Stable 17e complexes [Cp(CO)2Mn-C(PR3)=CHPh]PF 6

Full text of DOI:10.1007/s11172-007-0227-5

Russian Chemical Bulletin, International Edition, Vol. 56, No. 7, pp. 1477—1479, July, 2007
1477
Letters to the Editor
Stable 17e complexes [Cp(CO)2Mn—C(PR3)=CHPh]PF6
V. V. Krivykh,ꢀ E. S. Taits, S. P. Solodovnikov, I. V. Glukhov, M. Yu. Antipin, and N. A. Ustynyukꢀ
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (495) 135 5085. Eꢀmail: vkriv@ineos.ac.ru, ustynyuk@ineos.ac.ru
Only a few stable carbonylꢀcontaining openꢀshell tranꢀ
sition metal complexes are known. The stability of
17ꢀelectron (17e) complexes can be increased by either
introducing bulky substituents into the ligands or replacꢀ
ing CO ligands with electronꢀdonating tertiary phosphines,
Sꢀ or Seꢀcontaining ligands.1
We found the first example of stabilization of 17e comꢀ
plexes, in which the phosphorus atom is present in an
organic ligand rather than is directly bound to the metal
atom. Stable phosphoniostyryl 17e complexes 2a—c were
prepared by oxidation of, respectively, zwitterionic adꢀ
ducts 1a,b 2 and adduct 1c, which was synthesized analoꢀ
gously (Scheme 1).
Cp(CO)2Mn=C=CHPh. In the solid state, complexes
2a—c are stable at –(10–15) °C for a long period of time;
in a dichloromethane solution for several hours. The reꢀ
action of reducing agents (cobaltocene or sodium amalꢀ
gam) with complex 2 resulted in regeneration of adduct 1.
The structures of the reaction products were determined
by elemental analysis, IR spectroscopy, and ESR specꢀ
troscopy. The structure of complex 2b was established by
Xꢀray diffraction.
The ESR parameters of complexes 2a—c are
similar to those of the [Cp(CO)2MnPR3]+ (3) and
[Cp(CO)Mn(PR3)2]+ complexes (4) (R = Ar or Alk),3
which is evidence in favor of the lowꢀspin nature of 2a—c.
The isotropic character of the hyperfine coupling conꢀ
stants is indicative of the partial spin density delocalizaꢀ
tion to the phosphorus atom through the carbon atom. It
should be noted that the twoꢀbond coupling constants
aP(31P) are twice as small as those for complexes 3 and 4
and are equal to 1.5 mT.
The
Mn—[C(6)—C(10)],
Mn—C(11),
and
C(11)—C(12) bond lengths in complex 2b determined
by Xꢀray diffraction are similar to those in the
Cp(CO)2Mn—C(PPh3)=C=CPh2 complex (5).2 To the
contrary, the Mn—CO bonds in 2b are ~0.05 Å longer
than those in complex 5 (Fig. 1). The most substantial
R3 = Ph3 (a), Ph2Me (b), PhMe2 (c)
The stability of complexes 2a—c is comparable
to that of structurally similar 18e manganese deꢀ
rivatives, for example, of the vinylidene complex
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1423—1424, July, 2007.
1066ꢀ5285/07/5607ꢀ1477 © 2007 Springer Science+Business Media, Inc.

1478
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 7, July, 2007
Krivykh et al.
C(8)
C
28H24F6MnO2P2. Calculated (%): C, 53.95; H, 3.88; Mn, 8.81;
C(9)
C(7)
C(15)
C(14)
P, 9.94. IR, ν/cm–1: 2017, 1929 (CO).
C(16)
C(17)
5
Dicarbonyl(βꢀtriphenylphosphoniostyryl)(η ꢀcyclopentadiꢀ
enyl)manganese(II) hexafluorophosphate (2a) was synthesized
analogously to compound 2b. The yield was 95%, t.decomp.
117 °C. Found (%): C, 55.13; H, 3.70; P, 8.41.
C(10)
C(6)
Mn(1)
C(18)
C(11)
C(13)
C(12)
C33H26F6MnO2P2•0.5 CH2Cl2. Calculated (%): C, 55.27;
H, 3.74; P, 8.51. IR, ν/cm–1: 2019, 1929 (CO). ESR (20 °C,
CH2Cl2—C2H4Cl2 (1 : 1)): giso = 2.0635, aMn = 5.5 mT. Hyperꢀ
fine coupling aP = 1.5 mT was observed only on highꢀfield
components. At 77 K, the anisotropy of the g factor and the
hyperfine coupling constant with the manganese nucleus was
C(2)
C(4)
C(31)
C(30)
O(5)
P(1)
O(3)
observed (g1 = 2.1280, a1Mn = 11 mT; g2 = 2.0971, a2Mn
=
0.5 mT; g3 = 1.9654, a3Mn = 5 mT), while the anisotropy for the
C(29)
C(28)
C(19)
C(25)
phosphorus nucleus was absent.
5
Dicarbonyl(βꢀdimethylphenylphosphoniostyryl)(η ꢀcycloꢀ
C(24)
pentadienyl)manganese(II) hexafluorophosphate (2c) was syntheꢀ
sized analogously to compound 2b. The yield of 92%, t.decomp.
120 °C. Found (%): C, 49.27; H, 3.94; Mn, 10.30; P, 11.01.
C23H22F6MnO2P2. Calculated (%): C, 49.22; H, 3.95; Mn, 9.77;
P, 11.01. IR, ν/cm–1: 2020, 1929 (CO).
C(20)
C(21)
C(23)
C(22)
C(26)
C(27)
Reduction of complexes 2b. Tetrahydrofuran (2 mL) and
complex 2b (63 mg, 0.1 mmol) were added to sodium amalgam,
which was prepared from Na (5 mg) and mercury (0.5g). The
reaction mixture was magnetically stirred for 20 min and
then chromatographed on a silica gel column at –40 °C
using dichloromethane as the eluent. Compound 1b was isolated
in a yield of 31 mg (65%) from the orange band, which was
concentrated and triturated with hexane. IR, ν/cm–1: 1898,
1829 (CO).
Fig. 1. Molecular structure of 2b. Selected geometric paramꢀ
eters: Mn(1)—C(2), 1.814(5) Å; Mn(1)—C(4), 1.799(6) Å;
Mn(1)—C(6), 2.135(5) Å; Mn(1)—C(7), 2.124(5) Å;
Mn(1)—C(8), 2.128(5) Å; Mn(1)—C(9), 2.161(5) Å;
Mn(1)—C(10), 2.168(5) Å; Mn(1)—C(11), 2.060(5) Å;
C(11)—C(12) 1.328(6) Å; C(2)—Mn(1)—C(4), 81.0(2)°. The
displacement ellipsoids are drawn at the 30% probability level.
Xꢀray diffraction study. Crystals suitable for Xꢀray diffracꢀ
tion were grown by slow diffusion of hexane into a solution of 2b
in dichloromethane. C28.5H25ClF6MnO2P2, M = 665.82, triclinic
crystals, space group P–1, at T = 100 K, a = 10.2620(13) Å,
b = 10.6293(14) Å, c = 14.5861(17) Å, α = 81.362(2)°,
β = 73.730(3)°, γ = 84.837(3)°, V = 1508.1(3) Å3; F(000) = 676,
dcalc = 1.466 g cm–3, µ = 0.694 mm–1. The unit cell paramꢀ
eters and the intensities of 10814 reflections were measured
on an automated Bruker Apex2 diffractometer (T = 100 K,
λMoꢀKα radiation, graphite monochromator, ϕꢀ and ωꢀscanꢀ
difference between 2b and 5 is that the OC—Mn—CO
angle in the former complex is ~10° smaller, which is
apparently characteristic of the 17e CpM(CO)2Lꢀtype
complexes. This fact has been demonstrated earlier4 by
Xꢀray diffraction and theoretical calculations for the
18e complex Cp*(CO)2MnPMe3 and the 17e complex
Cp*(CO)2CrPMe3.
All operations associated with the synthesis and isolation
of the complexes were carried out under argon with the use
of waterꢀfree solvents. The IR spectra were recorded in
the 1800—2100 cm–1 region on a Specord 75 IR spectrophoꢀ
tometer in CH2Cl2. The ESR spectra were measured on a Varian
Eꢀ12 spectrometer equipped with a double resonator. One
resonator contained the sample under study, another one
the reference compound. The elemental analysis was carꢀ
ried out on a VRAꢀ30 Xꢀray fluorescence spectrometer (Karl
Zeiss, Jena).
ning technique, θ
= 26°). The absorption correction was
max
applied using the SADABS program.5 The structure was solved
by direct methods and refined by the fullꢀmatrix leastꢀsquares
technique with anisotropic displacement parameters for nonꢀ
hydrogen atoms. The hydrogen atoms were placed geometrically
and refined isotropically with fixed positional (riding model)
and thermal parameters. The final R factors were R1 = 0.0606
for 4012 independent reflections with I > 2σ(I ) and wR2 = 0.1429
for all 5840 independent reflections. All calculations were carꢀ
ried out with the use of the SHELXTL PLUS program package
(Version 5.10).6
5
Dicarbonyl(βꢀmethyldiphenylphosphoniostyryl)(η ꢀcycloꢀ
pentadienyl)manganese(II) hexafluorophosphate (2b). Ferroꢀ
cenium hexafluorophosphate (132 mg, 0.4 mmol) and adduct 1b
(192 mg, 0.4 mmol) were added with stirring to dichloromethane
(3 mL) cooled to –78 °C. The cooling bath was removed, and
the reaction mixture was allowed to warm to 0 °C. Then diethyl
ether (12 mL) was added. After 30 min, the precipitate that
formed was filtered off, washed with diethyl ether, and dried.
Complex 2b was obtained in a yield of 249 mg (100%), t.decomp.
119 °C. Found (%): C, 53.77; H, 3.86; Mn, 9.00; P, 9.41.
This study was financially supported by the Russian
Foundation for Basic Research (Project No. 05ꢀ03ꢀ32720)
and the Presidium of the Russian Academy of Sciences
(Program of Basic Research "Development of Methods
for the Synthesis of Chemical Compounds and Design of
New Materials").

Stable 17e manganese complexes
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 7, July, 2007
1479
Watson, K. Hensel, Y. Le Page, J.ꢀP, Charland, and A. J.
Williams, J. Am. Chem. Soc., 1991, 113, 542.
5. G. M. Sheldrick, SADABS, V2.01, Bruker/Siemens Area Deꢀ
tector Absorbtion Correction Program; Bruker AXS Inc., Madiꢀ
son, WI, 1998.
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Received January 31, 2007;
in revised form April 9, 2007