Monomer-Trimer Isomerism in 3-Substituted Pentane-2,4-dione Derivatives of Nickel(II)

Article abstract of DOI:10.1021/ic960441c

Bis(n³-allyl)nickel reacts with pentane-2,4-dione derivatives having alkenyl substituants in the 3-position to give Ni(3-R-pentane-2,4-dionato)₂ compounds which have been shown by X-ray diffraction and NMR spectroscopy to be monomeric [R = 5-hexenyl, C₂₂H₃₄NiO₄, a = 13.718(3) ?, b = 4.962(1) ?, c = 16.643(3) ?, β=92.46-(3)°. space group P2₁/n, Z = 2; R = 7-octenyl, C₂₆H₄₂NiO₄, a = 4.8449(5) ?, b = 8.3202(8) ?, c = 16.792(1) ?, α = 89.480(4)°, β= 88.240(4)°, γ = 77.30(1)°; R = 9-decenyl, C₃₀H₅₀NiO₄, a = 4.8067(2) ?, b = 8.2809(3) ?, c = 19.4014(7) ?, α = 90.974(4)°, β= 91.907(4)°, γ = 102.495(4)°, space group P1?, Z = 1; R = methyl, C₁₂H₁₈NiO₄ a = 4.9447(4) ?, 6 = 8.0649(7) ?, c = 9.0633(6) ?, α = 109.377(6)°, β = 93.706(7)°, γ = 106.283(7)°, space group P1?, Z = 1; R = phenylethano, C₂₆H₃₀NiO₄, a = 12.792(1) ?, b = 6.503(1) ?, c = 14.933(1) ?, β= 109.025(7)°, space group P2₁/n, Z = 2] in the crystal and in solution at room temperature. No inter- or intramolecular interaction of the alkenyl substituent with the 16c metal atom is observed. The corresponding Ni compounds containing the 3-phenyl-substituted dione have been shown to adopt both monomeric [C₂₂H₂₂NiO₄, a = 10.2261(5) ?, b = 6.6439(3) ?, c = 13.7862(7) ?, β= 93.677(6)°, space group P2₁/n, Z = 2] and trimeric [C₂₂H₂₂NiO₄)₃, a = 10.5917(7) ?, b = 12.3092(8) ?, c = 12.5926(5) ?, a = 103.937(4)°, β= 96.388(3)°, γ = 96.227(5)°, space group P1?, Z = 1] forms in the crystal while the compound formed by tert-butyl acetoacetate [(C₁₆H₂₆NiO₆)₃, a = 9.713(1) ?, b = 17.550(1) ?, c = 17.391(1) ?, β= 100.272(5)°, space group P2₁/n, Z = 2] is a trimer in which the central Ni atom interacts solely with bridging acetyl groups. The crystal structure of 3-phenyl-2,4-pentanedione [C₁₁H₁₂O₂, a = 19.2961(6) ?, b = 6.8561(2) ?, c = 7.5935(2) ?, space group Pnma, Z = 4] has also been determined.

Full text of DOI:10.1021/ic960441c

Inorg. Chem. 1997, 36, 177-183
177
Monomer-Trimer Isomerism in 3-Substituted Pentane-2,4-dione Derivatives of Nickel(II)
A. Do1hring, R. Goddard, P. W. Jolly,* C. Kru1ger, and V. R. Polyakov
Max-Planck-Institut fu¨r Kohlenforschung, D-45470 Mu¨lheim an der Ruhr, Germany
ReceiVed April 24, 1996X
Bis(η3-allyl)nickel reacts with pentane-2,4-dione derivatives having alkenyl substituents in the 3-position to give
Ni(3-R-pentane-2,4-dionato)2 compounds which have been shown by X-ray diffraction and NMR spectroscopy
to be monomeric [R ) 5-hexenyl, C22H34NiO4, a ) 13.718(3) Å, b ) 4.962(1) Å, c ) 16.643(3) Å, â ) 92.46-
(3)°, space group P21/n, Z ) 2; R ) 7-octenyl, C26H42NiO4, a ) 4.8449(5) Å, b ) 8.3202(8) Å, c ) 16.792(1)
Å, R ) 89.480(4)°, â ) 88.240(4)°, γ ) 77.30(1)°; R ) 9-decenyl, C30H50NiO4, a ) 4.8067(2) Å, b ) 8.2809(3)
Å, c ) 19.4014(7) Å, R ) 90.974(4)°, â ) 91.907(4)°, γ ) 102.495(4)°, space group P1h, Z ) 1; R ) methyl,
C12H18NiO4, a ) 4.9447(4) Å, b ) 8.0649(7) Å, c ) 9.0633(6) Å, R ) 109.377(6)°, â ) 93.706(7)°, γ )
106.283(7)°, space group P1h, Z ) 1; R ) phenylethano, C26H30NiO4, a ) 12.792(1) Å, b ) 6.503(1) Å, c )
14.933(1) Å, â ) 109.025(7)°, space group P21/n, Z ) 2] in the crystal and in solution at room temperature. No
inter- or intramolecular interaction of the alkenyl substituent with the 16e metal atom is observed. The
corresponding Ni compounds containing the 3-phenyl-substituted dione have been shown to adopt both monomeric
[C22H22NiO4, a ) 10.2261(5) Å, b ) 6.6439(3) Å, c ) 13.7862(7) Å, â ) 93.677(6)°, space group P21/n, Z )
2] and trimeric [(C22H22NiO4)3, a ) 10.5917(7) Å, b ) 12.3092(8) Å, c ) 12.5926(5) Å, R ) 103.937(4)°, â )
96.388(3)°, γ ) 96.227(5)°, space group P1h, Z ) 1] forms in the crystal while the compound formed by tert-
butyl acetoacetate [(C16H26NiO6)3, a ) 9.713(1) Å, b ) 17.550(1) Å, c ) 17.391(1) Å, â ) 100.272(5)°, space
group P21/n, Z ) 2] is a trimer in which the central Ni atom interacts solely with bridging acetyl groups. The
crystal structure of 3-phenyl-2,4-pentanedione [C11H12O2, a ) 19.2961(6) Å, b ) 6.8561(2) Å, c ) 7.5935(2) Å,
space group Pnma, Z ) 4] has also been determined.
Introduction
As part of our investigation of the catalytic and stoichiometric
reactions of diketones and diesters containing unsaturated
It has been known for at least 35 years that the substitution
of the methyl groups in the trimer [Ni(acac)2]3 (shown sche-
matically as 1) by sterically more demanding groups leads to
the formation of a monomeric species containing square-planar
Ni(II),1-4 and this has been confirmed in the crystal for the tert-
butyl-substituted derivative (2) by X-ray diffraction.5
substituents with transition metals,6 we have had occasion to
prepare a number of pentane-2,4-dione derivatives having
alkenyl substituents in the 3-position. The products of the
reaction of these with nickel(II) are also monomeric. The
surprising paucity of structural information for nickel com-
pounds having substituents in the 3-position (the only crystal
structure determination we are aware of is that of 3, which is
the product of the reaction between 1 and cyanogen)7 prompts
us to report our results and the structure of six additional
examples.
1
3
Experimental Section
General Techniques. Infrared spectra (KBr pellets) have been
recorded on a Nicolet MagnaIR 750 spectrophotometer in the range of
4000-400 cm-1. Mass spectra have been recorded on a Finigan MAT
8200 using an EI method with a 70 eV ionization energy. NMR spectra
have been recorded on a Bruker apparatus with 200 MHz in toluene
using TMS as an internal standard. DEPT technique has been used to
2
X Abstract published in AdVance ACS Abstracts, December 15, 1996.
(1) Bullen, G. J.; Mason, R.; Pauling, P. Nature 1961, 189, 291.
(2) Cotton, F. A.; Fackler, J. P. J. Am. Chem. Soc. 1961, 83, 2818.
(3) (a) Fackler, J. P.; Cotton, F. A. J. Am. Chem. Soc. 1960, 82, 5005. (b)
Cotton, F. A.; Fackler, J. P. J. Am. Chem. Soc. 1961, 83, 3775. (c)
Fackler, J. P. Prog. Inorg. Chem. 1966, 7, 361. (d) Fackler, J. P.;
Mittelman, M. L.; Weigold, H.; Barrow, G. M. J. Phys. Chem. 1968,
72, 4631.
(4) Chamberlain, C. S.; Drago, R. S. Inorg. Chim. Acta, 1975, 32, 75 and
references therein.
(5) Cotton, F. A.; Wise, J. J. Inorg. Chem. 1966, 5, 1200.
(6) Goddard, R.; Hopp, G.; Jolly, P. W.; Kru¨ger, C.; Mynott, R.; Wirtz,
C. J. Organomet. Chem. 1995, 163, 486.
(7) Corain, B.; Del Pra, A.; Filira, F.; Zanotti, G. Inorg. Chem. 1979, 18,
3523.
S0020-1669(96)00441-7 CCC: $14.00 © 1997 American Chemical Society

178 Inorganic Chemistry, Vol. 36, No. 2, 1997
Do¨hring et al.
Table 1. Analytical Data for the Bis(3-R-pentane-2,4-dionato)nickel Compounds (4-11)
anal. calcd (found) %
compd (R)
reactn time
Ni
C
H
MS/M+ (T °C)
4 (C4H8CH:CH2)
5 (C6H12CH:CH2)
6 (C8H16CH:CH2)
7 (C12H24CH:CH2)
8 (CH2CH:CHCH:CH2)
9 (Me)
48 h
48 h
24 h
24 h
7 d
7 d
12 h
12 h
13.95 (14.04)
12.30 (12.10)
11.00 (11.18)
9.09 (10.00)
15.18 (15.32)
20.60 (20.61)
14.35 (15.02)
12.61 (13.12)
62.75 (62.56)
65.41 (64.15)
65.75 (67.55)
70.69 (71.21)
62.06 (61.38)
50.58 (49.29)
64.87 (64.11)
67.12 (66.45)
8.08 (8.12)
8.81 (8.56)
9.45 (9.35)
10.31 (9.75)
6.21 (6.86)
6.34 (5.96)
5.42 (5.60)
6.51 (6.22)
420 (90)
476 (120)
532 (150)
664 (180)
388 (120)
284 (80)
408 (40)
464 (140)
10 (Ph)
11 (C2H4Ph)
assign unknown peaks in the 13C-NMR spectra. The general experi-
mental conditions have been described earlier.6
Bis(η3-allyl)nickel was prepared by literature methods.8 The 3-sub-
stituted 2,4-diones were prepared in high yield by reacting acetylacetone
with potassium tert-butylate and the appropriate organic halide.9
Bis(3-R-pentane-2,4-dionato)nickel(II) Complexes (4-9, 11). The
compounds have all been prepared by reacting bis(η3-allyl)nickel with
2 equiv of the 3-substituted 2,4-pentanedione in pentane or THF at
room temperature. A typical example is described below, and analytical
data are collected together in Table 1. The reaction is accompanied
by partial decomposition of the bis(η3-allyl)nickel, and the yields never
exceed 50%. A parent peak is observed for all of the compounds in
the mass spectra.
Bis[3-(5-hexenyl)pentane-2,4-dionato]nickel (4). A solution of bis-
(η3-allyl)nickel in THF (8.9 mmol in 66 mL THF) was cooled to -78
°C, and 3-(5-hexenyl)pentane-2,4-dione (3.86 g, 21.2 mmol) was added.
The reaction mixture was stirred at room temperature for 48 h to give
a brown solution which was filtered and concentrated to 70 mL.
Pentane (30 mL) was added, and the compound precipitated as a pink/
red solid and was dried under high vacuum. Yield: 1.28 g (34%
theory). The compound (yield ca. 30%) was also the product of an
analogous reaction with bis(cyclo-1,5-octadiene)nickel. The diamag-
netic nature of the compound has been confirmed by a solid state 13C-
NMR spectrum.
13C-NMR (solid state CP/MAS): δ 186.91/185.44 (C2/C4), 138.14
(C10), 117.59 (C11), 112.70 (C3), 36.66/34.37/32.35/34.05 (C6/C7/
C8/C9), 24.64/24.23 (C1/C5). For numbering scheme, see Figure 1a.10
Bis(3-phenylpentane-2,4-dionato)nickel (10). This compound was
prepared as described above from bis(η3-allyl)nickel and 3-phenyl-2,4-
pentanedione in pentane. However, since evaporation of the reaction
mixture led to the formation of a brown oil which could not be purified,
this was dissolved in ethanol and the green ethanol adduct was isolated.
Heating in pentane overnight led to the formation of pink crystals of
10 as well as green crystals, which were isolated and identified by
X-ray crystallography as the trimer [Ni(3-Phacac)2]3 (12) (see Figure
4a).
Figure 1. Molecular structures of (a) bis[3-(5-hexenyl)pentane-2,4-
dionato]nickel (4) (30% probability level) and (b) bis(3-methylpentane-
2,4-dionato)nickel (9) (50% probability level) with numbering scheme.
have been deposited with the other Supporting Information. Crystals
were sealed in glass capillaries under argon, and intensity data collection
was carried out using an Enraf-Nonius CAD-4 automatic diffractometer
using graphite-monochromated Cu KR radiation by a coupled ω-2θ
scan technique with the speed varying from 1.0 to 10.0°/min, depending
on a standard deviation to intensity ratio of a preliminary 10°/min scan.
The time taken to measure the background was half that taken to
measure the peak. A Ni filter was placed in front of the detector if the
peak count was greater than 50 000 counts/s.
Bis(tert-butyl acetoacetato)nickel Trimer (13). A solution of bis-
(η3-allyl)nickel in THF (10.49 mmol in 50 mL THF) was cooled to
-78 °C, and tert-butyl acetoacetate (3.65 g, 24.0 mmol) was added.
The yellow solution was slowly warmed to room temperature and stirred
overnight to give a green suspension. The reaction mixture was
evaporated to dryness and the residue extracted with THF (50 mL).
The solution was filtered, treated with pentane (10 mL), and cooled to
-78 °C to give the compound as bright green needles, which were
washed with pentane/THF (1:1) and dried under high vacuum. Yield:
2.57 g (66% theory). Anal. Calcd for C48H78O18Ni3: C, 51.5; H, 7.0;
Ni, 15.7. Found: C, 51.7; H, 6.6; Ni, 15.9. MS (FAB, 140 °C): m/e
1116 (M3+), 959, 744 (M2+), 587, 372 (M+), 316, 260. Magnetic
susceptibility: 4.9 µB. Crystal structure: see Figure 4b and Table 8.
X-Ray Crystallography. Details of the crystal data and refinement
for the compounds studied are given in Table 2. The atomic coordinates
Unit cell parameters were determined by the least-squares technique
from 25 reflections; data reduction was by DATAP.11 Because of the
low absorption coefficients, absorption corrections have not been
applied. All structures were solved by direct methods using SHELXS-
8612 and refined by full-matrix, least-squares on all Fo2 using SHELXL-
93.13 Real and imaginary parts of the atomic scattering factors have
been taken from the literature.14 All non-hydrogen atoms were refined
anisotropically. For 10 (R ) Ph) and 11 (R ) C2H4Ph), all hydrogen
atoms were found in the difference Fourier maps and refined isotro-
pically. For 9 (R ) Me), the hydrogen atoms were constrained to an
idealized tetrahedral and the isotropic thermal parameters were refined.
The two trans hydrogen atoms for 4, 5, and 6 (R ) (CH2)nCH:CH2, n
) 4, 6, 8) attached to the terminal double bond were not localized and
were included in the subsequent cycles in the idealized positions. The
remaining hydrogen atoms were included without constraint. The
(8) Henc, B.; Jolly, P. W.; Salz, R.; Wilke, G.; Benn, R.; Hoffmann, E.
G.; Mynott, R.; Schroth, G.; Seevogel, K.; Sekutowski, J. C.; Kru¨ger,
C. J. Organomet. Chem. 1980, 191, 425 and references therein.
(9) See, for example: Martin, D. F.; Fernelius, W. C; Shamma, M. J.
Am. Chem. Soc. 1959, 81, 130.
(11) Coppens, P.; Leiserowitz, L.; Rabinovich, D. Acta Crystallogr., Sect.
A 1965, 18, 1035.
(12) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467.
(13) Sheldrick, G. M. Univ. Go¨ttingen, 1993.
(14) International Tables for X-Ray Crystallography; Kynoch Press:
Birmingham, 1974; Vol 4, p 99.
(10) We thank Dr. A. Rufin´ska for interpreting the CP/MAS 13C NMR
spectrum and for stressing the diamagnetic nature of these species.

Isomerism in Pentane-2,4-dione Ni(II) Derivatives
Inorganic Chemistry, Vol. 36, No. 2, 1997 179
Figure 3. Molecular structure of 3-phenyl-2,4-pentanedione with
numbering scheme. The atoms C(7), C(8), C(10), and C(11) are
disordered in two positions (a) (50% probability level).
in toluene at room temperature and, upon cooling, form green,
paramagnetic solutions, from which the red monomer is
precipitated at low temperature.17
Figure 2. Molecular structures of (a) bis(3-phenylpentane-2,4-dionato)-
nickel (10) and (b) bis(3-phenylethanopentane-2,4-dionato)nickel (11)
with numbering scheme (50% probability level).
Representative preparative details for compounds 4-11 have
been included in the Experimental Section, and analytical data
are summarized in Table 1. The reaction with bis(η3-allyl)-
nickel occurs in a stepwise manner, and although we have not
isolated the intermediate (η3-allyl)Ni(diketonate) species, these
have been identified in the mass spectra. We had anticipated
that, in suitable cases, the terminal double bond in 4-8 might
interact with the metal atom; however, no evidence for either
inter- or intramolecular interaction has been found either in the
crystal or in solution.
The crystal structures of 4-6 [R ) (CH2)nCH:CH2, n ) 4,
6, 8] and 9-11 (R ) Me, Ph, C2H4Ph) have been determined
by X-ray diffraction. Selected structural data are listed in Tables
3 and 4, and the molecular structures of 4, 9, 10, and 11 are
shown in Figures 1 and 2 along with the numbering scheme.
The structures of 5 and 6 are very similar to that of 4 and have
been included in the Supporting Information.
The compounds are all monomeric, and there are no
intermolecular interactions to neighboring molecules. The
nickel atoms in 4-6, 9, and 11 lie in a strictly square-planar
environment, and the deviation of the non-hydrogen atoms of
the 2,4-diketonate fragment out of the molecular plane does not
exceed 0.1 Å. The H atoms have been refined, and one H atom
of each 2,4-Me group lies in the molecular plane.
disordered hydrogen atoms for 3-phenylpentane-2,4-dione were cal-
culated. H(10) was refined isotropically without constraint, and all
other hydrogen atoms were assigned an idealized (UH ) 1.3UC)
geometry.
The correct choice of space group was confirmed by the subsequent
refinements. Attempts to refine 9 in the noncentrosymmetric space
group Pna21 (No. 33) did not resolve the rotational disorder of the
phenyl groups.
Results and Discussion
The 3-substituted pentane-2,4-dionate derivatives 4-8 have
been prepared by reacting bis(η3-allyl)nickel [or (cod)2Ni] with
the appropriate alkenyl- or alkadienyl-substituted diketone in
pentane at room temperature.
In contrast to the other five examples, the 2,4-diketonate
fragments in the 3-phenyl-substituted derivative (10) are not
planar: the O1/Ni/O2 and C2/C3/C4 planes generate an angle
of 4.3(2)°. Furthermore, the central C atom (C3) and the phenyl
atom C6 lie 0.113(1) Å and 0.350(5) Å, respectively, out of,
and on the same side of, the NiO4 plane. The phenyl group is
twisted by ca. 69° out of the molecular plane, while C3-C6 is
significantly shorter than in the other examples (Table 3). In
order to assess the significance of these observations, we
undertook the crystal structure of the parent diketone, 3-phenyl-
2,4-pentanedione, and the molecular structure of this compound
is shown in Figure 3 and selected structural data in Table 5.
In the crystal the molecule adopts the enol form with all non-
hydrogen atoms located in the plane of either the phenyl or
enol groups. The phenyl group takes up two identical positions
with respect to a mirror plane through the enol group and is
twisted by 77.2° out of this plane. The enolic H atom is bonded
asymmetrically to the oxygen atoms [O1-H/O2-H, 1.45(6)/
In addition, we have used the same method to prepare the
derivatives in which R ) Me (9), Ph (10), and C2H4Ph (11).
915 and 103,16 are known compounds and have been suggested
to be in equilibrium in solution with a trimeric structure related
to 1 while UV evidence has been presented which indicates
that monomers are formed upon vaporization of the trimers.3d
The 3-phenyl-substituted derivative 10 proved difficult to
crystallize and was isolated by reacting the impure product with
ethanol, isolating the green ethanol adduct, and removing the
ethanol by refluxing in pentane. During the workup, we also
managed to isolate crystals of the green trimer, and the structure
of this compound is discussed below. Compounds 4-11 are
red to pink and stable at room temperature. They dissolve
readily in ethanol to give octahedral adducts, whose structures
and reactions will be discussed in a further publication along
with the magnetic behavior: the compounds are diamagnetic
(15) Addison, A. W.; Graddon, D. P. Aust. J. Chem. 1968, 21, 2003.
(16) Graddon, D. P.; Heng, K. B. Aust. J. Chem. 1972, 25, 2247.
(17) Polyakov, V. R. To be submitted for publication.

180 Inorganic Chemistry, Vol. 36, No. 2, 1997
Table 2. Crystal and Structure Refinement Detailsa
Do¨hring et al.
compd
empirical formula
fw
T (K)
wavelength (Å)
color
4
5
6
C22H34NiO4
421.20
293(2)
1.541 78
pink
C26H42NiO4
477.31
293(2)
1.541 78
pink
C30H50NiO4
533.41
293(2)
1.541 78
pink
cryst syst
monoclinic
P21/n (14)
16.14-31.48
triclinic
P1h (2)
triclinic
P1h (2)
space group (no.)
θ range for cell determination
unit cell dimens
a, b, c (Å)
18.7-44.6
18.755-33.9
13.718(3), 4.962(1), 16.643(3)
90, 92.46(3), 90
1131.8(4)
4.8449(5), 8.3202(8), 16.792(1)
89.480(4), 88.240(4), 77.30(1)
660.0(1)
4.8067(2), 8.2809(3), 19.4014(7)
90.974(4), 91.907(4), 102.495(4)
753.31(5)
R, â, γ (deg)
V (Å3)
Z
2
1
1
F
calcd (Mg/mm3)
1.236
1.409
452
1.201
1.264
258
1.176
1.156
290
abs coeff (mm-1
F(000)
)
cryst size, mm
θ range
0.70 × 0.14 × 0.11
4.09-75.01
-17 e h e 17, 0 e k e 6,
0 e l e 20
0.56 × 0.07 × 0.07
2.63-74.96
-5 e h e 6, -10 e k e 10,
0 e l e 21
2736
2651 [R(int) ) 0.002]
2417/1/215
1.153
0.22 × 0.10 × 0.05
2.28-74.93
-6 e h e 5, -10 e k e 10,
0 e l e 24
3118
3031 [R(int) ) 0.003]
2848/0/253
1.070
index ranges
rflns collected
indep rflns
obsd data/restrictions/params
GOF, S
2707
2332 [R(int) ) 0.01]
1924/4/185
1.061
final R1, wR2 [I > 2σ(I)]
0.0532, 0.1487
0.0619, 0.1574
0.692, -0.586
0.016(2)
0.0524, 0.1504
0.0564, 0.1538
0.588, -0.561
0.0447, 0.1292
0.0465, 0.1309
0.481, -0.496
R1, wR2 (all data)
(Fourier map) max, min (e/Å-3
extinction coeff, ꢀ
)
compd
empirical formula
fw
T (K)
wavelength (Å)
color
9
10
11
C12H18NiO4
284.97
293(2)
1.54178
pink
C22H22NiO4
409.11
293(2)
1.541 78
pink
C26H30NiO4
465.21
293(2)
1.541 78
pink
cryst syst
triclinic
P1h (2)
monoclinic
P21/c (14)
27.65-49.05
monoclinic
P21/c (14)
24.4-46.7
space group (no.)
θ range for cell determination
unit cell dimens
a, b, c (Å)
18.2-45.9
4.9447(4), 8.0649(7), 9.0633(6)
10.2261(5), 6.6439(3), 13.7862(7) 12.792(1), 6.503(1), 14.933(1)
R, â, γ (deg)
109.377(6), 93.706(7), 106.283(7) 90, 93.677(6), 90
90, 109.025(7), 90
1174.4(2)
V (Å3)
322.28(4)
934.72(8)
Z
1
2
2
F
calcd (Mg/mm3)
1.468
2.193
150
1.454
1.705
428
1.316
1.419
492
abs coeff (mm-1
F(000)
)
cryst size (mm)
θ range
0.53 × 0.25 × 0.03
5.25-74.83
-5 e h e 6, -10 e k e 9,
0 e l e 11
1389
1311 [R(int) ) 0.0134]
1280/0/92
1.226
0.37 × 0.22 × 0.21
4.33-74.91
-12 e h e 12, -7 e k e 8,
0 e l e 17
3758
1921 [R(int) ) 0.0165]
1848/0/169
1.037
0.56 × 0.32 × 0.18
3.13-74.82
-16 e h e 15, 0 e k e 7,
0 e l e 18
index ranges
rflns collected
indep rflns
obsd data/restrictions/params
GOF, S
2426
2342 [R(int) ) 0.0176]
2143/0/203
1.046
final R1, wR2 [I > 2σ(I)]
0.0625, 0.2124
0.0632, 0.2127
0.746, -0.520
0.029(6)
0.0339, 0.0968
0.0353, 0.0982
0.307, -0.498
0.0401, 0.1140
0.0428, 0.1159
0.316, -0.403
R1, wR2 (all data)
(Fourier map) max, min (e/Å-3
extinction coeff, ꢀ
)
compd
empirical formula
fw
MeCOC(Ph):C(Me)OH
C11H12O2
176.21
12
13
[C16H26NiO6]3
373.08
[C22H22NiO4]3
409.11
T (K)
wavelength (Å)
color
293(2)
1.541 78
colorless
293(2)
1.541 78
green
293(2)
1.541 78
green
cryst syst
orthorhombic
Pnma (62)
23.95-31.45
monoclinic
P21/c (14)
12.9-27.1
triclinic
P1h (2)
space group (no.)
θ range for cell determination
unit cell dimens
a, b, c (Å)
18.9-44.4
19.2961(6), 6.8561(2), 7.5935(2)
9.713(1), 17.550(1), 17.391(1)
10.5917(7), 12.3092(8), 12.5926(5)
R, â, γ (deg)
90, 90, 90
1004.59(5)
4
1.165
0.639
90, 100.272(5), 90
2917.0(4)
2
1.274
1.654
1188
103.937(4), 96.388(3), 96.227(5)
1567.9(2)
1
1.300
1.525
642
V (Å3)
Z
F
calcd (Mg/mm3)
abs coeff (mm-1
)
F(000)
376

Isomerism in Pentane-2,4-dione Ni(II) Derivatives
Inorganic Chemistry, Vol. 36, No. 2, 1997 181
Table 2 (Continued)
cryst size (mm)
θ range
0.56 × 0.46 × 0.21
4.58-74.93
0.74 × 0.22 × 0.11
0.30 × 0.20 × 0.19
3.65-75.05
3.61-74.95
index ranges
-24 e h e 24, 0 e k e 8,
-9 e l e 9
-11 e h e 11, 0 e k e 21,
0 e l e 21
5972
-13 e h e 99, -15 e k e 99,
0 e l e 99
rflns collected
3417
6778
indep rflns
obsd data/restrictions/params
GOF, S
1125 [R(int) ) 0.0417]
5790 [R(int) ) 0.0126]
6472 [R(int) ) 0.0173]
981/0/86
4635/0/469
5437/0/499
1.154
0.991
1.045
final R1, wR2 [I > 2σ(I)]
R1, wR2 (all data)
(Fourier map) max, min (e/Å-3
extinction coeff, ꢀ
0.0708, 0.2317
0.0756, 0.2381
0.412, -0.200
0.011(3)
0.0360, 0.0867
0.0491, 0.0919
0.217, -0.323
0.0383, 0.1075
0.0463, 0.1110
0.289, -0.388
)
2
2
a R(int) ) ∑|Fo2 - Fo2 (mean)|/∑|Fo |; R1 ) ∑(|Fo| - |Fc|)/∑|Fo|; wR2 ) {∑[w(Fo2 - Fc2)2]/∑[w(Fo )2]}0.5; S ) {∑[w(Fo2 - Fc2)2]/(n - p)}0.5
;
where Fo ) observed structure factors, Fc ) calculated structure factors, w ) weighting scheme (see instructions to SHELXL-93), n ) number of
elections, p ) total number of parameters refined. Corrections for extinction used the expression Fcnew ) kFc[1 + 0.001ꢀFc2λ3/sin(2θ)]-0.25
Table 3. Selected Bond Distances (Å) for Compounds 4-6 and 9-11a
.
4 (R ) C4H8CH:CH2)
5 (R ) C6H12CH:CH2)
6 (R ) C8H16CH:CH2)
9 (R ) Me)
10 (R ) Ph)
11 (R ) C2H4Ph)
Ni-O(1)
1.830(2)
1.837(2)
1.285(3)
1.281(3)
1.505(4)
1.505(4)
1.514(4)
1.524(4)
1.519(4)
1.519(4)
1.497(5)
1.236(7)
1.830(2)
1.831(2)
1.291(3)
1.290(3)
1.490(4)
1.504(3)
1.531(3)
1.527(3)
1.518(3)
1.521(3)
1.512(4)
1.523(4)
1.8326(13)
1.8318(12)
1.286(2)
1.289(2)
1.498(3)
1.499(3)
1.528(2)
1.526(2)
1.522(2)
1.519(3)
1.520(3)
1.520(3)
1.829(4)
1.834(3)
1.287(6)
1.289(6)
1.500(8)
1.505(7)
1.514(7)
1.8329(11)
1.8389(11)
1.277(2)
1.283(2)
1.503(2)
1.509(2)
1.502(2)
1.388(2)
1.387(2)
1.387(2)
1.383(3)
1.385(2)
1.393(2)
1.8251(14)
1.8327(12)
1.279(2)
1.285(2)
1.500(3)
1.504(3)
1.521(3)
1.532(3)
1.504(3)
1.368(3)
1.396(4)
1.352(6)
Ni-O(2)
O(1)-C(2)
O(2)-C(4)
C(2)-C(1)
C(4)-C(5)
C(3)-C(6)
C(6)-C(7)
C(7)-C(8)
C(8)-C(9)
C(9)-C(10)
C(10)-C(11)
C(11)-C(6)
C(11)-C(12)
C(12)-C(13)
C(13)-C(8)
C(13)-C(14)
C(14)-C(15)
1.492(4)
1.226(4)
1.520(3)
1.518(3)
1.338(7)
1.378(5)
1.376(4)
1.502(4)
1.227(4)
a See figures for numbering scheme.
Table 4. Selected Bond Angles (deg) for Compounds 4-6 and 9-11a
4 (R ) C4H8CH:CH2) 5 (R ) C6H12CH:CH2) 6 (R ) C8H16CH:CH2) 9 (R ) Me) 10 (R ) Ph) 11 (R ) C2H4Ph)
O(1)-Ni-O(2)
O(1)-Ni-O(2*)
O(1)-Ni-O(1*)
Ni-O(1)-C(2)
O(1)-C(2)-C(3)
C(2)-C(3)-C(4)
C(3)-C(4)-O(2)
C(4)-O(2)-Ni(1)
O(1)-C(2)-C(1)
C(1)-C(2)-C(3)
O(2)-C(4)-C(5)
C(5)-C(4)-C(3)
C(2)-C(3)-C(6)
C(4)-C(3)-C(6)
93.81(8)
86.19(8)
180.0
94.17(7)
85.83(7)
180.0
94.19(5)
85.81(5)
180.0
94.1(2)
85.9(2)
180.0
93.63(5)
86.37(3)
180.0
93.65(5)
86.35(5)
180.0
127.1(2)
125.9(2)
120.3(2)
125.4(2)
127.4(2)
112.6(3)
121.5(3)
113.1(2)
121.4(3)
119.6(3)
120.1(3)
127.5(2)
124.5(2)
121.4(2)
125.3(2)
127.1(2)
113.2(2)
122.3(2)
112.3(2)
122.3(2)
118.7(2)
119.9(2)
127.27(12)
125.2(2)
120.8(2)
125.3(2)
127.21(12)
112.8(2)
121.9(2)
112.9(2)
121.9(2)
119.4(2)
119.8(2)
127.3(4)
125.7(5)
120.0(4)
126.0(5)
126.8(4)
113.3(5)
120.9(5)
113.3(5)
120.6(5)
120.2(5)
119.8(5)
127.53(1)
124.97(14)
120.16(13)
125.46(13)
126.85(10)
114.10(14)
120.91(14)
113.18(14)
121.36(14)
119.34(14)
120.50(13)
127.30(13)
125.1(2)
120.1(2)
125.2(2)
127.08(12)
112.8(2)
122.1(2)
112.4(2)
122.4(2)
120.0(2)
119.9(2)
a See figures for numbering scheme.
1.14(6) Å]. The crystal structures of eight 3-aryl-substituted
2,4-pentanedione derivatives have been published,18-22 and all
are found to exist in the enol form. A significant difference in
these structures is the angle of twist adopted by the aryl ring
with respect to the enol plane, which varies from 88.6°
(practically orthogonal) to 65° (Table 6).
Although it is tempting to relate the angle of twist to the
electronic influence of the ring substituents, the lack of any
correlation with C3-C6 (Table 4) suggests that this is probably
the result of a combination of steric interference between the
ortho H atoms and the pentanedionate Me groups and crystal-
packing forces.
(18) Emsley, J.; Ma, L. Y. Y.; Nyburg, S. C.; Parkins, A. W. J. Mol. Struct.
1990, 240, 59.
(19) Emsley, J; Ma, L. Y. Y.; Karaulov, S. A.; Motevalli, M.; Hursthouse,
M. B. J. Mol. Struct. 1990, 216, 143.
The formation of bis(3-phenylpentane-2,4-dionato)nickel (10)
(see above) was accompanied by the deposition of a small
amount of a green crystalline compound, which we initially
suspected to be the ethanol adduct but which was shown by
X-ray diffraction to actually be the trimer [Ni(3-Phacac)2]3 (12)
(20) Emsley, J; Freeman, N. J.; Bates, P. A.; Hursthouse, M. B. J. Chem.
Soc., Perkin Trans. 1 1988, 297.
(21) Emsley, J; Ma, L. Y. Y.; Bates, P. A.; Hursthouse, M. B. J. Mol.
Struct. 1988, 178, 297.
(22) Emsley, J; Ma, L. Y. Y.; Bates, P. A.; Motevalli, M.; Hursthouse, M.
B. J. Chem. Soc., Perkin Trans. 1 1989, 527.

182 Inorganic Chemistry, Vol. 36, No. 2, 1997
Do¨hring et al.
(a)
(b)
Figure 4. Molecular structures of (a) [Ni(3-phenylpentane-2,4-dionato)2]3 (12) [Ni(1)‚‚‚Ni(2) ) 2.854 Å] and (b) [Ni(tert-butyl acetoacetato)2]3
(13) [Ni(1)‚‚‚Ni(2) ) 2.777 Å]. H atoms were omitted for clarity (25% probability level).
Table 5. Selected Bond Distances (Å) and Bond Angles (deg) for
Table 6. Selected Structural Data for 3-Ar-2,4-pentanedione
Derivatives
3-Phenyl-2,4-pentanedionea
O(1)-C(2)
O(2)-C(4)
C(2)-C(1)
C(4)-C(5)
1.287(3)
1.284(3)
1.491(4)
1.488(4)
C(3)-C(6)
C-C(Ph)
O(1)-H
1.502(3)
1.39b
1.45(6)
1.14(6)
Ar
C3-C6 (Å)a
angle (deg)
ref
4-PhOC6H4
4-O2NC6H4
4-PhC6H4
1.487(4)
1.495(5)
1.494(4)
1.502(3)
1.480(5)
1.484(7)
1.487(3)
1.499(4)
65.0
67.3
73.1
77.2
78.3
82.3
85
22
22
21
O(2)-H
Ph
this work
O(1)-C(2)-C(3)
C(2)-C(3)-C(4)
C(3)-C(4)-O(2)
O(1)-C(2)-C(1)
C(1)-C(2)-C(3)
121.8(2)
118.5(2)
121.4(3)
115.2(2)
123.0(3)
O(2)-C(4)-C(5)
C(5)-C(4)-C(3)
C(2)-C(3)-C(6)
C(4)-C(3)-C(6)
116.1(3)
122.5(3)
121.3(2)
120.2(2)
2,4-(MeO)2C6H3
4-i-PrC6H4
3,4,5-Me3C6H2
4-MeOC6H4
19
22
18
20
88.9
a See Figure 3.
a See Figure 3 for numbering scheme. b Assigned.
and as such is the only example of a trimer with 3-substituted
diketonato groups whose crystal structure has been determined.
The molecular structure is shown in Figure 4a, and selected
data are listed in Table 7. It has, however, been pointed out
that the UV spectra of the bis(3-chloropentane-2,4-dionato)-
nickel species suggest that this species is also trimeric in
solution.3d The structure is related to that of [Ni(acac)2]3:23-25
two molecules of the organic ligand are bonded in a chelating
manner to each of the three metal atoms while both oxygen
atoms of the inner organic ligands and one of the oxygen atoms
of the outer organic ligand form bridges to the neighboring
nickel atoms. As has been noted previously for [Ni(acac)2]3, it
is difficult to interpret the differences in the Ni-O bond for
the 3-phenyl-substituted derivative. In general, the bond to a
nonbridging O atom is shorter than to a bridging O atom, e.g.,
Ni(2)-O(5) 1.970(1) Å, Ni(1)-O(5) 2.219(1) Å, Ni(1)-O(1)
1.971(2) Å, Ni(1)-O(2) 1.999(1) Å, Ni(2)-O(2) 2.099(1) Å.
The central Ni atom adopts a symmetrical octahedral geometry
with slightly elongated axial Ni-O bonds, O(2)-Ni(2)-O(2*)
180°, O(5)-Ni(2)-O(6) 92.70(5)°, whereas the terminal Ni
atom shows considerable distortion, O(5)-Ni(1)-O(3) 162.99-
(6)°, O(2)-Ni(1)-O(4) 171.90(6)°. The three independent
phenyl groups adopt positions in which the two terminal rings
are almost perpendicular to the Ni-dione plane, 88.7(1)° and
89.2(1)°, and the central ring adopts an angle of 81.8(1)°.
In addition, we have prepared bis(tert-butyl acetoacetato)-
nickel(II) (13) by reacting the keto ester with bis(η3-allyl)nickel.
The compound is paramagnetic (4.9 µB), and the molecular
(23) Bullen, J.; Mason, R.; Pauling, P. Inorg. Chem. 1965, 4, 456.
(24) Hursthouse, M. B.; Laffey, M. A.; Moore, P. T.; New, D. B.; Raithby,
P. R.; Thornton, P. J. Chem. Soc., Dalton Trans. 1982, 307.
(25) Fackler, J. P. AdV. Chem. Ser. 1967, 580.

Isomerism in Pentane-2,4-dione Ni(II) Derivatives
Inorganic Chemistry, Vol. 36, No. 2, 1997 183
Table 7. Selected Bond Distances (Å) and Angles (deg) for [Ni(3-phenylpentane-2,4-dionato)2]3 (12)a
Ni(1)-Ni(2)
Ni(1)-O(2)
Ni(1)-O(4)
Ni(1)-O(6)*
Ni(2)-O(2)
Ni(2)-O(6)
O(2)-C(4)
O(4)-C(24)
2.8543(4)
1.9991(13)
1.9463(13)
2.3632(14)
2.0987(13)
1.9751(13)
1.292(2)
Ni(1)-O(1)
Ni(1)-O(3)
Ni(1)-O(5)
Ni(2)-O(6)*
Ni(2)-O(5)
O(1)-C(2)
O(3)-C(22)
O(5)-C(42)
1.971(2)
O(6)-C(44)
C(3)-C(4)
C(23)-C(24)
C(43)-C(44)
C(4)-C(5)
C(24)-C(25)
C(44)-C(45)
C(23)-C(26)
1.283(2)
1.391(3)
1.410(3)
1.414(3)
1.501(3)
1.513(3)
1.502(3)
1.495(3)
C(2)-C(3)
1.421(3)
1.406(3)
1.401(3)
1.514(3)
1.513(3)
1.501(3)
1.505(3)
1.504(3)
1.9516(14)
2.2189(13)
1.9751(13)
1.9695(12)
1.258(3)
1.264(2)
1.286(2)
C(22)-C(23)
C(42)-C(43)
C(1)-C(2)
C(21)-C(22)
C(41)-C(42)
C(3)-C(6)
1.268(2)
C(43)-C(46)
O(1)-Ni(1)-O(2)
O(5)-Ni(1)-O(6)*
O(5)-Ni(2)-O(6)*
O(2)-Ni(2)-O(6)*
Ni(1)-O(2)-C(4)
O(2)-C(4)-C(3)
89.27(6)
72.83(5)
87.30(5)
81.28(5)
127.87(12) O(1)-C(2)-C(3)
124.3(2) C(2)-C(3)-C(4)
O(3)-Ni(1)-O(4)
O(5)-Ni(2)-O(6)
O(5)-Ni(2)-O(2)
91.73(6)
92.70(5)
81.32(5)
N(1)-O(3)-C(22)
O(3)-C(22)-C(23)
126.75(13) Ni(1)-O(4)-C(24)
126.26(12)
125.9(2)
125.91(12)
125.2(2)
125.6(2)
O(4)-C(24)-C(23)
Ni(2)-O(5)-C(42)
C(22)-C(23)-C(24) 122.9(2)
Ni(1)-O(1)-C(2) 128.20(14) Ni(2)-O(6)-C(44)
125.44(13) O(5)-C(42)-C(43)
125.8(2)
123.5(2)
O(6)-C(44)-C(43)
125.4(2)
C(42)-C(43)-C(44) 125.2(2)
a See figures for numbering scheme.
Table 8. Selected Bond Distances (Å) and Angles (deg) for [Ni(tert-butyl acetoacetato)2]3 (13)a
Ni(1)-Ni(2)
Ni(1)-O(2)
O(2)-C(4)
2.772 (3)
2.0189(14)
1.237(3)
Ni(1)-O(1)
O(1)-C(2)
C(2)-C(3)
2.0336(13)
1.301(2)
1.360(3)
C(3)-C(4)
O(3)-C(4)
1.419(3)
1.340(2)
C(1)-C(2)
O(3)-C(5)
1.501(3)
1.479(3)
O(1)-Ni(1)-O(2)
91.68(6)
O(1)-Ni(2)-O(11)
78.12(5)
O(1)-Ni(2)-O(1)* 180
C(2)-C(3)-C(4)
127.0(2)
C(4)-O(3)-C(5)
122.1(2)
O(1)-Ni(2)-O(11)* 101.88(5)
Ni(1)-O(1)-Ni(2)
85.07(5) O(1)-Ni(1)-O(12) 170.99(6)
Ni(1)-O(1)-C(2)
O(1)-C(2)-C(3)
124.79(12) Ni(1)-O(2)-C(4)
124.5(2) O(2)-C(4)-C(3)
123.85(13) O(2)-Ni(1)-O(21) 172.42(6)
127.4(2)
a
See figures for numbering scheme.
structure is shown in Figure 4b. Selected structural data are
listed in Table 8. The three tert-butyl acetoacetato groups are
practically identical, and the data listed are for only one. The
compound is trimeric with a linear arrangement of the three Ni
atoms. In contrast to [Ni(acac)2]3 and [Ni(3-phenylpentane-
2,4-dionato)2]3, the organic ligand bonds in a chelate manner
exclusively to the terminal Ni atoms with the six tert-butoxy
groups located on the periphery of the molecule. The central
Ni atom is bonded to six bridging acetyl groups. This
arrangement of the organic ligand probably has a steric origin
and minimizes congestion at the central atom.
Conclusions
Our results suggest that, in the presence of electron-donating
substituents in the 3-position of the pentane-2,4-dionato group,
monomer formation is preferred, whereas in the presence of
the electron-withdrawing phenyl group, both monomeric and
trimeric species are possible.
Supporting Information Available: X-ray crystallographic files
in CIF format for C11H12O2 and compounds 4, 5, 6, 9, 12, and 13 are
available on the Internet only. Access information is given on any
current masthead page.
IC960441C