Complexes of copper and 1,10-phenanthroline have been utilized for organic transformations over the last 50 years. In many cases these systems are impacted by reaction conditions and perform best under an inert atmosphere. Here we explore the role the 1,10-phenanthroline ligand plays on the electronic structure and redox properties of copper coordination complexes, and what benefit related ligands may provide to enhance copper-based coupling reactions. Copper(II) triflate complexes bearing 1,10-phenanthroline (phen), ([Cu(phen) 2 -(OTf )]OTf, 1) and oxidized derivatives of phen including [Cu(edhp) 2 ](OTf ) 2 (2), [Cu(pdo) 2 ](OTf ) 2 (3), [Cu(dafo) 2 ](OTf ) 2 (4) [a] Previously, we have reported a discrete Cu 2+ phen complex, namely [Cu(phen) 2 OTf ]OTf (1), [14] which shows a good reactivity performing C-and N-atom transfer reactions. [15] However, the phen ligand can be easily oxidized to functionalize the central ring of this ligand system. The C=C bond between C5 and C6 positions can be oxidized to form the 5,6-epoxyphen (L2) [16] and 5,6-phendione (L3). [17] L3 can be further reacted to form the 4,5-diazafluorenone (L4) by the loss of CO. [18] These ligands Full Paper
Aziridines are valued as important building blocks for the synthesis of a wide range of active compounds. The development of efficient, cost effective catalysts for nitrene transfer reactions to olefins is a continuing area of research in modern chemistry. There are a number of transition metal complexes that are known to catalyse the aziridination of olefins, however most require expensive transition metal ions. Herein we report our efforts to generate aziridines using a copper(II) complex that offers high efficiency at forming aziridines from olefins and N-transfer agents. 2 3 4 5 6 7 8
The ambi-valent character of the
P–I bond in iodophosphonium
complexes ensures that it can be electrophilic at either P or I. Herein,
we use an ensemble of computational tools and methodologies to probe
the nature of this ambi-valent bond. Geometric and atomic electron
population analyses yielded strong trends between the electron donating
ability of the phosphine and the strength and polarity of the P–I
bond. Quasi-atomic orbital analysis demonstrated the near homo-polarity
of the P–I bond, and energy decomposition analysis calculations
demonstrated the ability to tune the polarization of the bond with
only mild changes in secondary structural features. Finally, the ambi-valent
nature of the P–I bond was demonstrated to follow hard–soft
considerations in reactions with nucleophiles, with harder nucleophiles
preferentially forming products of addition to P and softer nucleophiles
to I.
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