Preparation and organometallic complexes of the new unsymmetrical Ligand: Ph2PNHC6H4PPh2

Deprotonation of (2-diphenylphosphino)benzeneamine with BuLi followed by reaction with ClPPh2 in THF gave Ph2PNHC6H4PPh2 in good yields. The new unsymmetrical ligand has been incorporated into a number of complexes [[Rh(Ph2PNHC6H4PPh2)(cod)][ClO4] 2, RhCl2(eta(5)-C4Me5) (Ph2PNHC6H4PPh2-P-(N)) 3, [RhCl(eta(5)-C5Me5) (Ph2PNHC6H4PPh2-P(N)P)][Cl] 4, IrCl2(eta(5)-C5Me5) (Ph2PNHC6H4PPh2P(N)) 5, RuCl2(eta(6)-(MeC6H4Pr)-Pr-i) (Ph2PNHC6H4PPh2-P-(N)) 6, [RuCl(eta(6)-Me-(C6H4Pr)-Pr-i) (Ph2PNHC6H4PPh2-P-(N),P)][BF4] 7, RuCl2(eta(6)-C6Me6) (Ph2PNHC6H4PPh2-P-(N)) 8, [RuCl(eta(6)-C6Me6) (Ph2PNHC6H4PPh2-P-(N),P)][BF4] 9, RuCl2(eta(3):eta(3)-C10H16) (Ph2PNHC6H4PPh2-P-(N)) 10, OsCl2(eta(6)-(MeC6H4Pr)-Pr-i)(Ph2NHPC6H4PPh2-P-(N)) 11] to demonstrate its coordination behaviour as a monodentate or as a chelate ligand. The X-ray structures of for 5, 9 and 10 are reported. (C) 1999 Elsevier Science S.A. All rights reserved.PostprintPeer reviewe

Spontaneous dehydrocoupling in peri-substituted phosphine-borane adducts

This work was financially supported by the EPSRC and COST action CM1302 SIPs.Bis(borane) adducts Acenap(PiPr2·BH3)(PRH·BH3) (Acenap = acenaphthene-5,6-diyl; 4a, R = Ph; 4b, R = ferrocenyl, Fc; 4c, R = H) were synthesised by the reaction of excess H3B·SMe2 with either phosphino-phosphonium salts [Acenap(PiPr2)(PR)]+Cl− (1a, R = Ph; 1b, R = Fc), or bis(phosphine) Acenap(PiPr2)(PH2) (3). Bis(borane) adducts 4a–c were found to undergo dihydrogen elimination at room temperature, this spontaneous catalyst-free phosphine-borane dehydrocoupling yields BH2 bridged species Acenap(PiPr2)(µ-BH2)(PR·BH3) (5a, R = Ph; 5b, R = Fc; 5c, R = H). Thermolysis of 5c results in loss of the terminal borane moiety to afford Acenap(PiPr2)(µ-BH2)(PH) (14). Single crystal X-ray structures of 3, 4b and 5a–c are reported.Publisher PDFPeer reviewe

Synthesis and single crystal structures of substituted-1,3-selenazol-2-amines

This article belongs to the Special Issue Celebrating Two Centuries of Research in Selenium Chemistry: State of the Art and New ProspectivesThe synthesis and X-ray single crystal structures of a series of new 4-substituted-1,3-selenazol-2-amines is reported. The efficient preparation of 4-substituted-1,3-selenazol-2-amines was carried out by two-component cyclization of the selenoureas with equi-molar amounts of α-haloketones. The selenoureas were obtained from the reaction of Woollins’ reagent with cyanamides, followed by hydrolysis with water. All new compounds have been characterized by IR spectroscopy, multi-NMR (1H, 13C, 77Se) spectroscopy, accurate mass measurement and single crystal X-ray structure analysis.Publisher PDFPeer reviewe

Differential Cytostatic and Cytotoxic Action of Metallocorroles against Human Cancer Cells: Potential Platforms for Anticancer Drug Development

A gallium(III)-substituted amphiphilic corrole noncovalently associated with a targeting protein was previously found by us to confer promising cytotoxic and antitumor activities against a breast cancer cell line and a mouse xenograft breast cancer model. To further explore potential anticancer applications, the cytostatic and cytotoxic properties of six nontargeted metallocorroles were evaluated against seven human cancer cell lines. Results indicated that toxicity toward human cancer cells depended on the metal ion as well as corrole functional group substitution. Ga(III)-substituted metallocorrole 1-Ga inhibited proliferation of breast (MDA-MB-231), melanoma (SK-MEL-28), and ovarian (OVCAR-3) cancer cells primarily by arrest of DNA replication, whereas 2-Mn displayed both cytostatic and cytotoxic properties. Confocal microscopy revealed extensive uptake of 1-Ga into the cytoplasm of melanoma and ovarian cancer cells, while prostate cancer cells (DU-145) displayed extensive nuclear localization. The localization of 1-Ga to the nucleus in DU-145 cells was exploited to achieve a 3-fold enhancement in the IC_(50) of doxorubicin upon coadministration. Time–course studies showed that over 90% of melanoma cells incubated with 30 μM 1-Ga internalized metallocorrole after 15 min. Cellular uptake of 1-Ga and 1-Al was fastest and most efficient in melanoma, followed by prostate and ovarian cancer cells. Cell cycle analyses revealed that bis-sulfonated corroles containing Al(III), Ga(III), and Mn(III) induced late M phase arrest in several different cancer cell lines, a feature that could be developed for potential therapeutic benefit

Mechanism of Cu-catalyzed iododeboronation : a description of ligand-enabled transmetalation, disproportionation, and turnover in Cu-mediated oxidative coupling reactions

Funding: Biotechnology and Biological Sciences Research Council - BB/R013780/; Engineering and Physical Sciences Research Council - EP/R025754/1, EP/W007517/1, EP/S027165/1; Leverhulme Trust - RF-2022-014.We report a combined experimental and computational study of the mechanism of the Cu-catalyzed arylboronic acid iododeboronation reaction. A combination of structural and density functional theory (DFT) analyses has allowed determination of the identity of the reaction precatalyst with insight into each step of the catalytic cycle. Key findings include a rationale for ligand (phen) stoichiometry related to key turnover events─the ligand facilitates transmetalation via H-bonding to an organoboron boronate generated in situ and phen loss/gain is integral to the key oxidative events. These data provide a framework for understanding ligand effects on these key mechanistic processes, which underpin several classes of Cu-mediated oxidative coupling reactions.Publisher PDFPeer reviewe

Synthesis and structural studies of peri-substituted acenaphthenes with tertiary phosphine and stibine groups

Two mixed peri-substituted phosphine-chlorostibines, Acenap(PiPr2)(SbPhCl) and Acenap(PiPr2)(SbCl2) (Acenap = acenaphthene-5,6-diyl) reacted cleanly with Grignard reagents or nBuLi to give the corresponding tertiary phosphine-stibines Acenap(PiPr2)(SbRR’) (R, R’ = Me, iPr, nBu, Ph). In addition, the Pt(II) complex of the tertiary phosphine-stibine Acenap(PiPr2)(SbPh2) as well as the Mo(0) complex of Acenap(PiPr2)(SbMePh) were synthesised and characterised. Two of the phosphine-stibines and the two metal complexes were characterised by single-crystal X-ray diffraction. The peri-substituted species act as bidentate ligands through both P and Sb atoms, forming rather short Sb-metal bonds. The tertiary phosphine-stibines display through-space J(CP) couplings between the phosphorus atom and carbon atoms bonded directly to the Sb atom of up to 40 Hz. The sequestration of the P and Sb lone pairs results in much smaller corresponding J(CP) being observed in the metal complexes. QTAIM (Quantum Theory of Atoms in Molecules) and EDA-NOCV (Energy Decomposition Analysis employing Naturalised Orbitals for Chemical Valence) computational techniques were used to provide additional insight into a weak n(P)→σ*(Sb-C) intramolecular bonding interaction (pnictogen bond) in the phosphine-stibines.Peer reviewe