Jeffery W. Seyler

Structures of propionaldehyde, butyraldehyde, and pivalaldehyde complexes of the chiral rhenium fragment [(η5-C5H5)Re(NO)(PPh3)]+

The crystal structures of propionaldehyde complex (RS,SR)-(η5-C5H5)Re(NO)(PPh3)(η2-OCHCH2CH3)]+ PF6− (1b+ PF6s−; monoclinic, P21/c (No. 14), a = 10.166 (1) A, b = 18.316(1) A, c = 14.872(2) A, β = 100.51(1)°, Z = 4) and butyraldehyde complex (RS,SR)-[(η5-C5H5)Re(NO)(PPh3)(η2-OCHCH2CH2CH3)]+ PF6− (1c+PF6−; monoclinic, P21/a (No. 14), a = 14.851(1) A, b = 18.623(3) A, c = 10.026(2) A, β = 102.95(1)°, Z = 4) have been determined at 22°C and −125°C, respectively. These exhibit CO bond lengths (1.35(1), 1.338(5) A) that are intermediate between those of propionaldehyde (1.209(4) A) and 1-propanol (1.41 A). Other geometric features are analyzed. Reaction of [(η5-C5H5)Re(NO)(PPh3)(ClCH2Cl)]+ BF4− and pivalaldehyde gives [(η5-C5H5)Re(NO)(PPh3)(η2-OCHC(CH3)3)]+BF4− (81%), the spectroscopic properties of which establish a π CO binding mode.

A crystallographic map of chiral recognition in π complexes of aromatic aldehydes and a chiral transition metal Lewis acid: enantioface binding selectivities in solution correlate to distances between metal and carbon stereocentres in the solid state

The title claim is established with five π-aromatic aldehyde complexes [(η5-C5H5)Re(NO)(PPh3)(η2-OCHAr)]+ X–; electronegative aryl substituents give shorter rhenium–carbon bond lengths and higher binding selectivities, providing the first easily conceptualized mechanism for an electronic effect upon chiral recognition.

Redox pathways of Ru(OEP)(Ph)2 and Ru(OEP)(Ph)(OEP = octaethylporphyrin dianion)

Electrochemical, chemical, and spectroscopic methods reveal the redox and coupled reaction pathways of the organometallic porphyrin complex Ru(OEP)(Ph)2(OEP = octaethylporphyrin dianion)(1) and the corresponding monophenyl complex (2), an intermediate in the redox reactions of (1).