interactions. The intense orange/red colors of these compounds are because of low-energy ligand-to-metal charge-transfer electronic transitions.

Lithium(I) and uranium(VI) amido-tethered Bu(t)-substituted N-heterocyclic carbene (NHC) complexes exhibit very distorted metal-carbene bonds; the corresponding magnesium(II) and mesityl-substituted NHC uranium(VI) complexes are undistorted; the distortion does not affect the ligand binding strength, suggesting a dominance of electrostatic character in closed-shell electropositive metal-carbene bonds.