Synthesis, characterization, and X-ray structural study of a dinuclear organoindium phosphide complex with two different phosphide moieties, (Me3CCH2)2InP(t-Bu)2In(CH 2CMe3)2PPh2

Article abstract of DOI:10.1021/om950986z

An organoindium phosphide which incorporates two phosphido moieties in the same molecule, (Me₃-CCH₂)₂InP(t-Bu)₂In(CH ₂CMe₃)₂PPh₂ (1), has been synthesized in good yield from [(Me₃CCH₂)₂InP(t-Bu)₂]₂ and (Me₃CCH₂)₂InPPh₂ in pentane solution and fully char-acterized. The compound exists as a single compound in the solid state according to an X-ray structural study but is in equilibrium with the starting compounds in benzene solution according to ¹H and ³¹P NMR spectral data.

Full text of DOI:10.1021/om950986z

3088
Organometallics 1996, 15, 3088-3091
Notes
Syn th esis, Ch a r a cter iza tion , a n d X-r a y Str u ctu r a l Stu d y
of a Din u clea r Or ga n oin d iu m P h osp h id e Com p lex w ith
Tw o Differ en t P h osp h id e Moieties,
(Me3CCH2)2In P (t-Bu )2In (CH2CMe3)2P P h 2
O. T. Beachley, J r.,* Sun-Hua Leonard Chao, Melvyn Rowen Churchill,* and
Charles H. Lake
Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260
Received December 27, 1995X
Summary: An organoindium phosphide which incorpo-
rates two phosphido moieties in the same molecule, (Me3-
CCH2)2InP(t-Bu)2In(CH2CMe3)2PPh2 (1), has been syn-
thesized in good yield from [(Me3CCH2)2InP(t-Bu)2]2 and
(Me3CCH2)2InPPh2 in pentane solution and fully char-
acterized. The compound exists as a single compound
in the solid state according to an X-ray structural study
but is in equilibrium with the starting compounds in
benzene solution according to 1H and 31P NMR spectral
data.
Organoindium phosphide dimers with four-membered
rings provide interesting challenges for the syntheses
of isomers as well as of compounds which have different
substituents on the two phosphorus atoms, i.e. R2InPR1 -
2
InR2PR2 , or on the two indium atoms, i.e., R1 InPR2-
2
2
InR2 PR2. To our knowledge, there is only one example
2
of an indium-phosphorus dimer with either the two
phosphorus atoms or the two indium atoms with dif-
ferent substituents,1 [(Me3CCH2)2InP(SiMe3)2In(CH2-
CMe3)2P(H)(SiMe3). This compound was apparently
formed serendipitously as a minor product (ca. ∼2%
yield) from a reaction mixture of (Me3CCH2)2InCl and
P(SiMe3)3 in a 1:1 mole ratio. The compound was
reported to be unstable at room temperature under an
inert atmosphere or upon standing in hydrocarbon
solution. The products of decomposition were not
described. In this paper, the synthesis and complete
characterization of an organoindium phosphide dimer
with different substituents on each of the two phospho-
F igu r e 1. Labeling of atoms in the (Me3CCH2)2InP(t-
Bu)2In(CH2CMe3)2PPh2 molecule. Note the slight puckering
of the four-membered In2P2 ring (ORTEP-II diagram; 30%
probability ellipsoids).
data for the product include C, H analysis, physical
properties, 1H and 31P NMR spectra, and an X-ray
structural study.
An X-ray structural study of 1 (Figure 1) confirms the
presence of two different PR2 (R ) t-Bu, Ph) moieties
in the same organoindium phosphide molecule. The
unit cell consists of two molecules of 1 with puckered
In-P-In-P rings. Selected interatomic distances and
angles within the molecule are listed in Tables 1 and 2.
The In2P2 core of 1 consists of a puckered ring with a
fold angle of 12.2° about the In(1)‚‚‚In(2) axis (as defined
by the dihedral angle between the In(1)-P(3)-In(2) and
In(1)-P(4)-In(2) planes) and a fold angle of 10.7° about
the P(3)‚‚‚P(4) axis. The compound (Me3CCH2)2-
rus atoms is described. The compound (Me3CCH2)2InP(t-
Bu)2In(CH2CMe3)2PPh2, (1) was synthesized by reflux-
2
ing a pentane solution of (Me3CCH2)2InP(t-Bu)2 and
3,4
(Me3CCH2)2InPPh2 in equimolar quantities for 18 h
and was isolated by recrystallization. Characterization
X Abstract published in Advance ACS Abstracts, J une 1, 1996.
(1) Wells, R. L.; McPhail, A. T.; Self, M. F. Organometallics 1993,
12, 3363.
(2) Beachley, O. T., J r.; Chao, S.-H. L.; Churchill, M. R.; Lake, C.
H. Organometallics 1993, 12, 3992.
InP(SiMe3)2In(CH2CMe3)2PH(SiMe3)1 is the only other
organoindium phosphide which has a puckered In2P2
ring; this has a much larger fold angle (24.7°) across
(3) Beachley, O. T., J r.; Kopasz, J . P.; Zhang, H.; Hunter, W. E.;
Atwood, J . L. J . Organomet. Chem. 1987, 325, 69.
(4) Banks, M. A.; Beachley, O. T., J r.; Buttrey, L. A.; Churchill, M.
R.; Fettinger, J . C. Organometallics 1991, 10, 1901.
S0276-7333(95)00986-1 CCC: $12.00 © 1996 American Chemical Society
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Notes
Organometallics, Vol. 15, No. 13, 1996 3089
Ta ble 1. Selected Dista n ces (Å) for
substantially and significantly longer than those in the
PPh2 moiety (1.898 Å vs 1.832 Å for the present,
dissymmetric molecule).
(Me3CCH2)2In P (t-Bu )2In (CH2CMe3)2P P h 2
(A) Indium-Phosphorus Distances
The In-C bond lengths within the In(CH2CMe3)2
systems average 2.191 Å and may be compared with
those in [(Me3CCH2)2InP(t-Bu)2]2 (average 2.213 Å)2 or
in [(Me3CCH2)2InPPh2]3 (average 2.196 Å).4 The inter-
ligand angles are C(11)-In(1)-C(21) ) 121.5(2)° and
C(31)-In(2)-C(41) ) 130.5(2)° (average 126.0°) and are
much larger than those found in [(Me3CCH2)2InP(t-
Bu)2]2 (average 115.2°).2 The change in C-In-C angles
is likely the result of a reduction from four bulky tert-
butyl groups in [(Me3CCH2)2InP(t-Bu)2]22 to only two in
the present dissymmetric molecule. Dihedral angles are
83.2° between the C(11)-In(1)-C(21) and P(3)-In(1)-
P(4) planes and 89.3° between the C(31)-In(2)-C(41)
and P(3)-In(2)-P(4) planes.
In(1)-P(3)
In(1)-P(4)
2.674(1)
2.685(1)
In(2)-P(3)
In(2)-P(4)
2.689(1)
2.710(1)
(B) Indium-Carbon Distances
In(1)-C(11)
In(1)-C(21)
2.193(5)
2.174(5)
In(2)-C(31)
In(2)-C(41)
2.197(4)
2.200(4)
(C) Phosphorus-Carbon Distances
P(3)-C(51)
P(3)-C(61)
1.897(4)
1.898(5)
P(4)-C(71)
P(4)-C(81)
1.833(4)
1.830(5)
(D) Cross-Ring Contacts
4.028 P(3)‚‚‚P(4)
In(1)‚‚‚In(2)
3.631
Ta ble 2. Selected An gles (d eg) for
(Me3CCH2)2In P (t-Bu )2In (CH2CMe3)2P P h 2
(A) Angles around Indium Atoms
P(3)-In(1)-P(4)
82.8(1) P(3)-In(2)-P(4)
106.3(2) P(3)-In(2)-C(31)
114.8(2) P(3)-In(2)-C(41)
98.6(1) P(4)-In(2)-C(31)
125.4(1) P(4)-In(2)-C(41)
82.1(1)
114.8(1)
107.6(1)
108.2(1)
101.7(1)
The physical properties of 1 are unique when com-
pared with those of the symmetrical indium phosphides
from which it was prepared. As the properties are
compared, it should be noted that (Me3CCH2)2InP(t-
P(3)-In(1)-C(11)
P(3)-In(1)-C(21)
P(4)-In(1)-C(11)
P(4)-In(1)-C(21)
2
C(11)-In(1)-C(21) 121.5(2) C(31)-In(2)-C(41) 130.5(2)
Bu)2 is a dimer in the solid state and in benzene
solution according to NMR studies. The solubility of
[(Me3CCH2)2InP(t-Bu)2]2 in benzene was insufficient for
a cryoscopic molecular study. In contrast, (Me3CCH2)2-
(B) Angles around Phosphorus Atoms
In(1)-P(3)-In(2)
In(1)-P(3)-C(51)
In(1)-P(3)-C(61)
In(2)-P(3)-C(51)
In(2)-P(3)-C(61)
C(51)-P(3)-C(61)
97.4(1) In(1)-P(4)-In(2)
111.6(2) In(1)-P(4)-C(71)
110.4(1) In(1)-P(4)-C(81)
116.2(1) In(2)-P(4)-C(71)
110.8(1) In(2)-P(4)-C(81)
109.9(2) C(71)-P(4)-C(81)
96.6(1)
126.9(1)
102.5(1)
107.5(1)
121.1(1)
103.9(2)
4
InPPh2 exists as a trimer in the solid state and as a
monomer-dimer equilibrium mixture in benzene solu-
tion. Compound 1 decomposes at 171-173 °C. Both
starting compounds also decompose rather than melt.
The decomposition temperature of [(Me3CCH2)2InP(t-
(C) Selected Angles around Carbon Atoms
In(1)-C(11)-C(12) 126.7(4) In(2)-C(31)-C(32) 122.2(3)
In(1)-C(21)-C(22) 126.5(4) In(2)-C(41)-C(42) 122.5(3)
2
Bu)2]2 is 200-203 °C, whereas that for [(Me3CCH2)2-
P(3)-C(51)-C(52)
P(3)-C(51)-C(54)
P(3)-C(61)-C(63)
P(4)-C(71)-C(72)
P(4)-C(81)-C(82)
113.6(3) P(3)-C(51)-C(53)
111.0(3) P(3)-C(61)-C(62)
105.6(3) P(3)-C(61)-C(64)
121.5(3) P(4)-C(71)-C(76)
121.4(4) P(4)-C(81)-C(86)
106.1(3)
113.1(3)
111.8(3)
120.6(3)
120.3(3)
4
InPPh2]3 is 143-150 °C. The solubility of the new
mixed-bridge compound is much higher than of either
starting material.
Even though 1 exists as a single compound in the solid
state, an equilibrium mixture of species as represented
by eq 1 is present in benzene solution. The chemical
the In‚‚‚In vector. The P-In-P angles for 1 average
82.5° and are slightly smaller than the 83.4° found in
[(Me3CCH2)2InP(t-Bu)2]2,2 while the In-P-In bond
angles average 97.0° and are slightly larger than the
96.6(1)° found for [(Me3CCH2)2InP(t-Bu)2]2.2 The aver-
age In-P bond distance for the P(t-Bu)2 moiety is 2.682
Å and is slightly shorter than the average In-P
distances of 2.698 Å for the PPh2 moiety. (There is,
however, some overlap and no clean separation into
inequivalent sets.) The In-P(t-Bu)2 distances in 1 are
shorter than those in [(Me3CCH2)2InP(t-Bu)2]2 (2.690-
2.712 Å, average 2.701 Å).
The P(t-Bu)2 moiety of 1 is associated with the bond
lengths P(3)-C(51) ) 1.897(4) Å and P(3)-C(61) )
1.898(5) Å (average 1.898 Å). These bond lengths are
similar to values of 1.891-1.895 Å for [(Me3CCH2)2InP-
(t-Bu)2]2.2 The plane C(51)-P(3)-C(61) makes an angle
of 91.5° with the In(1)-P(3)-In(2) plane.
The PPh2 moiety of 1 is associated with the bond
lengths P(4)-C(71) ) 1.833(4) Å and P(4)-C(81) )
1.830(5) Å (average )1.832 Å). The P-C bond length
is shorter than that in [(Me3CCH2)2InPPh2]3 (average
1.845 Å),4 due, most probably, to the change from a
trimeric to a dimeric molecule. The angle between the
C(71)-P(4)-C(81) and In(1)-P(4)-In(2) planes is 75.3°;
these planes are clearly not perpendicular to each other.
The two phenyl groups are twisted away from each
other with a dihedral angle of 64.5° between the
C(71)fC(76) and C(81)fC(86) planes. Note that overall
the P-C bond lengths in the P(t-Bu)2 moiety are
(Me3CCH2)2InP(t-Bu)2In(CH2CMe3)2PPh2 y\
Kz
1/2[(Me3CCH2)2InP(t-Bu)2]2 + (Me3CCH2)2InPPh2
(1)
1
shifts of all observed 31P and H NMR resonances are
assigned in Table 3. The three species are readily
identified in the 31P NMR spectrum. It is noteworthy
that the equilibrium concentration of (Me3CCH2)2-
InPPh2 is so small that the dimer is not observed. The
1H NMR spectrum of 1 in benzene also confirms the
presence of the equilibrium mixture of species. The
equilibrium constant for eq 1 calculated from integration
data has a value of 0.2 ( 0.1. The difference in splitting
pattern is due either to the loss of symmetry in the In-
P-In-P core when the four-membered ring becomes
puckered or, more likely, to the dissymmetry introduced
by the two different substituents on phosphorus, which
precludes the possibility of “trans coupling”. “Trans
coupling” was observed for [(Me3CCH2)2InP(t-Bu)2]2.2
The proton signal for the methyl groups of the neopentyl
groups attached to indium atoms is 1.21 ppm, which is
between the corresponding signals for [(Me3CCH2)2InP-
(t-Bu)2]2 (1.39 ppm)2 and (Me3CCH2)2InPPh2 (1.06
ppm).3,4 The chemical shift for the methylene protons
of neopentyl ligands in 1 is 1.54 ppm, which is the same
2
as that observed for [(Me3CCH2)2InP(t-Bu)2]2 but is
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3090 Organometallics, Vol. 15, No. 13, 1996
Notes
Ta ble 3. 1H a n d 31P NMR Reson a n ces for (Me3CCH2)2In P (t-Bu )2In (CH2CMe3)2P P h 2, a n d for Solu tion s of
[(Me3CCH2)2In P (t-Bu )2]2 a n d (Me3CCH2)2In P P h 2 (p p m ) in Ben zen e-d 6
2
3,4
(Me3CCH2)2InP(t-Bu)2In(CH2CMe3)2PPh2
[(Me3CCH2)2InP(t-Bu)2]2
(Me3CCH2)2InPPh2
1.06 (s)
1H NMR
InCCCH3
PCCH3
1.07 (s)a
1.21 (s)
1.39 (s)b
1.39 (s)
1.43 (d, J ) 13 Hz)
1.46 (t, J ) 7 Hz)b
1.54 (br)
1.46 (t, J ) 7 Hz)
1.54 (s)
InCH2
PPh
6.96 (td)
7.09 (td)
7.70 (dd)
31P{1H} NMR
-49.7 (s, dimer)
-30.2 (s, monomer)
-28.5 (s)a
-25.6 (d, J ) 360 Hz)
46.7 (d, J ) 359 Hz)
56.3 (s)b
55.0 (s)
a
b
Resonances due to (Me3CCH2)2InPPh2. Resonances due to [(Me3CCH2)2InP(t-Bu)2]2.
Ta ble 4. Cr ysta l Da ta a n d Su m m a r y of In ten sity
Da ta Collection a n d Str u ctu r e Refin em en t of
lated in a standard vacuum line or under a purified argon
2
atmosphere. The starting materials [(Me3CCH2)2InP(t-Bu)2]2
and [(Me3CCH2)2InPPh2]33,4 were prepared by literature meth-
ods. Solvents were dried by conventional procedures. El-
emental analyses were performed by E+R Microanalytical
(Me3CCH2)2In P (t-Bu )2In (CH2CMe3)2P P h 2
mol formula
cryst syst
space group
temp, °C (K)
a, Å
C40H72In2P2
triclinic
P1h (No. 2)
22 (295)
9.9191(12)
12.1506(15)
18.7589(25)
97.974(10)
100.448(10)
90.052(10)
2201.3(5)
2
1
Laboratory, Inc., Corona, NY. The H spectra were recorded
at 400 MHz by using a Varian VXR-400 spectrometer. Proton
chemical shifts were reported in δ units (ppm) and were
referenced to SiMe4 at 0.00 ppm and to C6D6 at 7.15 ppm. The
31P NMR spectra were recorded at 161.9 MHz on a Varian
VXR-400 spectrometer. All phosphorus chemical shifts were
referenced to 85% H3PO4 at 0.00 ppm. All samples for NMR
spectra were contained in sealed NMR tubes. The infrared
spectrum of a Nujol mull between CsI plates was recorded with
a Perkin-Elmer 683 spectrometer. Melting points were ob-
served in sealed capillaries.
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å
Z
fw
844.6
1.274
1.126
5.0-45.0
h, 0-10
D, g/cm3
µ, mm-1
2θ range, deg
index ranges
Syn th esis of (Me3CCH2)2In P (t-Bu )2In (CH2CMe3)2P P h 2
(1). A small tube with a Solv-Seal joint was charged in the
glovebox with stoichiometric amounts of (Me3CCH2)2InP(t-Bu)2
(0.184 g, 0.458 mmol) and (Me3CCH2)2InPPh2 (0.203 g, 0.459
mmol). The assembled apparatus was then degassed, and
pentane (50 mL) was added by vacuum distillation. The
resulting solution was heated by an oil bath to 60-75 °C for
18 h. The solution was then concentrated to about saturation
by removing part of the pentane by vacuum distillation.
Recrystallization by slowly lowering the temperature to -30
°C produced X-ray-quality crystals of 1: 0.254 g, 0.301 mmol,
65.7% yield based on (Me3CCH2)2InP(t-Bu)2; mp 170.9-172.9
°C dec. Anal. Calcd: C, 56.88, H, 8.59. Found: C, 56.74; H,
8.71. IR (Nujol mull; cm-1): 3073 (w), 3060 (m), 2730 (vw),
2706 (vw), 2280 (vw), 1957 (vw), 1944 (w), 1886 (vw), 1872
(vw), 1809 (vw), 1580 (m), 1563 (w), 1431 (w), 1357 (s), 1298
(vw), 1275 (vw), 1232 (s, sh), 1169 (m, sh), 1116 (m), 1103 (m),
1095 (m), 1063 (w), 1022 (m), 1010 (m), 999 (m), 929 (w, sh),
904 (vw), 809 (w), 739 (vs), 731 (vs), 717 (vw), 688 (s), 562 (m),
504 (m), 472 (m), 447 (w), 430 (w), 375 (w).
X-r a y Da ta Collection , Str u ctu r e Deter m in a tion , a n d
Refin em en t for 1. A colorless, transparent single crystal
(dimensions 0.23 × 0.20 × 0.20 mm) was sealed under an
argon atmosphere in a drybox, under extremely strict anaero-
bic and moisture-free conditions, into a thin-walled glass
capillary. The crystal was then accurately centered in a
eucentric goniometer on a Siemens R3m/V automated four-
circle diffractometer. Determination of unit cell dimensions
and data collection (Mo KR radiation, λ ) 0.710 730 Å) were
carried out as has been described in detail previously.5 Details
are provided in Table 4.
k, -13 to +13
l -20 to +19
6278
no. of rflns collected
no. of unique rflns
no. of rflns >6σ
weighting scheme
no. of params refined
goodness of fit
5787
4162
1/[σ2(F) + 0.0005F2]
398
1.04
largest and mean ∆/σ
data-to-param ratio
R indices (all data), %
R indices (6s data), %
largest diff peak, e/Å3
deepest diff hole, e/Å3
0.002, 0.000
14.5:1
R ) 4.53, Rw ) 3.78
R ) 2.54, Rw ) 2.70
0.61
-0.44
different from the chemical shift of the corresponding
proton for (Me3CCH2)2InPPh2 (1.43 ppm).3,4 The pres-
ence of only one set of proton resonances for the
neopentyl protons in 1 indicates all the neopentyl
ligands are magnetically equivalent in solution. This
equivalence could be due to either a rapid inversion of
the In2P2 ring on the NMR time scale or the rapid
breaking of the ring and rotation of groups. In contrast,
it should be noted that the exchange between 1 and its
symmetrical derivatives [(Me3CCH2)2InP(t-Bu)2]2 and
(Me3CCH2)2InPPh2 is slow on the NMR time scale, as
all three species are observed in benzene solution at the
normal operating temperature of the spectrometer.
Exp er im en ta l Section
All compounds described in this investigation were ex-
tremely sensitive to oxygen and moisture and were manipu-
(5) Churchill, M. R.; Lashewycz, R. A.; Rotella, F. J . Inorg. Chem.
1977, 16, 265.
+
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Notes
The crystal belongs to the triclinic crystal system. Possible
Organometallics, Vol. 15, No. 13, 1996 3091
syntheses, and least-squares refinement. All non-hydrogen
atoms were located, and hydrogen atoms were included in their
appropriate idealized staggered tetrahedral or trigonal posi-
tions with d(C-H) set at 0.96 Å.11
Convergence was reached with R ) 4.53% and Rw ) 3.78%
for all 5787 unique reflections and R ) 2.54% and Rw ) 2.70%
for those 4162 reflections with |Fo| > 6σ(|Fo|).
space groups are the noncentrosymmetric P1 (C11; No. 1) or
the centrosymmetric P1h (Ci1; No. 2). Intensity statistics,
frequency of occurrence data,6 and the probability of a syn-
thetic material from achiral precursors being itself achiral7
all militate in favor of the centrosymmetric possibility, P1h. This
space group was assumed and was confirmed by the successful
solution of the structural analysis.
Ack n ow led gm en t. This work was supported in part
by the Office of Naval Research. The purchase of the
diffractometer was made possible by Grant 89-13733
from the Chemical Instrumentation Program of the
National Science Foundation.
Crystallographic calculations were carried out on a VAXs-
tation 3100 computer system with use of the Siemens SHELX-
TL PLUS program package (Release 4.11,VMS).8,9
The analytical scattering factors for neutral atoms were
corrected explicitly for both the real (∆f ′) and imaginary (i∆f ′′)
components of anomalous dispersion.10 The structure was
solved by a combination of direct methods, difference-Fourier
Su p p or tin g In for m a tion Ava ila ble: Complete tables of
atomic coordinates, bond lengths, bond angles, anisotropic
thermal parameters, and calculated positions for hydrogen
atoms (6 pages). Ordering information is given on any current
masthead page.
(6) Nowacki, W.; Matsumoto, T.; Edenharter, A. Acta Crystallogr.
1967, 22, 935.
(7) J ones, P. G. Chem. Soc. Rev. 1984, 13, 155.
(8) SHELXTL PLUS Manual, 2nd ed.; Siemens Analytical
Instruments: Madison, WI, 1990.
OM950986Z
(9) Sheldrick, G. M.; SHELXTL PLUS: An Integrated System for
Solving, Refining and Displaying Crystal Structures from Diffraction
Data (for Nicolet R3m/V); University of Go¨ttingen, Go¨ttingen, Ger-
many, 1987.
(10) International Tables for X-Ray Crystallography; Kynoch
Press: Birmingham, England, 1974; Vol. IV, pp 99-101, 149-150.
(11) Churchill, M. R. Inorg. Chem. 1973, 12, 1213.
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