Palladium carbene complexes as persistent radicalsElectronic supplementary information (ESI) available: Characterization data for all new compounds, computational results, single crystal X-ray structure analysis of complexes {2}2, 3-6, 8, 9, 11, 12. CCDC 1002269, 1058170-1058177. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01441g

A series of palladium( ii ) radical carbene complexes, [PC&z.rad;(sp 2 )P]PdI, [PC&z.rad;(sp 2 )P]PdBr, and [PC&z.rad;(sp 2 )P]PdCl (PC(sp 3 )H 2 P = bis[2-(di-iso-propylphosphino)-phenyl]methane), is described. Compound [PC&z.rad;(sp 2 )P]PdI dimerizes to {[PC(sp 2 )P]PdI} 2 in the solid state, akin to the formation of Gomberg's dimer. While the bromo and the iodo derivatives could be obtained from the oxidation of [PC(sp 2 )P]Pd(PMe 3 ) by the respective dihalogens, a halogen transfer reaction from CH 2 Cl 2 was used for the formation of [PC&z.rad;(sp 2 )P]PdCl. The halogen transfer from CH 2 X 2 (X = Cl, Br, I) could be used to obtain all three radical carbene palladium complexes and also allowed the isolation of [PC(CH 2 )P]Pd(PMe 3 ), which is the result of methylene group transfer from CH 2 X 2 . Compound [PC(CH 2 )P]Pd(PMe 3 ) was independently synthesized from [PC(CH 3 )HP]PdCl 2 , which contains a supporting ligand analogous to that of the radical carbene complexes but has one of the hydrogen atoms replaced by a methyl group. All three carbene radical species abstract a hydrogen from 9,10-dihydroanthracene or n Bu 3 SnH. A series of palladium( ii ) persistent radical carbene complexes, [PC&z.rad;(sp 2 )P]PdX (X = Cl, Br, I), was synthesized from the nucleophilic carbene [PC(sp 2 )P]PdPMe 3 .