Synthesis of Terminal and Bridging Acetonyl Complexes of Palladium(II). Crystal Structures of [{(AsPh₃)(C₆F₅)Pd}₂{μ-CH₂C(O)CH₃}₂], [(AsPh₃)(C₆F₅)Pd{CH₂C(O)CH₃}(t-BuNC)], and [(o-C₆H₄CH₂NMe₂)Pd{O,O‘-CH(CO₂Et)₂}]

The reaction of the palladium-hydroxo complex [{( o -C 6 H 4 CH 2 NMe 2 )Pd} 2 ( μ -OH) 2 ] with acetone leads to the formation of the bridging O, C-acetonyl complexes [{( o -C 6 H 4 CH 2 NMe 2 )Pd} 2 ( μ -OH){ μ -CH 2 C(O)CH 3 }] ( 1 ) and [{( o -C 6 H 4 CH 2 NMe 2 )Pd} 2 { μ -CH 2 C(O)CH 3 } 2 ] ( 2 ). The reaction (1:2 molar ratio) of [{(AsPh 3 )(C 6 F 5 )Pd} 2 ( μ -Cl)} 2 ] with 20% aqueous [NBu 4 ]OH in acetone yields [{(AsPh 3 )(C 6 F 5 )Pd} 2 { μ -CH 2 C(O)CH 3 } 2 ] ( 3 ). The reaction (1:1 ratio) between 2 or 3 and t -BuNC gives the monomeric complexes [( o -C 6 H 4 CH 2 NMe 2 )Pd{CH 2 C(O)Me}( t -BuNC)] ( 4 ) and [(AsPh 3 )(C 6 F 5 )Pd{CH 2 C(O)CH 3 }( t -BuNC)] ( 5 ). Heating an acetone solution of [NBu 4 ] 2 [{(C 6 F 5 ) 2 Pd} 2 ( μ -OH) 2 ] gave the 2,4-dimethyl-1-oxapenta-1,3-dienyl palladium complex [NBu 4 ][(C 6 F 5 ) 2 Pd( η 5 -2,4-Me 2 −C 4 H 3 O)] ( 6 ). The reaction of [{( o -C 6 H 4 CH 2 NMe 2 )Pd} 2 ( μ -OH) 2 ] with CH 2 (CO 2 R) 2 (R = Et, Me) leads to [( o -C 6 H 4 CH 2 NMe 2 )Pd{ O, O ‘-CH(CO 2 R) 2 }] ( 7, R = Me; 8, R = Et). The crystal structures of 3, 5, and 8 have been established by X-ray diffraction studies. The structure of 3 shows the C,O-enolate anion bridging two palladium atoms with a head-to-tail arrangement. In the monomeric complex 5 the C-bound acetonyl is trans to triphenylarsine. In 8 the diethyl malonate ligand and the palladium atom form a six-membered chelate ring.