Vanadium nitride functionalization and denitrogenation by carbon disulfide and dioxide

A dramatic difference in behavior is observed for the dithiocarbamate and carbamate complexes [Ar(But)N]3V(NCE2)Na(THF)2(E = S or O, respectively), prepared from the corresponding nitride species ([Ar(But)N]3V identical to NNa)2 by way of a nucleophilic addition reaction involving carbon disulfide or dioxide, and is rationalized with the aid of DFT calculations.     

Quantum dot-labelled polymer beads by suspension polymerisation

CdSe quantum dots with polymerisable ligands have been incorporated into polystyrene beads, via a suspension polymerisation reaction, as a first step towards the optical encoding of solid supports for application in solid phase organic chemistry.     

Coordination chemistry of a chelating amidoximato ligand

A potentially general strategy for accessing the rarely encountered coordination of amidoximates through both oximato O and amido N atoms was developed. The new amidoxime (Z)-R(1)C(=NOH)NR(2)H (R(1) = mesityl, R(2) = 2-[[dimethylamino]methyl]phenyl), H(2)L, was prepared by reaction of equimolar amounts of the appropriate nitrile oxide and primary amine. Treatment of H(2)L with 1 equiv of AlMe(3) produced the dimeric species (MeAlL)(2) (1) possessing the formally dianionic ligand L(2)(-) bound to the aluminum via the oximato oxygen and the amido and amino nitrogens. The oximato oxygen atoms serve to link the two monomeric organoaluminum units together. Reaction of (ON)Cr(N(i)Pr(2))(3) with H(2)L provided the diamagnetic complex (ON)Cr(N(i)Pr(2))(eta(3)-L) (2). Interaction of 2 with excess methanol led, in particular, to the oxidative loss of NO and yielded the paramagnetic dimer [Cr(LH)(OMe)(mu-OMe)](2) (3) containing the eta(3)-bound amidoximato ligand protonated at its oximato nitrogen. In addition to spectroscopic characterizations of the new substances, single-crystal X-ray structures of H(2)L, 1.(4)/(3)C(6)H(6), and 3.MeOH were obtained.     

Resonance offset tailored composite pulses

We describe novel composite pulse sequences which act as general rotors and thus are particularly suitable for nuclear magnetic resonance quantum computation. The resonance offset tailoring to enhance nutations approach permits perfect compensation of off-resonance errors at two selected frequencies placed symmetrically around the frequency of the radiofrequency source.     

Niobium and vanadium iminophosphinimide complexes

The iminophosphinimide complexes [Ar(R)N]3M(NPNBut) (M = V, Nb) were prepared from the corresponding anionic nitride species ([Ar(R)N]3M identical to NNa)2 by way of a four-step synthetic strategy.     

Using slow light to enhance acousto-optical effects: application to squeezed light

We propose a technique for achieving phase matching in Brillouin scattering in a dielectric fiber doped by three-level Lambda-type ions. This can lead to a dramatic increase of efficiency of ponderomotive nonlinear interaction between the electromagnetic waves and holds promise for applications in quantum optics such as squeezing and quantum nondemolition measurements.     

Breaking Chemistry's Strongest Bond: Can Three‐Coordinate [M{N(R)Ar}3] Complexes Cleave Carbon Monoxide?

The reaction pathway for the interaction of CO with three-coordinate TaIII, WIII and ReIII complexes (modelled on the experimental [M{N(tBu)Ar}3] system) has been explored by using density functional methods. Calculations show that CO binds without a barrier to [Re(NH2)3], forming the encounter complex [OC--Re(NH2)3], which is stabilized by approximately 280 kJ mol-1 relative to the reactants. The binding of [Ta(NH2)3] to the oxygen terminus of CO is inhibited by a barrier of only 20 kJ mol-1 and is followed by spontaneous cleavage of the C--O bond to form the products [C--Re(NH2)3] and [O--Ta(NH2)3]. The salient features of the potential energy surface are more favourable to CO cleavage than the analogous N2 cleavage by [Mo(NH2)3], which is less exothermic (335 vs. 467 kJ mol-1) and is impeded by a significant barrier (66 kJ mol-1). The ReIII/TaIII/CO system therefore appears to be an excellent candidate for cleaving the exceptionally strong C--O bond under mild laboratory conditions. The related WIII/TaIII dimer, which significantly weakens but does not cleave the CO bond, may be a suitable alternative when the chemistry is to be performed on activated CO rather than on the strongly bound oxide and carbide cleavage products.