McMahon, S;Amirjalayer, S;Buma, WJ;Halpin, Y;Long, C;Rooney, AD;Woutersen, S;Pryce, MT

2015

January

Dalton Transactions

An investigation into the photochemistry of, and the electrochemically induced CO-loss from, [(CO)(5)MC(OMe)Me](M = Cr or W) using low-temperature matrix isolation, picosecond infrared spectroscopy, cyclic voltammetry, and time-dependent density functional theory

Published

12 ()

CHROMIUM CARBENE COMPLEXES RESONANCE RAMAN-SPECTROSCOPY TRANSITION-METAL-COMPLEXES KINETIC-ENERGY DENSITY EXCITED-STATES CYCLIZATION REACTIONS EXCITATION-ENERGIES PHOTOLYTIC REACTION HAPTOTROPIC SHIFT LARGE MOLECULES

44

15424

15434

The photophysics and photochemistry of [(CO)(5)MC(OMe)Me] (M = Cr or W) were investigated using pico-second time-resolved infrared spectroscopy (M = Cr or W), low-temperature matrix isolation techniques (M = Cr), and time-dependent density functional calculations (M = Cr or W). These studies provide unambiguous evidence for the photochemical formation of a long-lived, 18-electron metallaketene species capable of acting as a synthetically useful intermediate. For the Cr complex, an intermediate metallacyclopropanone singlet excited state was detected on the reaction path to the metallaketene species. This metallacyclopropanone excited state species has a lifetime of less than 100 ps and a characteristic bridging carbonyl band at 1770 cm(-1). The tungsten ketene species was also detected but in contrast to the chromium system, this forms directly from a low-lying triplet excited state. The electrochemical release of CO showed a greater efficiency for the chromium complex when compared to the tungsten.

CAMBRIDGE

1477-9226

10.1039/c5dt01568e