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Potentially Tridentate Hydrazonic Ligands in the Synthesis of Methyl and Acetyl Palladium(II) Complexes
Author(s) -
Pelagatti Paolo,
Carcelli Mauro,
Franchi Francesca,
Pelizzi Corrado,
Bacchi Alessia,
Fochi Andrea,
Frühauf HansWerner,
Goubitz Kees,
Vrieze Kees
Publication year - 2000
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(200003)2000:3<463::aid-ejic463>3.0.co;2-6
Subject(s) - chemistry , palladium , deprotonation , denticity , medicinal chemistry , ligand (biochemistry) , carbonylation , carbon monoxide , reactivity (psychology) , methyl group , stereochemistry , organic chemistry , catalysis , crystal structure , group (periodic table) , medicine , ion , biochemistry , receptor , alternative medicine , pathology
Potentially tridentate hydrazonic ligands of the type HNNO have been used in the synthesis of some methyl palladium(II) complexes. Depending on the applied experimental conditions two different kinds of complexes are obtained. Thus, the reactions between HL1–HL5 and (COD)PdMeCl in diethyl ether led to the formation of bidentate methyl complexes of the type Pd(HNN)MeCl ( 1–5 ), where the ligands maintain a neutral character. However, in the presence of a base such as Et 3 N or NaOMe, the ligands are deprotonated with the consequent formation of tridentate methyl complexes of the type Pd(NNO)Me ( 7–10 ). In solution, complexes 1–5 tend to lose the hydrazonic proton with elimination of methane and formation of a tridentate chloride complex Pd(NNO)Cl ( 6 ); this tendency can be correlated with the acidity of the free ligands, which has been determined. On bubbling carbon monoxide through solutions of 1–5 , the corresponding acetyl complexes Pd(HNN)[C(O)Me]Cl ( 11–15 ) are formed, in which both the cis and trans isomers are present. Their molar ratio is rationalised from the results of a molecular modelling study on the basis of electronic considerations. A remarkably different reactivity has been found in the carbonylation of the tridentate complexes 7–10 : they decompose rapidly and quantitatively to palladium black and an organic product corresponding to the ligand with an acetyl group bonded to the hydrazonic nitrogen. The X‐ray structures of a methyl complex ( 3 ) and its corresponding acetyl ( 13 ) derivative have been determined.