Oligonuclear tricarbonylchromium- and tricarbonyltungsten derivatives of tris(1-cyclohepta-2,4,6-trienyl)phosphane, P(C7H7)3, and related ligands

Article abstract of DOI:10.1515/znb-1999-0114

A series of trinuclear carbonylmetal complexes of tri(1-cyclohepta-2,4,6-tnenyl)phosphane, P(C₇H₇)₃ (1), has been prepared by the reaction of P(SiMe₃)₃ η⁷-tropylium halfsandwich salts, [(η⁷-C₇H₇)M(CO)₃]BF₄, (M = Cr, Mo, W). While phosphorus remains uncoordinated in the chromium complex P[(η⁶-C₇H₇)Cr(CO)₃]₃ (2a), the molybdenum and tungsten analogues, P[(η⁴-C₇H₇)M(CO)₃][(η ⁶-C₇H₇)M(CO)₃]₂ (M = Mo (2b), W (2c)), contain a coordinated phosphorus atom together with a η⁴-norcaradienyl substituent. Reaction of 2a with pentacarbonylmetal fragments, [M(CO)₅], leads to trinuclear products, P[η₂-C₇H₇)M-(CO)₄][η ⁶-C₇H₇)M(CO)₃]₂ (M = Cr (5a), W (5c)), in which phosphorus is coordinated next to an η²-cycloheptatrienyl substituent. Several alkyl- and arylphosphanes containing [(η⁶-C₇H₇)Cr(CO)₃] substituents (X), e. g. Ph₂P(X) (6a), RP(X)₂ (R = Me (7a), CH₂Ph (8a), Ph (9a)) and (X)₂P(R′)P(X)₂ (R′ = methylene (10a) or 0-phenylene (11a)), have also been synthesized. The chromium complexes 6a - 11a contain an uncoordinated phosphorus center, but in contrast to 9a, the corresponding tungsten compound PhP[η⁴-C₇H₇)W(CO)₃][η ⁶-C₇H₇)W(CO)₃]₂ (9c) has again a structure similar to 2c. The arsenic complexes, As[(η⁶-C₇H₇)M(CO)₃]₃ (M = Cr (12a), W (12c)) both contain an uncoordinated arsenic center, analogous to 2a. The molecular structures of all new complexes in solution at room temperature were deduced from a consistent set of ¹H, ¹³C and ³¹P NMR data, and X-ray structure determinations were carried out for 2a and 5c.

Full text of DOI:10.1515/znb-1999-0114

Oligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives of
Tris(l-cyclohepta-2,4,6-trienyl)phosphane, P(C7H7) , and Related Ligands
3
Max Herberhold*, Kurt Bauer, W olfgang M ilius
Laboratorium für Anorganische Chemie, Universität Bayreuth, D-95440 Bayreuth
Herrn Prof. Dr. Dr. h.c. mult. Heinrich Nöth zum 70. Geburtstag gewidmet
Z. Naturforsch. 54 b, 63-72 (1999); received August 3, 1998
Halfsandwich Compounds, Cycloheptatrienyl Complexes, Chromium, Tungsten, X-Ray Data
A series of trinuclear carbonylmetal complexes of tri(l-cyclohepta-2,4,6-trienyl)phosphane,
P(C?1^7)3 (1), has been prepared by the reaction of P(SiMe3)3 with ^-tropylium halfsand-
wich salts, [(7/7-C7H7)M(CO)3]BF4, (M = Cr, Mo, W). While phosphorus remains uncoor-
dinated in the chromium complex P[(?/6-C7Hv)Cr(CO)3]3 (2a), the molybdenum and tung-
sten analogues, P[(//4-C7H7)M(CO)3][(??6-C7H7)M(CO)3]2 (M = Mo (2b), W (2c)), contain
a coordinated phosphorus atom together with a //4-norcaradienyl substituent. Reaction of 2a
with pentacarbonylmetal fragments, [M(CO)s], leads to trinuclear products, P[(/;2-C7H7)M-
(CO)4][(>7/6-C7H7)M(CO)3]2 (M = Cr (5a), W (5c)), in which phosphorus is coordinated next
to an //'-cycloheptatrienyl substituent. Several alkyl- and arylphosphanes containing [(^6-
C7H7)Cr(CO)3] substituents (X), e. g. Ph2P(X) (6a), RP(X)2 (R = Me (7a), CH2Ph (8a), Ph (9a))
and (X)2P(R')P(X)2 (R' = methylene (10a) or o-phenylene (11a)), have also been synthesized.
The chromium complexes 6a - 11a contain an uncoordinated phosphorus center, but in contrast
to 9a, the corresponding tungsten compound PhP[(?;4-C7H7)W(CO)3][(?/6-C7H7)W(CO)3]2 (9c)
has again a structure similar to 2c. The arsenic complexes, As[(?/6-C7H7)M(CO)3]3 (M = Cr
(12a), W (12c)) both contain an uncoordinated arsenic center, analogous to 2a. The molecular
structures of all new complexes in solution at room temperature were deduced from a consistent
set of 'H, l,C and 31P NMR data, and X-ray structure determinations were carried out for 2a
and 5c.
Introduction
Results and Discussion
1. Syntheses
The phosphane ligand, P(C7H7)3 (1), has the
tendency to form mononuclear transition metal
complexes in which one, two or three cyclohep-
tatrienyl substituents may be coordinated to the
metal through olefinic bonds in addition to phos-
phorus. Several mononuclear com plexes have been
described with central metals such as Cr, Mo, W [1];
Fe, Ru [2] and Rh, Ir [3,4]. In all cases, phospho-
rus is rigidly fixed to the metal, and up to three
supporting olefinic side-arms can be used, mak-
ing 1 eventually an 8-electron donor ligand as in
Cr(CO)2[P(C7 H7X>)2-C7H7)(>j4-C7H7)] [1] and in
MC1[P(;)2-C7H7)3] (M = Rh, Ir) [3, 4],
In the present communication, o//gonuclear
derivatives of the group 6 carbonylmetal com plexes
(M = Cr, Mo, W) are presented in which the three
independent cycloheptatrienyl substituents o f 1 act
as 67r-electron donors, thus carrying [M(CO)3 ] units
and making 1 formally an 18-electron donor ligand,
We had reported [5] that the reaction
o f tris(trimethylsilyl)phosphane, P(SiM e3)3, with
three equivalents of
a
tropylium salt such
as [C7 H7]+Br~ leads to tri(l-cyclohepta-2,4,6-
trienyl)phosphane (1). The analogous reaction of
P(SiM e3)3 with salts of the halfsandwich tropy-
lium cation, [(/77 -C7H7)Cr(CO)3]+, can be used
as a convenient route to the phosphane P[(/76-
C7 H7 )Cr(CO)3 ]3 (2a).
The chromium complex 2a is a trinuclear deriva-
tive o f P(C7 H7)3 (1) in which the three cyclohep-
tatrienyl rings each carry a tricarbonylchromium
fragment and the phosphorus atom remains un-
coordinated. The corresponding molybdenum (2b)
and tungsten (2c) com plexes, although of analo-
gous com position, have a different structure with
only two [(/76-C7H7 )M (CO)3 ] units; the third ring is
coordinated in the norcaradiene structure, and phos-
phorus is involved in complex formation.
as in P[(^6-C7H7 )Cr(CO)3]3 (2a).
It is interesting to note that the direct reac-
tion o f P(C7H7 )3 (1) with organonitrile-stabilized
Reprint requests to Prof. Dr. M. Herberhold.
0932-0776/99/0100-0063 $ 06.00 © 1999 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com
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M. Herberhold et al. • O ligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives
P(SiMe3)3
3 [(C7H7)Cr(CO)3]BF4
3 [C7H7]Br
3 [(C7H7)M(CO)3]BF4
( c ) \ (M = Mo, W)
M(CO)3L3
(L = nitrile)
c'-'
co
\
P[(t1‘,-C7H7)M(CO)3][(t16-C7H7)M(CO)3]2
(M = Mo (2b), W (2c))
S=P[(n -C7H7)Cr(CO)3]3 (4a)
P(C7H7)2[(r| -C7H7)M(CO)3]
(M = Cr (3a), Mo (3b), W (3c)) [1]
Scheme 1. Reaction of P (S iM e^ with a threefold excess of (a) [C7FI7]+Br , (b) [(?/7-C7H7)Cr(CO)3]+BF4 , and
(c) [(777-C7H7)M(CO)3]+BF4“ (M = Mo, W).
P[(n6-C7H7)Cr(CO)3]3 (2a)
+ [M(CO)5(thf)]
tricarbonylmetal fragments, M (CO)3L3 (M = Cr,
Mo, W; L = acetonitrile or propionitrile) produced
the mononuclear tricarbonylmetal com plexes 3a - c
[1] (Scheme 1).
- [Cr(CO)3]
(THF)
The lone pair at the phosphorus(III) cen-
ter in 2a is available for reactions with Lewis
acids, as shown by the formation of the sul-
- thf, - CO
fur adduct, S =P [(//,-C7H7 )Cr(CO)3 ]3 (4a). How-
ever, the reaction of 2a with THF-stabilized pen-
tacarbonylmetal fragments, [M(CO)5(thf)] (M
=
Cr, W ), does not stop after the first addition
step; subsequent rj2-coordination of a cyclohepta-
trienyl side-arm under loss of a [Cr(CO)3l group
leads to the trinuclear derivatives P[(?72-C7 H7)M-
(CO)4][(i)6-C7H7)Cr(CO)3]2 (M = Cr (5a), W (5c)),
(Scheme 2). Analogous tetracarbonyl com plexes
P(C7 H7 )2[(r72-C7 H7 )M(CO)4] (M = Cr, M o, W)
had been obtained [1] by photo-induced decar-
bonylation of the pentacarbonyl phosphane com -
plexes, M (CO)5 [P(C7 H7)3]. The reaction o f 2a with
[M o(CO)5(thf)] did not give definable products due
to the lability of the carbonylmetal groups. In a
similar manner, 2b is always contaminated with a
[M o(CO)3]-deficient species.
P[(n2-C7H7)M(CO)4][(ri6-C7H7)Cr(CO)3]2
(M = Cr (5a), W (5c))
Scheme 2. Reaction of 2a with pentacarbonylmetal frag-
ments.
For the spectroscopic comparison with the tri-
nuclear com plex 2a. som e representative phos-
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M. Herberhold et al. ■Oligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives
65
Table I. Spectroscopic data of tris[(^6--cycloheptatrienyl)tricarbonylmetal] phosphanes.
Position3
'H NMR
C7H8Cr(CO)3b
As[(C7H7)M(CO)3]3b
P[(C7H7)Cr(CO)3]3b SP[(C7H7)Cr(CO)3]3C
12c (M = W)
4a
12a (M = Cr)
2a
3.59
3.63
4.74
6.31
3.96
3.96
4.88
6.37
2.99 eq.; (1.71 ax.) 3.36
3.46
3.60
4.92
6.17
W D
<$(H2 ,H
)
3.49
4.98
6.24
3.60
4.85
6.26
6(H3 ,H6 )
<$(H4 ,H5 )
l3CNM Rd
24.2
36.5
64.3
102.0
100.3
39.6
59.0
101.9
95.6
36.7 [30.9]
40.6 [22.5]
6 (C 'X
58.4
102.3
99.8
62.6 [11.1]
102.3 [5.0]
100.8 [ 1. 1]
62.0 [2.0 ]
103.1 [4.9]
99.2
H C l J )
<5(C3 ,6 )
6(C4 ,5 )
e
28.9
31P NMR
—
IR, v(CO) [cm “'] 1977
1909, 1879
1978
1915, 1884
1972 (KBr)
1975
1983
1920, 1883
1928/1913; 1879/1861 1913, 1883
(CH2C12)
a Positions in the (2"'-7'") //6-coordinated cycloheptatrienyl substituents are triply-marked
b in acetone-d6 at room
temperature; all proton NMR signals are multiplets; c in THF-d8; d coupling constants nJ( ‘P,13C) (Hz) in [ ] ; e not
observed.
,p -
c°
-^co
w
PhP[(n4-C7H7)W(CO)3][(Ti6-C7H7)W(CO)3] (9c)
R = Me
CH2Ph (8a)
Ph (9a)
(7a)
P-
-P.
C H 2
CH2
Scheme 3. Dinuclear phosphane
and tetranuclear diphosphane
complexes.
o-C6H4{CH2P[(T16-C7H7)Cr(CO)3]2}2 (11a)
phanes (6a
-
11a) containing alkyl or aryl
A s expected in analogy to the pair 2a /2c, the
tungsten com plex 9c differs in its molecular struc-
ture from that o f the chromium counterpart 9a.
Finally, the reaction of tris(trimethylsilyl)arsane,
A s(SiM e3)3 , with the halfsandwich cations [{rj1-
C7H7 )M (CO)3]+ gave trinuclear arsanes, As [(rj1-
groups at phosphorus were prepared using
the standard reaction o f the trimethylsilyl-
substituted phosphane with a suspension of [(/?7-
C7 H7 )Cr(CO)3 ]BF4 in dichloromethane. The ex-
amples include mononuclear Ph2P [(//)-C7H 7)Cr-
(CO)3] (6a), ^nuclear RP[(/76-C7H7)Cr(CO)3]2 C7H7)M (CO)3]3 (M = Cr (12a), W (12c)). Unlike
(R = Me (7a), CH2Ph (8a), Ph (9a)) and te/ranuclear
R'{P[(7/6-C7H7)Cr(CO)3]2}2 (R' = methylene (10a)
or o-xylylene (11a)) complexes.
the corresponding phosphanes 2a/2c, the arsanes
12a/12c possess both the structure analogous to 2a.
with uncoordinated arsenic(III).
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66__________________ M. Herberhold et al. • Oligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives
Table II. Spectroscopic data of trinuclear complexes containing a ij4-norcaradienyl ligand
Position“
PhP[(7/4-C7H7)W(CO)3][(//6-C7H7)W(CO)3]
9c
P[(//4-C7H7)M(CO)3][(//f
2b (M = Mo)
’-C7H7)M(CO)3]2
2c (M = W )
‘H NMRbc
6(Hn
<5(H2 ,H7 )
<S(H3',H6')
6(H4",H5")
1.57( 1H)
1.25(2H)
3.36(1 H); 3.96(1 H)
5.24(1H); 5.33(1H)
0.97(1 H)
1.11(2H)
3.76(2H)
5.24(2H)
0.68(1 H)
1.13(2H)
3.95(2H)
5.27(2H)
5.00(1 H)
4.68(2H)
4.9K2H)
^(H1 )
3.70(1 H); 4.30(1 H)
4.99(1H); 5.35(1H)
6.18( 1H); 6.29(1H)
<?>(H2 ,H7")
<$(H3",H6")
<5(H4 ',H5"')
3.97(2H); 4.59(2H)
5.20(2H); 5.30(2H)
6.31(2H); 6.36(2H)
4.00(2H); 4.60(2H)
5.3K4H)
6.29(4H)
7.50(3H); 7.75(2H)
<$(C6H5)C
l3C NMRb'd
39.3 [41.9]
37.7 [24.8]
16.9 [7.6]
80.4 [2]
83.4
40.6 [31.1]
16.3 [7.1]
73.0 [2.2]
79.7
<S(Cn
<$(C2",C7")
<§(C3",C6")
<5(C4 ,C5")
14.0 [10.2]; 14.2 [6.9]
70.4 [1.7]; 70.8 [2.6]
78.7; 80.2
44.6 [7.6]
42.3
42.9 [1.1]
59.9 [3.4]; 61.0 [5.1]
101.2 [3.8]; 102.0 [4.9] 101.7 [4.3]; 102.5 [4.9]
57.9 [4.4]; 62.6 [6.5]
66.1 [4.9]; 71.0 [6.5]
103.2 [3.3]; 103.9 [4.9]
98.5; 98.7
6(C2"\CT")
<5(C3"',C6"')
<$(C4",C5"')
^(C6H5)
94.2; 94.6
130.3 [24.0] (i); 132.7 [8.9];
129.4 [9.0]; 131.0 [2.2]
95.0; 95.4
88.6 {227.0}e
31P NMR
132.4
122.8 {226.7}e
1988
1918
1882
]
1987
1921
1885
1986
1917
1882
IR, i/(C0 ) [cm“ 1
(CH2C12)
a Positions in the (3"-6") r/4-coordinated norcaradienyl substituents are double-marked ("), those in the (2"'-7'") if-
coordinated cycloheptatrienyl substituents are triple-marked b in acetone-da at room temperature; L all proton
NMR signals are multiplets;d coupling constants nJ(3lP,l3C) (Hz) in [ ] ;e coupling constant 1J( 3W,3IP) (Hz) in { }.
2. Spectroscopic characterization
As(SiMe3)3
+ 3 [(t17-C7H7)M(CO)3]BF4
The structural identification of all new complexes
has been unequivocally achieved on the basis of
the 'H, i3C and 31P NMR spectra, together with
the pattern of the carbonyl stretching absorptions
in the IR spectra. The data are collected in Tables
I - IV; the numbering of the cyclopentadienyl ring
positions is included in Scheme 2 for the example
5a, c.
- 3 SiMe3F
- 3 BF3
Table I presents the data o f the trinuclear com -
plexes 2a, 4a, 12a which contain three identical [(//6-
C7 Hy)Cr(CO)3 ] substituents attached to the phos-
phorus (2a, 4a) or arsenic (12a) center. The 'H and
13C NM R spectra show only 4 signals, similar to
the situation in the parent halfsandwich (//6-C7Hg)-
Cr(CO)3.
As[(n6-C7H7)M(CO)3]3
(M = Cr (12a), W (12c))
Scheme 4. Trinuclear arsane complexes.
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67
M. Herberhold et al. ■Oligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives
Table III. Spectroscopic data of trinuclear complexes
P[(r-C 7H 7)M(CO)4][(/;6-C7H7)Cr(CO)3]2.
NM R signal to lower field by ca. 52 ppm [<*)31P
161.0 (5a) and 149.9 (5c), respectively].
The diphenylphosphane Ph2P[((//6-C7 H7 )Cr-
(CO)3] (6a) shows comparatively simple 'H and
l3C NM R spectra. However, the NMR spectra of the
mono-alkyl- and -arylphosphanes 7a - 11a contain
seven ‘H and seven l3C signals for their two [(r/6-
C7H7 )Cr(CO)3] substituents, indicating that the car-
bon atom Cl'" is prochiral.
Position“
5a (M = Cr)bc
'H NMR l3CNM R 'H N M R i3CNM R
5c (M = W)bc
r
4.02
5.71
6.46
5.18
34.1
129.5
130.3
85.7
4.08
5.52
6.50
5.34
34.1 [4.9]
128.1 [2.7]
130.4 [9.3]
79.3
2’, 7'
3’, 6'
4’, 5'
I-,,
[8.8]
3.39
3.72
3.91
5.08
40.3 [3.4] 3.36
71.0
69.1
103.8 [2.8] 5.02
104.8 [3.2]
40.4
The 31P NMR spectra of all tungsten com -
plexes (2c, 5c, 9c) exhibit the expected tungsten-
phosphorus spin-spin coupling. The *J(183W,3 IP)
coupling constant in f>(C7 H7)2[(r/2-C7 H7)W (CO)4]
{288.1 Hz} [1] is only slightly modified if
[Cr(CO)3 ] fragments are attached to the free cy-
cloheptatrienyl rings to give 5c {280.8 Hz}. In a
similar manner, the coupling remains almost un-
changed upon addition of two [W (CO)3] fragments
to P(C7 H7 )2[ ( r - C 7 H7)W (CO)3] (3c) (<53IP 74.8
{229.5} in acetone-de [I j), forming 2c (<53IP 122.8
{226.7}, Table II), although the signal is shifted
downfield by 48 ppm.
2'", T"
3'", 6"’
4'", 5"'
3.65
3.81
71.3
69.1
103.6 [3.3]
104.5 [3.3]
98.1
6.46
98.6
99.4
6.41
99.1
31P NMR :
161.0
149.9 {280.8} d
IR, i'(CO)
[cm"1]
(CH2CI2)
2002, 1973
1920, 1882
2014; 1985
1917, 1881
a Positions in the (4'-5') ?/2-coordinated eycloheptatrienyl
substituent are singly marked ('), those in the (2"'-7'")
/^-coordinated cycloheptatrienyl substituents are triply-
marked
b in acetone-dft at room temperature; all
proton NMR signals are multiplets;c coupling constants
V (3IP,I3C) (Hz) in [ ] ;d coupling constant 7j ( l83W,3lP),
(Hz) in { }.
3. X-ray structural analyses of 2a and 5c
The molecular structures of 2a and 5c are pre-
sented in Figs. 1 and 2; relevant bond distances and
angles are given in Tables V and VI.
The reactions of P(SiM e3)3 with the tropylium
cations [(/77-C7 H7)M(CO)3]+ (M = Mo and W) lead
to the trinuclear complexes 2b and 2c in which
one seven-membered ring is present in the /;4-nor-
caradienyl form, whereas the remaining two rings
It is informative to compare the molecular geo-
metry of the parent phosphane, P(C7H7 )3 (1) [5],
with that of its derivative P[(776-C7 H7 )Cr(CO)3]3
(2a) in which all three cycloheptatrienyl rings
carry a [Cr(CO)3] fragment. The trinuclear com -
plex 2a crystallizes from dichloromethane in the
orthorhombic space group Pnma with one solvent
m olecule (Z = 4), the phosphane 1 itself in the mono-
clinic space group P2i/n (Z = 8 ). The m olecules 2a
contain a crystallographically imposed mirror plane
which involves P, C(16), Cr(2), C(5) and 0 (5 ).
Whereas the phosphorus atom may occupy ei-
ther the axial or the equatorial position at the tetra-
hedral ring carbon in P(C7H7 )3 (1) [5], the three
seven-membered rings in 2a are exclusively sub-
stituted in the axial position (Fig. 1). This is the
expected exo-isom er obtained by nucleophilic at-
tack o f P(SiM e3)3 at the planar C7H7 ring of [(//7-
C7H7 )Cr(CO)3]+ from the side which is opposite to
the [Cr(CO)3] fragment [6 , 7]. The sum of the 3 CPC
angles at phosphorus (300.1° in 1) is only slightly
reduced in the trinuclear complex 2a (297.0°). The
carry
a [M(CO)3] fragment (Table II). The 'H
and l3C NMR spectra of 2b/2c are therefore sim i-
lar to those of the mononuclear r/4-norcaradienyl
com plexes, P(C7H7)2[(^4-C7 H7)M (CO)3] (M = Mo
(3b), W (3c)) [1]. In the case of molybdenum, the
reaction of P(SiM e3)3 with [(t77 -C7H7)M o(CO )3]+
produces not only 2b but also a [Mo(CO )3]-de-
ficient species P(C7H7)[(f74-C7H7)Mo(CO):i][(776-
C7H7)M o(CO)3], the 31P NM R signal of which
(<531P 112.0) appears between those of 2b (132.4)
and 3b (95.2 [1]).
In
a
similar manner,
a close analogy can
be expected between the mononuclear tetracar-
bonyls P(C7H7)2[(r -C 7H7)M(CO)4] (M = Cr [63]P
108.31, W [<531P 97.6]) [1] and the tetracarbonyls
5a and 5c in which two additional [Cr(CO)3] units
have been attached to the free cycloheptatrienyl sub-
stituents (Table III). This results in a shift of the 31P
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Table IV. Spectroscopic data of alkyl and arylphosphanes containing [(//6-C7Hv)Cr(COb] substituents.
M. Herberhold et cd. ■O ligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives
Position3
R^P[(?/6-C7H7)-
Cr(COh]
6a (R = Ph)
RP[(//6-C7H7)Cr(COh]7
R'{P[(7/6-C7H7)C r(C O hF^
10a 11a
(R' = CH2) (R = o-C6H4(C H ^ )
7a
8a
9a
(R = Me)
(R = CH2Ph)
(R = Ph)
'H NMRb
4.18(1 H)
3.57(2H)
3.28
3.36
3.27
3.75
4.53
4.85
6.17
6.23
3.82
3.47(4H)
3.23(4H)
3.72(4H)
4.90(8H)
3.52(4H)
3.27(4H)
3.86(4H)
4.59(4H)
4.95(4H)
6.32(8H)
* H p 7,„
<5(H2 ,H
)
3.50
3.80
4.85
3.09
3.92
4.60
4.91
6.14
6.22
<$(H3"',H6"')
<5(H4",H5")
4.92(2H)
6.33(2H)
6.29(4H)
6.38(4H)
6.25
0.38 (d, [4,0])
<5(CHi )
<5(CH2)
<5(arene)
2.40s
7.12(3H)
7.24(2H)
0.57(2H)
2.41s(4H)
7.04(2H)
7.37(10H)
7.33(5H)
7.12(2H)
13C NMRb'c
37.4 [20.2]
64.0 [14.7]
36.7 [24.5]
63.6 [7.6]
66.0 [14.7]
102.1
102.2
99.6
36.5 [27.8]
62.2 [10.4]
64.4 [12.5]
101.5 [5.5]
101.9 [5.5]
99.9
36.8 [25.0] 37.4 [25.0] 36.8 [27.8]
« C D .
6(C2 ,7 )
62.1 [9.6]
65.2 [15.6] 65.2 [7.1]
101.6 [5.8]
102.2 [3.3]
99.6 [1.4]
99.9 [0.8]
64.1 [6.5]
63.1 [9.8]
64.6 [13.1]
101.8 [5.5]
102.1 [3.3]
102.4 [3.3] 102.2 [5.5]
99.8
99.9
<HC3"',6"')
101.9 [6.5]
100.1
99.9
100.1
<5(C4",5 ')
<5(CH3)
6(CH2)
<5(arene)
99.7
5.1 [23.4]
d
30.3 [24.2]
138.9 [6.5]
130.1 [5.5]
129.1
29.6 [25.5]
136.9 [3.3]
131.5 [8.2]
126.8
136.1 [24.2]
134.3 [19.1]
129.3 [7.1]
129.9
131.7 [23.4]
135.6 [19.7]
129.2 [7.1]
130.7 [0.8]
126.5 [1.6]
3lPN M Rb
12.1 e
- 0.1e
8.0
22.3
11.8
14.8
1981
IR, //(CO) [cm-1] 1980
1973
1976
1979
1979
(CH2C12)_________ 1918,1886
1912,1882
1914,1883
1916,1884 1915,1884 1916,1884_________
a Positions in the (2"'-7'") /^-coordinated cycloheptatrienyl substituents are triply-marked ("');b in acetone-d6 at room
temperature;Lcoupling constants V (31P,LC) (Hz) in [ ] ; d not observed;e the ,!P NMR singlet is shifted upheld in
the order 2a (<53IP 28.9), 9a (12.1), 6a (-0.1), PPh^ (-3.7); all measurements in actone-d6.
to that in 2a. The pseudo-octahedral coordination
sphere of W contains a c/s-chelating P(r/2-C7H7)
ligand (Fig. 2); the coordinated double bond C(14)-
C(15) is arranged almost perpendicular to the P-
W-C(2) axis. The bond length of this olefinic bond
in 5c (C=C 137.7(11) pm, W-C 249.5 pm av.) is
shorter than the corresponding olefinic bonds in
R hC l[P(/r-C 7H7 h ] (C=C 140.7(3) pm av., Rh-C
228.4 pm av.) [3] and Fe(CO )2 [P(C7 H7)(t72-C7H7)2]
(C=C 142.5(3) pm av., Fe-C 216.4 pm av.) [2]. The
tetrahedral coordination sphere at phosphorus is dis-
torted, and angles between 101.6(3) and 120.5(2)°
have been found instead of the ideal value 109.5°.
The com m only used description of the confor-
mation of 1-cyclohepta-2,4,6-trienyl substituents by
structure of the three halfsandwich substituents in
2a corresponds to the geometry which is gener-
ally observed for /76-cyclohepta-2 ,4 ,6 -trienyl tricar-
bonylmetal complexes of chromium [8 ], m olyb-
denum [9] and tungsten [8 ]: The three-legged
[Cr(CO)3] fragment is always coordinated in a posi-
tion in which one of the carbonyl ligands is ecliptic
with the sp3 ring carbon [8 ]. The four inner car-
bon atoms of the /^-system s in 2a stand closer to
chromium than the two outer carbon atoms; thus
the average distance from C r(l) to C(6 ), C(7), C(8 )
and C(12) is 222.5(6) pm versus 231.6(5) pm from
C r(l) to C(9) and C (11).
The structural situation of the two [(if-
C7H7 )Cr(CO)3] substituents in 5c is closely similar
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M. Herberhold et al. • Oligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives
69
Table VI. Selected bond distances and angles in
Table V. Selected bond distances and angles in P[(r/6-
P[(?r-C 7H7)W(CO)4][(//6-C7H7)Cr(CO)3]2 (5c).
C7H7)Cr(CO)3]3 (2a).
Distances [pm]
Distances [pm]
P-C(IO)
P-C(lOa)
P-C(16)
Cr(l)-C(6)
Cr(l)-C(7)
Cr(l)-C(8)
Cr(l)-C(9)
C r(l)-C (l 1)
Cr( 1)-C( 12)
188.7(5)
188.7(5)
187.1(7)
223.1(6)
222.7(5)
222.8(6)
232.0(5)
231.2(5)
221.4(6)
C r(l)-C (l)
C r(l)-C (2)
Cr(l)-C (3)
C(6)-C(7)
185.8(5)
186.1(6)
185.8(6)
141.2(8)
139.1(8)
140.1(8)
150.8(8)
151.1(7)
136.8(7)
141.8(7)
184.4(6)
W-P
248.9(2)
249.3(7)
249.7(7)
201.2(8)
198.1(8)
203.8(9)
196.0(7)
P -C (ll)
P-C(18)
P-C(25)
C( 11 )-C( 12)
C( 12)-C( 13)
C( 13)-C( 14)
C(14)-C(15)
C(15)-C(16)
C(16)-C(17)
C (11)-C( 17)
188.5(7)
189.5(7)
187.9(7)
148.2(10)
133.2(11)
147.5(11)
137.7(11)
146.7(11)
132.0(11)
151.4(10)
W-C( 14)
W-C(15)
W -C(l)
W-C(2)
W-C(3)
W C(4)
C(7)-C(8)
C(8)-C(9)
C(9)-C(10)
C (10)C ( 11)
C( 11 )-C( 12)
C(6)-C(13)
Cr(2)-C(4)
Cr(l)-C(5)
Cr(l)-C(6)
Cr(l)-C(7)
Cr(l)-C(19)
Cr(l)-C(20)
Cr(l)-C(21)
Cr(l)-C(22)
Cr(l)-C(23)
Cr(l)-C(24)
185.6(9)
186.7(7)
186.3(8)
233.9(8)
222.7(7)
218.5(8)
217.7(7)
219.8(8)
229.7(8)
Cr(2)-C( 13)
Cr(2)-C(14)
Cr(2)-C( 15)
C(13)-C(13a)
C(13)-C(14)
223.0(5)
221.9(6)
232.6(5)
139.3(11)
140.8(8)
C( 18)-C( 19)
C(19)-C(20)
C(20)-C(21)
C(21)-C(22)
C(22)-C(23)
C(23)-C(24)
C(18)-C(24)
149.2(11)
134.9(11)
142.1(13)
139.8(13)
140.5(12)
135.8(11)
151.1(11)
183.9(9)
138.8(8)
149.5(7)
Cr(2)-C(5)
C(14)-C(15)
C (15)-C (16)
Angles [°]
C(10)-P-C(10a)
C(10)-P-C(16)
C( 10a)-P-C(16)
C(9)-C(10)-C(l 1)
C(15)-C(16)-C(15a)
96.0(3)
100.5(2)
100.5(2)
106.9(4)
107.4(6)
C (l)-C r(l)-C (2)
C (l)-C r(l)-C (3)
C(2)-Cr(l)-C(3)
C r(l)-C (l)-0(1)
C r(l)-C (2)-0(2)
C r(l)-C (3)-0(3)
Cr(2)-C (4)-0(4)
Cr(2)-C (5)-0(5)
91.8(3)
91.4(3)
85.0(3)
177.9(6)
176.9(7)
176.0(5)
177.9(5)
177.7(8)
Angles [°]
110.7(2)
120.5(2)
112.9(2)
90.1(3)
172.7(3)
86.8(3)
84.9(3)
91.1(3)
88.0(4)
90.0(2)
173.8(2)
95.6(3)
95.1(2)
109.7(6)
110.3(5)
C( 11)-P-C( 18)
C( 11)-P-C(25)
C( 18)-P-C(25)
W -C (l)-0(1)
W -C(2)-0(2)
W -C(3)-0(3)
W -C(4)-0(4
105.6(3)
101.6(3)
103.7(3)
176.3(7)
179.2(6)
174.3(8)
178.5(8)
W -P-C (ll)
W-P-C(18)
W-P-C(25)
C(l)-W -C(2)
C(l)-W -C(3)
C(l)-W -C(4)
C(2)-W-C(3)
C(2)-W-C(4)
C(3)-W-C(4)
P-W -C(l)
P-W-C(2)
P-W-C(3)
P-W-C(4)
C(19)-C(18)-C(24)
C(26)-C(25)-C(31)
C(4)-Cr(2)-C(4a)
C(4)-Cr(2)-C(5)
85.9(4)
90.4(3)
Dihedral angles [°]a
51.7
51.7
56.0
qio (axial)
QiOa(axial)
Qiö(axial)
~ 0 b
~ 0
~ 0
ß\o
ßlOa
ß\(>
P-W-C( 14)
P-W-C(15)
C( 14)-W-C( 15)
85.4(2)
83.4(2)
32.0(2)
a The numbering of the dihedral angles a and ß (Fig. 3) refers
to the carbon atom bound to phosphorus; b the six carbon atoms
coordinated to the [Cr(CO) ] fragment lie in a plane.
3
C(5)-Cr( 1)-C(6)
C(5)-Cr(l)-C(7)
C(6)-Cr(l)-C(7)
C r(l)-C (5)-0(5)
C r(l)-C (6)-0(6)
C r(l)-C (7)-0(7)
94.1(3)
82.9(3)
91.2(3)
176.6(7)
176.3(7)
177.8(7)
Dihedral angles [°]a
a n (axial)
Qi8(axial)
a 25(axial)
45.9
37.4
40.7
34.4
~ 0 b
~ 0 b
ß\ i (axial)
ß\s
ßl5
a The numbering of the dihedral angles a and ß (Fig. 3) refers
to the carbon atom bound to phosphorus; b the six carbon atoms
coordinated to the [Cr(CO) ] fragment lie in a plane.
3
two angles a and ß is also included in Tables V
and VI (Fig. 3, cf. [3]).
Although all [(/y6-C7H7 )Cr(CO)3 ] substituents in
2a and 5c are halfchair conformers, i. e. ß is close to
zero, the dihedral angles a in 2a (51.7 - 56.0°) are
significantly greater than in 5c (37.4 - 40.7°). The
halfchair rings are flattened in 5c.
Fig. 1. Molecular structure of P[(7/6-C7H7)Cr(CO)3]3
(2a).
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M. Herberhold et al. ■Oligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives
70
was treated dropwise with 0.33 mmol (83 mg, 97 p\)
P(SiMe3)3. The orange halfsandwich educt slowly dis-
solved. and a homogeneous red solution was formed. In
most cases it proved necessary to provide a small excess
of P(SiMe3)3. The reaction vessel was opened periodi-
cally (under argon) to let most of BF3 escape. The prod-
uct partially precipitated as a dark-red powder from the
solution. The reaction mixture was concentrated under
vacuum to a few milliliters, then diethyl ether (Et:0) was
added to complete the precipitation, and the product was
repeatedly washed using Et2Ü. For the sake of further
purification, a layer of hexane was placed on top of a
concentrated solution in CH2CI2 in order to initiate slow
crystallization at -28 °C in the refrigerator.
P[(?/6-C7H7)Cr(CO)3]3 (2a): dark-red crystals, yield
195 mg (82%), dec. above 200 °C.
Fig. 2. Molecular structure of P[(?/2-C7H7 )W(COh][(//6-
C7H7)Cr(CO) 3]2 (5c).
P[(//4-C7H7)Mo(CO)3][(?/6-C7H7)Mo(CO)3]2 (2b),
red powder. 2:1 mixture of 2b with the [Mo(CO)3]-de-
ficient (binuclear) complex, yield 248 mg (88%), dec.
above 200°C.
P[(//4-C7H7)W(CO)3][(//6-C7H7)W(CO)3]2 (2c),
violet-red powder, yield 332 mg (90%), dec. above
200 °C. FD-MS: m/e 1108 (M+), correct isotope pattern.
Fig. 3. Conformation of the l-cyclohepta-2,4,6-trienyl
substituents.
b) Addition of sulfur to 2a
712 mg (1 mmol) 2a were added to a solution of 32
mg (1 mmol) sulfur in 20 ml of THF, and the mixture
stirred overnight. The pink precipitate of 4a was washed
with THF and dried.
Experimental
An argon atmosphere was routinely used for all syn-
thetic operations and for the handling of samples; the
solvents were dry and saturated with argon (cf [1, 2]).
The synthesis of the tripod ligand P(C7H7)? (1) has
been described [5]. The silylated phosphanes and ar-
sanes, P(SiMe3)3 [10], RP(SiMe3)2 (R = Me, CH2Ph)
[11], As(SiMe3)3 [12], as well as the ?/6-cyclohepta-
2,4,6-triene complexes (C7Hg)M(CO)3 (M = Cr [13],
Mo [14], W [15]) and the //7-tropylium salts, [(//7-
C7H7)M(CO)3]+BF4“ (M = Cr [16], Mo [17], W [18])
were prepared according to literature procedures.
The trimethylsily 1 phosphanes Ph2P(SiMe3) and
PhP(SiMe3)2 were obtained by lithiation of PI12PH and
PhPH2 and subsequent reaction of the lithium phosphides
[19] with Me3SiCl.
S=P[(?/6-C7H7)Cr(CO)3]3 (4a), pink platelets, dec.
above 230 °C, yield 677 mg (91%). Insoluble in most
common solvents, but very low solubility in THF.
c) Addition ofpentacarbonylmetalfragments to 2a
A solution containing 1 mmol M(CO)6 (M = Cr or W)
in 100 ml of THF was irradiated (with a mercury high-
pressure arc, Hanovia 200W), until the is(CO) absorption
band had almost disappeared (3 -5 h). Then 712 mg (1
mmol) 2a were added to the yellow THF solution and the
reaction mixture was stirred for 12 h. The red solution was
brought to dryness, and the product slowly crystallized at
-28°C by adding hexane on top of a concentrated CH2CI2
solution.
Instrumentation: IR: Perkin-Elmer 983G, 'H-, l3C-and
31P NMR: Bruker ARX 250 and AC 300. FD-MS: Varian
MAT 311 A.
P[(/r-C 7H7)Cr(CO)4][(//6-C7H7)Cr(CO)3]2 (5a):
dark-red crystals, dec. above 200 °C. yield 430 mg (58%).
FD-MS: m/e 740 (M+).
a) Reactions of P(SiMej)3 with i f -tropylium
halfsandwich cations
P[(//2-C7H7)W(CO)4][(//6-C7H7)Cr(CO)3]2 (5c):
A stirred suspension of 1 mmol of [(?/7-C7H7)M-
dark-red crystals, dec. above 200 °C. yield 532 mg (61 %).
(CO)3]+BF4~ (M = Cr. Mo. W) in 20 ml of CH2C12 FD-MS: m/e 872 (M+). correct isotope pattern.
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M. Herberhold et al. • O ligonuclear Tricarbonylchromium- and Tricarbonyltungsten Derivatives__________________ 71
Table VII. Data relevant to the single crystal X-ray analyses of 2a and 5c.
Compound
5c
2a
Formula
C3|H 2iO,oPCr2W
C3oH2i0 9PCr3 •CH2CI2
Crystal; dimensions [mm]
Crystal system; Space group
Unit cell dimensions:
a, b, c [pm]
ß [°]
V; Z; F(000)
Isometric, dark-red, 0.22x0.22x0.25
Orthorhombic; Pnma
Dark-red prism, 0.20x0.24x0.30
Monoclinic; P2i/c
1912.2(4), 1233.4(2), 1291.4(3)
100.79(3)
2992.0(11)- 106 pm3; 4; 1696
1670.7(3), 1687.1(3), 1144.6(2)
—
3226.1(10) • 106 pm3; 4; 1440
1.467
1.091
1.936
4.661
Dcaic [g • cm-3]
Absorption coefficient [mm- 1]
Diffractometer
Siemens P4 (MoKQ; A = 71.073 pm, graphite monochromator)
Temperature [K]; scan mode
scan range
173; Lc-
2° < 26 < 50°
173; w
3° < 2e < 50°
Measured reflections
Independent reflections
Observed reflections
Solution
4022
2920
6883
5235
2463 (F0 > 2.0a (F„))
5235 (no reflections omitted)
Direct methods (program SHELXTL-PLUS)
Refinement (against F0):
Refined parameters
R\ wR (w ~‘ = cr(F0))
Max./min. residual electron
density [10~6 e • pm-3]
224
0.067; 0.035
1.78/—1.10
406
0.056; 0.038
1.39/-1.92
d) Synthesis of alkyl- and aryl phosphanes containing
[(if-C7Hy)Cr(CO)</ substituents
CH2{P[(/;6-C7H7)Cr(CO)3]2}2 (10a): dark-red pow-
der, dec. above 150 °C, yield 200 mg (81%).
o-C6H4{CH2P[(//7-C7H7)Cr(CO)3]2}2 (Ha): dark-red
powder, dec. above 160 °C, yield 225 mg (84%). FD-MS:
m/e 848 (M+-[(C7Hx)Cr(CO)3]).
General procedure: A suspension of 1 mmol (314 mg)
[(?/7-C7H7)Cr(CO)3]BF4 in 20 ml of CH2CI2 was reacted
with the stoichiometric amount of a phosphane such as
Ph2P(SiMe3) (1:1) or RP(SiMe3)2 (R = Me, CH2PH, Ph)
(1:0.5) to give red solutions. The solution was concen-
trated and the product precipitated by addition of Et2 0 .
f) Reactions ofAs(SiMej)3 with rf -tropylium
halfsandwich cations
The reactions were carried out in analogy to a) and d).
As[(r?6-C7H7)Cr(CO)3]3 (12a), yield 197 mg (78%)
and As[(7/6-C7H7)W(CO)3]3 ( 1 2 c ), yield 288 mg (75%).
Both 12a and 12c are dark-red powders which decom-
posed above 140 °C.
Ph2P[(?/7-C7H7)Cr(CO)3] (6a): red crystals, dec. above
130 °C, yield 370 mg (90%).
MeP[(777-C7H7)Cr(CO)3]2 (7a): dark-red powder, dec.
above 160°C, yield 235 mg (94%).
PhCH2P[(//7-C7H7)Cr(CO)3]2 (8a): dark-red powder,
dec. above 160°C, yield 276 mg (96%).
g) X-ray structure determinations of 2a and 5c
PhP[(//7-C7H7)Cr(CO)3]2 (9a): dark-red powder, dec.
above 150 °C, yield 256 mg (91%).
The block-shaped crystals of either 2a or 5c were sealed
in glass capillaries under argon. The experimental details
related to X-ray measurement, structure solution and re-
finement are given in Table VII; the complete set of struc-
tural informations has been deposited at the Fachinforma-
tionszentrum Karlsruhe, D-76344 Eggenstein-Leopolds-
hafen, under the numbers CSD-410479 (2a) and CSD-
410478 (5c).
Starting with a suspension of 1 mmol (446 mg) [(//7-
C7H7)W(CO)3]BF4 and PhP(SiMe3)2 (1:1), the binuclear
tungsten complex 9c was obtained.
PhP[(7?4-C7H7)W(CO)4][(//6-C7H7)W(CO)3] ( 9 c ):
dark-red powder, dec. above 140 °C, yield 367 mg (89%).
e) Synthesis of tetranuclear complexes
Acknowledgements
Following the general procedure described under d),
the suspension of 1 mmol [(//7-C7H7)Cr(CO)3]BF4 was
reacted with 0.25 mmol of either CH2[P(SiMe3)2]2 or
0-C6H4[CH2P(SiMe3)2b in 20 ml of dichloromethane.
We gratefully acknowledge the support of our work by
the Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie.
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72
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