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Chelate-Stabilized Diphosphene and Diphosphorus Complexes of Nickel.

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(red crystals, dec. > 160°C; 3.4% yield). All spectroscopic
data of 3 and 4 agree well with the assumption of bis(tricarbonyliron) complexes of 1 and 2, respectively.[41
With regard to the bonding sites of the two tricarbonyliron units the molecular structure obtained for 4 by X-ray
analysis was of special interest. Figure l a shows a sideview of the C, structure of the complex, from which the positions of the tricarbonyliron groups above and below the
para-quinodimethane unit and the deformation from planarity of the latter can be seen. The complex consists of
two trimethylenemethane-like sections with short distances
between Fe and C(1), C(4), C(3i) and C(2) [195.2(1),
209.7(1), 220.5(1) and 230.8(1) pm, resp.]. This type of
bonding is also supported by the carbon-carbon bondlengths of the quinodimethane moiety which shows equal
distances for C( 1 ) . . .C(4), C( 1). . .C(2) and C( 1 ) . . . C(3i)
(Fig. lb). Furthermore, the subdivision into two trimethylenemethane parts is impressively demonstrated by the long
bond length of 146.2(1) pm found for the bonds
C(2)...C(3) which are the formal double bonds of the
para-quinodimethane ligand. Theoretical calculations
(EHT-MO) agree well with the complex structure
found.161
As was to be expected on the basis of structures 3 and 4
both compounds react readily with bromine (tetrachloromethane, OOC) to yield 1,4-bis(bromomethyl)benzene
(67%) and
1,4-bis(bromomethyl)-2,5-dimethylbenzene
(63%), respectively. Further reactions which can be rationalized as 'in-situ' generation of the para-quinodimethanes
from bis(tricarbony1iron) complexes are under investigation.
Received: February 1 I , 1985 [Z 1163 IE]
German version: Angew Chem. 97 (1985) 513
CAS Registry numbers:
3, 96453-09-7: 4, 96453-10.0; 1,4-b1s(bromomethyl)henzene, 623-24-5; 1,4-
b1s(bromomethyl)-2,5-dimethylbenzene.
[ I ] Cf. J. M. Landesherg in E. A. Koerner von Gustorf, F.-W. Grevels, 1.
Fischler (Eds.): n?e Organic Chemisrry of Iron. Vol. 1. Academic Press,
London 1978, p. 627.
(21 L. A. Errede, M. Szwarc, Q. Reo. Chem. SOC. 12 (1958) 301: H. E. Winberg, F. S. Fawcett, W. E. Mochel, C. W. Theobald, J . A m . Chem. SOC.82
(1960) 1428; L. A. Errede, R. S. Gregorian, J. M. Hoyt, ibid. 8 2 (1960)
5218: J. H. Golden, J. Chem. Soc. 1961. 3741; D. J. Cram, C. K. Dalton,
G. R. Knox, J . Am. Chem. SOC.85 (1963) 1088; W. F. Gorham, J . Po!yrn.
Sci. A - I , 4 (1966) 3027: J. W. Lown, A. S. K. Aidoo, Can. J . G e m . 44
(1966) 2507; G. W. Brown, F. Sondheimer, J . Am. Chem. Sur. 8 9 (1967)
7116; Y . lto, S. Miyata, M. Nakatsuka, T. Saegusa, J. Org. Chem. 46
(1981) 1043, and references cited therein.
[3] D. J. Williams, J. M. Pearson, M. Levy. J . Am. Chem. SOC.92 (1970) 1436:
J . M. Pearson, H. A. Six, D. J. Williams, M. Levy, ihid. 93 (1971) 5034.
[4] Correct elemental analyses (C, H, Fe) were obtained for 3 and 4 . - 3 : IR
(hexane): v(CO)= 1984, 2040 c m - ' ; 'H-NMR (80 MHz, CDzClz):
6 = 1.76 (s, 4 H ) . 4.27 (s, 4H): "C-NMR (90.5 MHz, CDICI2): 6=38.76,
80.31, 103.47, 211.03; MS: m/z=384 (30?:a, M+).356 (7), 328 (40), 300
(16),272(40), 244(100),216(80), 160(37), 112(21), l04(18),56(l3)[5].4 : IR (hexane): v(CO)= 1980,2038 cm - ' ; ' H - N M R (360 MHz, CDzC12):
6 = 1.75 (s, 6H). 1.79 (d, J = 1.6 Hz, 2H), 2.16 (d, J = 1.6 Hz, 2H), 3.74 (9,
2H): "C-NMR (90.5 MHz, CDlCI?): 6= 19.44, 37.43, 78.39, 102.88,
102.94, 211.34; MS: m/r=412 (3246, M*),384 (X), 356 (37), 328 (16), 300
(37). 272 (100). 244 (73), 216 (3). 188 (72), 160 (20), 132 (54). I12 (24), 56
(35) 151.
[ 5 ] Details about the mass spectrometric fragmentation of 3 and 4 : M. Rentzea, A. R. Koray, H. A. Staab, Tefrahedron Letr. 26 (1985) 2563.
[6] H. Vogler, unpublished results.
Chelate-Stabilized Diphosphene and Diphosphorus
Complexes of Nickel**
By Hans Schafer,* Dieter Binder, and Dieter Fenske
Diphosphenes R-P=P-R have two lone pairs of electrons and a double bond and can therefore coordinate in
different ways to transition metals."] We are interested in
complexes of the q2-type in which only the double bond is
formally bonded to a metal center.'21 This coordination
pattern corresponds to the bonding of olefins to transition
metals.
../ R
.P
A
L,M(\
'I;..\
Fig. I . Side-view (a) and top-view (b) of 4 with bond lengths (pm] and bond
angles ["I. a=643.6(1), h=746.6(1), c=919.6(1) pm, n= 103.31(2),
/1=108.77(2), y=91.42(2)": space group Pi, Z = 1: number o f reflections
measured 2061, number of reflections with 1 > 1 . 9 6 ~ ( 1 )1827: R=0.021. Further details of the X-ray structure analysis of 4 are available on request from
the Fachinformationszentrum Energie Physik Mathematik, D-7514 Eggenstein-Leopoldshafen 2, o n quoting the registry number C S D 51246, the
names of the authors, and the full citation of this journal.
522
0 VCH Verlagsgesellrchaft mbH, 0-6940 Weinheim, 1985
I*]
[**I
R
-
p/ R
L,M+
j/
B
P
.-\
R
Prof. Dr. H. SchBfer, Dip1.-Chem. D. Binder, Prof. Dr. D. Fenske
Institut fur Anorganische Chemie der Universitat
Engesserstrasse, Geb. Nr. 30.45, D-7500 Karlsruhe (FRG)
Transition-Metal Phosphido Complexes, Part 10. This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie. The crystal data were collected at the Institut fur
Kristallographie der Universitat.-Part 9: H. Schafer, J. Zipfel, B. Gutekunst, U. Lemmert, Z . Anorg. A& Chem., in press.
0570-0833/85/0606-0522 $ 02.50/0
Angew. Chem. In,. Ed. Engl. 24 (1985) No. 6
The use of two resonance structures, A and B, to describe such complexes is supported by the P-P distances
(212-2 15 pm)['a-d.2Jand the "P-NMR spectra (see below).
We are interested exclusively in complexes which formally
contain diphosphene ligands that are not stable as free
species. We obtained the first P-functional compounds of
this kind from t r ~ n s - ( R ~ P ) ~ N i C(R=alkyl)
l~
and
LiP(SiMe,),.[" This method can be extended to the synthesis of the chelate-stabilized diphosphene complexes 2a
and 2b [Reaction (l)].
..\ SiMe,
RZ
la-c
a, R
In Reactions (1)-(8), variable amounts of (chelate),Ni
are always formed, making the isolation of the diphosphene or diphosphorus complexes somewhat difficult.
Reaction (6) proved to be the preparatively most convenient synthetic method for 6a-c.
According to H o f f r n ~ n n , the
' ~ ~ (che1ate)Ni group, viewed
as a 14-electron fragment, is isolobal with the CH2 group.
The complexes 6a- c are therefore formally bicyclobutane derivatives according to the resonance structure C
and thus represent a new class of P2 complexes, analogous
to the AsZ complexe [(C2Me,)(CO)2Mn]zAs2of Herrmann
et a1.14J
2a, 2b
=
Et; b, R = c-C6HI1; c , R = Ph
In these reactions, some of the intermediates were
shown by N M R spectroscopy to be nickel complexes containing terminal P(SiMe3)2groups. For k, however, redox
reactions predominate, forming (Me3Si)2P-P(SiMe3)2 and
(chelate)*Ni. When l a - c are reacted with LiP(R')SiMe,
(R'=Me, tBu, Ph), redox reactions are also mainly observed, yielding diphosphanes and (chelate),Ni. Complexes containing diphosphene (PR')2 ligands are accessible, however, via the simple reaction (2) and, in some
cases, even better, starting from silylated diphosphanes
[Reaction ( 3 ) ] .
+ R'P(SiMe,),/THF.
-
20°C
"/ R'
R2
Me3SiC1
II
(;;Nit
la-c
-
P
.*\
R2
Me3SiC1/50-800C
3, R'
(2)
P
=
R'
(3)
Me; 4 , R' = t B u ;
5 , R' = Ph
In all P2 complexes known so far, the Pz group is
bonded to two 15-electron fragments, which, as units isolobal to the C H group, are connected by a metal-metal bond,
resulting in a closed tetrahedron.[,' 6a crystallizes with two
crystallographically independent molecules in the asymmetric unit."] The two molecules primarily differ only in
the fold angle between the (NIP2) planes (95.4 and 98.3",
see Fig. 1). This is presumably due to packing effects and
causes a marked difference in the Ni-Ni distances (291
and 296 pm, respectively; no Ni-Ni bonding). Comparison of the structure of 6a (see Fig. 1) with the tetraphosphabicyclobutane derivative P4[N(SiMe3)J2I7' reveals the
analogy to main-group chemistry. Both the P-P distance
and the fold angle are very similar to those in the P4 derivative (P-P=213 pm, fold angle 95.2"). The Ni-Ni distance in 6a corresponds to the transannular P-P distance
(281 pm) of the open P4 tetrahedron. The P-P distance of
the P2 group of 6a (212 pm) lies, as in other P2 com~ I e x e s , ~between
~]
the typical values for a single bond
Surprisingly, attempts to synthesize complexes containing (PSiMe,), ligands in an analogous way from l a - c
and P(SiMe,), o r (Me3Si)2P-P(SiMe3)2 or complexes containing ( PH2) ligands from l a - c and HP(SiMe3)2 yielded
the P2 complexes 6a-c.
+ P(SiMe,),/THF.
20°C
(4)
-
Me,SiCl
+
[PSiMe,),],/toluene.
-
Me3SiCl
___
2OoC
R2
..
la-c
+ HP(SiMe3)&FIF.
-
+
Me3SiC1, -H,,
20°C
Rz
-PH,
..
R,
(6)
C8
6a-c
1 LiP(SiMes)Z/toluene. ZOoC
- LiCI, -Me3SiC1, -P(SiMe3)3
>
(7)
6a and 6b can also be identified by NMR spectroscopy
for Reaction (1) when a 1 : 1 stoichiometry is used. Even
the cleavage of the Me,Si groups in 2a and 2b with methanol leads to 6a and 6b, presumably via (PH)2 complexes.
Anyew. Chem Int Ed Engl 24 (1985) No. 6
Fig. 1. Molecular structure of 6a (molecule I). The iYi atom> J I C L . L I I I \ N I I I I ~ ~
by a nearly planar array of four P atoms and lie 9 pm below the mean plane.
Fold angle (Nil-P3-P4-Ni2-P3-P4) 95.4". Important distances [pm] and
bond angles ["I: Nil-PI 212.5(5), Nil-P2 213.1(4), Nil-P3 223.8(5),
Nil-P4 223.1(5), Nil-Ni2 290.8(3), P3-P4 212.1(6), Ni2-P3 223.3(3),
Ni2-P4 223.3(3), Ni2-P5 213.4(4), Ni2-P6 214.9(5), P-C 182-186(1);
Ni 1 -P3-P4 6 l.5(2), P3- P4- Nil 6 1.8(2), P3- Nil - P4 56.7(2), PI -Ni I -P2
9 l.5(2), P3-Ni 1 -PI 101.9(3), P4-Ni I - P2 109.6(2), P3-Ni 1 -P2 165.7( 2),
P4-Nil-PI
158.3(2), Nil-P3-Ni2 Sl.l(2), NilLP4-Ni2 81.3(2). The distances in molecule 2 correspond to the values given above within the standard deviation.
0 VCH Verfagsgesellschaf~mbH, 0-6940 Wernheim. 1985
0570-0833/85/0606-0523 $ 02.50/0
523
(220-225 pm) and the values for a P-P double bond in
sterically protected free diphosphenes (200-205 pm).[81
This is analogous to the C-C bond in alkyne complexes
such as [(~od)Ni],(CPh),['~and supports the resonance
structure D .[Io1
The reaction mixture is concentrated to half of its volume in vacuo at 20'C,
cooled to - 78°C for 2 d, and filtered. The mother liquor is evaporated in vacuo at 20°C and the residue recrystallized from toluene at -20°C. Yield:
1.86 g 6c.3toluene (31%). brown crystals.
Received: February 18, 1985;
supplemented: April 3, 1985 [Z 1179 IE]
German version: Angew. Chem. 97 (1985) 523
Table I . 3'P{'HJ-NMRdata for the diphosphene and phosphorus complexes.
Standard: 85% H,PO,, high-field signals have negative signs, 6 + I ppm; Jr?-I
Hz.
la1
S(3'P)
(chelate)
S(3'P)
(P2R2)
J( PNi P)
Ibl
To1
To1
TH F
To1
TH F
THF
To1
To1
+58 (t)
76 (t)
72 (t)
+53 (t)
+68 (t)
+52 (t)
+58 (t)
75 (t)
- 101 (t)
- 103 (t)
+
-
28
24
28
25.5
20
21
30
27
6(3'P)
(chelate)
6(3'P)
(PZ)
J(PNiP)
[cl
+ 55 (t)
+ 133 (41
33
27.5
28
Solvent
Za
Zb
3b
4a
4b
4c
5a
5b
6a
6b
6c
To1
To1
To1
+
+
+67 (t)
+ 4 8 (t)
- 30 (t)
+
+
+
55 (t)
39 (t)
66 (t)
19 (t)
34 (t)
+ 135 (4)
+ 161 (4)
CAS Registry numbers:
la, 37504-45-3; lb, 96555-88-3; lc, 14647-23-5; Za, 96555-89-4; 2b, 96555.907; 3b, 96555-96-3; 4a, 96555-97-4; 4b, 96575-43-8; 4c, 96555-91-8; 5a, 9655598-5; 5b, 96555-92-9; 6a, 96555-93-0; 6b, 96555-95-2; 6c, 96555-94-1 ;
LiP(SiMe3)2,59624-9 1-8; t-BuP(SiMe3)2, 55793-25-4; PhP(SiMe&, 24103.444; HP(SiMe&, 15573-39-4; LiP(Me)SiMe3, 96555-99-6.
[a] To1 = toluene, T H F = tetrahydrofuran. [b] AA'XX' spectra, J(PNiP)=
I/2lci~-~J(AX)+trans-~J(AX')I;
since 'J(PP)%all 2J(PNiP), two pseudo triplets result, which d o not allow a further calculation of the coupling constants. [c] A2A;XX' spectra, J(PNiP) as for [a], pseudo triplet and pseudo
quintet; further calculation of the coupling constants not possible.
The 3'P('H}-NMR spectra are most useful for the characterization of the diphosphene and diphosphorus complexes.["' As shown in Table 1, 2-6 exhibit simple splitting patterns. The signals of the diphosphene ligands show
significant downfield shifts relative to those of P-containing three-membered rings,[''] which correspond to the resonance structure A . However, the signals of the diphosphene ligands lie at much higher field than those of free
diphosphenes.181The signals of the Pz ligands (see Table 1)
exhibit a downfield shift of 350-450 ppm relative to those
of P,[N(SiMe3)z]2.[7' Thus, the resonance structure D
should not be neglected.
Experimental Procedures
Za [Reaction (l)]: A solution containing 4.7g (15 mmol) of
LiP(SiMe&. I.8THF (THF=tetrahydrofuran) is slowly added under argon
to a stirred suspension of l a (2.5 g, 7.5 mmol) in 50 mL of toluene at -30°C.
After 2 d at -2O"C, the reaction mixture is slowly warmed to 20°C and filtered, and the solvent is removed in vacuo. Fractional crystallization from
pentane at -78 and -20°C affords reddish brown crystals of Za (1.31 g,
37%). 2b is synthesized analogously from l b (2 g, 3.6 mmol) and
LiP(SiMe3)2.I.8THF (2.26 g, 7.2 mmol). After evaporation of the solvent, the
residue is washed with pentane until a yellow powder remains. Recrystallization from toluene at -20°C gives yellow crystals of Zb (0.69 g, 28%).
4c [Reaction (3)]: A suspension of l c (2 g, 3.8 mmol) in 20 mL of T H F and
[(tBu)(Me,Si)P], (1.22 g, 3.8 mmol) is heated under argon to 50°C for 20 h.
After removal of the solvent in vacuo at 2 0 ° C the residue is recrystallized
from toluene at -20°C. Yield: 1.45 g 4c (60%), orange crystals.
5b [Reaction (Z)]: A suspension of Ib (2 g, 3.6 mmol) in 60 mL of T H F and
PhP(SiMe,)> (1.83 g, 7.2mmol) is stirred under argon for IOd at 2OOC. The
solvent of the suspension (green solid, greenish yellow solution) is evaporated in V ~ C U O at 20°C. Recrystallization of the residue from CH2C12 at
- 2 O T affords 5b (1.12 g, 44%), yellow crystals.
6a [Reaction (6)]: A suspension of l a (2 g, 6 mmol) in 60 mL of T H F and
HP(SiMe,)* (2.13 g, 12 mmol) is stirred under argon for 2 h. After removal of
the solvent in vacuo at 20"C, the residue is recrystallized from pentane at
-20°C. Yield: 6a (1.04 g, 59%), brown crystals.-& is obtained analogously
from l c ( 5 g, 9.5 mmol) and HP(SiMe& (3.37 g, 19 mmol) in 130 mL of THF.
524
0 V C H Verlagsgesellschaft mbH. 0-6940 Weinheim, 1985
[I] a) J. C. Green, M. L. H. Green, G. E. Morns, J. Chem. SOC.Chem. Commun. 1974. 212; E. Cannillo, A. Coda, K. Prout, J . C. Daran, Acta Crysfallogr. 8 3 3 (1977) 2608; h) P. S. Elmes, M. L. Scudder, B. 0. West, J.
Organomet. Chem. 122 (1976) 281; c) J. Chatt, P. B. Hitchcock, A. P.
Pidcock, C. P. Warrens, K. R. Dixon, J . Chem. SOC.
Chem. Commun.
1982, 932; J. Chem. SOC.Dalton Trans. 1984. 2237; d) D. Fenske, K.
Merzweiler, Angew. Chem. 96 (1984) 600; Angew. Chem. Int. Ed. Engl.
23 (1984) 635; e) K. M. Flynn, M. M. Olmstead, P. P. Power, J . Am.
Chem. Sac. 105 (1983) 2085; K . M. Flynn, B. D. Murray, M. M. Olmstead, P. P. Power, ibid. I05 (1983) 7460; K. M. Flynn, H. Hope, B. D.
Murray, M. M. Olmstead, P. P. Power, ibid. I05 (1983) 7750; M. M.
Olmstead, P. P. Power, ibid. 106 (1984) 1495; f) A. H. Cowley, J. E. Kilduff, J. G. Lasch, N. C . Norman, M. Pakulski, F. Ando, T. C. Wright,
ihid. 105 (1983) 7751 ; Orgartometal/ics 3 (1984) 1044; g) H. Vahrenkamp,
D. Wolters, Angew. Chem. 95 (1983) 152; Angew. Chem. Inf. Ed. Engl. 22
(1983) 154: h) J. Borm, L. Zsolnai, G. Huttner, ibid. 95 (1983) 1018 and
22 (1983) 977; Angew. Chem. Suppl. 1983. 1471.
[2] H. Schafer, Z. Nafurforsch. 8 3 4 (1979) 1358: B. Deppisch, H. SchBfer,
Acts Crysfall~gr.8 3 8 (1982) 748.
131 R. Hoffmann, Angew. Chem. 94 (1982) 7 2 5 ; Angew. Chem. Int. Ed. Engl.
21 (1982) 711.
W. A. Herrmann, B. Kournbouris, T. Zahn, M. L. Ziegler, Angew. Chem.
96 (1984) 802; Angew. Chem. I n f . Ed. Engl. 23 (1984) 812.
A. Vizi-Orosz, J. Organomel. Chem. I l l (1976) 61; G. Varadi, A. ViziOrosz, S. Vastag, G. Palyi, ibid. 108 (1976) 225; C. F. Campana, A. ViziOrosz, G. Palyi, L. Marko, Inorg. Chem. 18 (1979) 3054; H. Lang, L.
Zsolnai, G. Huttner, Angew. Chem. 95 (1983) 1017; Angew. Chem. I n f .
Ed. Engl. 22 (1983) 976; Angew. Chem. Suppl. 1983, 1463; 0. J. Scherer,
H. Sitzmann, G. Wolmershauser, J. Organomet. Chem. 268 (1984) C9:
Angew. Chem. 96 (1984) 979: Angew. Chem. Int. Ed. Engl. 23 (1984)
968.
6a: acentric space group PnaZ,, Z = 8 , a=1791.4(11), b=1201.0(6),
c=2691.5(15) pm (180 K). p(Mo,,)= 15.1 cm-'. Syntex R3, to 26=50",
5043 reflections, 3440 of these with I > Za(r), empirical absorption correction. Structure solution: Patterson method, Ni and P anisotropic, C
isotropic, H positions calculated and refined as rigid groups. R ,= 0.064,
R 2 =0.069. Further details of the crystal structure investigation are available on request from the Fachinformationsrentrum Energie Physik
Mathematik, D-75 14 Eggenstein-Leopoldshafen,by quoting the depository number CSD 51 389, the names of the authors, and the journal citation.
E. Niecke, R. Riiger, B. Krebs, Angew. Chem. 94 (1982) 553; Angewa.
Chem. Int. Ed. Engl. 21 (1982) 544.
A. H. Cowley, Polyhedron 3 (1984) 389.
V. W. Day, S . S. Abdel-Meguid, S. Dabestani, M. G. Thomas, W. R.
Pretzer, E. L. Muetterties, J. Am. Chem. Soc. 98 (1976) 8289; E. L. Muetterties, W. R. Pretzer, M. G. Thomas, B. F. Beier, D. L. Thorn, V. W.
Day, A. B. Anderson, ibid. 100 (1978) 2090; N. M. Boag, M. Green, J. A.
K. Howard, J. L. Spencer, R. F. D. Stansfield, F. G. A. Stone, M. D. 0.
Thomas, J. Vicente, P. Woodward, J. Chem. Soc. Chem. Commun. 1977.
930.
The Ni-Ni distance in 6a is appreciably longer than in [ ( ~ o d ) N i ] ~ ( C P h ) ~
(262 pm),[9' since the fold angle in 6a is larger and the Ni-P bond is
longer than the Ni-C bond in [(cod)Ni],(CPh),. Thus, no direct Ni-Ni
interaction needs to be assumed in 6a.
All diphosphene complexes isolated so far can be evaporated in vacuo
without noticeable decomposition, so that the molecular peaks in the
mass spectra show reasonable relative intensities. The P2 complexes
6a-c exhibit the molecular peaks with only minor intensities, if at
all.
M. Baudler, Angew. Chem. 94 (1982) 520; Angew. Chem. Int. Ed. Engl.
21 (1982) 492.
0570-0833/85/0606-0524 $ 02.50/0
Angen'. Chem. Int. Ed. Engl. 24 (198s~No. 6
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