[Au(C6F5)3(PPh2H)]: A precursor for the synthesis of gold(III) phosphide complexes

Article abstract of DOI:10.1002/(SICI)1521-3773(19981116)37:21<3042::AID-ANIE3042>3.0.CO;2-C

The covalent radius of Au(I) is about 0.07 A smaller than that of Ag(I). This was determined from the crystal structures of the isostructural complexes [N(PPh₃][{Au(C₆F₅)₃-(μ-PPh₂)}₂M] (M = Au (structure shown in the picture), Ag). These mixed Au(III)-M phosphides were synthesized from [Au(C₆F₅)₃-(PPh₂H)], the first gold complex to contain a secondary phosphane.

Full text of DOI:10.1002/(SICI)1521-3773(19981116)37:21<3042::AID-ANIE3042>3.0.CO;2-C

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[Au(C6F5)3(PPh2H)]: A Precursor
for the Synthesis of Gold(iii)
Phosphide Complexes**
M. Carmen Blanco, Eduardo J.
Â
Fernandez, Peter G. Jones, Antonio
Â
Â
Laguna,* Jose M. Lopez-de-Luzuriaga,
and M. Elena Olmos
Although a rich and fascinating chemistry
of phosphido-bridged transition metal com-
plexes has recently been developed for metals
of Groups 9 and 10,[1] the corresponding gold
chemistry has experienced little progress
since Puddephatt and Thompson prepared
[AuPPh2]n in 1976;[2] only a few AuI species
containing PR2H[3] or PR2 ligands[2±4] are
known. The chemistry of AuIII is even more
poorly represented, and only the dinuclear
complex [Au2Me4(m-PPh2)2] has been report-
ed.[2] Attempts to prepare AuIII complexes
with PPh2H have led only to reduction of the
AuIII centers.[3a]
We have succeeded in synthesizing a di-
phenylphosphanylgold(iii) complex by ex-
ploiting the stabilizing effect of pentafluor-
ophenyl groups. The starting material
[Au(C6F5)3(tht)] (tht ˆ tetrahydrothiophene)
Scheme 1. Synthesis of phosphane and phosphide derivatives.
was
treated
with
PPh2H,
giving
[Au(C6F5)3(PPh2H)] (1, Scheme 1). This is the first AuIII
derivative containing a secondary phosphane.
would allow a comparison of the covalent radii of these three
metals, a subject of recent discussion.[6] Reaction of 1 with
AgClO4 or [Cu(NCMe)4]TfO (TfO ˆ CF3SO3) in the presence
of PPN(acac) led to PPN[{Au(C6F5)3(m-PPh2)}2M] (M ˆ Ag
(3), Cu (4)). Both are air- and moisture-stable solids whose
physical and spectroscopic data are in accordance with the
proposed formulation.
Crystals of 2 and 3 suitable for X-ray diffraction studies
were obtained from solutions in dichloromethane layered
with hexane; unfortunately, we have not been able to obtain
good crystals of 4. Complexes 2 and 3[7] are isotypic and thus
allow a comparison of metal ± ligand bond lengths (Fig-
ure 1).[6a] The MI atom lies on an inversion center, so its
Further reaction of 1 with suitable coinage metal species
should furnish hitherto unknown phosphido-bridged AuIII ± M
species. As 1 can only be isolated in low yields as an oily
material, freshly prepared solutions of 1 were used directly for
further reactions. The reaction of PPN[Au(acac)2][5] (PPN ˆ
‡
[N(PPh3)2] , acac ˆ CH(COCH3)2) with such a solution (1:2)
afforded the first mixed AuIII ± M phosphido-bridged com-
plex, PPN[{Au(C6F5)3(m-PPh2)}2Au] (2), which can be easily
isolated as a solid in high yield. It behaves as a 1:1 electrolyte
1
in acetone; its H NMR spectrum displays only signals from
the aromatic protons.
We wished to synthesize a set of isostructural complexes
containing AuI, AgI, or CuI centers, whose crystal structures
[*] Prof. Dr. A. Laguna
Â
Departamento de Química Inorganica-ICMA
Universidad de Zaragoza-CSIC
E-50009 Zaragoza (Spain)
Fax: (‡34)976-761187
E-mail: alaguna@posta.unizar.es
Â
Â
M. C. Blanco, Dr. E. J. Fernandez, Dr. J. M. Lopez-de-Luzuriaga,
Dr. M. E. Olmos
Departamento de Química, Universidad de La Rioja
Ä
Obispo Bustamante 3, E-26001 Logrono (Spain)
Prof. Dr. P. G. Jones
Institut für Anorganische und Analytische Chemie der Technischen
Universität
Postfach 3329, D-38023 Braunschweig (Germany)
[**] This work was supported by the DGICYT. (PB94 ± 0079), the
University of La Rioja (API-98/B09), and the Fonds der Chemischen
Industrie.
Figure 1. Structure of the inversion-symmetric anion of 2 in the crystal (the
radii are arbitrary). Only the asymmetric unit is numbered. Complex 3 is
isostructural; the central gold atom is replaced by silver.
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Angew. Chem. Int. Ed. 1998, 37, No. 21

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precipitate PPNClO4, which was removed by filtration. The solution was
concentrated, and hexane was added to afford 4 as a pale yellow solid
(0.121 g, 51%). 31P NMR: d ˆ 21.1 (s, PPN), 7.0 (s, PPh2); 1H NMR: d ˆ
7.61 ± 7.09 (m, Ph).
environment is exactly linear. The bond lengths and angles are
almost identical in both structures (Table 1) except for the
MI ± P distance, which is shorter by 0.07 Š in the gold
complex. This confirms the results obtained by Schmidbaur
et al., who compared the bond lengths in complexes
Received: June 18, 1998 [Z12007IE]
German version: Angew. Chem. 1998, 110, 3199 ± 3201
Keywords: copper ´ gold ´ P ligands ´ silver
Table 1. Bond lengths [Š] and angles [8] for 2 and 3.
2 (M ˆ Au)
3 (M ˆ Ag)
Au1 C31
Au1 C21
Au1 C11
Au1 P
M P
P C41
2.052(5)
2.058(6)
2.073(6)
2.365(2)
2.319(2)
1.814(6)
1.818(7)
2.052(5)
2.068(5)
2.078(5)
2.365(2)
2.386(1)
1.804(5)
1.813(5)
[1] a) G. A. Acum, M. J. Mays, P. R. Raithby, H. R. Powel, G. A. Solan,
Chem. Commun. 1997, 3427 ± 3434; b) K. Wang, T. J. Emge, A. S.
Goldman, Inorg. Chim. Acta 1997, 255, 395 ± 398; c) E. Alonso, J.
Â
Ä
Fornies, C. Fortuno, A. Martín, G. M. Rosair, A. J. Welch, Inorg. Chem.
1997, 36, 4426 ± 4431.
[2] R. J. Puddephatt, P. J. Thompson, J. Organomet. Chem. 1976, 117, 395 ±
403.
P C51
[3] a) R. G. Pritchard, D. B. Dyson, R. V. Parish, C. A. McAuliffe, B.
Beagley, J. Chem. Soc. Chem. Commun. 1987, 371 ± 372; b) D. B. Dyson,
R. V. Parish, C. A. McAuliffe, R. G. Pritchard, R. Fields, B. Beagley, J.
Chem. Soc. Dalton Trans. 1989, 907 ± 914; c) H. Schmidbaur, A. A. M.
Aly, Z. Naturforsch. B 1979, 34, 23 ± 26; d) H. Schmidbaur, G.
Weidenhiller, A. A. M. Aly, O. Steigelmann, G. Müller, Z. Naturforsch.
B 1989, 44, 1503 ± 1508.
C31-Au1-C21
C31-Au1-C11
C21-Au1-C11
C31-Au1-P
C21-Au1-P
C11-Au1-P
P-M-P'
176.4(2)
87.6(2)
89.5(2)
92.0(2)
90.9(2)
176.6(2)
88.1(2)
89.3(2)
91.9(1)
90.6(1)
178.0(1)
180.0
177.7(2)
180.0
[4] a) J. Vicente, M. T. Chicote, P. G. Jones, Inorg. Chem. 1993, 32, 4960 ±
4964; b) G. A. Carriedo, V. Riera, M. L. Rodríguez, P. G. Jones, J.
Lautner, J. Chem. Soc. Dalton Trans. 1989, 639 ± 643; c) F. S. Livotto,
M. D. Vargas, D. Braga, F. Grepioni, J. Chem. Soc. Dalton Trans. 1992,
577 ± 584.
C41-P-C51
C41-P-Au1
C51-P-Au1
C41-P-Au1
C41-P-M
101.4(3)
110.6(2)
110.7(2)
110.6(2)
111.9(2)
109.1(2)
112.54(7)
101.3(2)
110.9(2)
110.8(2)
110.9(2)
113.7(2)
108.2(2)
111.48(5)
Â
[5] a) E. J. Fernandez, M. C. Gimeno, P. G. Jones, A. Laguna, M. Laguna,
C51-P-M
M-P-Au1
Â
J. M. Lopez-de-Luzuriaga, J. Chem. Soc. Dalton Trans. 1992 3365 ±
3370; b) J. Vicente, M. T. Chicote, I. Saura-Llamas, M. C. Lagunas, J.
Chem. Soc. Chem. Commun. 1992 915 ± 916.
[6] a) A. Bayler, A. Schier, G. A. Bowmaker, H. Schmidbaur, J. Am. Chem.
Soc. 1996, 118, 7006 ± 7007; b) G. A. Bowmaker, H. Schmidbaur, S.
Krüger, N. Rösch, Inorg. Chem. 1997, 36, 1754 ± 1757.
[(Mes3P)2M]BF4 (M ˆ Au, Ag).[6a] The AuI ± P bond distance
in 2 is similar to those observed in PPN[Mn(CO)4{(m-
PPh2)Au(C6F5)}2] (2.313(2) and 2.322(1) Š),[4b] but slightly
shorter than those in [{Mn(CO)4(m-PPh2)2Au}2] (2.332(3) ±
2.341(3) Š).[4b] The AuIII centers display the expected planar
coordination, and the AuIII ± C bond lengths of 2.052(5) ±
2.078(5) Š are similar to those in other tris(pentafluoro-
phenyl)gold(iii) derivatives.[8] The AuIII ± P bond length
of 2.365(2) Š is closely similar to that in NBu4-
[{Au(C6F5)3(Ph2PCHPPh2)}2Au] (2.367(2) Š).[8a]
[7] Structure analysis of 2: C96H50Au3F30NP4, rectangular block 0.25 Â
0.22  0.20 mm3, monoclinic, C2/c, a ˆ 28.174(3), b ˆ 11.0751(9), c ˆ
30.202(3) Š, b ˆ 113.757(8)8, Vˆ 8625.5(14) Š3, Z ˆ 4, l(MoKa) ˆ
0.71073 Š, m ˆ 5.28 mm-1, 1calcd ˆ 1.927 Mgm 3, Tˆ 1008C. Of 9917
reflections collected to 2q ˆ 508, 7559 were unique and used for all
calculations. Absorption corrections were carried out by y scans with
transmissions of 0.72 ± 0.98. The structure was solved with Patterson
methods, and refined anisotropically on F 2 (program SHELXL-93,
G. M. Sheldrick, Universität Göttingen) with 580 restraints to U
components of light atoms and local ring symmetry. Hydrogen atoms
were included with a riding model. Final values: wR2 ˆ 0.051, R1 ˆ
0.036 for 606 parameters; S ˆ 0.79, D1 0.89 eŠ 3. Structure analysis of
3: C96H50AgAu2F30NP4, prism 0.5 Â 0.4 Â 0.4 mm3, monoclinic, C2/c,
a ˆ 28.145(3), b ˆ 11.064(1), c ˆ 30.316(4) Š, b ˆ 114.08(8)8, Vˆ
8619(2) Š3, Z ˆ 4, m ˆ 3.81 mm 1, 1calcd ˆ 1.860 Mgm 3, Tˆ 1008C.
Of 10198 reflections collected to 2q ˆ 508, 7514 were unique; trans-
missions of 0.57 ± 0.76. Final values: wR2 ˆ 0.055, R1 ˆ 0.033; S ˆ 0.85,
D1 1.00 eŠ 3. The structure was solved and refined as for 2. Crystallo-
graphic data (excluding structure factors) for the structures reported in
this paper have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication no. CCDC-101732 (2) and
CCDC-101733 (3). Copies of the data can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge CB21EZ, UK (fax:
(‡44)1223-336-033; e-mail: deposit@ccdc.cam.ac.uk).
Experimental Section
1: To a solution of [Au(C6F5)3(tht)] (0.236 g, 0.3 mmol) in diethyl ether was
added PPh2H (0.5 mL, 0.3 mmol). After 30 min the solvent was concen-
trated in vacuo, and cold hexane was added to afford 1 as a white solid
(0.098 g, 37%). 31P NMR (300 MHz, CDCl3, 258C, 83% H3PO4): d ˆ 8.4
(s, PPh2H); 1H NMR: d ˆ 7.57 ± 7.43 (m, 10H; Ph), ꢀ6.8 (d, 1J(H,P) ꢀ
440 Hz, 1H; PPh2H).
2: To a freshly prepared solution of 1 (0.2 mmol) in dichloromethane was
added PPN[Au(acac)2] (0.093 g, 0.1 mmol). After the reaction mixture was
stirred for 1 h at room temperature, part of the solvent was evaporated, and
hexane (20 mL) was added to afford 2 as a white solid (0.225 g, 90%). 31
P
NMR: d ˆ 30.9 (s, PPh2), 21.1 (s, PPN); 1H NMR: d ˆ 7.60 ± 7.17 (m, Ph).
Â
[8] a) E. J. Fernandez, M. C. Gimeno, P. G. Jones, A. Laguna, M. Laguna,
Â
J. M. Lopez-de-Luzuriaga, Organometallics 1995, 14, 2918 ± 2922; b) B.
3: AgClO4 (0.021 g, 0.1 mmol) and PPN(acac) (0.127 g, 0.2 mmol) were
added to a solution of 1 (0.2 mmol) in diethyl ether. After 1 h a white
precipitate (PPNClO4) was removed by filtration, the solution was
concentrated, and hexane was added to precipitate 3 as a white solid
(0.159 g, 66%). 31P NMR: d ˆ 21.1 (s, PPN), 4.5 (dd, 1J(P,109Ag) ˆ 512.5,
Â
Alvarez, E. J. Fernandez, M. C. Gimeno, P. G. Jones, A. Laguna, M.
Â
Laguna, J. M. Lopez-de-Luzuriaga, J. Organomet. Chem. 1996, 525,
Â
109 ± 113; c) E. J. Fernandez, M. C. Gimeno, P. G. Jones, A. Laguna,
Â
J. M. Lopez-de-Luzuriaga, E. Olmos, Chem. Ber. 1997, 130, 1513 ± 1517.
1
1J(P,107Ag) ˆ 446.3 Hz; PPh2); H NMR: d ˆ 7.63 ± 7.14 (m, Ph).
4: [Cu(NCMe)4]TfO (0.038 g, 0.1 mmol) and PPN(acac) (0.127 g,
0.2 mmol) were added to a solution of 1 (0.2 mmol) in dichloromethane.
After 1 h the solvent was evaporated, and diethyl ether was added to
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