Correlations and Contrasts in Homo- and Heteroleptic Cyclic (Alkyl)(amino)carbene-Containing Pt super(0) Complexes

• Published in: Chemistry : a European journal Vol. 21; no. 35; pp. 12357 - 12362
• Main Authors: Arnold, Nicole, Braunschweig, Holger, Brenner, Peter B, Celik, Mehmet Ali, Dewhurst, Rian D, Haehnel, Martin, Kramer, Thomas, Krummenacher, Ivo, Marder, Todd B
• Format: Journal Article
• Language: English
• Published: 01-08-2015
• Subjects: Bonding; Carbon; Color; Concerts; Density functional theory; Electrochemical analysis; Mathematical analysis; Spectroscopy
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201502048

An improved synthetic route to homoleptic complex [Pt(CAAC super(Me)) sub(2)] (CAAC=cyclic (alkyl)(amino)carbenes) and convenient routes to new heteroleptic complexes of the form [Pt(CAAC super(Me))(PR sub(3))] are presented. Although the homoleptic complex was found to be inert to many reagents, oxidative addition and metal-only Lewis pair (MOLP) formation was observed from one of the heteroleptic complexes. The spectroscopic, structural, and electrochemical properties of the zero-valent complexes were explored in concert with density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The homoleptic [Pt(CAAC) sub(2)] and heteroleptic [Pt(CAAC)(PR sub(3))] complexes were found to be similar in their spectroscopic and structural properties, but their electrochemical behavior and reactivity differ greatly. The unusually strong color of the CAAC-containing Pt super(0) complexes was investigated by TD-DFT calculations and attributed to excitations into the LUMOs of the complexes, which are predominantly composed of bonding pi interactions between Pt and the CAAC carbon atoms. An improved synthetic route to homoleptic complex [Pt(CAACMe) sub(2)] and convenient routes to new heteroleptic complexes of the form [Pt(CAACMe)(PR sub(3))] are presented. The reactivity, spectroscopic, structural, and electrochemical properties of the zero-valent complexes were explored in concert with DFT and time-dependent DFT calculations. The homoleptic [Pt(CAAC) sub(2)] and heteroleptic [Pt(CAAC)(PR sub(3))] complexes were found to be similar in their spectroscopic and structural properties, but their electrochemical behavior and reactivity differ greatly (see figure).