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(Phenylalkyl)palladium Complexes Containing β‐Hydrogen Atoms: Synthesis and Characterization of [PdR 2 (dppe)], [PdR(SPh)(dppe)] (R = CH 2 CH 2 Ph, CH 2 CH 2 CH 2 Ph, CH 2 CHMePh), and [Pd(CH 2 CH 2 CH 2 Ph)X(dppe)] (X = I, Br, Cl)
Author(s) -
Spaniel Thomas,
Schmidt Harry,
Wagner Christoph,
Merzweiler Kurt,
Steinborn Dirk
Publication year - 2002
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 - 10.1002/1099-0682(200211)2002:11<2868::aid-ejic2868>3.0.co;2-s
Subject(s) - chemistry , palladium , ligand (biochemistry) , medicinal chemistry , lithium (medication) , stereochemistry , crystallography , toluene , catalysis , organic chemistry , medicine , biochemistry , receptor , endocrinology
Reactions of HgR 2 (R = CH 2 CH 2 Ph, 1a ; CH 2 CH 2 CH 2 Ph, 1b ; CH 2 CHMePh, 1c ) (prepared from HgCl 2 and the requisite Grignard compounds) with lithium in toluene afforded (phenylalkyl)lithium compounds LiR ( 2a − c ) in yields of between 64 and 81%. At −30 °C, they react with [PdCl 2 (dppe)] [dppe = 1,2‐bis(diphenylphosphanyl)ethane] yielding bis(phenylalkyl)palladium( II ) complexes [PdR 2 (dppe)] ( 3a − c ) which were isolated ( T dec = 159 °C, 3a ; 80 °C, 3b ; 145 °C, 3c ) and fully characterized by 1 H, 13 C, and 31 P NMR spectroscopy. Single‐crystal X‐ray diffraction of [Pd(CH 2 CH 2 Ph) 2 (dppe)] ( 3a ) showed that the palladium atom is square‐planar coordinated by two 2‐phenylethyl ligands and the dppe ligand. The two CH 2 CH 2 Ph ligands exhibite nearly a fully staggered conformation. Overall, a good approximation for the complex is that it has C 2 symmetry with the C 2 axis defined by the Pd atom and the midpoint of the central C−C bond of the dppe ligand. Bis(phenylalkyl)palladium complexes 3a and 3b reacted with PhSH in a 1:1 ratio yielding [PdR(SPh)(dppe)] (R = CH 2 CH 2 Ph, 5a ; CH 2 CH 2 CH 2 Ph, 5b ), whereas in the case of complex 3c , besides [Pd(CH 2 CHMePh)(SPh)(dppe)] ( 5c ), a considerable amount of [Pd(SPh) 2 (dppe)] ( 6a ) was formed. Reactions of 3b with the less acidic alkanethiols i PrSH and t BuSH resulted in the formation of [Pd(CH 2 CH 2 CH 2 Ph)(SR′)(dppe)] (R′ = i Pr, 5d ; t Bu, 5e ) along with smaller amounts of [Pd(SR′) 2 (dppe)] ( 6 ) and [Pd(dppe) 2 ] ( 7 ). Furthermore, complex 3b was found to react in THF with disulfides R′SSR′ (R′ = Ph, Bz, Me), yielding [Pd(CH 2 CH 2 CH 2 Ph)(SR′)(dppe)] (R′ = Ph, 5b ; Bz, 5f , Me, 5g ) with small amounts (3−13%) of [Pd(SR′) 2 (dppe)] ( 6 ) as side products. The corresponding reaction with MeSeSeMe afforded [Pd(CH 2 CH 2 CH 2 Ph)(SeMe)(dppe)] ( 8a ) and 3% of [Pd(SeMe) 2 (dppe)] ( 9a ) and [Pd(dppe) 2 ] ( 7 ). Reactions of complex 5b with MeI and H 2 C=CHCH 2 Br in tetrahydrofuran and with neat H 2 C=CHCH 2 Cl readily proceeded at −30 °C to give halo(3‐phenylpropyl)palladium complexes [Pd(CH 2 CH 2 CH 2 Ph)X(dppe)] (X = I, 10a ; Br, 10b ; Cl, 10c ). They were isolated as pale yellow powdery/microcrystalline substances and fully characterized by 13 C and 31 P NMR spectroscopy. Solutions of complexes 10 in THF decompose rapidly above −30 °C. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)