The unexpectedly facile insertion of Rh or Ir into a B-Ph bond (reversible for Rh) converts a borane/bis(phosphine) precursor into a boryl/bis(phosphine) PBP pincer ligand. Interconversions between the boryl/borane/borate central functionality are demonstrated in reactions with dihydrogen.

The synthesis of the novel S,CNHC type half‐pincer ligand precursors (L1 and L2) is described herein by using the atom economy reactions of 1‐(2‐(phenylthio)ethyl)‐1H‐imidazole with benzyl bromide and bromodiphenylmethane, respectively. The analogous reaction of 1‐(2‐(phenylselanyl)ethyl)‐1H‐imidazole with 2‐bromoethyl phenyl sulfide has also resulted in a imidazolium bromide (L3) which is a precursor of novel S,CNHC,Se type pincer ligand. The route of silver‐NHC transmetalation was employed to get the palladium complexes [Pd(L1/L2–HBr)Cl2] (C1 and C2) and [Pd(L3–HBr)Cl]BF4 (C3). The imidazolium bromide (L1–L3) and palladium complexes (C1–C3) were characterized by using multinuclear NMR and HR‐MS. The structure and bonding in the complexes C1 and C2 were validated by X‐ray crystallography. Thermally robust and moisture/air insensitive palladium complexes C1–C3 have been explored in the catalysis of C–H bond arylation of imidazoles. The protocol operates under mild reaction conditions in air with an excellent regioselective C–H bond arylation at C‐5 position in imidazoles. All the complexes were found to be efficient (yield up to 97 % in 12 h) in the catalysis; however, the activating pincer ligand framework containing Pd catalyst C3, was found to be utmost effective among the three catalysts. Only 0.5 mol‐% catalyst loading is required to achieve admirable yield of the desired cross‐coupled products. A wide range of substrates was examined, and the developed protocol was applicable to all derivatives with high functional group tolerance and greater efficiency. More importantly, the catalyst C3 has also been found recyclable up to five cycles with minor decrease in efficiency which is highly desirable feature for the development of economical and sustainable industrial reaction processes. The PPh3 and Hg poisoning tests have established the complete homogeneous nature of the catalysis.

Five new safe, solid, and soluble H2O2 adducts of triarylphosphine oxides, including the displayed (p-Tol3PO·H2O2)2, have been synthesized and characterized.

Treatment of Na2PdCl4 or [MCl2(PhCN)2] with bis(4-pyridyl)diselenide yielded an insoluble product of composition [MCl2(4,4′-(C5H4N)2Se2)]n (1). The reactions of Na2PdCl4 with one and two eq. of Na(4-SeC5H4N) afforded insoluble products [PdCl(4-SeC5H4N)]n (2) and [Pd(4-SeC5H4N)2]n (3), respectively. On treatment with PPh3, 2 and 3 gave trans-[PdCl(4-SeC5H4N)(PPh3)2] (4a) and trans-[Pd(4-SeC5H4N)2(PPh3)2] (5a), respectively. The oxidative addition of bis(4-pyridyl)diselenide to Pt(PPh3)4 exclusively yielded trans-[Pt(4-SeC5H4N)2(PPh3)2] (5b). The treatment of two eq. of Na(4-SeC5H4N) with cis-[PtX2(PR3)2] afforded 5b (X = Cl) and trans-[Pt(4-SeC5H4N)2(PEt3)2] (5c) (X = Cl or CF3SO3). The reactions of cis-[MCl2(P∩P)] and [M2Cl2(μ-Cl)2(PR3)2] with two eq. of Na(4-SeC5H4N) exclusively yielded cis-[M(4-SeC5H4N)2(P∩P)] (M/P∩P = Pd/dppe (6a), Pt/dppm (6b) and Pt/dppp (6c)) and [MCl(4-SeC5H4N)(PR3)]n (7), respectively. The complex trans-[PtCl(4-SeC5H4N)(PEt3)2] (4b) was isolated from the redistribution reaction between 5c and cis-[PtCl2(PEt3)2]. The complex [PdCl(4-SeC5H4N)(PPh3)]n (7b) exists in bi- and tri-nuclear forms, whereas [MCl(4-SeC5H4N)(PEt3)]n (7a, 7c) and [PtCl(4-SeC5H4N)(PMe2Ph)]n (7d) retain their trinuclear structure in solution. Molecular structures of 4a, 4b, 5a, 5c, 6a, 6c, 7a, 7b and 7c were established by single crystal X-ray diffraction analyses. The complexes trans-[PdCl(4-SeC5H4N)(PPh3)2] and [PdCl(4-SeC5H4N)(PPh3)]n can act as catalysts for Suzuki C–C cross coupling reaction.

Nitrosyls as electron reservoirs guide protons to favorable sites in bimetallic HER catalysts.

The dibridgehead diphosphine ((CH)) P (1) can rapidly turn inside-out (homeomorphic isomerization) to give a mixture of in,in and out,out isomers. The exo directed lone pairs in the latter are able to scavenge Lewis acidic MCl; cagelike adducts of the in,in isomer, trans- Cl(P((CH)) P) (M = 2/Pt, 3/Pd, 4/Ni), then form. The NiCl unit in 4 may be replaced by PtCl or PdCl, but 2 and 3 do not give similar substitutions. U-tubes are charged with CHCl solutions of 1 (lower phase), an aqueous solution of KMCl (charging arm; M = Pt, Pd), and an aqueous solution of excess KCl (receiving arm). The MCl units are then transported to the receiving arm until equilibrium is reached (up to 22 d). When the receiving arm is charged with KCN, transport is much faster (ca. 100 h) and higher KMX equilibrium ratios are obtained (≥96≤4). Analogous experiments with KPtCl/KPdCl mixtures show PdCl transport to be more rapid. A similar diphosphine with longer methylene chains, P((CH))P, is equally effective. No transport occurs in the absence of 1, and other diphosphines or monophosphines assayed give only trace levels.

The synthesis of highly substituted imidazole derivatives has been achieved from various α-azido chalcones, aryl aldehydes, and anilines. This multicomponent protocol employs erbium triflate as a catalyst resulting in excellent yield of the imidazoles.

Both monomeric and dimeric tetraacetylglucose-containing {Fe(NO)} dinitrosyl iron complexes (DNICs) were prepared and examined for NO release in the presence of both chemical NO-trapping agents and endothelial cells.