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Synthesis and Properties of para ‐Substituted NCN‐Pincer Palladium and Platinum Complexes
Author(s) -
Slagt Martijn Q.,
Rodríguez Gema,
Grutters Michiel M. P.,
Klein Gebbink Robertus J. M.,
Klopper Wim,
Jenneskens Leonardus W.,
Lutz Martin,
Spek Anthony L.,
van Koten Gerard
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200305336
Subject(s) - chemistry , pincer movement , substituent , palladium , platinum , medicinal chemistry , ligand (biochemistry) , pincer ligand , metalation , hydrogen bond , population , stereochemistry , crystallography , molecule , catalysis , organic chemistry , biochemistry , receptor , demography , sociology
A variety of para ‐substituted NCN‐pincer palladium( II ) and platinum( II ) complexes [MX(NCN‐Z)] (M=Pd II , Pt II ; X=Cl, Br, I; NCN‐Z=[2,6‐(CH 2 NMe 2 ) 2 C 6 H 2 ‐4‐Z] − ; Z=NO 2 , COOH, SO 3 H, PO(OEt) 2 , PO(OH)(OEt), PO(OH) 2 , CH 2 OH, SMe, NH 2 ) were synthesised by routes involving substitution reactions, either prior to or, notably, after metalation of the ligand. The solubility of the pincer complexes is dominated by the nature of the para substituent Z, which renders several complexes water‐soluble. The influence of the para substituent on the electronic properties of the metal centre was studied by 195 Pt NMR spectroscopy and DFT calculations. Both the 195 Pt chemical shift and the calculated natural population charge on platinum correlate linearly with the σ p Hammett substituent constants, and thus the electronic properties of predesigned pincer complexes can be predicted. The σ p value for the para ‐PtI group itself was determined to be −1.18 in methanol and −0.72 in water/methanol (1/1). Complexes substituted with protic functional groups (CH 2 OH, COOH) exist as dimers in the solid state due to intermolecular hydrogen‐bonding interactions.