Cyclometallated compounds of Pd(II):: C=N to C=O conversion through acid hydrolysis.: Crystal and molecular structures of [Pd{4-(CHO)C6H3C(H)=NCy}(Cl)(PPh3)2] and [Pd{ 2,4-(CHO)2C6H3}(Cl)(PPh3)2]

Treatment of the chloro-bridged complex [Pd{4-(CHO)C6H3C(H)=NCy}(Cl)](2) (1) with tertiary monophosphines in a 1:4 molar ratio gave the non-cyclometallated monomer complexes [Pd{4-(CHO)C6H3C(H)=NCy}(Cl)(PR3)(2)] (PR3: (2) PPh3, (3) PEtPh2, (4) PEt2Ph, (5) PMePh2). The crystal structure of 2 is described. Reaction of complexes 2-5 with a mixture of glacial acetic acid-water gave the monomeric complexes [Pd{2,4-(CHO)(2)C6H3}(Cl)(PR3)(2)] (PR3 (6), PPh3 (7), PEtPh2 (8), PEt2Ph (9), PMePh2) after cleavage of the C=N group. Complex 6 was characterized crystallographically. Treatment of I with the triphosphine bis(2-diphenylphosphinoethyl)phenylphosphine in 1:2 molar ratio gave the mononuclear complex [Pd{4-(CHO)C6H3C(H)=NCy} {Ph2P(CH2)(2)PPh(CH2)(2)PPh2-P,P,P}][Cl] (10) in which the phosphine is coordinated through the three phosphorus atoms. Treatment of 10 with a mixture of acetic acid-water also caused cleavage of the C=N bond giving the complex [Pd{2,4-(CHO)(2)C6H3} {Ph2P(CH2)(2)PPh(CH2)(2)PPh2-P,P,P}][Cl] (11). (C) 2002 Elsevier Science B.V.. All rights reserved.