Cylometallated semicarbazone complexes of palladium(II). Crystal and molecular structure of [{Pd[C6H4C(Et)NN(H)C(O)NH2]}2(μ-Ph2P(CH2)3PPh2)][ClO4]2

Abstract Treatment of the semicarbazones 4-MeC 6 H 4 C(Me)NN(H)C(O)NH 2 a , 3,4-Me 2 C 6 H 3 C(Me)NN(H)C(O)NH 2 b and C 6 H 5 C(Et)NN(H)C(O)NH 2 c , gave the [C,N,O] cyclometallated compounds [Pd{4-MeC 6 H 3 C(Me)NN(H)C(O)NH 2 }(Cl)] 1a , [Pd{3,4-Me 2 C 6 H 2 C(Me)NN(H)C(O)NH 2 }(Cl)] 1b and [Pd{C 6 H 4 C(Et)NN(H)C(O)NH 2 }(Cl)] 1c , after CH activation. Treatment of compounds 1a , 1b , and 1c with silver perchlorate followed by treatment with tertiary diphosphine ligands gave the dinuclear [C,N,O] cyclometallated compounds [{Pd[4-MeC 6 H 3 C(Me)NN(H)C(O)NH 2 ]} 2 ( μ -L)][ClO 4 ] 2 2a–7a , [{Pd[3,4-Me 2 C 6 H 2 C(Me)NN(H)C(O)NH 2 ]} 2 ( μ -L)][ClO 4 ] 2 2b – 7b , [{Pd[C 6 H 4 C(Et)NN(H)C(O)NH 2 ]} 2 ( μ -L)][ClO 4 ] 2 2c–7c , [L=Ph 2 P(CH 2 ) 4 PPh 2 (dppb), Ph 2 P(CH 2 ) 3 PPh 2 (dppp), Ph 2 P(CH 2 ) 2 PPh 2 (dppe), trans -Ph 2 PCHCHPPh 2 ( trans -dppe), Ph 2 PC(CH 2 )PPh 2 (vdpp) and Ph 2 PCH 2 PPh 2 (dppm)] as 1:2 electrolytes. Reaction of 1a and 1c with diphosphines gave the dinuclear [C,N] cyclometallated compounds [{Pd[4-MeC 6 H 3 C(Me)NN(H)C(O)NH 2 ](Cl)} 2 ( μ -L)] 8a , 9a , [{Pd[C 6 H 4 C(Et)NN(H)C(O)NH 2 ](Cl)} 2 ( μ -L)] 8c , 9c , [L=Ph 2 P(CH 2 ) 3 PPh 2 (dppp) and Ph 2 P(CH 2 ) 4 PPh 2 (dppb)]. The complexes were characterised by their elemental analysis (C,H,N) and by IR and 31 P{ 1 H} and 1 H-NMR data, and [{Pd[C 6 H 4 C(Et)NN(H)C(O)NH 2 ]} 2 ( μ -Ph 2 P(CH 2 ) 3 PPh 2 )][ClO 4 ] 2 ( 3c ) was characterised crystallographically.