Metal phosphine complexes incorporating alkyl substituents with ethane and ethylene backbones
No Thumbnail Available
Date
2008-03-12T10:49:17Z
Authors
Khanye, Setshaba D.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Abstract
The new chelating bis-phosphine ligands 1,2-bis(butylphenylphosphino)ethane
(bppe) and cis-1,2-bis(butylphenylphosphino)ethylene (bppey) have been
synthesised by (i) a one-pot synthesis from Ph2PBu and Li/dihalo alkyl, (ii) the
reaction of 1,2-bis(diphenylphosphino)ethane (dppe) or cis-1,2-
bis(diphenylphosphino)ethylene (dppey) and Li/n-BuCl and, (iii) in the case of
bppe by sequential synthesis (all intermediates were isolated) from Ph2PBu via
PhBuPLi and Ph2PH. bppe and bppey as well as the new lithium phosphide
[(TMEDA)•LiPPh(Bu)]2 (17) were fully characterised by multinuclear NMR
spectroscopy, mass spectrometry and, in the case of [(TMEDA)•LiPPh(Bu)]2 (17),
by X-ray crystallography.
Reaction of the bis-phosphines bppe and bppey with suitable metal precursors
yielded the corresponding metal complexes: [PdCl2(bppe)] (18), [Pd(bppe)2](ClO4)2
(20), [(AuCl)2(bppe)] (21a), [(AuCl)2(bppey)] (21b), [Au(bppe)2]Cl (22a),
[Au(bppey)2]Cl (22b), [(AgNO3)2(bppe)] (23) and [Au(bppe)2]ClO4 (24) in
moderate to good yields. All were characterised by multinuclear NMR spectroscopy
and mass spectrometry, while 18 and 20 were further characterised by X-ray
crystallography.
Preliminary stability tests showed, that of all new metal complexes only 18, 20 and
22a were adequately stable to justify further tests for anti-tumour activity. The
cationic complexes 20 and 22a showed activity against HeLa cells while the neutral
complex 18 was not active. A comparison with the previously investigated
analogous dppe and dppey complexes revealed that 20 and 22a were found to be
less active as a result of the replacement of a Ph groups with butyl groups in the
phosphine ligand.