Arsinocarbyne reactivity

The reactivity of the tungsten diphenylarsinocarbyne [W(uCAsPh2)(CO)2(Tp*)] (1; Tp* = hydrotris(dimethylpyrazolyl)borato) is described. The pyramidal arsenic coordinates to a selection of 5d metal centres, forming heterobi- or trimetallic complexes with osmium(II), iridium(III), platinum(II) and gold(I). In the latter case, the WuC bond provides a competitive site for gold(I) coordination. Treatment with MeOSO2CF3 results in methylation at arsenic to give the first example of an arsoniocarbyne, [W (uCAsPh2CH3)(CO)2(Tp*)]O3SCF3, for which only the WuC bond remains available for gold(I) coordination.We gratefully acknowledge the Australian Research Council (DP190100723 and DP200101222) for funding

Regioselective Nitration and/or Halogenation of Iridabenzofurans through Electrophilic Substitution

Regioselective electrophilic substitution reactions of the iridabenzofurans [Ir(C7H5O{OMe-7})(CO)(PPh3)(2)]-[OTf] (1) and IrCl(C7H5O{OMe-7})(PPh3)(2) (2) provide a convenient route to mononitro-, dinitro-, and mixed nitro-/halo- substituted derivatives. Treatment of cationic 1 with copper(II) nitrate in acetic anhydride ("Menke" nitration conditions) gives the mononitrated iridabenzofuran [Ir(C7H4O{NO2-2}{OMe-7})(CO)(PPh3)(2)][O3SCF3] (3). Under the same conditions neutral 2 undergoes dinitration to form IrCl(C7H3O{NO2-2}{NO2-6}{OMe-7}) (PPh3)(2) (5). Simple substitution of the carbonyl ligand in 3 with chloride gives the neutral mononitro derivative IrCl(C7H4O{NO2-2}{OMe-7})(PPh3)(2) (4). Depending on the conditions employed, treatment of the iridabenzofurans 1 and 2 with Cu(NO3)(2) and either lithium chloride or lithium bromide in acetic anhydride gives either the mixed nitro-/halo-substituted iridabenzofurans IrCl(C7H3O{NO2-2}{Cl-6}(OMe-7})(PPh3)(2) (6) and IrCl(C7H2O{NO2-2}{NO2-4}{Cl-6}{OMe-7})(PPh3)(2) (7) or the simple halo-substituted iridabenzofurans [Ir(C7H4O-{Cl-6}{OMe-7}) (CO) (PPh3)(2)] [OTf] (8), [Ir(C7H4O{Br-6}1 OMe-7}) (CO) (PPh3)(2)] [OTf] (9), and IrBr(C7H3O{Br-2}{Br-6}{OMe-7})(PPh3)(2) (10). Bromination of 4 with pyridinium tribromide gives IrCl(C7H3O{NO2-2}{Br-6}{OMe-7})(PPh3)2 (11). The molecular structures of 3-7 and 11 have been obtained by X-ray crystallography

Bis(alkylidynyl)tellurides and ditellurides

The tellurocarbonylates [M(CTe)(CO)2(Tp*)]− (M = Mo, W; obtained from [M(CBr)(CO)2(Tp*)] and Li2Te or [M(CLi)(CO)2(Tp*)] and Te) react with an additional equivalent of [M(CBr)(CO)2(Tp*)] to give bis(alkylidynyl)tellurides, [M2(μ-CTeC)(CO)4(Tp*)2], whilst oxidation with [Fe(η-C5H5)2]PF6 affords the corresponding ditellurides [M2(μ-CTe2C)(CO)4(Tp*)2].</p

Tetrahedral Pegs in Square Holes: Stereochemistry of Diboron Porphyrazines and Phthalocyanines

The first examples of diboron complexes of the tetrapyrroles octaethylporphyrazine (OEPz) and 2,9,16,23‐tetra‐t‐butyl‐phthalocyanine (Pc) are reported, counterpoints to the better known monoboron tripyrroles, subporphyrazine and subphthalocyanine. Two stereochemical possibilities are observed, with cisoid‐B2OF2(OEPz), both cisoid‐B2OPh2(OEPz) and transoid‐B2OPh2(OEPz), transoid‐B2OF2(Pc) and cisoid‐B2OPh2(Pc) having been isolated and characterised, including structure determinations for the OEPz complexes. This variation in stereochemistry, which can be extended to include the previously reported transoid‐B2OF2(porphyrin), cisoid‐[B2OF2(corrole)]−, and both transoid‐ and cisoid‐B2OF2(calixphyrin), prompted a wider DFT study to elucidate the factors influencing the stereochemical preferences. This shows that the cisoid/transoid preference is correlated to the ease with which the macrocycle accommodates a rectangularly distorted N4 cavity.This work was supported by project 262 229 of the Research Council of Norway (A.G.), and the South African National Research Foundation (grant numbers 113327 and 96111) and the Central Research Fund of the University of the Free State, Bloemfontein, South Africa (J.C.)