Isomorphism in the structural chemistry of two-coordinate adducts of diphenyl(2-formylphenyl)phosphine and triphenylphosphine with gold(I) halides

Article abstract of DOI:10.1016/j.molstruc.2014.05.020

Single crystal X-ray structure determinations are recorded for diphenyl(2-formylphenyl)phosphine gold(I) halides [Ph₂(Ph-CHO)PAuX], X = Cl, Br and I, and for redeterminations of enhanced precision for triphenylphosphine gold(I) halides [Ph₃PAuX], X = Cl, Br, I, and SCN_0.91Br_0.09. These complexes, other than [Ph ₂(Ph-CHO)PAuCl], together with a diverse array of other structures, crystallize as an isomorphous series in the orthorhombic space group P2 ₁2₁2₁ a = 9.804(1)-11.906(3), b = 11.771(2)-12.996(3) and c = 12.871(1)-14.169(3) ?. In these complexes, introduction of the formyl group results in only minor differences between the conformations of the two phosphine ligands and the corresponding Au-P, Au-X, and Au-P-X bond lengths and angles. The crystal packings of [Ph₃PAuX] for X = Cl, Br, I and of [Ph₂(Ph-CHO)PAuX] for X = Br and I show that, while these structures are isomorphous, different supramolecular synthons may be present, suggesting global packing considerations are all-important rather than specific supramolecular interactions. This is borne out by the different packing found for the centrosymmetric [Ph₂(Ph-CHO)PAuCl] structure. Crystallization of the mixed anion structure [Ph ₃PAuSCN_0.91Br_0.09] in the above P2 ₁2₁2₁ lattice rather than the P2₁/c lattice reported for pure [Ph₃PAuSCN] suggests that co-crystallization with bromide may impose constraints on packing considerations which favor crystallization in the P2₁2₁2₁ lattice.

Full text of DOI:10.1016/j.molstruc.2014.05.020

Accepted Manuscript
Isomorphism in the structural chemistry of two-coordinate adducts of diphen-
yl(2-formylphenyl)phosphine and triphenylphosphine with gold(I) halides
Samuel P.C. Dunstan, Peter C. Healy, Alexandre N. Sobolev, Edward R.T.
Tiekink, Allan H. White, Michael L. Williams
PII:
S0022-2860(14)00504-3
DOI:
http://dx.doi.org/10.1016/j.molstruc.2014.05.020
MOLSTR 20619
Reference:
Journal of Molecular Structure
To appear in:
Received Date:
Revised Date:
Accepted Date:
28 March 2014
1 May 2014
9 May 2014
Please cite this article as: S.P.C. Dunstan, P.C. Healy, A.N. Sobolev, E.R.T. Tiekink, A.H. White, M.L. Williams,
Isomorphism in the structural chemistry of two-coordinate adducts of diphenyl(2-formylphenyl)phosphine and
triphenylphosphine with gold(I) halides, Journal of Molecular Structure (2014), doi: http://dx.doi.org/10.1016/
j.molstruc.2014.05.020
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

1
Isomorphism in the structural chemistry of two-coordinate adducts of
diphenyl(2-formylphenyl)phosphine and triphenylphosphine with gold(I)
halides.
Samuel P. C. Dunstana, Peter C. Healya,*, Alexandre N. Sobolevb, Edward R. T. Tiekinkc,
Allan H. Whiteb, Michael L.Williamsa
a
School of Biomolecular and Physical Sciences, Griffith University, Brisbane, Qld 4111, Australia
b
School of Chemistry and Biochemistry M310, The University of Western Australia, Crawley, WA 6009,
Australia
c
Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
ABSTRACT
Single crystal X-ray structure determinations are recorded for diphenyl(2-formylphenyl)phosphine gold(I)
halides [Ph2(Ph-CHO)PAuX], X = Cl, Br and I, and for redeterminations of enhanced precision for
triphenylphosphine gold(I) halides [Ph3PAuX], X = Cl, Br, I, and SCN0.91Br0.09. These complexes, other than
[Ph2(Ph-CHO)PAuCl], together with a diverse array of other structures, crystallize as an isomorphous series in
the orthorhombic space group P212121 a = 9.804(1) – 11.906(3), b = 11.771(2) – 12.996(3) and c = 12.871(1) –
14.169(3) Å. In these complexes, introduction of the formyl group results in only minor differences between
the conformations of the two phosphine ligands and the corresponding Au-P, Au-X, and Au-P-X bond lengths
and angles. The crystal packings of [Ph3PAuX] for X = Cl, Br, I and of [Ph2(Ph-CHO)PAuX] for X = Br and I
show that, while these structures are isomorphous, different supramolecular synthons may be present,
suggesting global packing considerations are all-important rather than specific supramolecular interactions.
This is borne out by the different packing found for the centrosymmetric [Ph2(Ph-CHO)PAuCl] structure.
Crystallization of the mixed anion structure [Ph3PAuSCN0.91Br0.09] in the above P212121 lattice rather than the
P21/c lattice reported for pure [Ph3PAuSCN] suggest that co-crystallization with bromide may impose
constraints on packing considerations which favour crystallization in the P212121 lattice.
Keywords: Gold(I) complexes; Phosphine ligands; Crystal structures; Isomorphism.
*Corresponding author. Tel +617 3735 7442
E-mail address: P.Healy@griffith.edu.au
U:\ES\Autopdf\sfive\OutPS\ForPS\MOLSTR_20619.doc/ib/15/05/2014

2
1. Introduction
Structural studies of the neutral 1:1 complexes of the univalent coinage metal halides
with monodentate tertiary aryl-phosphine ligands, [R3P-M-X]n (M = Cu, Ag, Au; X = Cl, Br,
I) have shown that adducts with M = Cu and Ag crystallize as three- and four- coordinate
molecular oligomeric clusters (most notably for n = 4 as ‘cubane’ and ‘step’ M4X4 tetramers
for triphenylphosphine [1]) with two-coordinate monomeric [R3P-M-X] isolated only with
highly sterically hindered ligands such as tris(trimethylphenyl)phosphine or
tris(trimethoxyphenyl)phosphine [2]. By contrast, the analogous complexes with M = Au
crystallize exclusively as [R3P-Au-X] monomers with the P-Au-X bond angle deviating only
slightly from linearity, irrespective of the steric or electronic properties of the phosphine [3].
For these complexes, formal charges on the gold and halide atoms are +1 and -1 respectively.
However, density functional calculations on [Ph3PAuCl] [4] have suggested that electron
density is transferred from phosphorus to gold with the resultant charges on the P, Au and Cl
atoms calculated to be 1.135, 0.003 and −0.963 (electron units) respectively, with the
possibility that the charge on the phosphorus may be further delocalized to result in increased
positive charge on the phenyl hydrogen atoms [5]. Thus, rather than the formation of
oligomeric clusters through inter-molecular M...X bonding as found for the copper and silver
complexes, aggregation of the gold complexes in crystalline solids has been found to occur
through a range of intermolecular interactions including Au...X interactions, aurophilic
Au...Au and Au...π interactions, which, together with C-H...X, X... πand π…π interactions
results in the formation of diverse arrays of supramolecular crystal structures [6, 7].
A survey of the literature shows that the triphenylphosphine gold(I) halide complexes,
[Ph3PAuX], are members of an isomorphous series of [R3L-M-X] compounds for L = P, As;
M = Au, I, Br; X = monovalent anion, which crystallize in the orthorhombic space group
P212121 Z = 4 with unit cell dimensions a = 9.804(1) – 11.906(3), b = 11.771(2) – 12.996(3)
and c = 12.871(1) – 14.169(3) Å (labelled here as the alpha series). Complexes currently
identified as belonging to this series include [Ph3P-Au-X] for X = Cl, Br, I, CN, CNO, NCO,
SCN, O2CCH3and O2CCF3 [4, 8]; [Ph2(2-NH2Ph)P-Au-I], [Ph2(1-Me-imidazole)P-Au-Cl],
[m-tolyl3P-Au-X] for X = Cl and CN, [(m-FPh)3P-Au-Cl] [9]; [Ph3As-Au-X] for X = Cl and
Br [10]; and [Ph3P-Br-Br], [Ph3P-I-I] [11]. A second, closely related, series of isomorphous
structures in the space group P212121 with unit cell dimensions a = 11.5642(1) – 12.689(4), b =
12.622(2) – 13.963(3) and c = 10.974(2) – 11.403(1) Å (beta series) have been recorded for
the complexes [Ph3As-Au-Cl] [10a], [Ph3P-Au-N3] [12a] [Ph3P-Au-(1,2,3-triazolate)] [12b],
[Ph3P-Au-(perfluorovinyl))] [12c] and Ph3As-I-I [12d], with polymorphs of [Ph3AsAuCl]
represented in both αand βseries.

3
In this present study, we have determined single crystal structures of the diphenyl(2-
formylphenyl)phosphine complexes [Ph2(Ph-CHO)AuX] for X = Cl, Br and I. The bromide
and iodide complexes in this series crystallize as new members of the αseries, while, as also
reported previously [13], the chloride crystallizes in the centrosymmetric space group P1
with two independent molecules comprising the asymmetric unit. As part of this work we
have also re-determined the crystal structures of the gold triphenylphosphine complexes
[Ph3P-Au-X] for X = Cl, Br, I and SCN with the aim of providing structural data of
comparable precision for these compounds.
2. Experimental
2.1. Preparation and crystallization of compounds.
The ligands Ph2(Ph-CHO)P and Ph3P were obtained commercially. [Ph2(Ph-
CHO)PAuX] for Cl, Br and I and [Ph3PAuBr] were prepared by dissolution of equimolar
quantities of [NBu4][AuX2] and the phosphine ligand in warm dimethylformamide to give
clear solutions from which slow evaporation of solvent yielded colourless air-stable crystals.
[Ph2(Ph-CHO)PAuCl] [Bu4N][AuCl2] (0.112 mg, 0.22 mmol) and Ph2(Ph-CHO)P (64 mg,
0.22 mmol), m.p. 196-197oC. Anal. Found C 43.82, H 2.87; Calc. for C19H15AuClOP C
43.66, H 2.89%. [Ph2(Ph-CHO)PAuBr] [Bu4N][AuBr2] (0.114 g, 0.19 mmol) and Ph2(Ph-
CHO)P (54 mg, 0.19 mmol), m.p. 201-203oC. Anal. Found C 40.26, H 2.58; Calc. for
C19H15AuBrOP C 40.24, H 2.67%. [Ph2(Ph-CHO)PAuI] [Bu4N][AuI2] (0.130 g, 0.19 mmol)
and Ph2(Ph-CHO)P (54 mg, 0.19 mmol), m.p. 202-204oC. Anal. Found C 36.99, H 2.35;
Calc. for C19H15AuIOP C 37.16, H 2.85%. [Ph3PAuBr] [Bu4N][AuBr2] (0.300 g, 0.50
mmol) and Ph3P (0.138g, 0.53 mmol) m.p 253-254oC.
Crystals of [Ph3PAuCl] were obtained by recrystallization from dichloromethane of a
sample previously prepared by the addition of chloroauric acid to triphenylphosphine
according to the method of ref. [14]. Crystals of [Ph3PAuI] were obtained from a sample
prepared previously [8a] which had been crystallized from an acetone solution of Ph3PAuCl
and hydro-iodic acid according to the method of ref. [15]. Synthesis of both the chloride and
iodide adducts by the reaction of Ph3P and [NBu4][AuX2], X = Cl, I, followed by re-
crystallization from a range of organic solvents and determination of unit cell dimensions
revealed no evidence for polymorphism in the resultant crystal lattices. A crystal of
‘[Ph3PAuSCN]’ was retrieved from the original sample prepared by crystallization from a
solution of Ph3PAuBr and KSCN [8a] and, as discussed below, has been modelled in a
subsequent improved redetermination as a SCN/Br co-crystal with 91% [Ph3PAuSCN] and
9% [Ph3PAuBr].

4
2.2 X-ray structure determinations
CCD area-detector diffractometer data sets were measured at ca. 153 and 223 K
(monochromatic Mo Kαradiation, λ= 0.71073 Å) yielding N(total) reflections, these merging to
N unique (Rint cited) after 'empirical'/multi-scan absorption correction (proprietary software),
No with I > 2σ(I) being considered 'observed'; all data were used in the full-matrix least-
squares refinements on F2, refining anisotropic displacement parameter forms for the non-
hydrogen atoms, hydrogen atom treatment following a 'riding' model; reflection weights were
2
[σ(Fo2) + (aP)2 + (bP)]-1 [P = (Fo2 + 2Fc2)/3]. Friedel data were retained distinct and xabs
refined in all cases. Computation used SHELX 97, ORTEP-3 for Windows and PLATON
[16]. Pertinent results are given below and in the Tables and Figures, the latter showing 50%
probability amplitude displacement ellipsoids for the non-hydrogen atoms, hydrogen atoms
having arbitrary radii of 0.1 Å. Crystal data and final refinement details are given in Table 1.
The phenyl carbon atoms of the phosphine ligands are labelled (mn where m is the ring
number (1-3) and n the atom number (1-6). Atom 1 is the ipso carbon and atom 2 the ortho
carbon endo to the gold coordination sphere. Full .cif files have been deposited with the
Cambridge Crystallographic Data Centre, CCDC Nos. 638229 – 638232 for [PPh3AuX], X =
Cl, Br, I, SCN and 969332 - 969334 for [Ph2(Ph-CHO)PAuX], X = Cl, Br, I. Copies can be
obtained free of charge on application to The Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (Fax: int. (1223)336-033; e-mail for inquiry: fileserv@ccdc.clam.ac.uk.
Variata. The structure determination of [Ph3PAuSCN] recorded in ref. [8a] was less
satisfactory at that time than those of the chloride and bromide, with limited data supporting
only isotropic displacement parameter refinement for the peripheral non-hydrogen atoms.
Redetermination of the structure using the data acquired in the present study yielded a model
in which it became evident that the thiocyanate sulfur site was overlaid with another heavy
atom component. Trial refinement as bromide, presumably originating from the starting
materials and noted earlier as 'minor impurities', refined to 9% occupancy, yielding a credible
model in terms of associated geometry and displacement parameter refinement. With the
results of this experiment in mind, particular attention was paid to the modelling of the halide
throughout the other structures reported here, but in no case was anything other than a
homogeneous model with occupancy of unity for the anion considered necessary.
3. Results and discussion
3.1. Gold coordination environments for [Ph2(Ph-CHO)PAuX] and [Ph3PAuX], X = Cl, Br, I.
Interatomic distances, bond angles and torsion angles for the complexes and related
data for the parent ligands, Ph2(Ph-CHO)P [17a] and Ph3P [18] are presented in Tables 2 and

5
3. In the molecular structure of Ph2(Ph-CHO)P [17a] the formyl group adopts the O-cis
conformer and is co-planar with the phenyl ring with the C-C-C-O torsion angle 1.8(5)o
(Fig. 1). The carbonyl oxygen atom is located above the plane of the three ipso carbons of
the aromatic rings and acts as a donor to the phosphorus atom with the P...O distance
2.834(2) Å [19]. The P-C bond lengths and C-P-C bond angles are equivalent within
experimental error to those reported for Ph3P, with average P-C bond lengths and C-P-C
angles of 1.837(3) Å and 102.4(5)o for Ph2(Ph-CHO)P compared to 1.831(3) Å and
102.8(9)o for Ph3P. The conformational structures of the phenyl rings in the two compounds
are also similar, with the torsion angles between the normal to the plane of the three ipso
carbons and the Cipso – Cortho bonds -51.9, -44.8 and -27.9o for Ph2(Ph-CHO)P and 55.9,
27.1, 24.7o for Ph3P.
Fig. 1 Molecular structure of Ph2(Ph-CHO)P showing the close O...P approach [17a].
For the [Ph3PAuX] halide complexes, unlike the previous less precise structure
determinations for the bromide and iodide [8a], it is now evident that the Au-P bond lengths
show the expected monotonic increase [20] with values of 2.2280(11) Å (Cl), 2.2368(8) Å
(Br) and 2.2533(5) Å (I).
For the [Ph2(Ph-CHO)PAuX] halide complexes, the bromide and iodide are

6
isomorphous with the αseries. For the bromide, no significant difference compared to the
[Ph3PAuBr] counterpart is observed in either the Au-P or Au-Br bond lengths, while for the
iodide complexes, there is a small difference of the order of 0.01 Å in the Au-I bond length.
In contrast, as also previously reported [13], [Ph2(Ph-CHO)PAuCl] crystallizes in the
centrosymmetric triclinic space group P1, with two independent molecules comprising the
asymmetric unit. Nevertheless, with two independent determinations of comparable
precision, the differences in the Au-P and Au-Cl with the [PPh3AuCl] adduct are relatively
minor. In both series of complexes, the P-Au-X angles lie above 178º, with only small
differences between the angular parameters of Ph2(Ph-CHO)P and PPh3 (Tables 2, 3).
The impact of the carbonyl oxygen on the gold atom coordination environment in the
[Ph2(Ph-CHO)PAuX] complexes appears to be minor or non-existent. As for the parent
ligand [17a], the 2-formyl group in the complexes exists as the O-cis isomer and is coplanar
with the parent phenyl rings with τ(C-C-C-O): Cl (molecules 1, 2), 0.8(8)o, 1.4(8)o; Br;
1.8(11)o; I, –0.6(8)º. The P…O distances are 2.890(4), 2.892(3) Å for molecules 1 and 2 of
the chloride complex, 2.852(5) Å for the bromide complex and 2.815(3) Å for the iodide
complex. The Au...O distances are 3.114(4), 3.120(3) Å (Cl), 3.112(5) Å (Br) and 3.136(4)
Å (I) with only small, if any, impact on the associated phenyl ring dispositions. These
distances may be compared with those found in other systems with an oxygen atom pendant
from the 2-position in one of the phenyl rings: for systems immediately pendant, in the 2-
OH/chloride complex [21], Au...O is 3.160(7) Å, comparable with the present structures,
while with the more sterically demanding 2-Me3SiO substituted ligand in the chloride and
iodide arrays, the distances are appreciably longer 3.353(2), 3.297(7) and 3.251(7) Å [22]. In
the 2-carboxymethyl/chloride complex with the oxygen atom further displaced, Au...O is
3.037(5) Å [21]; while in tris(2-methoxy-phenyl)phosphine gold chloride, bromide and
iodide [7j], all Au...O distances are greater than 3.24 Å. In none of these structures, does the
Au...O contact appear to have anything other than a minor impact on the P-Au-X angle.
3.2. Crystal packings for [Ph3PAuX] and [Ph2(Ph-CHO)PAuX], X = Cl, Br, I
As noted above, the [Ph3PAuX] crystal structures for X = Cl, Br and I and the [Ph2(Ph-
CHO)PAuX] crystal structures for X = Br and I form part of the isomorphous αseries. Cell
dimensions for the full series of these compounds (transformed where required from the
original data to form a consistent packing array), together with M-P bond lengths and M-P-
Cm1-Cm2 torsion angles, τ , (m = 1-3) are listed in Table 4. The atom numbering adopted
m

7
globally for the present series of complexes, and to which the data of other studies, including
free ligands, have been referred in making the present comparisons, is shown in Fig. 2.
Fig. 2
Molecular projection of [Ph2(Ph-CHO)PAuBr] showing the atom numbering
scheme adopted in the description of the present comparative study of complexes and
ligands.
In these compounds, the three phenyl rings are numbered in a counter clock-wise
direction viewed down the X-M-P axis with values of τ generally decreasing in the order τ >
m
1
τ > τ with the range of values 54–71o, 21–50o, and 22–43o respectively. For the [Ph2(Ph-
2
3
CHO)PAuX] adducts , the 2-formyl group is located in ring 1. The similarities in the
conformational structures of the Ph2(Ph-CHO)P and Ph3P ligands is reflected also in the
small differences observed in the magnitudes of τ .
m
In the crystal lattices of these complexes, the Au...Au distances range from 6.8 - 7.6 Å.
The P-Au-X vectors are directed along the [100] direction with inter-molecular C-H...X
interactions in the Ph3P complexes of 2.79 Å (Cl), 2.92 Å (Br) and 3.11 Å (I) between the
halide and para proton H24 from ring in the molecule at (½+x, ½-y, -z). The anion
environment is characterized by the P-Au-X vector lying approximately perpendicular to ring
1 of the molecule at (1+x, y, z) with X...Cg distances of 4.25 Å (Cl), 4.07 Å (Br) and 4.04 Å

8
(I), indicating increasing significance of these interactions in their respective crystal
structures. Along the [010] direction, crystal packing for this structure consists of a helical
chain of antiparallel monomers linked by (EF)3 embraces [6]. Within this chain weak
Au…π interactions, are also apparent between Au and ring 3 of the adjacent molecule at (-x,
aryl
½+y, ½-z) with Au….Cg distances (d) of 4.05 Å (Cl), 4.19 Å (Br), 4.26 Å (I), Fig. 3.
Fig. 3. View of the crystal packing down the c-axis for Ph3PAuBr with Au...πand Br...π
interactions shown as orange and purple dashed lines, respectively.
While crystallizing as members of the αseries, the crystal packing of [Ph2(Ph-
CHO)PAuX] for X = Br and I presents different features with the appearance of C-H...O
contacts [H...O distances = 2.41 Å (Br) and 2.45 Å (I)], that lead to supramolecular chains
along the c axis, and C-H...π(ring 1) [H...Cg distances = 2.89 Å (Br) and 2.93 Å (I)]; the
Br...π(ring 1) contacts persist with Br….Cg distances (d) of 4.03 Å (Br) and 3.99 Å (I), (Fig.
4).

9
Fig. 4. View of the crystal packing down the a-axis for [Ph2(Ph-CHO)PAuBr] with C-H...O,
C-H...πand Br...πinteractions shown as orange, purple and blue dashed lines, respectively.
For the centrosymmetric chloride complex, [Ph2(Ph-CHO)PAuCl], Fig. 5, the values of
τ are found to be similar for the two independent molecules in the asymmetric unit, with
m
values of -60.2(4), -42.4(4), -3.1(4)o for molecule 1 and -65.1(4), -41.4(4) and 0.5(4)o for
molecule 2. The major difference in these angles with respect to the αstructures is the
rotation of ring 3
by ~ 30o.

10
Fig. 5 Molecular projection of one of the two independent molecules of [Ph2(Ph-
CHO)PAuCl] also representative of the second which incorporates an additional 'a' in the
atomic labels.
Both molecules in this lattice crystallize in close association with an inversion related
image to form loose dimer pairs in which the Au...Au distances of 5.48 Å (molecule 1) and
5.62 Å (molecule 2) are shorter than those observed for the αstructures, but are still too long
to indicate the presence of significant Au...Au aurophilic interactions. Centrosymmetrically
related molecules associate via weak Au...π(ring 3) interactions of 3.71 Å (molecule 1) and
3.90 Å (molecule 2), and other pairs via C-H...O contacts to form a supramolecular layer in
the ab-plane (Fig. 6a). These are connected in a three-dimensional architecture by a
combination of C-H...Cl interactions, whereby molecules of 1 are linked into a linear
supramolecular chain (H...Cl = 2.82 Å), and C-H...π(ring 2) interactions (Fig. 6b).

11
(a)
(b)
Fig. 6. (a) View of the supramolecular layer in the ab-plane in the crystal structure of
[Ph2(Ph-CHO)PAuCl] sustained by Au...πand C-H...O interactions, and (b) view of the unit
cell contents in projection down the a-axis. The Au...π, C-H...O, C-H...Cl and C-H...π
interactions are shown as orange, brown, blue and purple dashed lines, respectively.
3.3 General features of the P212121 αseries of complexes.
While this present paper has focused on the similarities and differences in
homomolecular structure and crystal packing of the [Ph3PAuX] and [Ph2(Ph-CHO)PAuX]
series of complexes for X = Cl, Br, I, there are a number of interesting features of the αseries
of compounds that warrant mention:
• The range of anions for these isomorphous / isostructural complexes extends from
simple halides and pseudo halides to acetate and trifluoroacetate.
• The range of phosphine and arsine ligands include Ph3P, Ph3As, Ph2(2X-Ph)P, Ph2(Me-
imidazoly)P, m-tolyl3P, m-tolyl3As, m-FPh3P. i.e. ortho and meta H atoms and the
presence of either P or As atoms are not critical in the determination of the crystal
lattice.
• The substitution of Au by halide in Ph3PX2 and Ph3AsX2 structures – suggesting that

12
the weak Au...πinteractions in these complexes are similar to X....πinteractions [6].
• The lack of polymorphism in the gold(I) members of the series - with the only
exception to date being observed for [Ph3AsAuCl] [10a] which crystallizes
simultaneously as needles (αseries) and as prisms (βseries), and, potentially, for
[Ph3PAuSCN] [7b, 8a] (see below).
3.4 The P212121 structure of [Ph3PAuSCN]
Since the original determination of the structure of [Ph3PAuSCN] in space group
P212121 [8a], a further determination [7c] has proved to be that of a new monoclinic P21/c
form, one molecule devoid of crystallographic symmetry comprising the asymmetric unit of
the structure, indicating polymorphism for this complex. The refinement of the P21/c
structure was straightforward, resulting in Au-P, S bond lengths of 2.2542(13), 2.3312(15) Å
and P-Au-S, Au-S-C angles of 177.88(5), 85.4(3)º. In this form, unlike the P212121 complex,
the Au-X (= SCN) component lies in close proximity to an inversion image, forming a loose
dimer (Au...S' 3.495(1) Å), impacting only weakly on the P-Au-S angle. As noted in the
Experimental section, our original structure determination of ‘[Ph3PAuSCN]’ in space group
P212121 was of inferior quality with limited data supporting only isotropic displacement
parameter refinement for the light atoms. With stable crystals of the original sample of
[Ph3PAuSCN] associated with this determination still in hand, the acquisition of greatly
improved low-temperature data supported a superior model, with incorporation of bromide as
a minor impurity component, consistent with the earlier solid-state 31P CPMAS NMR data
[8a] and refinement behaviour, to the extent of ca. 9%. With that model, Au-P, S, Br are
2.2552(8), 2.3242(10), 2.407(5) Å, with P-Au-S, Br 174.70(4), 167.42(11)º and Au-S-C
102.7(12)º, the distances being very similar to those of related compounds although the
angular deviations are considerable, probably beyond what might be expected as consequent
upon the disorder. Crystals of the monoclinic form were reported as being obtained from
dichloromethane/pentane solution, a system not unlike that which yielded our P212121 α
complex, suggesting that crystallization with bromide may impose constraints consequent on
solubilities/solvent interactions which favour the formation of the complex as a member of
the αseries.
Conclusion
In the structures of the [Ph3PAuX] and [Ph2(Ph-CHO)PAuX] halide complexes,
introduction of the -CHO group results in only very minor differences in the conformational
structures of the phosphine ligands and the corresponding Au-P, Au-X and P-Au-X bond

13
lengths and angles. There is also remarkable homogeneity in the symmetry of crystal
packing exhibited by a range of related/similar phosphine gold(I) species, in that they
uniformly adopt the non-centrosymmetric orthorhombic space group P212121. As shown by
an examination of the crystal packing of [Ph3PAuX], X = Cl, Br, I, and [Ph2(Ph-
CHO)P)AuX], X = Br, I, while these are isomorphous, different supramolecular synthons
may be present, suggesting that global crystal packing considerations, i.e. the packing of
quasi-spherical aggregates, are all important - rather than specific supramolecular
interactions. This is borne out by the different packing found for the centrosymmetric
[Ph2(Ph-CHO)P)AuCl] complex. The isolation of [Ph3PAuSCN] as a member of the αseries
when crystallized in the presence of bromide as a minor impurity suggests that further co-
crystallization experimentation may expand the range of complexes found for this
polymorph.
Acknowledgements
We thank the University of Western Australia and Griffith University for support of this
work, and Dr Bradley Loughrey and Dr Ben Cunning for helpful assistance with the project.
The Ministry of Higher Education (Malaysia) and the University of Malaya is also thanked
for funding through the High-Impact Research scheme (UM.C/HIR-MOHE/SC/03).
References
[1] (a) L. Maini, D. Braga, P.P. Mazzeo, B.Ventura, Dalton Trans. 41 (2012) 531;
(b) P.F. Barron, J.C. Dyason, L.M. Engelhardt, P.C. Healy, A.H. White, Inorg. Chem.
23 (1984) 3766;
(c) J.C. Dyason, P.C. Healy, L.M. Engelhardt, C. Pakawatchai, V.A. Patrick, C.L.
Raston, A.H. White, J. Chem. Soc., Dalton Trans. (1985) 831;
(d) G.A. Bowmaker, Effendy, R.D. Hart, J.D. Kildea, A.H. White, Aust. J. Chem. 50
(1997) 653;
(e) G.J.S. Venter, A. Roodt, R. Meijboom, Inorg. Chim. Acta 362 (2009) 2475.
[2] (a) E.C. Alyea, G. Ferguson, J. Malito, B.L. Ruhl, Inorg. Chem. 24 (1985) 3719;
(b) G.A. Bowmaker, J.D. Cotton, P.C. Healy, J.D. Kildea, S. bin Silong, B.W. Skelton,
A.H. White, Inorg. Chem. 28 (1989) 1462;
(c) L.-J. Baker, G.A. Bowmaker, R.D. Hart, P.J. Harvey, P.C. Healy, A.H. White,

14
Inorg. Chem. 33 (1994) 3925;
(d) L.-J. Baker, G.A. Bowmaker, D. Camp, Effendy, P.C. Healy, H. Schmidbaur, O.
Steigelmann, A.H. White, Inorg. Chem. 31 (1992) 3656.
[3] (a) P.G. Jones, A.F. Williams, J. Chem. Soc., Dalton Trans. (1977) 1430;
(b) R.C. Bott, G.A. Bowmaker, R.W. Buckley, P.C. Healy, M.C. Senake Perera, Aust.
J. Chem. 52 (1999) 271.
[4] A.O. Borissova, A.A. Korlyukov, M.Y. Antipin, K.A. Lyssenko, J. Phys. Chem. A 112
(2008) 11519.
[5] B.T. Loughrey, B.V. Cunning, P.C. Healy, C.L. Brown, P.G. Parsons, M.L. Williams,
Chem. Asian J. 7 (2012) 112.
[6] (a) N.A. Barnes, K.R. Flower, S.M. Godfrey, P.A. Hurst, R.Z. Khan, R.G. Pritchard,
CrystEngComm 12 (2010) 4240;
(b) I. Dance, M. Scudder, CrystEngComm 11 (2009) 2233.
[7] (a) N.A. Barnes, K.R. Flower, S.A. Fyyaz, S.M. Godfrey, A.T. McGown, P.J. Miles,
R.G. Pritchard, J.E. Warren, CrystEngComm 12 (2010) 784;
(b) H.W. Chen, E.R.T. Tiekink, Acta Crystallogr., Sect. E 59 (2003) m50;
(c) D. Schneider, S. Nogai, A. Schier, H. Schmidbaur, Inorg. Chim. Acta 352 (2003)
179;
(d) R.C. Bott, P.C. Healy, G. Smith, Aust. J. Chem. 57 (2004) 213;
(e) K. Nunokawa, S. Onaka, T. Tatematsu, M. Ito, J. Sakai, Inorg. Chim. Acta 322
(2001) 56;
(f) E.R.T. Tiekink, J. Zukerman-Schpector, CrystEngComm 11 (2009) 1176;
(g) I. Caracelli, J. Zukerman-Schpector, E.R.T. Tiekink, Gold Bull. 46 (2013) 81.
(h) D.V. Partyka, T.J. Robilotto, M. Zeller, A.D. Hunter, T.G. Gray, Organometallics
27 (2008) 28;
(i) P.C. Healy, Acta Crystallogr., Sect. E 59 (2003) m1112;
(j) R.C. Bott, P.C. Healy, G. Smith, Polyhedron 26 (2007) 2803;
(k) P. Politzerm, P. Lane, M.C. Concha, Y. Ma, J.S. Murray, J. Mol. Model. 13 (2007)
305.
[8] (a) P.F. Barron, L.M. Engelhardt, P.C. Healy, J. Oddy, A. H. White, Aust. J. Chem. 40
(1987) 1545;
(b) S. Arland, K. Dreisch, B. Noren, A. Oskarsson, Acta Chem. Scand. A 41 (1987)
173;
(c) P.L. Bellon, M. Manassero, M. Sansoni, Ric. Sci. 39 (1989) 173;
(d) P.G. Jones, J. Lautner, Acta Crystallogr., Sect. C 44 (1988) 2091;

15
(e) W.P. Bosman, W. Bos, J.M.M. Smits, P.T. Beurskens, J.J. Bour, J.J. Steggerda,
Inorg. Chem. 25 (1986) 2093;
(f) P.G. Jones, Acta Crystallogr., Sect. C 40 (1984) 1320;
(g) Z.-Y. Zhang, E. Szlyk, G.J. Palenik, S.O. Colgate, Acta Crystallogr., Sect. C 44
(1988) 2197.
[9] (a) P. Papathanasiou, G. Salem, P. Waring, A.C. Willis, J. Chem. Soc., Dalton Trans.
(1997) 3435;
(b) V.J. Catalano, S.J. Horner, Inorg. Chem. 42 (2003) 8430;
(c) C.S.W. Harker, E.R.T. Tiekink, Acta Crystallogr., Sect. C 47 (1991) 878;
(d) A.R. Al-Arfaj, J.H. Reibenspies, M.S. Hussain, A.A. Isab, Acta Crystallogr., Sect.
C 54 (1998) 716;
(e) O. bin Shawkataly, A. Tariq, S.S. Ghani, C.S. Yeap, H.-K. Fun, Acta Crystallogr.,
Sect. E 66 (2010) m1217.
[10] (a) B. Weissbart, L.J. Larson, M.M. Olmstead, C.P. Nash, D.S. Tinti, Inorg. Chem. 34
(1995) 393;
(b) F.W.B. Einstein, R. Restivo, Acta Crystallogr., Sect. B 31 (1975) 624.
[11] (a) N. Bricklebank, S.M. Godfrey, A.G. Mackie, C.A. McAuliffe, R.G. Pritchard, J.
Chem. Soc., Chem. Commun. (1992) 355;
(b) S.M. Godfrey, D.G. Kelly, C.A. McAuliffe, A.G. Mackie, R.G. Pritchard, S.M.
Watson, J. Chem. Soc., Chem. Commun (1991) 1163.
[12] (a) W. Beck, T.M. Klapötke, P. Klüfers, G. Kramer, C.M. Rienäcker, Z. Anorg. Allg.
Chem. 627 (2001) 1669;
(b) K. Nomiya, R. Noguchi, K. Ohsawa, K. Tsuda, J. Chem. Soc., Dalton Trans.
(1998) 4101.
(c) N.A. Barnes, A.K. Brisdon, W.I. Cross, J.G. Fay, J.A. Greenall, R.G. Pritchard, J.
Sherrington, J. Organomet. Chem. 616 (2000) 96.
(d) C.A. McAuliffe, B. Beagley, G.A. Gott, P.P MacRory, R.G. Pritchard, Angew.
Chem., Int Ed., 26 (1987) 264.
[13] M.R.J. Elsegood, M.B. Smith, S.H. Dale, Acta Crystallogr., Sect. E 62 (2006) m1850.
[14] C. Kowala, J.M. Swan, Aust. J. Chem. 19 (1966) 547.
[15] A.D. Westland, Can. J. Chem. 47 (1969) 4135.
[16] (a) G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112;
(b) L.J. Farrugia, J. Appl. Cryst. 45 (2012) 849;
(c) A.L. Spek, J. Appl. Cryst. 36 (2003) 7.
[17] (a) A. Chandrasekaran, R.O. Day, R.R. Holmes, Inorg. Chem. 40 (2001) 6229;

16
(b) E.F. Landvatter, T.B. Rauchfuss, Organometallics 1 (1982) 506. Delaunay cell
reduction shows the structures reported in these papers to have the same unit cell.
[18] B.J. Dunne, A.G. Orpen, Acta Crystallogr., Sect. C 47 (1991) 345.
[19] T. Schaefer, R. Sebastian, R.W. Schurko, F.E. Hruska, Can. J. Chem. 71 (1993) 1384.
[20] A.Y. Sokolov, O.V. Sizova, Russian J. Gen. Chem. 80 (2010) 1223.
[21] C. Hollatz, A. Schier, H. Schmidbaur, Z. Naturforsch. 54b (1999) 30.
[22] U. Monkowius, M. Zabel, Acta Crystallogr., Sect. E 64 (2008) m196.

17
Table 1
4
Crystal data for [Ph3PAuX] for X = Cl, Br, I, (SCN)0.91Br0.09 and [Ph2(Ph-CHO)PAuX] for X = Cl, Br, I. All are space group P212121 (orthorhombic, D2 , No. 19), Z = 4.*
[C18H15PAu
(SCN)0.91Br0.09
[C18H15PAuI]
Compound
[C18H15PAuBr]
[C19H15OPAuCl]*
[C19H15OPAuBr]
[C19H15OPAuI]
[C18H15PAuCl]
]
Mr (Da)
a (Å)
494.7
539.2
586.1
519.3
522.7
567.2
614.1
10.116(2)
12.266(3)
13.002(3)
1613.3(6)
2.037
9.9916(8)
12.338(1)
13.362(1)
1647.2(2)
2.174
10.1325(8)
12.348(1)
13.794(1)
1725.9(2)
2.256
10.7673(9)
11.9860(10)
13.6240(10)
1758.3(2)
1.962
10.2723(6)
10.5347(7)
16.7150(11)
1696.4(2)
2.047
9.9223(8)
12.5063(10)
14.0493(11)
1743.4(2)
2.161
10.0367(5)
12.6677(7)
14.1504(8)
1799.1(2)
2.267
b (Å)
c (Å)
V (Å3)
dcalc (g cm–3)
specimen (mm)
µMo (mm–1)
'T'min/max
2θmax (o)
0.14x0.07x0.06
9.4
0.14x0.11x0.11
11.4
0.19x0.11x0.09
10.4
0.25x0.10x0.10
8.8
0.47x0.21x0.16
8.9
0.49x0.34x0.22
10.8
0.39x0.26x0.12
10.0
0.59
0.81
0.53
0.46
0.26
0.182
0.169
75
75
75
75
60
60
60
Nt
32325
32857
34521
35010
14249
14327
14934
N (Rint)
8516 (0.053)
6725
8649(0.047)
7493
9079(0.026)
8448
9244(0.041)
7470
9730(0.024)
7970
5081(0.034)
4645
5220(0.031)
4716
No
R1
0.036
0.029
0.019
0.036
0.034
0.032
0.024
wR2 (a(,b))
0.068 (0.027, 0.24) 0.056 (0.021)
0.041 (0.021)
1.01
0.070 (0.033)
1.00
0.084 (0.042)
0.98
0.078 (0.037)
1.09
0.047 (0.010)
0.83
S
1.00
1.05
xabs
T (K)
-0.028(6)
153
-0.020(6)
153
-0.017(2)
153
-0.001(6)
153
n/a
0.013(10)
223
0.019(4)
223
223
*Exception: [Ph2(Ph-CHO)PAuCl] which is P1, Z = 4 (α, β, γ= 97.249(1), 103.535(1), 101.270(1)º).
U:\ES\Autopdf\sfive\OutPS\ForPS\MOLSTR_20619.doc/ib/15/05/2014

18
Table 2
Au-P and Au-X bond lengths and P-Au-X bond angles for [Ph2(Ph-CHO)PAuX] and [PPh3AuX] for X = Cl, Br, I.
Au-P (Å)
X = Br
Au-X (Å)
X = Br
P-Au-X(º)
X = Br
Ref., T (K)
This work, 223
[13], 120
R3P
X = Cl
X = I
X = Cl
X = I
X = Cl
178.13(4)
178.80(5)
178.12(5)
178.79(5)
X = I
Ph2(Ph-CHO) P
2.2315(12) 2.2398(14) 2.2515(10)
2.2810(13)
2.2807(11)
2.2836(14)
2.2819(13)
2.4050(7)
2.5539(4)
179.89(4)
179.17(3)
2.2304(11)
2.2304(14)
2.2297(13)
Ph3P
2.2280(11) 2.2366(8)
2.2308(4)
2.2533(5)
2.2883(12)
2.2915(4)
2.4059(4)
2.5633(3)
179.17(4)
179.24(1)
179.74(2)
178.70(1)
This work, 153
[4], 100
U:\ES\Autopdf\sfive\OutPS\ForPS\MOLSTR_20619.doc/ib/15/05/2014

19
Table 3
Interatomic distances (Å), bond angles (o) and torsion angles τm (= Au-P-C(m1)-C(m2)) (º) for [Ph2(Ph-
CHO)PAuX] and [Ph3PAuX] complexes (present determinations) and for the free ligands Ph2(Ph-CHO)P [16a]
and Ph3P [17].
R3P
X
m
P-Cm1
Au-P-Cm1
Cm1-P-C(m+1)1
τm
______________________________________________________________________________________
R3PAuX
Ph2(Ph-CHO)P
Cl
Cl
Br
I
1
2
3
1
2
3
1
2
3
1
2
3
1.826(5)
1.809(4)
1.812(4)
1.830(5)
1.819(4)
1.812(5)
1.833(6)
1.828(6)
1.819(6)
1.837(4)
1.813(4)
1.811(4)
113.4(2)
114.3(2)
111.9(2)
112.9(2)
117.0(2)
110.9(2)
112.3(2)
110.6(2)
116.4(2)
112.8(1)
110.4(1)
116.8(2)
105.6(2)
109.1(2)
101.5(2)
106.3(2)
106.6(2)
102.3(2)
107.3(3)
104.7(3)
104.6(3)
107.0(2)
104.7(2)
104.1(2)
–60.2(4)
–42.4(4)
–3.1(4)
–65.1(4)
–41.4(4)
0.5(4)
59.6(5)
40.6(5)
28.1(6)
58.5(4)
39.1(4)
29.8(4)
Ph3P
Cl
Br
I
1
2
3
1
2
3
1
2
3
1.813(1)
1.808(1)
1.811(1)
1.812(3)
1.803(3)
1.813(3)
1.814(2)
1.813(2)
1.814(2)
112.8(1)
111.9(1)
114.2(1)
112.9(1)
111.9(1)
114.4(1)
113.7(1)
111.3(1)
114.7(1)
107.6(2)
105.9(2)
103.8(2)
107.8(1)
105.2(2)
103.9(1)
107.0(1)
104.9(1)
104.6(1)
–57.4(1)
–42.41)
–30.2(1)
58.3(2)
42.8(3)
32.8(3)
–60.0(2)
–39.7(2)
–32.8(2)
Ligands
Ph2(Ph-CHO)P
1
2
3
1.839(2)
1.833(2)
1.838(3)
102.3(1)
102.9(1)
101.9(1)
–51.9
–44.8
–27.9
Ph3P
1
2
3
1.832(2)
1.828(2)
1.834(2)
101.7(1)
103.3(1)
103.3(1)
55.9
27.1
24.7
_______________________________________________________________________________________
τm for the ligands Ph2(Ph-CHO)P and Ph3P are the torsion angles between the normal to the plane of the three ipso
carbons and the Cipso – Cortho bonds.
U:\ES\Autopdf\sfive\OutPS\ForPS\MOLSTR_20619.doc/ib/15/05/2014

20
Table 4
Unit cell dimensions and torsion angle data τ for αand βP2 2 2 R L-M-X complexes wher L = P,As; M = Au, Br,
m
1
1
1
3
I, X= monovalent anion.
τ
1
τ
2
τ
3
R3L-M-X
a (Å)
b (Å)
c (Å)
V(Å)
M-L (Å) Ref. CCDC
αform
Ph3P-Au-Cl
Ph3P-Au-Br
Ph3P-Au-I
10.116(2)
9.9916(1)
12.266(3)
12.338(1)
13.002(3)
13.362(1)
13.794(1)
13.057(2)
12.871(1)
13.077(1)
13.624(1)
13.839(5)
14.169(3)
14.049(1)
1613.3
1647.2
1725.9
1684.6
1705.8
1692.9
1758.3
1849.0
1985.7
1743.2
–58
58
–42
43
–30
33
2.228(1)
2.237(1)
2.253(1)
2.278(2)
2.274(3)
2.222(1)
2.255(8)
2.207(3)
2.208(4)
2.240(1)
2.252(1)
2.269(4)
2.227(6)
2.288(2)
2.286(2)
2.225(1)
2.334(3)
2.342(5)
2.181(3)
2.481(4)
This work
This work
10.1325(8) 12.348(1)
–60
56
–40
45
–33
32
This work
Ph3P-Au-CN
Ph3P-Au-CNO
Ph3P-Au-NCO
10.388(2)
10.891(1)
10.782(1)
12.420(2)
12.169(1)
12.007(1)
[8d] CYTPAU01
[8e] DUCROI
[8e] DUCRIC
This work
–57
–56
63
–39
–36
26
–30
–29
30
Ph3P-AuSCN0.91Br0.09 10.7673(9) 11.986(1)
Ph3P-Au-O2CCH3
Ph3P-Au-O2CCF3
Ph2Ph-CHOP-Au-Br
Ph2(Ph-CHO)P-Au-I
Ph2(Ph-NH2)P-Au-I
(MeIm)Ph2P-Au-Cl
m-tolyl3P-Au-Cl
m-tolyl3P-Au-CN
m-FPh3P-Au-Cl
Ph3As-Au-Cl
11.088(3)
11.906(3)
9.9223(8)
12.050(4)
11.771(2)
12.506(1)
–54
59
–30
21
–33
36
[8f] CILYAX
[8g] GOJJOE
This work
60
41
28
10.0367(5) 12.6677(7) 14.1504(8) 1799.1
58
39
30
This work
10.220(2)
9.804(1)
12.689(4)
12.370(2)
12.994(4)
12.996(3)
14.112(4)
13.267(2)
13.371(2)
13.308(3)
13.221(1)
13.228(5)
13.637(1)
13.312(5)
13.673(3)
1830.1
1608.9
1952.2
1956.4
1695.6
1644.7
1728.6
1699.7
1858.4
56
41
29
[9a] NOWJIS
[9b] AVACIJ
[9c] SIVCEF
[9d] NOZMAQ
[9e] XAKGOH
[10a] YIKVIX
[10b] BTPASG
[11a] JOMSEJ
[11b] JITSIO
62
50
36
11.236(1)
11.312(2)
–68
–71
57
–45
–46
39
–27
–23
22
10.4028(8) 12.328(1)
10.203(4)
10.191(1)
10.030(5)
10.461(6)
12.186(4)
12.438(1)
12.73(1)
59
40
30
Ph3As-Au-Br
–59
58
42
–31
43
Ph3P-Br-Br
49
Ph3P-I-I
12.993(1)
57
45
38
βform
Ph3As-Au-Cl
Ph3P-Au-NNN
Ph3P-Au-N3C2
Ph3P-Au-CFCF2
Ph3As-I-I
11.929(2)
12.622(2)
10.974(2)
1644.7
46
–43
40
10
–13
15
12
8
31
–36
51
2.334(3)
2.237(1)
2.229(5)
2.272(3)
2.64(1)
[10a] YIKVIX01
[12a] EBUXEE
[12b] FIKQIZ
11.5642(1) 13.0993(1) 10.9252(1) 1655.0
12.689(4)
11.736(1)
12.056(4)
13.660(7)
13.433(2)
13.963(3)
10.93(1)
11.403(1)
10.990(4)
1894
1797.6
1850.0
47
43
[12c] GUKHUP
[12d] FESKAP
49
50

21
Graphical Abstract

22
Highlights
• [Ph3PAuX] (X = Cl, Br and I) crystallize as members of an isomorphous series the
chiral space group P212121.
• [Ph2(Ph-CHO)PAuX] (X = Br, I) belong to the same isomorphous series.
• [Ph2(Ph-CHO)PAuCl] crystallizes in the centrosymmetric space group P-1.
• The -CHO group results in very minor differences in the conformational structures.
• The observation of different supramolecular synthons suggest global packing dominates while
specific supra-molecular interactions comply with overall crystal packing.