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Introduction
GOLD 2006 PRESENTATION
Tertiary bis-phosphines of the form R P-(CH ) -PR (n = 1 – 4 and R = Me, Et, t-Bu and Ph) and cis-R PCH=CHPR (R = Ph) are often used as chelating ligands for a wide range of transition metals.[1-4] These ligands have shown wider applications in metal complexation reactions and have attracted much attention, especially in the fields of medicine and catalysis.[5- 9] They are versatile ligands in stabilising metal ions, especially transition metals in their lower oxidation states,[10] and have contributed to the fundamental understanding of the coordination chemistry of transition metals.[6] It is now well established that the strong p-acceptor ability of phosphines enables the stabilisation of even relatively electron-rich transition metals.[11] Since the early application of 1,2-bis(diphenylphosphino) ethane (dppe) (1) and cis-1,2-bis(diphenylphosphino)
ethylene (dppey) (2) (Figure 1) as chelating phosphine
ligands, research efforts have more recently been centred
on modifying the organic substituents on the phosphorus
David S. Khanye1, Judy Caddy1,2* and
atom by the introduction of alkyl groups,[12] pyridyls,[13,14] Marcus Layh1
or substituted aryls such as o-anisyl, 1-naphthyl, c-C H ,[15] in 1 School of Chemistry, University of the an effort to tailor the ligand to suit the specific application. Witwatersrand, Private Bag 3, WITS, 2050, South The modification of bis-phosphines has been extended to the introduction of solubilising groups into the ethane bridge 2 Project AuTEK, Mintek, Private Bag X3015, Randburg, of dppe.[16] Thus, properties such as the electronic nature, the steric requirements or solubility of the ligand and their * To whom the correspondence should be addressed. corresponding metal complexes can be fine-tuned to suit the Gold(I) has been known to form numerous complexes with phosphine ligands, the majority of them being two-coordinate Abstract
gold complexes. It was not until 1984, that 31P NMR studies The well established and known chemistry of metal
of the bridged di-gold diphosphine complex, [(AuCl) (dppe)] phosphides as nucleophilic and reactive precursors
(3), in presence of free dppe ligand demonstrated the
has been used as a suitable synthetic approach in
formation of a four-coordinate complex, [Au(dppe) ]+Cl- (4)
the synthesis of 1,2-bis(butylphenylphosphino)
ethane (bppe) (5) and cis-1,2-bis(butylphenyl-
Silver, as the lighter congener of gold, shows an equally phosphino)ethylene (bppey) (6). Adducts of bridged
interesting coordination chemistry with phosphine ligands and bis-chelated gold(I) with 5 and 6, as well as
leading to a large variety of complexes of different nuclearity silver(I) with 5, have been prepared in moderate to
(mononuclear to polynuclear)[18] and bonding modes good yields. These complexes have been
characterised by solution NMR spectroscopy, mass
Due to our ongoing research in the coordination chemistry spectrometry (FAB) and microanalysis in case of 10a,
of metal-phosphine complexes, we became interested in the 10b and 11.
coordination chemistry of ligands 5 and 6.[20,21] Thus, the
research efforts presented herein compliment reports which
describe the significant change in metal complex properties
as a result of substitution on the phosphorus atom or the
bridging carbon atom of dppe analogues.[16] Here, we report
the synthesis of 5 and 6 (Figure 3), as modified analogues of
1 and 2, and their subsequent metal complexation with gold
and silver (in case of 5).
Gold Bulletin 2007 • 40/1
Figure 1
Bis-phosphine ligands, dppe and dppey.
Figure 2
Bis- phosphine gold complexes, [AuCl (dppe)] and [Au(dppe) ]+Cl -.
Figure 3
Modified bis-phosphine ligands with butyl groups, bppe and bppey.
Experimental Section
FAB-MS spectra were collected using a VG70-SEQ instrument in positive ion mode. Elemental analyses were determined All manipulations were carried out under argon atmosphere, on a Thermo Flash EA1112 CHNS-O elemental analyzer at using standard Schlenk-techniques. Solvents were distilled the University of Cape Town. The following abbreviations from sodium/benzophenone ketyl or calcium hydride and are used throughout the experimental section: bs = broad degassed. Deuterated solvents were degassed by freeze- singlet, d = doublet, dd = doublet of doublet, m = multiplet, s drying and kept under argon and on molecular sieves. NMR = singlet. Coupling constants, J, are measured in Hertz (Hz).
spectra were recorded in CDCl or d -DMSO at 298 K using the following Bruker instruments, AVANCE 300 (1H 300.13; 31P 121.5; 13C 75.5 MHz) AVANCE DRX 400 (1H 400.13; 31P 161.9; Synthesis of butyldiphenylphosphine,
13C 100.6 MHz) and referenced internally to residual solvent resonances (data in d) in the case of 1H and 13C spectra, while the 31P spectra were referenced externally to 85% H PO . All Ph P (26.4 g, 104.8 mmol) was dissolved in 100 cm3 of NMR spectra other than 1H NMR were proton-decoupled. tetrahydrofuran (THF). The mixture was added dropwise at Gold Bulletin 2007 • 40/1
0 °C to a suspension of granular lithium metal (1.60 g, 230.5 -19.6, -19.9. 13C-NMR (CDCl ): d 13.7 [s, CH ], 24.1 – 24.3 mmol) in 100 cm3 of THF. The reaction was stirred at 0 °C [pseudo triplet, CH ], 27.2 – 28.0 [m, CH ], 128.2 [m, p-Ph], for 1 hr. This was accompanied by a colour change from 128.6 [d, o/m-Ph, J = 3.3 Hz], 132.1 – 132.4 [m, o/m-Ph], colourless to red-brown. The mixture was allowed to warm to 137.9 - 138.0 [m, ipso-Ph]. Mass spectrum (EI): m/z = 358.2 room temperature and then stirred for 72 hrs. The unreacted lithium metal was removed by filtration. To the red-brown filtrate, n-butylchloride (22.7 cm3, 217.4 mmol) in 20 cm3 hexane was added dropwise at 0 °C, while rapidly stirring. Synthesis of cis-Ph(Bu)PCH=CHP(Bu)Ph (6)
The reaction mixture was stirred at room temperature overnight. After removing the volatiles in vacuo, 100 cm3 Ph PCH=CHPPh (3.0 g, 7.57 mmol) was dissolved in 100 of dried hexane were added to the red-brown viscous oil to cm3 of THF. Further, the mixture was added dropwise to precipitate LiCl from the solution. The colourless solution was a suspension of granular lithium metal (0.236 g, 34.0 filtered by means of a cannula to remove LiCl. Hexane was mmol) in 100 cm3 of THF at 0 °C. The reaction mixture was removed from the filtrate in vacuo to give a yellow viscous stirred at 0 °C for 1 hr. This was accompanied by a colour oil, which became a colourless liquid after distillation under change from colourless to red-brown. The mixture was vacuum. Yield: 13.97 g, 64%. Boiling point: 105 – 110 °C / allowed to warm to room temperature and then stirred 85.5 x 10-4 mmHg (lit. [22]. 100 – 102 ºC / 2.63 x 10-4 mmHg). for 24 hrs. The unreacted lithium metal was removed by filtration. To the red-brown filtrate, n-butylchloride (4 cm3, 34.1 mmol) in 30 cm3 hexane was added dropwise at 0 °C, while rapidly stirring. The reaction mixture was Synthesis of Ph(Bu)PCH CH P(Bu)Ph (5)
stirred at room temperature overnight. The solvent was removed in vacuo to give a red-brown oil. Dry hexane Method A: A solution of Ph BuP (5 g, 20.6 mmol) in
(2 x 100 cm3) was added and a yellow-white precipitate 25 cm3 THF was added dropwise to a suspension of granular formed, which was separated by filtration. The solvent lithium metal (0.285 g, 41.2 mmol) in 60 cm3 of THF at was removed in vacuo off the filtrate and the obtained 0 °C. The reaction mixture was stirred at 0 °C for 1 hr. viscous oil was vacuum distilled to give a yellow oil. Yield: This was accompanied by a colour change from colourless 2.09 g, 78 %. Boiling Point: 110 – 115 °C / 131.6 mmHg. to red-brown. The mixture was al owed to warm to room 1H NMR (DMSO): d 0.86 [t, CH , 3H, 3J = 6.8 Hz], 1.28 temperature and then stirred for 72 hrs. The unreacted – 1.40 [m, CH , 4H], 2.06 [pseudo t, CH , 2H, J = 7.2 Hz], lithium metal was removed by filtration. To the red-brown 7.30 – 7.40 [m, Ph, CH=CH, 6H]. 31P NMR (DMSO): d -16.7 filtrate, 1,2-dichloroethane (1.02 g, 10.3 mmol) in 25 cm3 ppm. 13C NMR (DMSO): d 13.5 [s, CH ], 23.4 [d, CH , J hexane was added dropwise at 0 °C, while rapidly stirring. = 13.1 Hz], 26.4 [d, CH , J = 11.1 Hz], 27.6 [d, CH , J = The reaction mixture was stirred at room temperature 15.8 Hz], 128.3 [s, p-Ph], 128.4 [s, m/o-Ph], 132.1 [s, o/m- overnight. The white-yel ow reaction mixture was extracted Ph] 132.3 [s, CH=CH], 138.5 [d, ipso-Ph, 1J = 14.1 Hz]. with hexane. The hexane was removed in vacuo to give Mass spectrum (EI): m/z = 356.2 (10 %) [M+], 243.2 (100 a yel ow oil (0.5 g, 17%). Method B: 1,2-Bis(diphenylphos
phino)ethane (dppe) (10.0 g, 25.1 mmol) was dissolved in 100 cm3 of THF. Further, the mixture was added dropwise to a suspension of granular lithium metal (0.784 g, 112.9 Synthesis of [(AuCl) Ph(Bu)PCH CH P(Bu)
mmol) in 120 cm3 at 0 °C. The reaction was stirred at 0 °C for 1 hr. This was accompanied by a colour change from colourless to red-brown. The mixture was al owed [AuCl(SMe )] (0.17 g, 0.56 mmol) was dissolved in 10 cm3 to warm to room temperature and then stirred for 72 hrs. of CH Cl . Further, a solution of Ph(Bu)PCH CH P(Bu)Ph The unreacted lithium metal was removed by filtration. (0.10 g, 0.28 mmol) in 5 cm3 of CH Cl was slowly added To the red-brown filtrate, n-butylchloride (12.3 cm3, to the reaction mixture at room temperature. After the 112.9 mmol) in 20 cm3 of hexane was added dropwise at mixture was stirred for 2 hrs at room temperature, the -30 °C, while rapidly stirring. The reaction mixture was colourless solution was filtered by means of a cannula and stirred at room temperature overnight. After removing the the solvent removed in vacuo to give a white solid. Yield: solvent in vacuo, a further 100 cm3 of hexane were added to 0.17 g, 74 %. 1H NMR (CDCl ): d 0.81 – 0.92 [m, 2CH , 6H], the red-brown viscous oil to precipitate LiCl from the oil. 1.35 – 1.42 [m, CH , 8H], 2.07 – 2.10 [m, CH , 4H], 2.40 The hexane was removed in vacuo to give a yel ow viscous – 2.44 [m, CH , 2H], 7.46 – 7.63 [m, Ph, 10H]. 31P-NMR oil, that after vacuum distil ation yielded a colourless oil. (CDCl ): d 33.2, 32.4. Mass spectrum (FAB): m/z = 786.7 Yield: 4.85 g, 54 % (Mixture of diastereomers). Boiling point: (100 %) [M+-Cl], 555.4 (18 %) [Au(bppe)]+.
170 – 175 oC/140 mmHg. 1H-NMR (CDCl ): d 0.79 [t, CH , 6H, 3J = 6.9 Hz], 1.27 [unresolved t, CH , 8H], 1.56 – 1.61 [m, CH , 8H], 7.34 – 7.37 [m, 2Ph, 10H]. 31P-NMR (CDCl ): d Gold Bulletin 2007 • 40/1
Synthesis of [(AuCl) Ph(Bu)PHC=CHP(Bu)
Synthesis of [(AgNO ) (Ph(Bu)PCH CH P
(Bu)Ph)] (8b)
[AuCl(SMe )] (0.17 g, 0.56 mmol) was dissolved in 10 cm3 AgNO (0.096 g, 0.57 mmol) was suspended in 15 cm3 of of CH Cl . Further, a solution of Ph(Bu)PCH=CHP(Bu)Ph (0.10 CH Cl . Further, a solution of Ph(Bu)PCH CH P(Bu)Ph (0.10 g, 0.28 mmol) in 5 cm3 of CH Cl was slowly added to the g, 0.28 mmol) in 10 cm3 of CH Cl was slowly added to the reaction mixture at room temperature. After the mixture was reaction mixture at room temperature. After the mixture stirred for 3 hrs at room temperature, the brown solution was was stirred for 90 mins at room temperature, the colourised filtered by means of a cannula and the solvent removed in solution was filtered by means of a cannula and the solvent vacuo to give a brown solid. Yield: 0.18 g, 78 %. 1H NMR removed to give a brown solid. Yield: 0.1 g, 51 %. 1H NMR (DMSO): d 0.69 [t, CH , 3H, 3J = 6.7 Hz], 1.24 [s, CH , 4H], (CDCl ): d 0.71 – 0.87 [m, CH , 6H], 1.22 – 1.29 [m, CH , 8H], 2.44 [m, CH , 2H], 7.40 – 7.60 [m, Ph / HC=CH, 6H]. 31P-NMR 1.87 – 2.24 [m, CH , 8H], 7.31 – 7.60 [m, Ph 10H]. 31P-NMR (DMSO): d 31.5. Mass spectrum (FAB): m/z = 785.2 (0.5 %) (CDCl ): d 9.5. [d, J = 225 Hz] 13C-NMR (CDCl ): d 13.50 [s, [M+-Cl], 439.2 (25 %) [Au(PhPCH=CHPPh)]+. CH ], 13.52 [s, CH ], 23.8 [s, CH ], 24.0 [s, CH ], 27.7 [s, CH ], 125.5 – 133.5 (m, Ph). Mass spectrum (FAB): m/z = 636.2 (6.8 %) [Ag (bppe)NO ]+, 466.3 (61 %) [Ag(bppe)]+.
Synthesis of [Au(Ph(Bu)PCH CH P(Bu)Ph) ]
Synthesis of [Ag(Ph(Bu)P(CH CH P(Bu)Ph) ]
[AuCl(SMe )] (0.49 g, 1.68 mmol) was dissolved in 10 cm3 of ClO (10b)
CH Cl . Further, a solution of Ph(Bu)PCH CH P(Bu)Ph (1.20 g, 3.35 mmol) in 10 cm3 of CH Cl was added dropwise to the AgClO (0.36 g, 1.68 mmol) was suspended in 10 cm3 of reaction mixture at room temperature. The reaction mixture CH Cl . Further, a solution of Ph(Bu)PCH CH P(Bu)Ph (1.20 g, was stirred overnight at room temperature. The colourless 3.35 mmol) in 10 cm3 of CH Cl was added dropwise to the solution was filtered by means of a cannula and the solvent reaction mixture at room temperature. The reaction mixture removed in vacuo to give a white solid. Yield: 1.35 g, 85 %. was stirred overnight at room temperature. The colourless Calc. for C H AuP Cl: C, 55.7; H, 6.79 %. Found: C, 53.7; H, solution was filtered by means of a cannula and the solvent 6.77 %. 1H NMR (CDCl ): d 0.70 – 0.86 [m, CH , 12H], 0.91 removed in vacuo to give a white solid. Yield: 1.40 g, 91 %. – 1.45 [m, CH , 16H], 1.91 – 2.15 [m, CH , 16H], 7.27 – 7.65 Calc. for C H AgClO : C, 57.2; H, 7.0 %. Found: C, 55.8; H, [m, Ph, 20H]. 31P-NMR (CDCl ): d 15.1 and 15.5 (Isomeric 6.82 %. 1H NMR (CDCl ): d 0.72 – 0.88 [m, CH , 3H], 1.29 -1.4 mixture). 13C-NMR (CDCl ): d 13.3 [s, CH ], 23.6 [s, CH ], 24.0 [m, CH , 4H], 1.9 – 2.3 [m, CH , 4H], 7.34 – 7.50 [m, Ph, 5H]. [s, CH ], 27.4 [m, CH ], 29.0 [m, CH ], 128.8 [d, Ph, J = 9.8 31P-NMR (CDCl ): d -2.1 [d, J = 240 Hz]. 13C-NMR (CDCl ): d Hz], 129.1 [br s, Ph], 130.4 [s, Ph], 133.0 [d, ipso-Ph, 1J = 13.6 [s, CH ], 24.1 [s, br, CH ], 27.8 [s, br, CH ], 128.9 – 132.7 13.9 Hz]. Mass spectrum (FAB): m/z = 913.2 (100 %) [M+-Cl], (Ph). Mass spectrum (FAB): m/z = 823.5 (31 %) [M+-ClO -], Synthesis of [Au(Ph(Bu)PHC=CHP(Bu)Ph) ]
Results and Discussion
Various synthetic routes exist for the preparation of bis- [AuCl(SMe )] (0.44 g, 1.49 mmol) was dissolved in 15 cm3 of phosphine ligands. These include reaction methods such CH Cl . Further, a solution of Ph(Bu)PHC=CHP(Bu)Ph (1.09 g, as reductive metallation of halophosphines, metal-halogen 2.97 mmol) in 20 cm3 of CH Cl was added dropwise to the exchange, the metallation of primary and secondary reaction mixture at room temperature. The reaction mixture phosphines with a strong base such as n-BuLi and the cleavage was stirred overnight at room temperature. The brown solution of P-C bonds in tertiary phosphines with an alkali metal.[17] was filtered by means of a cannula and the solvent removed In this work the latter principle of P-C bond cleavage, [23-27], in vacuo to give a brown solid. The solid was washed with a has been employed towards the synthesis of novel bppe (5)
mixture of CH Cl /hexane and then dried in vacuo. Yield: 1.31 g, and bppey (6).
93 %. Calc. for C H AuP Cl: C, 55.9; H, 6.4 %. Found: C, The reaction schemes towards the synthesis of the ligands 53.2; H, 5.97 %. 1H NMR (DMSO): d 0.73 [m, CH , 12H], 1.28 and metal complexes are summarised in Scheme 1. The first [m, CH , 18H], 2.36 [m, CH , 6H], 7.40 – 7.51 [m, Ph, CH=CH, method involved the synthesis of n-butyldiphenylphosphine 24H]. 31P-NMR (DMSO): d 22.3. 13C-NMR (DMSO): d 13.7 [s, from triphenylphosphine (PPh ) (7), and thereafter the desired
CH ], 20.4, [s, CH ], 24.5 [m, CH ], 28.0 [m, CH ], 129.3 [s, p- ligand via a lithium butylphenylphosphide intermediate. The Ph], 131.9 [m, o/m-Ph], 132.3 [m, o/m-Ph], 133.9 [s, -CH=CH-], second method involved the synthesis of bppe directly from 135.5 [m, ipso-Ph]. Mass spectrum (FAB): m/z = 909.3 (1.5 %) bis-phosphine, dppe (1) (Figure 1).
[M+-Cl], 795.2 (6.0 %) [M+-2Bu], 681.3 (100 %) [M+-4Bu].
The synthesis of the bis-phosphine, bppe (5), via P-C bond
Gold Bulletin 2007 • 40/1
B = (i) Li / THF / 0°C, (i ) ClCH2CH2Cl / cis -ClCH-CHCl 8b: n = 2, MX = AgNO39: n = 1, MX = AuCl10a: n = 2, M = Au, X = Cl-10b: n = 2, M = Ag, X = ClO -411: n = 1, M = Au, X = Cl- Scheme 1
Synthesis of cationic and neutral bis-phosphine group 11 metal complexes.
cleavage with an alkali metal involved the cleavage of PPh (7)
bonds of the Ph P(CH ) PPh ligands, where n = 2, x = 2 (1) or
by lithium metal in tetrahydrofuran, which results in a source n = 1, x = 2 (2), by an alkali metal.[2,12,24-27] The reaction
of lithium diphenylphosphide (LiPPh ), a useful precursor for of Ph P(CH ) PPh (1 or 2) with at least 4mol equivalents of
the preparation of bis-phosphine ligands. The reaction of lithium metal to 1mol phosphine resulted in the formation PPh and lithium metal (step A) via lithium diphenylphosphide of the characteristic red-brown lithium diphosphide intermediate was accompanied by a red-brown colour, intermediate, Li(Ph)P(CH ) P(Ph)Li (step C). Further reaction characteristic of the formation of the metal-phosphide.[27] of Li(Ph)P(CH ) P(Ph)Li with 4.5 equivalents of n-butylchloride Treatment of the red-brown solution with a solution of (step C) resulted in the formation of both ligands, 5 as mixture
n-butylchloride readily afforded the butyldiphenylphosphine of isomers in moderate (54%) and 6 in good yield (78%).
precursor (Ph PBu) in moderate yield (64%).
Both were characterised by both NMR spectroscopy and mass When Ph PBu was subjected to similar reaction conditions the corresponding lithium butylphenylphosphide The bis-phosphines 5 and 6 on complexation to gold(I),
(LiPBuPh) intermediate (step B) was readily formed. In situ yielded the two and four co-ordinated gold(I) complexes 8a,
preparation of 5 by treating the LiPBuPh intermediate with
9 and 10a, 11 (Scheme 1). The bridged digold(I) complexes,
1,2-dichloroethane (step B) at low temperature yielded 5 in
8a and 9, were synthesised by a procedure similar to the
low yield (17 – 40%). Although, the stereospecific reaction one described in the literature for [(AuCl) dppe],[1] which of LiPPh with either cis-1,2-dichloroethylene or trans-1,2- involved the addition of half an equivalent of the appropriate dichloroethylene to successfully yield the corresponding ligand, 5 or 6 (step D), to a solution of [AuCl(SMe )] at room
phosphines, cis-Ph PCH=CHPPh or trans-Ph PCH=CHPPh has temperature, resulting in the formation of 8a (57%) and
been reported previously,[28] treating LiPBuPh with cis-1,2- 9 (78%) as white and light brown solids, respectively. The
dichloroethylene (step B) to form 6 resulted in a mixture of
four co-ordinated bis-chelated complexes 10a and 11 were
synthesised via the established procedure of a 2:1 mol ratio of Although many bis-phosphine ligands are being (P-P):Au(I).[1, 16,17,29] Thus, the reaction of two equivalents synthesised from PPh , an attractive alternative approach, of 5 or 6 with a solution of [AuCl(SMe )] in DCM (step E),
consisting of fewer synthetic steps, is the cleavage of the P-C readily afforded complexes 10a and 11 in good yields (85%
Gold Bulletin 2007 • 40/1
Table 1: 31P{1H} chemical shift resonances of the bridged and bis-chelated gold(I) and silver(I) complexes.
Ligand Type
[(MX) (P-P)]
[(M(P-P) ]X
A similar bridged silver complex [(Ag O C H (dppe)] with a The complexation of 5 with stoichiometric amounts of
carboxylic group bridging two silver atoms, showed a coupling silver salts [AgNO (step D) and AgClO (step E)], via a similar constant of J = 230 Hz in CDCl .[18] A coupling constant procedure described for the gold complexes, yielded both the for the bis-chelated complex [Ag(dppe) ]NO with the value bridged di-silver (8b) and bis-chelated silver (10b) complex in
of J = 231 / 266 Hz had been reported.[30] moderate and good yields (51% and 91%, respectively).
Due to the hygroscopic nature of the compounds accurate Complimentary to the one step preparation of the elemental analyses could not be performed. Degrees of bis-chelated complexes, 10a-b and 11, a two step approach
deviation were overcome by accounting for the presence could be undertaken, incorporating the bridged analogues of co-crystallised solvent in the crystal lattice, which were (8a-b and 9) as intermediates. (Scheme 1, step F).
not removed after extended periods under high vacuum. The corresponding gold and silver complexes This has been previously observed with a similar series of (Scheme 1) were fully characterised by multinuclear NMR compounds within our research group,[33] where structures spectroscopy, elemental analysis (except 8b and 9) and
were confirmed by x-ray diffraction.
mass spectrometry. The 1H NMR spectra of the complex
8a, 9, 8b, 10a, 10b and 11 showed a deshielding of the
ethylenic protons on complexation compared to that of
Conclusions
the free ligand. The deshielding of the ethylenic protons has been observed for various other complexes in the This paper reports the successful preparation of two literature, such as [(AuCl) (dnpype)],[28] where n = 2 alkyl, aryl-substituted bis-phosphines ligands, differing only – 4, and dnpype = 1,2-bis(di-n-pyridylphosphino)ethane, in the composition of their backbone, and their subsequent [Au(dppe) ]Cl,[1,16] [Ag(dppe) ]NO ,[30] Ag(dnpype) ]NO ,[31] and [Cu(dppe) ]BF .[32] Furthermore, the ethylenic protons Two synthetic approaches were investigated in order to of the bridged di-gold(I) complexes, 8a and 9, are more
obtain the desired ligands. The first method involved the deshielded than those of the bis-chelated complexes synthesis of butyldiphenylphosphine from triphenylphosphine 10a and 11. This is consistent with the reported bridged
(7), and thereafter the desired ligand was obtained via a
complex [(AuCl) (dnpype)] vs the bis-chelated complex lithium butylphenylphosphide intermediate. The second method involved the synthesis directly from bis-phosphines, The 31P NMR spectra of the bridged di-gold(I) (8a) and
dppe (1) and dppey (2).
bis-chelated gold(I) (10a) in deuterated chloroform showed
The synthesis of two-coordinate (bridged) and four signals around d 32.4, 33.2 and 15.1, 15.5 ppm, respectively coordinate (bis-chelate) novel gold(I) complexes 8a, 9 and
(Table 1). The observed trend in 31P NMR spectra of 8a and
10a, 11, and silver (I) complexes 8b and 10b has been
10a, where the chemical shift of 8a is deshielded to a greater
achieved. All of the synthesised complexes compared extent than that of 10a, is consistent with that observed for the
favourably to analogues reported in literature. dppe analogues, [(AuCl) (dppe)] and [Au(dppe) ]Cl.[1,16,17] The 31P NMR spectrum in DMSO of 9 and 11 showed signals
at d 31.5 and 22.3, respectively. This is also consistent with
Acknowledgements
the observations made for complexes [(AuCl) (dppe)] and [Au(dppe) ]Cl. However, the reported 31P{1H} resonance The authors would like to thank Project AuTEK (Mintek and of the analogous complex [(AuCl) (dppey)], is at 12.8 ppm Harmony Gold) for permission to publish this paper and for financial support. Further thanks go to University of the The 31P{1H} NMR spectra of the bridged complex 8b and
Witwatersrand for use of their facilities.
bis-chelated complex 10b showed a doublet at d 9.5 ppm
[J = 225 Hz] and d -2.1 ppm [J = 240 Hz], respectively.
Gold Bulletin 2007 • 40/1
About the Authors
7 R.H. Crabtree, J. Organomet. Chem., 2005, 690, 5451-5457
8 M.J. McKeage, S.J. Berners-Price, P. Galettis, R.J. Bowen, W. Bouwer,
Mr. David Khanye
L. Ding, L. Zhuang, B.C. Baguley, Cancer Chemother. Pharmacol., 2000, 46, 343 – 350
9 P. Le Floch, Coord. Chem. Rev., 2006, 250, 627-681
10 M.S. Balakrishna, R.M. Abhyankar, J.T. Mague, J. Chem Soc., Dalton Trans., under supervision of Prof. Kelly Chibale, 11 N. Mézail es, L. Ricard, F. Mathey, P. Le Floch, Eur. J. Inorg. Chem., 1999, 12 G.A. Bowmaker, J.P. Wil iams, Aust. J. Chem., 1994, 47, 451–460
Dr. Marcus Layh
13 S.J. Berners-Price, R.J. Bowen, P. Galettis, P.C. Healy, M.J. McKeage, Coord. Chem. Rev., 1999, 185 – 186, 823–836
associate at the University of Münster and 14 R.J. Bowen, A. C. Garner, S.J. Berners-Price, I.D. Jenkins, R.E. Sue, has held previous industrial and academic J. Organomet. Chem., 1998, 554, 181–184
15 F. Mainza, F. Spindler, M. Thommen, B. Pugin, C. Malan, A. Mezzetti, Africa. His research interests are in the field J. Org. Chem., 2002, 67, 5239 – 5249
of main group organometal ic chemistry.
16 S.J. Berners-Price, R.J. Bowen, M.A. Fernandes, M. Layh, W.J. Lesueur, S. Mahepal, M.M. Mtotywa, R.E. Sue, C.E.J. van Rensburg, Inorg. Chim. Dr. Judy Caddy
Acta, 2005, 358, 4237 – 4246
17 S.J. Berners-Price, M.A. Mazid, P.J. Sadler, J. Chem. Soc., Dalton Trans., 18 A.F.M.J. van der Ploeg, G. van Koten, A.L. Spek, Inorg. Chem., 1979, 18,
research career looking at the synthesis 19 A.F.M.J. van der Ploeg, G. van Koten, Inorg. Chim. Acta, 1981, 51,
phosphine compounds in a secondment to University of 20 R.J. Bowen, J. Caddy, M.A. Fernandes, M. Layh, M. Mamo, R. Meijboom, Witwatersrand. During this time Judy undertook a research J. Organomet. Chem., 2006, 691, 717–725
visit to Heidelberg, Germany, where she investigated the gold 21 R.J. Bowen, M.A. Fernandes, P.W. Gitari, M. Layh, R.M. Moutloali, labelling of neurologically active pentapeptides. Shortly after her return to South Africa she began heading up the AuTEK 22 R.J. Bowen, D. Camp, Effendy, P.C. Healy, B.W. Skelton, A.H. White, Biomedical Programme, along with taking on an honorary Aust. J. Chem., 1994, 47, 693 –701
position at the University of Witwatersrand. Over the past 23 N.K. Roberts, S.B. Wild, J. Am. Chem. Soc., 1979, 101, 6254–6260 three years Judy has actively supervised and co-supervised 24 J. Dogan, J.B. Schulte, G.F. Swiegers, S.B. Wild, J. Org. Chem., 2000, 65,
student projects at collaborating universities, along with her research activities at Mintek, where she is now involved in the 25 R.S. Dickson, P. S. Elmes, W.R. Jackson, Organometal ics, 1999, 18,
development of therapies for cancer, HIV and malaria.
26 A.L. Airey, G.F. Swieger, A.C. Wil is, S.B. Wild, Inorg. Chem., 1997, 36,
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Studies centred around the use of a dialkyl-hydrazine backbone”, PhD Thesis, University of Witwatersrand, School of Chemistry, to be submitted 6 J.S. Lewis, S.L. Heath, A.K. Powel , J. Zweit, P.J. Blower, J. Chem. Soc., Gold Bulletin 2007 • 40/1

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