Reactivity of [Pd{CH2C(O)Me}Cl]n toward Isocyanides

[Pd{CH 2 C(O)Me}Cl] n ( 1 ) reacts at low temperature with RNC (RNC:Pd = 1 or 2) to give [Pd 2 {CH 2 C(O)Me} 2 (μ-Cl) 2 (CNR) 2 ] [R = t Bu ( 2a ), Xy ( 2b )] or trans -[Pd{CH 2 C(O)Me}Cl(CNR) 2 ] [R = t Bu ( 5a ), Xy ( 5b )], respectively. These complexes decompose at room or higher temperature to give [Pd 2 {κ 2 - C,O -C(NHR)CHC(O)Me} 2 (μ-Cl) 2 ] [R = t Bu ( 3a ), Xy ( 3b )] or [Pd{κ 2 - C,O -C(NHR)CHC(O)Me}Cl(CNR)] [R = t Bu ( 6a ), Xy ( 6b )], respectively, via insertion of the isocyanide into the Pd−C bond plus a tautomerization process from β-ketoimine to β-ketoenamine. The complex [Pd{κ 2 - C,O -C(NHXy)CHC(O)Me}Cl(NCMe)] ( 4b ) can be obtained by reacting 1 with XyNC (Pd:XyNC = 1) in MeCN or complex 3b in CHCl 3 with excess MeCN. Complexes trans -[Pd{C(NHR) CHC(O)Me}Cl(CNR) 2 ] [R = t Bu ( 8a ), Xy ( 8b )] can be obtained (i) by reacting 1 with RNC (RNC:Pd = 3) or better (ii) by reacting 6 with 1 equiv of RNC at low temperature. The Pd(I) complexes [Pd 2 Cl 2 (CNR) 4 ] [R = t Bu ( 7a ), Xy ( 7b )] are decomposition products obtained by heating 1 with RNC (RNC:Pd = 4−5), but they are detected in trace amounts in the reaction of 1 with RNC (RNC:Pd = 2−3). Addition of RNC and KTfO to a cooled suspension of 1 (Pd:RNC:KTfO = 1:3:1) gives complexes [Pd{CH 2 C(O)Me}(CNR) 3 ]TfO [R = t Bu ( 9a ), Xy ( 9b )], which decompose at room temperature. The decomposition of 9b gives [Pd{κ 2 - C,O -C(NHXy)CHC(O)Me}(CNXy) 2 ]TfO ( 10b ), which can be obtained, as can the corresponding 10a, by reacting complexes 6 with 1 equiv of TlTfO and RNC. The reactions of the dimers 3 with PPh 3 (Pd:PPh 3 = 1) gives [Pd{κ 2 - C,O -C(NHR)CHC(O)Me}Cl(PPh 3 )] [R = t Bu ( 11a ), Xy ( 11b )], with PEt 3 (PEt 3:Pd = 2), trans -[Pd{C(NHR) CHC(O)Me}Cl(PEt 3 ) 2 ] [R = t Bu ( 12a ), Xy ( 12b )], and with Tl(acac) (Pd:acac = 1), [Pd{κ 2 - C,O -C(NHR)CHC(O)Me}(κ- O,O -acac)] [R = t Bu ( 13a ), Xy ( 13b )]. The crystal structures of 6a, 9b, 10a, and 10b have been determined. In complex 10b there are intermolecular π−π stacking and C−H···Pd agostic interactions giving dimers.