393 research outputs found
Alien Registration- Peters, Theodore S. (Houlton, Aroostook County)
https://digitalmaine.com/alien_docs/34701/thumbnail.jp
Group VIII Coordination Chemistry of a Pincer-Type Bis(8-quinolinyl)amido Ligand
This paper provides an entry point to the coordination chemistry of the group VIII chemistry of the bis(8-quinolinyl)amine (BQA) ligand. In this context, mono- and disubstituted BQA complexes of iron, ruthenium, and osmium are described. For example, the low-spin bis-ligated Fe(III) complex [Fe(BQA)2][BPh4] has been prepared via amine addition to FeCl3 in the presence of a base and NaBPh4. Complexes featuring a single BQA ligand are more readily prepared for Ru and Os. Auxiliary ligands featuring a single BQA ligand, along with two other L-type donor ligands, allow for a variety of ligand types to occupy a sixth coordination site. Representative examples include the halide and pseudohalide complexes trans-(BQA)MX(PPh3)2 (M = Ru, Os; X = Cl, Br, N3, OTf), as well as the hydride and alkyl complexes trans-(BQA)RuH(PMe3)2 and trans-(BQA)RuMe(PMe3)2. Electrochemical studies are discussed that help to contextualize the BQA ligand with respect to its neutral counterpart 2,2′,2′′-terpyridine (terpy) in terms of electron-releasing character. Bidentate ligands have been explored in conjunction with the BQA ligand. Thus, the bidentate, monoanionic aryl(8-quinolinyl)amido ligand 3,5-(CF3)2-(C6H3)QA has been installed onto the (BQA)Ru platform to provide (BQA)Ru(3,5-(CF3)2-(C6H3)QA)(PPh3). A bis(phosphino)borate ligand stabilizes the five-coordinate complex [Ph2B(CH2PPh2)2]Ru(BQA). Finally, access to dinitrogen complexes of the types [(BQA)Ru(N2)(PPh3)2][PF6], [(BQA)Ru(N2)(PMe3)2][PF6], and [(BQA)Os(N2)(PPh3)2][PF6] is provided by exposure of the sixth coordination site under a N2 atmosphere
Issues Relevant to C-H Activation at Platinum(II): Comparative Studies between Cationic, Zwitterionic, and Neutral Platinum(II) Compounds in Benzene Solution
Cationic late metal systems are being highly scrutinized due to
their propensity to mediate so-called electrophilic C-H
activation reactions. This contribution compares the reactivity
of highly reactive cationic platinum(II) systems with
structurally related but neutral species. Our experimental
design exploits isostructural neutral and cationic complexes
supported by bis(phosphine) ligands amenable to mechanistic
examination in benzene solution. The data presented herein
collectively suggests that neutral platinum complexes can be
equally if not more reactive towards benzene than their
cationic counter-parts. Moreover, a number of unexpected
mechanistic distinctions between the two systems arise that
help to explain their respective reactivity
Dinitrogen Chemistry from Trigonally Coordinated Iron and Cobalt Platforms
This report establishes that trigonally coordinated “[PhBP^(iPr)_(3)]M” platforms (M = Fe, Co) will support both π-acidic (N_2) and π-basic (NR) ligands at a fourth binding site. The N_2 complexes of iron that are described are the first thoroughly characterized examples to exhibit a 4-coordinate geometry. Methylation of monomeric {Fe^(0)(N_(2))-} and {Co^(0)(N_(2))-} species successfully derivatizes the β-N atom of the coordinated N_(2) ligand and affords the diazenido products {Fe^(II)(N_(2)Me)} and {CoII(N2Me)}, respectively. One-electron oxidation of the mononuclear M^(0)(N_(2))- species produces dinuclear and synthetically versatile M^(I)(N_(2))M^(I) complexes. These latter species provide clean access to the chemistry of the “[PhBP^(iPr)_(3)]M^(I)” subunit. For example, addition of RN_(3) to M^(I)(N_(2))M^(I) results in oxidative nitrene transfer to generate [PhBP^(iPr)_(3)]M_(≡)NR with concomitant N_(2) release
Synthesis of the (Dialkylamino)borate, [Ph_2B(CH_2NMe_2)_2]-, Affords Access to N-Chelated Rhodium(I) Zwitterions
This paper reports the synthesis of the first bis(amino)borate ligand, [Ph_2B(CH_2NMe_2)_2]-, an anionic equivalent of tertiary diamines. Anionic [Ph_2B(CH_2NMe_2)_2] is an excellent bidentate ligand auxiliary and is used to prepare a series of N-chelated, zwitterionic rhodium(I) complexes
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