A variety of methods are available to investigate the bonding in inorganic compounds. In contrast to wavefunction-based analyses, topological analysis of the electron density affords the advantage of analyzing a physical observable: the electron density. Classical topological analyses of bonding interactions within the Atoms in Molecules framework typically involve location of a bond path between two atoms and evaluation of a range of real-space functions at the (3, -1) critical point in the electron density that exists on that bond path. We show here that counter-intuitive trends are obtained from the analysis of the electron density (ρ), the Laplacian (∇ 2 ρ), and ellipticity (ε) at the O-E (3, -1) critical points in the CCSD electron densities of a series of compounds featuring a range of oxygen-pnictogen bond types: EO + , HEO, H2EOH, H3EOH + and H3EO (where E = N, P, As, Sb, or Bi). If, instead, these real-space functions are evaluated along the length of the bond path, the discrepancies in the trends are resolved. We show that robust results are also obtained using electron densities from less computationally demanding DFT calculations. The increased computational efficiency allowed us to also investigate organic derivatives of these oxygen-pnictogen bonded compounds and observe that the trends hold in these instances as well. We anticipate that these results will be of use to inorganic chemists engaged in the synthesis and evaluation of novel bonding interactions, particularly those involving heavy main-group elements.

Herein we report the synthesis, characterization, and cellular internalization properties of two visible-light active luminescent Mn-based photoCORMs. The enhanced membrane permeability of the photoactive Mn carbonyl complex (photoCORM) derived from a designed lipophilic ligand namely, [Mn­(CO)3(Imdansyl)­(L1)]­(CF3SO3) (1) (where L1 = a diazabutadiene-based ligand containing two highly lipophilic adamantyl motifs, Imdansyl = dansylimidazole) promoted rapid internalization within human colorectal adenocarcinoma (HT-29) cells compared to [Mn­(CO)3(Imdansyl)­(L2)]­(CF3SO3) (2) (where L2 = a diazabutadiene ligand bearing two hydrophilic 1,3,5-triazaadamantyl group). Colocalization experiments using membrane stain indicate different extents of localization of the two CO complexes within the cellular matrix. Visible-light triggered CO release from the lipophilic photoCORM induced caspase-3/7 activation on HT-29 cells, which was detected using confocal microscopy. The rapid accumulation of the lipophilic photoCORM 1 in the cellular membrane resulted in more efficient CO-induced cell death compared to the hydrophilic analogue 2.

Attempts to investigate the properties and reactivity of the stiboryl moiety (R3Sb+–O– or R3Sb=O), as in monomeric stibine oxides free of interaction with Lewis acids/bases, led us to conclude that...

In contrast to phosphine oxides and arsine oxides, which are common and exist as stable monomeric species featuring the corresponding pnictoryl functional group (Pn=O/Pn+–O−; Pn = P, As), stibine oxides are generally polymeric, and the properties of the unperturbed stiboryl group (Sb=O/Sb+–O−) remain unexplored. We now report the isolation of the monomeric stibine oxide, Dipp3SbO (where Dipp = 2,6-diisopropylphenyl). Spectroscopic, crystallographic and computational studies provide insight into the nature of the Sb=O/Sb+–O− bond. Moreover, isolation of Dipp3SbO allows the chemistry of the stiboryl group to be explored. Here we show that Dipp3SbO can act as a Brønsted base, a hydrogen-bond acceptor and a transition-metal ligand, in addition engaging in 1,2-addition, O-for-F2 exchange and O-atom transfer. In all cases, the reactivity of Dipp3SbO differed from that of the lighter congeners Dipp3AsO and Dipp3PO.