Generating and dimerizing the transient 16-electron phosphinidene complex [Cp*Ir=PAr]: a theoretical and experimental study.
The properties of the 16-electron phosphinidene complex [CpRIr=PR] were investigated experimentally and theoretically. Density functional theory calculations show a preferred bent geometry for the model complex [CpIr=PH], in contrast to the linear structure of [CpIr=NH]. Dimerization to give [[CpIr=PH]2] and ligand addition to afford [Cp(L)Ir=PH] (L=PH3, CO) were calculated to give compounds that were energetically highly favorable, but which differed from the related imido complexes. Transient 16-electron phosphinidene complex [Cp*Ir=PAr] could not be detected experimentally. Dehydrohalogenation of [Cp*IrCl2(PH2Ar)] in CH2Cl2 at low temperatures resulted in the novel fused-ring systems 17 (Ar=Mes*) and 20 (Ar=Mes), with dimeric [[Cp*Ir=PAr]2] being the likely intermediate. Intramolecular C-H bond activation induced by steric factors is considered to be the driving force for the irreversible formation of 17 and 20. ONIOM calculations suggest this arises because of the large steric congestion in [[Cp*Ir=PAr]2], which forces it toward a more reactive planar structure that is apt to rearrange.
Department of Chemistry, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands.
Arjan T
AT
Termaten
Tom
T
Nijbacker
Andreas W
AW
Ehlers
Marius
M
Schakel
Martin
M
Lutz
Anthony L
AL
Spek
Michael L
ML
McKee
Koop
K
Lammertsma
D003198:Computer Simulation; D018360:Crystallography, X-Ray; D019281:Dimerization; D004583:Electrons; D007495:Iridium / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D013816:Thermodynamics
D009942:Organometallic Compounds; D010720:Phosphines; D007495:Iridium