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Syntheses, Dynamic Behaviour and Theoretical Studies of [(Piperidinomethyl)silyl]methyl‐Cyclopalladated Dimetallic Complexes
Author(s) -
Colquhoun Victoria P.,
Schildbach Daniel,
MartínRomo Raquel,
Strohmann Carsten,
Villafañe Fernando
Publication year - 2012
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/ejic.201200257
Subject(s) - chemistry , cationic polymerization , medicinal chemistry , stereochemistry , nuclear magnetic resonance spectroscopy , crystallography , polymer chemistry
The cationic complex [Pd{ C H 2 SiPh 2 (CH 2 N C 5 H 10 )‐κ 2 C , N }(NCMe) 2 ]BF 4 (CH 2 NC 5 H 10 = piperidinomethyl) is obtained from the reaction of [Pd{ C H 2 SiPh 2 (CH 2 N C 5 H 10 )‐κ 2 C , N }(μ‐Cl)] 2 with TlBF 4 in the presence of NCMe. It reacts with KO 2 CCH 3 leading to the dimetallic complex [Pd{ C H 2 SiPh 2 (CH 2 N C 5 H 10 )‐κ 2 C , N }(μ‐ O 2 CCH 3 ‐κ O :κ′ O )] 2 , which exists only as the transoid isomer in solution. A dynamic process due to inversion of the acetato bridges is detected by variable‐temperature 1 H NMR spectroscopy. The reaction of the same parent complex with Kdmpz (dmpz = dimethylpyrazolate) leads to the dinuclear complex [Pd{ C H 2 SiPh 2 (CH 2 N C 5 H 10 )‐κ 2 C , N }(μ‐dmpz‐κ N :κ′ N )] 2 , which in solution exists as a mixture of cisoid and transoid isomers, but no inversion of the bridging pyrazolato groups has been observed. The reaction between equimolar amounts of these two complexes in CH 2 Cl 2 affords low yields of the expected mixed acetato/pyrazolato‐bridged complex [Pd 2 { C H 2 SiPh 2 (CH 2 N C 5 H 10 )‐κ 2 C , N } 2 (μ‐ O 2 CCH 3 ‐κ O :κ′ O )(μ‐dmpz‐κ N :κ′ N )]. The mixed chlorido‐pyrazolato‐bridged complex [Pd 2 { C H 2 SiPh 2 (CH 2 N C 5 H 10 )‐κ 2 C , N } 2 (μ‐Cl)(μ‐dmpz‐κ N :κ′ N )] is obtained by mixing equimolar amounts of the parent dichlorido‐ and bis(dimethylpyrazolato)‐bridged dinuclear complexes, and exhibits a dynamic process in solution corresponding to the inversion of the bridges. Only the cisoid isomers are detected for both dimetallic complexes with mixed bridging ligands. The experimental findings of the preferred transoid or cisoid structure in these dinuclear Pd complexes were supported by quantum chemical calculations.