Multinuclear NMR Spectroscopic and X-ray Crystallographic Studies of a Series of Mercury(II) Complexes Containing the Bidentate Phosphine Ligand Ph2PCH2Si(CH3)2CH 2PPh2 (L2)

Article abstract of DOI:10.1021/ic9704243

The bidentate phosphine ligand Ph₂PCH₂Si(CH₃)₂CH ₂PPh₂ (L²), an analogue of 1,3-bis(diphenylphosphino)-propane (dppp), coordinates to mercury(II) salts to form complexes of the general formula [HgX₂·L²] (X = Cl, Br, I, NCS). Infrared, Raman, and multinuclear (¹H, ¹³C, ³¹P, ¹⁹⁹Hg) NMR spectroscopic studies show that the complexes exhibit four-coordinate pseudotetrahedral metal geometry. [HgI₂(Ph₂PCH₂Si(CH₃) ₂CH₂PPh₂)] (1) crystallizes in the monoclinic space group P2₁/n with a = 13.028(2) A?, b = 17.402(5) A?, c = 13.849(2) A?, β = 90.635(14)°, V= 3139.5(11) A?³, and Z = 4. The structure contains a tetrahedral mercury center with the phosphine ligand bound in a bidentate fashion: Hg-P 2.511(2), 2.515(2) A?; P-Hg-P 105.28(6)°. The complex [HgCl₂]₂·L² has also been generated via a 2:1 metal:phosphine stoichiometry.

Full text of DOI:10.1021/ic9704243

Inorg. Chem. 1997, 36, 4749-4752
4749
Multinuclear NMR Spectroscopic and X-ray Crystallographic Studies of a Series of
Mercury(II) Complexes Containing the Bidentate Phosphine Ligand
Ph2PCH2Si(CH3)2CH2PPh2 (L2)
Elmer C. Alyea,* George Ferguson, Ram P. Shakya, and Paul R. Meehan
Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1
ReceiVed April 11, 1997X
The bidentate phosphine ligand Ph2PCH2Si(CH3)2CH2PPh2 (L2), an analogue of 1,3-bis(diphenylphosphino)-
propane (dppp), coordinates to mercury(II) salts to form complexes of the general formula [HgX2‚L2] (X ) Cl,
Br, I, NCS). Infrared, Raman, and multinuclear (1H, 13C, 31P, 199Hg) NMR spectroscopic studies show that the
complexes exhibit four-coordinate pseudotetrahedral metal geometry. [HgI2(Ph2PCH2Si(CH3)2CH2PPh2)] (1)
crystallizes in the monoclinic space group P21/n with a ) 13.028(2) Å, b ) 17.402(5) Å, c ) 13.849(2) Å, â )
90.635(14)°, V ) 3139.5(11) Å3, and Z ) 4. The structure contains a tetrahedral mercury center with the phosphine
ligand bound in a bidentate fashion: Hg-P 2.511(2), 2.515(2) Å; P-Hg-P 105.28(6)°. The complex [HgCl2]2‚L2
has also been generated via a 2:1 metal:phosphine stoichiometry.
Table 1. Crystallographic Data for 1
Introduction
formula
fw
color
space group
a/Å
b/Å
c/Å
C28H30I2HgP2Si
910.94
colorless
P21/n
13.028(2)
17.402(5)
13.849(2)
90.635(14)
V/Å3
Z
T/°C
3139.5(11)
4
20
0.709 30
1.927
7.024
0.0472
0.0727
Very few ditertiary phosphine complexes of mercury(II) are
known. Several groups have studied the reactions of mercury
halides with (diphenylphosphino)alkanes, and species of the
general formulas [Hg(dppe)X2] and [(HgX2)2(dppe)] (dppe )
1,2-bis(diphenylphosphino)ethane) have been assigned on the
basis of vibrational spectroscopy.1 The crystal structure of [Hg-
(CN)2(dppe)] was found to consist of infinite chains in which
four-coordinate mercury centers were linked by bridging dppe
ligands.2 The sole structurally-characterized mononuclear mer-
cury(II) species containing a chelating bidentate phosphine
ligand reported prior to this study was [HgBr2(Ph2PCHd
CHPPh2)].3 Mercury phosphine complexes are amenable to
study by multinuclear (199Hg, 31P) NMR spectroscopy.4,5
However, the inherent insolubility of [HgX2((diphenylphosphino)-
alkane)] complexes has often precluded such investigation.
We have previously detailed our interest in the design of
bidentate phosphine ligands that incorporate a dimethylsilicon
component into the backbone.6 The Si(CH3)2 unit solubilizes
the ligands and also provides an excellent NMR handle. The
ligand 2,2-dimethyl-1,3-bis(diphenylphosphino)-2-silapropane
(L2) is an analogue of dppp and has been complexed to a range
of metals.7 The crystal structures of [Ni(NO3)2‚L2]8 and
[CoBr2‚L2]9 have been reported; each featured a four-coordinate
tetrahedral metal center. The improved solubility and proven
mononuclear complex formation engendered by L2 thus make
the ligand highly suitable for the study of mercury(II) phosphines
by NMR spectroscopic and X-ray crystallographic techniques.
λ(Mo KR)/Å
F
calcd/g cm-3
µ/mm-1
Ra
Rw
a
â/deg
a Residuals calculated for reflections with I > 2σ(I); R ) Σ||Fo| -
|Fc||/Σ|Fo|; Rw ) [Σw(|Fo| - |Fc|)2/Σw|Fo| ]1/2
.
2
Experimental Section
General Comments. Ligand L2 was prepared according to the
literature method.6 All complexes were prepared and handled under a
nitrogen atmosphere using standard Schlenk techniques. The solvents
used were reagent grade and were dried and distilled immediately prior
to use. Elemental analyses were performed by MHW Laboratories,
Phoenix, AZ. Infrared spectra were recorded between CsI plates as
Nujol mulls on a Perkin-Elmer 180 double-beam spectrometer.
X-ray Crystallography. Diffraction-quality crystals of 1 were
obtained by slow evaporation of a dichloromethane solution of the
complex. The crystallographic data are summarized in Table 1. X-ray
measurements were made on an Enraf-Nonius CAD4 diffractometer
using graphite-monochromated Mo KR radiation. Data were collected
in the range 4° e 2θ e 55° and corrected for Lorentz, polarization,
and absorption effects. The structure was solved using the heavy-atom
method and the NRCVAX10 program system. Final refinement was
performed with SHELXL-9311 using all F2 data, with all non-H atoms
allowed anisotropic motion and hydrogen atoms allowed for as riding
atoms. An absorption correction was applied, based on ψ-scan data.12
X Abstract published in AdVance ACS Abstracts, September 15, 1997.
(1) Strommen, D. P. J. Inorg. Nucl. Chem. 1975, 37, 487.
(2) Camalli, M.; Caruso, F.; Zambonelli, L. Acta Crystallogr. 1982, B48,
2468.
(3) Buergi, H. B.; Fischer, E.; Kunz, R. W.; Parvez, M.; Pregosin, P. S.
Inorg. Chem. 1982, 21, 1246.
(4) Colton, R.; Dakternieks, D. Aust. J. Chem. 1980, 33, 1463.
(5) Allman, T.; Goel, R. G. Can. J. Chem. 1982, 62, 621.
(6) Alyea, E. C.; Fisher, K. J.; Shakya, R. P.; Vougioukas, A. E. Synth.
React. Inorg. Met.-Org. Chem. 1988, 18, 163.
(7) Alyea, E. C.; Shakya, R. P.; Vougioukas, A. E. Transition Met. Chem.
(London) 1985, 10, 435.
[HgX2‚L2] (X ) Cl, Br, I). Equimolar quantities of the mercury
salt dissolved in THF and solutions of the ligand in dichloromethane
were mixed and stirred for 5 h at room temperature. The slow addition
of dry ether afforded the products as white precipitates, which were
filtered off, washed with ethanol and dry ether, and pumped dry
overnight. Yields: 75%. Anal. Calcd: for C28H30HgCl2P2Si: C,
46.47; H, 4.29. Found: C, 46.20; H, 4.15. Calcd for C28H30HgBr2P2-
(10) Gabe, E. J.; Le Page, Y.; Charland, J.-P.; Lee, F. L.; White, P. S. J.
Appl. Crystallogr. 1989, 22, 384.
(8) Alyea, E. C.; Ferguson, G.; Ruhl, B. L.; Shakya, R. Polyhedron 1987,
6, 1223.
(9) Alyea, E. C.; Meehan, P. R.; Shakya, R. P.; Ferguson, G. Polyhedron,
in press.
(11) Sheldrick, G. M. SHELXL-93: Program for the refinement of crystal
structures. University of Go¨ttingen, Germany, 1993.
(12) North, A. C. T.; Phillips, D. C.; Mathews, F. S. Acta Crystallogr.
1968, A24, 351.
S0020-1669(97)00424-2 CCC: $14.00 © 1997 American Chemical Society

4750 Inorganic Chemistry, Vol. 36, No. 21, 1997
Table 2. 1H NMR Data for Mercury(II) Complexes
Alyea et al.
coupling constb/Hz
chem shifta/ppm
2J(31P-1H) +
complex
Ph2P-
>P-CH2-
-Si(CH3)2-
4J(31P-1H)
3J(199Hg-1H)
HgCl2‚L2
7.82-7.43 (m)
7.79-7.38 (m)
7.77-7.36 (m)
7.77-7.48 (m)
7.78-7.29 (m)
2.02 (t)
2.02 (t)
1.99 (t)
2.35 (t)
1.85 (t)
-0.27 (s)
-0.28 (s)
-0.29 (s)
-0.31 (s)
-0.01 (s)
6.0
6.6
6.8
7.1
6.5
62.2
57.4
41.7
55.1
HgBr2‚L2
HgI2‚L2 (1)
Hg(SCN)2‚L2
[HgCl2]2‚L2
not obsd
a Solvent CDCl3, referenced to 7.25 ppm. b Coupling constants ( 0.1 Hz; m ) multiplet, t ) apparent triplet, s ) singlet.
Si: C, 41.17; H, 3.70. Found: C, 40.98; H, 4.02. Calcd for C28H30-
HgI2P2Si (1): C, 36.92; H, 3.32. Found: C, 37.22; H, 3.46.
[Hg(SCN)2‚L2]. Equimolar amounts of a THF solution of mercury
thiocyanate and a dichloromethane solution of the ligand were added
together and stirred at 50 °C for 5 h. On cooling and addition of
n-hexane, a white precipitate was deposited; this was washed with dry
ether and n-hexane and dried in Vacuo overnight. Yield: 73%. Anal.
Calcd for C30H30HgN2P2S2Si: C, 46.59; H, 3.91; N, 3.62. Found: C,
46.68; H, 4.08; N, 3.65.
[HgCl2]2‚L2. Addition of mercury chloride dissolved in acetone to
a solution of the ligand in dichloromethane in a 2:1 ratio yielded a
white precipitate. The mixture was stirred at 50 °C for 1 h, cooled,
and filtered. The precipitate was washed with dry ether and pumped
dry overnight. Yield: 76%. Anal. Calcd for C28H30Hg2Cl4P2Si: C,
33.65; H, 3.03. Found: C, 33.66; H, 3.09.
Results and Discussion
The 1:1 stoichiometric addition of L2 to HgX2 (X ) Cl, Br,
I, SCN) salts produced a series of moisture-sensitive white
powders whose general formula was shown to be [HgX2‚L2]
from elemental analysis data. The compounds were sparingly
soluble in chloroform and dichloromethane. The complexes
were studied using multinuclear NMR and vibrational spec-
troscopic techniques. Recrystallization from dichlorometh-
ane produced diffraction-quality crystals of HgI2‚L2 (1). Ad-
Figure 1. Two-dimensional 31P-1H heteronuclear correlated NMR
contour plot for Hg(NCS)2‚L2.
dition of 2 equiv of HgCl2 to L2 produced [(HgCl2)2‚L2],
but a corresponding attempt to generate [Hg(L2)2](ClO4)2
via the reaction of Hg(ClO4)2 and L2 in a 1:2 ratio was
unsuccessful.
1
Multinuclear NMR Studies. The H NMR spectra of the
[HgX2‚L2] complexes are summarized in Table 2. In each
example, the methylene P-CH2 protons (A2XX′A′2 system)
appear as a triplet, downfield from the free ligand at δ 1.50
ppm; the triplet is due to two- and four-bond coupling to the
Figure 2. 1H NMR spectrum of Hg(NCS)2‚L2 at 298 K.
The 13C NMR spectra of the complexes are all very similar.
The methylene P-CH2 protons in the chloride and thiocyanate
appear downfield from the free ligand, at 14.54 and 15.22 ppm,
respectively (free ligand 14.20 ppm); the bromide (13.78 ppm)
and iodide (12.56 ppm) complexes are shifted slightly upfield.
This apparent discrepancy in chemical shift values is presumably
a reflection of the differing electronic properties of the ligands.
An overnight (15 h) run of the thiocyanate complex produced
a highly detailed 13C NMR spectrum; inspection of the aromatic
region showed clear 13C-31P coupling, with values of 21.5 Hz
(1J(13C-31P)) for the ipso carbon, 7.6 Hz (2J(13C-31P)) for the
phosphorus atoms, with J(31P-1H) + J(31P-1H) ) 6.0-7.7
Hz. The apparent phosphorus coupling was confirmed by
performing 2-dimensional 1H and 31P heteronuclear correlation
experiments; an example is shown in Figure 1. In addition,
three-bond coupling to the mercury center is clearly shown by
the presence of mercury satellites (Figure 2) (3J(199Hg-1H) )
41.7-62.2 Hz: 199Hg I ) 1/2). The methyl groups attached to
the silicon appear as a singlet, indicating their chemical equiv-
alency; they are shifted upfield from the free ligand (δ 0.15
ppm).
2
4

Hg(II) Complexes Containing a Bidentate Phosphine
Inorganic Chemistry, Vol. 36, No. 21, 1997 4751
Table 3. 31P NMR Data for Mercury(II) Complexes
chem shifta/ppm (1J(199Hg-31P)/Hz)b
complex
298 K
273 K
243 K
213 K
183 K
HgCl2‚L2
17.5 (3684)
7.6 (3199)
-7.5 (2355)
19.5 (3010)
26.4 (7653)
18.1 (3743)
12.4 (3256)
-2.5 (2436)
19.7 (3031)
18.5 (3780)
13.1 (3302)
-1.6 (2517)
20.0 (3085)
HgBr2‚L2
13.7 (3373)
-1.2 (2563)
20.4 (3127)
14.7 (3454)
0.1 (2654)
20.8 (3163)
HgI2‚L2 (1)
Hg(SCN)2‚L2
[HgCl2]2‚L2
b
a In CH2Cl2, referenced to 85% H3PO4, δ ( 0.1 ppm. 1J ( 5 Hz.
Figure 4. 199Hg NMR spectrum of HgBr2‚L2 at 298 K.
Figure 3. 31P NMR spectrum of Hg(NCS)2‚L2 at 298 K.
Due to the sparingly soluble nature of the complexes and
the fast relaxation time associated with the isotope, a 199Hg NMR
spectrum could only be obtained for [HgBr2‚L2]; this is shown
in Figure 4. Prior studies4 have shown that the metal atom
geometry can be obtained by examining the metal-phosphorus
coupling. When one, two, or three phosphorus atoms are bound
to the mercury atom, the signal in the 199Hg NMR spectrum
appears as a doublet, triplet, or quadruplet, respectively. In this
case, a clear 1:2:1 triplet results from bis coordination of L2.
The coupling constant (1J(199Hg-31P) ) 3199 Hz) obtained from
the spectrum is identical to that observed in the 31P NMR
spectrum, as expected. The chemical shift value of -611 ppm,
relative to (CH3)2Hg, is much greater than the value of -250
ortho, and 5.6 Hz (3J(13C-31P)) for the meta. No coupling was
observed for the para carbon in the aromatic region.
31P NMR spectra of HgX2(PR3)2 complexes have been well
documented.13 The 1J(199Hg-31P) coupling constant has been
correlated to Hg-P distance, X-Hg-X and P-Hg-P bond
angles, the ionization potential of X, nucleophilicity, and the
6s(Hg)/3s(P) orbital overlap. A summary of the 31P NMR data
for the L2 complexes is presented in Table 3. At room
temperature, there is no evidence for phosphine/halide/thio-
cyanate exchange: the spectra always appear as single sharp
resonances, with visible mercury satellites (Figure 3). The
magnitude of the coupling constant here is comparable to
values noted3 for [HgI2(Ph2PCHdCHPPh2)] (2547 Hz) and
[HgI2(Ph2P(CH2)2S(CH2)2PPh2)] (3420 Hz). The magnitude of
1J(199Hg-31P) varies in the order Cl > Br > SCN > I; this
correlates with the order observed for monodentate phosphine
complexes.14 Upon a decrease in temperature, the spectra
broaden and the coupling constants increase as exchange
becomes slower on the NMR time scale. The fact that coupling
is observed at room temperature indicates that exchange is slow,
while the lack of any abrupt change in J between 280 and 180
K implies that exchange is still occurring at low temperature;
although a broadening of the spectra is noted, the signals are
still fairly sharp even at 180 K.
ppm noted for [Hg(dppp)2]2+ 16
A value of -657 ppm has been
.
noted4 for [HgBr2(pmp)2] (pmp ) tris(4-methoxyphenyl)-
phosphine). Allman and Goel17 showed that the 199Hg chemical
shift is directly related to coordination number, with 1:2 > 1:4
> 1:3. The similarity in values here implies that L2 is
coordinated via both available phosphorus donor sites to give a
four-coordinate mercury center. It was also concluded that the
magnitude of the Hg-P coupling constants was directly related
to phosphine basicity, with J values increasing with increased
basicity; the value observed for the L2 complex here is very
similar to that reported for the pmp complex, indicating that L2
is comparable in σ-donor character and basicity to pmp.
IR and Raman Spectroscopy. Vibrational spectroscopy is
well established as a tool for characterizing metal geometries
in phosphine complexes of mercury halides and pseudoha-
lides.18,19 Mercury halide ν(Hg-X) stretching modes for X )
Cl, Br, I, SCN have been assigned on the basis of far-IR and
Raman studies on dppe complexes;1 both terminal and bridging
species were identified.
Comparison of 1J(199Hg-31P) values for [HgCl2‚L2] and
[(HgCl2)2‚L2] is noteworthy. It has been shown that the one-
bond coupling in dimeric [HgX2.PR3]2 species is greater than
that in the monomeric analogues.15 In this case, the J values
are 3684 Hz [HgCl2‚L2] and 7653 Hz [(HgCl2)2‚L2], thus
indicating that a structure incorporating a bridged “HgCl3P”
environment is likely.
Notable peaks in the IR and Raman spectra of the L2
complexes are presented in Table 4. The various modes are
assigned with respect to Strommen’s studies.1 An important
point to note is that the 1:1 complexes display only terminal
(13) Pregosin, P. S.; Kunz, R. W. 31P and 13C NMR of Transition Metal
Phosphine Complexes; NMR Series 16; Springer-Verlag: Berlin,
Germany, 1979.
(14) Alyea, E. C.; Dias, S. A.; Goel, R. G.; Ogini, W. O.; Pilon. P.; Meek,
D. W. Inorg. Chem. 1978, 17, 1697.
(15) Grim, S. O.; Pui, J. L.; Keiter, R. L. Inorg. Chem. 1974, 13, 342.
(16) Dean, P. A. W.; Srivastava, R. S. Can. J. Chem. 1985, 63, 2829.
(17) Allman, T.; Goel, R. G. Can. J. Chem. 1984, 62, 615.

4752 Inorganic Chemistry, Vol. 36, No. 21, 1997
Alyea et al.
Table 4. Vibrational Spectroscopic Data for Mercury(II)
Complexes
Raman ν/cm-1
complex
IR ν/cm-1 and assignta
and assigntb
HgCl2‚L2
280 vs, 270 vs νt(Hg-Cl);
165 m ν(Hg-P)
HgBr2‚L2
HgI2‚L2 (1)
175 vs, 155 vs νt(Hg-Br);
145 vs ν(Hg-P)
175 w, 158 m νt(Hg-Br);
135 w ν(Hg-P)
130 vs, 112 s νt(Hg-I);
145 w ν(Hg-P)
Hg(SCN)2‚L2 2090 s ν(CN); 840 vs, 795 vs
ν(CS); 465 m δ(SCN);
215 br νt(Hg-SCN);
160 vw ν(Hg-P)
280 br s νt(Hg-Cl);
200 w νb(Hg-Cl);
160 w ν(Hg-P)
[HgCl2]2‚L2
295 w, 278 w νt(Hg-Cl);
205 w νb(Hg-Cl);
168 m ν(Hg-P)
a Nujol-KBr plates (4000-400 cm-1), Nujol-polyethylene plates
(500-32 cm-1). b Raman samples in capillaries (500-50 cm-1). vs
) very strong, s ) strong, m ) medium, w ) weak, vw ) very weak.
Figure 5. ORTEP21 view of 1. Thermal ellipsoids are drawn at the
30% probability level.
Hg-X stretching bands in their IR spectra, together with lower
energy Hg-P stretches: this implies the presence of discrete
monomeric tetrahedral complexes. The IR spectrum of the
bromide complex shows intense bands at 175 and 155 cm-1
(terminal Hg-Br), together with a strong band at 145 cm-1
(Hg-P). The Raman spectrum of the HgBr2 complex shows
weak bands at 175, 158, and 135 cm-1, with bridging Hg-Br
modes clearly absent. Strommen also predicted, and showed,
that terminal ν(Hg-Br) bands appeared at frequency values
roughly 0.7 times those of ν(Hg-Cl) positions. For the L2
complexes reported here, bands for the HgBr2 complex are at a
value approximately 0.61 times those of the HgCl2 complex
(280, 270 cm-1 for HgCl2, 175, 155 cm-1 for HgBr2). The
[HgCl2]2‚L2 complex should theoretically contain bridging
chlorine atoms; the bands observed at 200 cm-1 (IR) and 205
cm-1 (Raman) confirm this; this is in agreement with the
prediction of “HgCl3P” environments made from NMR studies.
The complex [Hg(SCN)2‚L2] contains S-bonded thiocyan-
ate: although the value of 2090 cm-1 for ν(CN) is quite low,
there is a clear, broad ν(Hg-SCN) stretch observed at 215
cm-1 in the far-IR spectrum; M-NCS stretches in related
N-bonded systems are noticeably shifted to higher frequency
(330, 290 cm-1 for [Co(NCS)2‚L2];9 325, 285 cm-1 for [Ni-
(NCS)2‚L2]20).
Table 5. Selected Bond Distances (Å) and Angles (deg) for 1
Hg1-I1
Hg1-I2
Hg1-P1
Hg1-P2
P1-C1
2.8393(7)
2.7242(8)
2.515(2)
2.511(2)
1.820(7)
P1-C11
P1-C21
P2-C2
P2-C31
P2-C41
1.814(7)
1.816(7)
1.806(6)
1.811(6)
1.812(7)
I1-Hg1-I2
I1-Hg1-P1
I1-Hg1-P2
I2-Hg1-P1
I2-Hg1-P2
P1-Hg1-P2
Hg1-P1-C1
Hg1-P1-C11
Hg1-P1-C21
114.87(2)
96.42(4)
95.83(5)
118.44(5)
121.17(4)
105.28(6)
105.8(2)
115.2(2)
115.3(2)
Hg1-P2-C2
Hg1-P2-C31
Hg1-P2-C41
C1-Si1-C2
C1-Si1-C3
C1-Si1-C4
C2-Si1-C3
C2-Si1-C4
105.9(2)
112.4(2)
118.0(2)
110.0(3)
111.9(3)
106.7(3)
112.2(3)
106.1(3)
enhancements are presumably due to the incorporation of a
silicon atom into the ligand backbone. The range of values
observed for the chelate bite in L2 complexes is testament to
the conformational flexibility of the ligand. As previously
observed for the cobalt complex, the six-membered ring
comprising Hg1, P1, C1, Si1, C2, and P2 adopts a chair
conformation, with torsion angles ranging from 35.5(2)° for P2-
Hg1-P1-C1 to -73.1(4)° for C1-Si1-C2-P2.
Conclusions
Crystal Structure of [HgI2(Ph2PCH2Si(CH3)2CH2PPh2)]
(1). A view of the complex appears in Figure 5. The mercury
center exhibits tetrahedral geometry, with the ligand L2 bound
in bidentate fashion; this correlates with the spectroscopic
observations previously discussed. Selected bond lengths and
angles for 1 appear in Table 5. The Hg-I distances are
noncontroversial (Hg1-I1 2.8393(7), Hg1-I2 2.7242(8) Å).
The angles around the mercury atom are in the range 95.83(5)
(P2-Hg1-I1) to 121.17(4)° (P2-Hg1-I2). The phosphorus
ligand acts as a bidentate chelate (Hg1-P1 2.515(2), Hg1-P2
2.511(2) Å) with a P1-Hg1-P2 bite angle of 105.28(6)°. This
compares with the values of 101.54(6) and 94.81(3)° observed
in [CoBr2‚L2]9 and [Ni(NO3)2‚L2],8 respectively. Each of these
values is considerably enhanced over the value of 89.3(2)° noted
for the analogous dppp ligand in [Pd(NCS)2(dppp)].22 The
The increased solubility of L2 over analogous (diphenylphos-
phino)alkane ligands makes mercury L2 complexes amenable
to multinuclear NMR studies. These NMR investigations,
together with vibrational spectroscopic studies, have suggested
four-coordinate metal centers in the [HgX2‚L2] complexes; this
was established for the mercury iodide species by X-ray
crystallography. We are pursuing further research into group
12 and other transition metal phosphine complexes using L2
and related ligands.
Acknowledgment. E.C.A. and G.F. thank the NSERC
(Canada) for research grants.
Supporting Information Available: Tables of all atomic coordi-
nates, anisotropic displacement parameters, and bond distances and
angles, as well as a printout of the CIF file, for the crystal structure of
1 (16 pages). Ordering information is given on any current masthead
page.
(18) Goel, R. G.; Henry, W. P.; Srivastava, R. C. Inorg. Chem. 1981, 20,
1727.
(19) Bell, N. A.; Dee, T. D.; Goldstein, M.; McKeuna, P. J.; Nowell, I. W.
Inorg. Chim. Acta. 1983, 71, 135.
IC9704243
(20) Shakya, R. P. M.Sc. Thesis, University of Guelph, 1986.
(21) Johnson, C. K. ORTEPII; Report ORNL-5138; Oak Ridge National
Laboratory: Oak Ridge, TN, 1976.
(22) Palenik, G. J.; Mathew, M.; Steffen, W. L.; Beran, G. J. Am. Chem.
Soc. 1975, 97, 1059.