The structure of [Ir{(4-Cl-CHN)C(dppm)-κ ,,}(dppm-κ ,')]Cl·1.5CHCl·0.5CH (CHClIrNP·1.5CHCl·0.5CH) (), dppm = bis-(di-phenyl-phosphino)methane {systematic name: [7-(4-chloro-phen-yl)-1,1,3,3-tetra-phenyl-5,6,7-tri-aza-κ -1,3λ-diphospha-κ -hepta-4,6-dien-4-yl][methyl-ene-bis(di-phenyl-phosphine)-κ ,']iridium(I) chloride-di-chloro-methane-toluene (2/3/1)}, resulting from the reaction of [IrClH{C(dppm)-κ ,,)(MeCN)]Cl () with 1-azido-4-chloro-benzene, shows a monocationic five-coordinate Ir complex with a distorted trigonal-bipyramidal geometry. In , the iridium centre is coordinated by the neutral triazeneyl-idene-phospho-rane (4-Cl-CHN)C(dppm) acting as a PCN pincer ligand, and a chelating dppm unit. The structure of the coordination compound [IrCl(CN)H(C(dppm)-κ ,,)]·CHCN, (CHClIrNP·CHCN) () [systematic name: chlorido-cyanidohydrido(1,1,3,3,5,5,7,7-octa-phenyl-1,3λ,5λ,7-tetra-phospha-κ , -hept-3-en-4-yl)iridium(III) aceto-nitrile monosolvate], prepared from and KCN, reveals an octa-hedral Ir central atom with a meridional PCP pincer carbodi-phospho-rane (CDP) ligand; the chloride ligand is located to the central carbon of the CDP functionality while the hydrido and cyanido ligands are situated to each other. The chiral coordination compound [Ir(CN)((4-Cl-CHN)CH(CH(P(Ph)))-κ ,,)(dppm-κ ,')]·2CHOH, (CHClIrNP·2CHOH) () (systematic name: {4-[3-(4-chloro-phen-yl)triazenido-κ ]-1,1,3,3-tetra-phenyl-1,3λ-diphospha-κ -but-2-en-4-yl}cyanido[methyl-enebis(di-phenyl-phosphine)-κ ,']iridium(III) methanol disolvate), formed via prolonged reaction of 1-azido-4-chloro-benzene with , features a six-coordinate Ir central atom. The iridium centre is coordinated by the dianionic PCN pincer ligand [(4-Cl-CHN)CH(CH(P(Ph)))], a cyanido ligand to the central carbon of the PCN pincer ligand and a chelating dppm unit. Complex exhibits a 2:1 positional disorder of the Cl anion. The CHCl and CH solvent mol-ecules show occupational disorder, with the toluene mol-ecule exhibiting additional 1:1 positional disorder with some nearly overlying carbon atoms.
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http://dx.doi.org/10.1107/S2056989018017644 | DOI Listing |
Molecules
October 2024
Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel.
In our recent work, we revisited C-H and C-C bond activation in rhodium (I) complexes of pincer ligands PCP, PCN, PCO, POCOP, and SCS. Our findings indicated that an η-CCH agostic intermediate acts as a common precursor to both C-C and C-H bond activation in these systems. We explore the electronic structure and bonding nature of these precleavage complexes using electron density and molecular orbital analyses.
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November 2024
Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, India.
In this article, the synthesis of bis(phosphine), -PhPCHC(O)N(H)CHCHPPh- (1) (hereafter referred to as "PNHP" and its anionic form as "PNP") and its group 10 metal chemistry and catalytic studies are described. PNHP (1) on reaction with NiCl(DME) and PdCl(COD) afforded pincer complexes, [MCl{(PNP)κ-,,}] (M = Ni, 2; Pd, 3). A similar reaction of 1 with PtCl(COD) yielded a chelate complex, [PtCl{(PNHP)κ-,}] (4), which on further treatment with LiHMDS produced the 1,2-azaphospholene-phosphine complex, [PtCl(Ph){(-P(Ph)CHCONCHCHPPh-)κ-,}] (5) P-C/P-N bond metathesis.
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April 2024
Department of Chemistry, Texas A&M University, College Station, TX 77842, USA.
A bimetallic Pd complex of a bis(pincer) with a diarylpyrazine core has been prepared. The complex demonstrates near-perfect coplanarity of the aromatic core, is fluorescent under UV irradiation, and displays two quasi-reversible reduction events.
View Article and Find Full Text PDFOrganometallics
February 2024
Organic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
Nickel carbenes are attracting attention for the development of more sustainable catalysts, among others, for cyclopropanation. Intramolecular trapping of a nickel carbene intermediate with an olefin incorporated in a P(C=C)P Ni pincer complex had previously allowed the isolation of a nickelacyclobutane intermediate and a detailed characterization of its reactivity. Herein, we report the reactivity of related nickel pincer complexes bearing a ketone P(C=O)P or an imine P(C=N)P with diazoalkanes as the carbene precursor.
View Article and Find Full Text PDFJ Am Chem Soc
February 2024
The State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
Despite half a century's advance in the field of transition-metal-catalyzed asymmetric alkene hydrogenation, the enantioselective hydrogenation of purely alkyl-substituted 1,1-dialkylethenes has remained an unmet challenge. Herein, we describe a chiral PCN-pincer iridium complex for asymmetric transfer hydrogenation of this alkene class with ethanol, furnishing all-alkyl-substituted tertiary stereocenters. High levels of enantioselectivity can be achieved in the reactions of substrates with secondary/primary and primary/primary alkyl combinations.
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