Insertion of acetonitrile into the Zr-P bond of [Cp°2ZrCl(PHCy)] (Cy = cyclohexyl, Cp° = η5-C5EtMe4) followed by PHCy elimination to give [Cp°2(Cl)Zr(μ-N=CMe-CMe=N)Zr(Cl)Cp°2]

Article abstract of DOI:10.1021/om9901271

[Cp°₂ZrCl(PHCy)] (Cy = cyclohexyl, Cp° = η⁵-C₅EtMe₄) undergoes insertion of MeCN into the Zr-P bond, yielding [Cp°₂ZrCl{N=C(Me)(PHCy)}] (1). Isomers with a Z (1a) or E (1b) configuration at the C-N double bond are obtained in a ratio of 13:1. At room temperature, 1 slowly decomposes in solution with elimination of a PHCy fragment and formation of [Cp°₂-(Cl)Zr(μ-N=CMe-CMe=N)Zr(Cl)Cp°₂] (2). Two isomers are obtained with a trans (2a) or cis (2b) arrangement around the C-N double bonds of the bridging butane-2,3-diimino(2-)-N,N′ ligand. 1a, 2a, and 2b were isolated and characterized by IR, MS, and NMR spectroscopy (¹H, ³¹P, ¹³C), and crystal structure determinations were carried out on 1a and 2a. In the solid state, the short Zr-N bonds and the almost linear Zr-N-C angles of 1a and 2a indicate the presence of Zr-N double bonds.

Full text of DOI:10.1021/om9901271

2838
Organometallics 1999, 18, 2838-2842
In ser tion of Aceton itr ile in to th e Zr -P Bon d of
[Cp °2Zr Cl(P HCy)] (Cy ) Cycloh exyl, Cp ° ) η5-C5EtMe4)
F ollow ed by P HCy Elim in a tion To Give
[Cp °2(Cl)Zr (µ-NdCMe-CMedN)Zr (Cl)Cp °2]†
Ulrike Segerer, Steffen Blaurock, J oachim Sieler, and Evamarie Hey-Hawkins*
Institut fu¨r Anorganische Chemie der Universita¨t, Talstrasse 35, D-04103 Leipzig, Germany
Received February 22, 1999
[Cp°2ZrCl(PHCy)] (Cy ) cyclohexyl, Cp° ) η5-C5EtMe4) undergoes insertion of MeCN into
the Zr-P bond, yielding [Cp°2ZrCl{NdC(Me)(PHCy)}] (1). Isomers with a Z (1a ) or E (1b)
configuration at the C-N double bond are obtained in a ratio of 13:1. At room temperature,
1 slowly decomposes in solution with elimination of a PHCy fragment and formation of [Cp°2-
(Cl)Zr(µ-NdCMe-CMedN)Zr(Cl)Cp°2] (2). Two isomers are obtained with a trans (2a ) or
cis (2b) arrangement around the C-N double bonds of the bridging butane-2,3-diimino(2-)-N,N′
ligand. 1a , 2a , and 2b were isolated and characterized by IR, MS, and NMR spectroscopy
(1H, 31P, 13C), and crystal structure determinations were carried out on 1a and 2a . In the
solid state, the short Zr-N bonds and the almost linear Zr-N-C angles of 1a and 2a indicate
the presence of Zr-N double bonds.
Although the first dinuclear zirconocene phosphanido
of the P-H-functionalized zirconocene monophosphan-
ido complex [Cp°2ZrCl(PHCy)] to give [Cp°2ZrCl{Nd
C(Me)(PHCy)}] (1). At room temperature, 1 slowly
decomposes in solution with elimination of a PHCy
fragment to give [Cp°2(Cl)Zr(µ-NdCMe-CMe)N)Zr(Cl)-
Cp°2] (2).
complexes were prepared as early as 1966,1 these
complexes remained largely unexplored until 1983,
when Baker et al.2 prepared the first zirconocene(IV)
complexes with terminal dialkyl- or diarylphosphanido
ligands. To date, several group 4 complexes with dialkyl-
or diarylphosphanido ligands are known; however,
complexes of this type with P-functionalized phos-
phanido ligands are still rare.3
Resu lts a n d Discu ssion
For some time we have been interested in the prepa-
ration of zirconocene phosphanido complexes with P-H-
functionalized ligands and their synthetic potential.
Thus, the insertion of polar multiple-bond systems such
as CS2,4,5 diazoalkanes,6 phenylacetylene,7 carbodiim-
ides,5,8,9 phenylisothiocyanate,5 or isonitriles9 into the
Zr-P bond of P-functionalized zirconocene monophos-
phanido complexes [CpR2ZrCl{P(SiMe3)2}] [CpR ) η5-
C5H5, η5-C5H4Me (Cp′)] or [Cp°2ZrCl(PHCy)] (Cp° ) η5-
C5EtMe4) allows the synthesis within the coordination
sphere of zirconium of novel P-functionalized phosphino
ligands which are either difficult to synthesize or
inaccessible by other routes.7,10 Similarly, insertion of
ketones11 and benzonitrile11 was observed. We now
report the insertion of acetonitrile into the Zr-P bond
Syn th esis a n d P r op er ties of 1 a n d 2. Whereas
insertion of acetonitrile into the Zr-P bond of [Cp′2ZrCl-
{P(SiMe3)2}] is not observed,12 [Cp°2ZrCl(PHCy)] un-
dergoes insertion of MeCN into the Zr-P bond, yielding
[Cp°2ZrCl{NdC(Me)(PHCy)}] (1). In the 31P NMR spec-
trum of the reaction mixture signals are observed for
1
isomers of 1 with a Z (1a : -17.3 ppm, d, J P-H 208.9
1
Hz) or E (1b: -11.3 ppm, d, J P-H 217.0 Hz) configura-
tion at the C-N double bond in a ratio of 13:1 (Scheme
1).
The related alkylideneamido complexes with an
M-NdCR1R2 fragment are readily accessible by hy-
drozirconation of nitriles,3,13 and E and Z isomers are
observed for R1 * R2.3,13 The phosphinoarylideneamido
complex [Cp2Zr(Me){NdC(Ph)PHMes*}] was obtained
from methyl zirconocene chloride, benzonitrile, and
LiPHMes*.11 Hydrozirconation of (NiPr2)2PCN gives
[Cp2ZrCl{NdCHP(NiPr2)2}], the only other zirconocene
compound in which a phosphinoalkylideneamido ligand
is present.14 However, when diphenylcyanophosphine
† These results have been presented in part at the XIV International
Conference on Phosphorus Chemistry, Cincinnati, OH, J uly 12-17,
1998.
(1) Issleib, K.; Hackert, H. Z. Naturforsch. 1966, 21B, 519.
(2) Baker, R. T.; Krusic, P. J .; Tulip, T. H.; Calabrese, J . C.; Wreford,
S. S. J . Am. Chem. Soc. 1983, 105, 6763. Baker, R. T.; Whitney, J . F.;
Wreford, S. S. Organometallics 1983, 2, 1049.
(3) Hey-Hawkins, E. Chem. Rev. 1994, 94, 1661.
(4) Hey, E.; Lappert, M. F.; Atwood, J . L.; Bott, S. G. J . Chem. Soc.,
Chem. Commun. 1987, 421.
(5) Segerer, U.; Hey-Hawkins, E. Polyhedron 1997, 16, 2537.
(6) (a) Hey, E.; Lappert, M. F.; Atwood, J . L.; Bott, S. G. Polyhedron
1988, 7, 2083. (b) Hey, E.; Mu¨ller, U. Z. Naturforsch. 1989, 44B, 1538.
(7) Hey-Hawkins, E.; Lindenberg, F. Chem. Ber. 1992, 125, 1815.
(8) Hey-Hawkins, E.; Lindenberg, F. Z. Naturforsch. 1993, 48B, 951.
(9) Lindenberg, F.; Sieler, J .; Hey-Hawkins, E. Polyhedron 1996,
15, 1459.
(10) (a) Appel, R.; Moors, R. Angew. Chem. 1986, 98, 570. (b) Fritz,
G.; Ha¨rer, J .; Stoll, K.; Vaahs, T. Phosphorus Sulfur Relat. Elem. 1983,
18, 65. (c) Lindenberg, F.; Sieler, J .; Hey-Hawkins, E. Phosphorus,
Sulfur, Silicon 1996, 108, 279.
(11) Breen, T. L.; Stephan, D. W. Organometallics 1996, 15, 4509.
(12) Lindenberg, F. Dissertation, Universita¨t Leipzig, 1995.
(13) Erker, G. Angew. Chem., Int. Ed. Engl. 1989, 28, 397.
(14) Boutonnet, F.; Dufour, N.; Straw, T.; Igau, A.; Majoral, J .-P.
Organometallics 1991, 10, 3939.
10.1021/om9901271 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 07/19/1999

Insertion of Acetonitrile into the Zr-P Bond
Organometallics, Vol. 18, No. 15, 1999 2839
Sch em e 1
is employed in this reaction, the resulting hydrozircona-
tion product is unstable.14 The possible existence of two
isomers for [Cp2Zr(Me){NdC(Ph)PHMes*}]11 and [Cp2-
ZrCl{NdCHP(NiPr2)2}]14 was not discussed. Nitriles
also insert into the Zr-P bond of the thermally unstable
iminozirconiophosphorane [Cp2ZrCl(PMe2dNMes*)] at
-40 °C to give the cyclic compound [Cp2ZrCl(NdCR-
ppm (1J P-C 26.6 Hz), which is comparable to [Cp2Zr-
1
(Me){NdC(Ph)PHMes*}] (177.9 ppm, J P-C 30.5 Hz)11
and [Cp2ZrCl{NdCHP(NiPr2)2}] (184.56 ppm, 1J P-C 13.7
Hz).14 A doublet (2J P-C 9.3 Hz) is observed for the
methyl group (Me-C-P) of 1a at 34.09 ppm. The 13C
chemical shifts and P-C coupling constants of the
cyclohexyl ring of 1a are comparable to those of the
starting material and other insertion products thereof.5
The CdN stretching vibration in 1a gives rise to a
strong band at 1651 cm-1, which is comparable to that
of the related complex [Cp2ZrCl{NdCHP(NiPr2)2}] (1654
cm-1).14 The aminoalkylideneamido complexes [Ti{Nd
C(Ph)NMe2}3]17 and [M{NdC(R)NMe2}4] (M ) Zr, Hf;
R ) Bz, p-toluene)18 show a strong CdN stretching
vibration between 1571 and 1595 cm-1, but no absorp-
tion between 2000 and 2500 cm-1 for a nitrile adduct.
The P-H stretching band of 1a is shifted to lower
wavenumbers (2270 cm-1) relative to the starting mate-
rial [Cp°2ZrCl(PHCy)] (2311 cm-1).5
i
PMe2dNMes*)] (Mes* ) 2,4,6-tBu3C6H2, R ) Me, Pr,
Ph).15
Insertion reactions of nitriles into metal-nitrogen
(amide) bonds are also known.16 Thus, benzonitrile
reacts with [{Ti(NMe2)3}2] to give [Ti{NdC(Ph)NMe2}3]
as a red oil.17 The other group 4 metal amides [M(NMe2)4]
(M ) Zr, Hf) react exothermically with benzo- or
p-toluonitrile to give [M{NdC(R)NMe2}4].18
The signals of the insertion products 1a and 1b are
shifted to high field relative to [Cp°2ZrCl(PHCy)] (71.7
ppm, d, 1J P-H 209 Hz).5 Only 1a can be obtained in pure
form from the reaction mixture. In 1a , eight singlets
are observed for the Me groups of the inequivalent Cp°
At room temperature, 1 slowly decomposes in solution
with elimination of a PHCy fragment, which dimerizes
to P2H2Cy2 (31P: -84.6 ppm, m, -87.8 ppm, m, two
diastereomers), which is also unstable and slowly
decomposes to (PCy)4 (31P: -68.0 ppm, s) and PH2Cy
(-111.0 ppm, t). The resulting zirconocene product,
[Cp°2(Cl)Zr(µ-NdCMe-CMedN)Zr(Cl)Cp°2] (2), has a
bridging butane-2,3-diimino(2-)-N,N′ ligand with a trans
(2a ) or cis (2b) arrangement around the C-N double
bonds (Scheme 1). In contrast, benzonitrile inserts into
the Zr-P bond of [Cp2Zr(Me)(PHMes*)] to give [Cp2Zr-
(Me){NdC(Ph)PHMes*}],11 which has only one 31P
1
ligands in the H NMR spectrum. The P-H group gives
rise to a doublet of doublets at 4.00 ppm (1J P-H 208.9
2
Hz, J P-H 5.1 Hz). In the comparable complex [Cp2Zr-
(Me){NdC(Ph)PHMes*}], the P-H signal is at 6.17 ppm
1
1
(d, J P-H 234.3 Hz).11 In the H NMR spectrum of 1a ,
the methyl group of the inserted acetonitrile molecule
is observed as a doublet at 1.96 ppm (3J P-H 6.0 Hz) (pure
acetonitrile: 1.727 ppm, s). In the 13C NMR spectrum
of 1a , the CdN moiety gives rise to a doublet at 177.10
(15) Igau, A.; Dufour, N.; Mathieu, A.; Majoral, J .-P. Angew. Chem.
1993, 105, 76.
(16) Lappert, M. F.; Power, P. P.; Sanger, A. R.; Srivastava, R. C.
Metal and Metalloid Amides; Ellis Horwood Ltd.: Chichester, England,
1980.
(17) Lappert, M. F.; Sanger, A. R. J . Chem. Soc. A 1971, 1314.
(18) Chandra, G.; J enkins, A. D.; Lappert, M. F.; Srivastava, R. C.
J . Chem. Soc. A 1970, 2550.
1
NMR signal at -44.8 ppm (d, J P-H 233.9 Hz).11
However, no structural data are available, and decom-
position in solution is not mentioned in the paper.
There are only four other reports of reductive coupling
of alkyl- or arylnitriles. The two-electron reductive

2840 Organometallics, Vol. 18, No. 15, 1999
Segerer et al.
Ta ble 1. Su m m a r y of Cr ysta l Da ta for 1a a n d 2a
Ta ble 2. Selected Bon d Len gth s [Å] a n d Bon d
An gles [d eg] for 1a
1a
2a
Zr(1)-N(1)
P(1)-C(25)
P(1)-H(1P)
C(6)-C(7)
C(23)-C(24)
C(Cy)-C(Cy)
Zr(1)-C(Cp°)
2.029(2)
1.846(3)
1.359(1)
1.534(5)
1.508(4)
1.498(5)-1.549(6)
2.549(2)-2.586(2)
Zr(1)-Cl(1)
P(1)-C(23)
N(1)-C(23)
C(17)-C(18)
2.5107(6)
1.866(3)
1.260(3)
1.532(4)
formula
fw
cryst size, mm
cryst. syst.
space group
a, Å
C
30H49ClNPZr
C48H74Cl2N2Zr2
932.44
581.34
0.5 × 0.3 × 0.2
monoclinic
P21/n (no. 14)
10.596(1)
18.588(1)
15.553(1)
90
98.46(1)
90
3029.94(4)
4
0.25 × 0.25 × 0.2
triclinic
P1h (no. 2)
8.750(1)
10.623(1)
13.635(1)
73.608(1)
77.941(1)
72.720(1)
1150.0(2)
1
b, Å
c, Å
N(1)-Zr(1)-Cl(1)
100.07(6) C(25)-P(1)-C(23) 103.2(1)
C(25)-P(1)-H(1P) 105.5(1)
C(23)-P(1)-H(1P) 100.06(9)
N(1)-C(23)-C(24) 124.4(3)
C(24)-C(23)-P(1) 112.1(2)
C(26)-C(25)-P(1) 113.9(2)
R, deg
C(23)-N(1)-Zr(1)
N(1)-C(23)-P(1)
174.2(2)
123.1(2)
â, deg
γ, deg
V, Å3
C(30)-C(25)-P(1) 110.0(2)
Z
Ta ble 3. Selected Bon d Len gth s [Å] a n d Bon d
An gles [d eg] for 2a
temp, K
F(000)
220(2)
1232
1.274
0.522
3.4-55.8
27729
6780
0.0374
491
213(2)
490
1.346
0.603
3.1-52.2
5174
3793
0.0238
325
0.0474
0.1114
1.093
D
calcd, mg m-3
Zr(1)-N
2.018(3)
1.266(5)
1.510(7)
2.531(5)-2.585(4)
Zr(1)-Cl
C(23)-C(23a)
2.497(1)
1.524(8)
µ, mm-1
N-C(23)
2θ range, deg
no. of data collected
no. of unique data
Rint
C(23)-C(24)
Zr(1)-C(Cp°)
N-Zr(1)-Cl
99.5(1) C(23)-N-Zr(1)
177.9(3)
no. of params
R [I > 2σ(I)]
wR2 (all data)
GooF
N-C(23)-C(24)
123.7(4) N-C(23)-C(23a) 120.8(5)
0.0352
0.0861
1.076
C(24)-C(23)-C(23a) 115.5(5)
coupling of acetonitrile to form a (µ-butane-2,3-diimino-
(2-)-N,N′)ditungsten complex, [{LW(CO)2}2{µ-NdCMe-
CMedN}], was observed in the reaction of [LW(CO)3Br]
[L ) HB(Me2pz)3] with NaSiPr in acetonitrile. Here, the
i
oxidation product is PrSSiPr.19 Reduction of titanocene
dichloride with Zn in the presence of benzyl cyanide
gave the (µ-alkylideneamido)titanocene complex [(Cp2-
TiCl)2{µ-NdC(Bz)-C(Bz)dN}] with C-C bond forma-
tion between the two benzyl cyanide molecules.20 Simi-
larly, [Cp2TiR] reacts with R′CN to give [(Cp2TiR)2(µ-
NdCR′-CR′dN)] (R ) Ph, o-, m-, p-MeC6H4, Bz, C6F5,
Cl; R′ ) Ph, o-MeC6H4, Me).21 The related binuclear
complex [{WCl3[1-NH-2-(H2N)C6H4]}2(µ-1,2-N2C6H4)] was
obtained from the reaction of WCl6 with o-phenylene-
diamine in 2-propanol.22 The complexes [{MCl4(CH3-
CN)}2{µ-NdCMe-CMedN}]2- and [(MCl5)2{µ-NdCMe-
CMedN}]4- (M ) Nb, Ta) were obtained from the
reaction of MCl4 with acetonitrile in the presence of zinc
followed by addition of (Ph3P)2NCl, LiCl, or CsCl.23
The strong CdN stretching band of 2b at 1667 cm-1
lies in the range observed for [(Cp2TiR)2(µ-NdCR′-
CR′dN)] (R ) Ph, o-, m-, p-MeC6H4, Bz, C6F5, Cl; R′ )
Ph, o-MeC6H4, Me) (1638-1705 cm-1).21
Molecu la r Str u ctu r e of 1a a n d 2a . 1a crystallizes
in the monoclinic space group P21/n (no. 14), and 2a in
the triclinic space group P1h (no. 2) (Table 1). In 1a and
2a , the zirconium atom is coordinated in a distorted
tetrahedral fashion by two Cp° rings, one chloro ligand,
and the N atom.
We carried out a structure determination on the Z
isomer of 1 (1a , Figure 1, Table 2). The short Zr-N
distance [Zr(1)-N(1) 2.029(2) Å] indicates the presence
F igu r e 1. Molecular structure of [Cp°2ZrCl{NdC(Me)-
(PHCy)}] (1a ) showing the atom-numbering scheme em-
ployed (ORTEP, 50% probability, SHELXTL PLUS; XP).24
Hydrogen atoms (other than P-H) are omitted for clarity.
of a Zr-N double bond. This is also supported by the
near linearity of the Zr-N-C bond [174.2(2)°]. The Cd
N bond length [N(1)-C(23) 1.260(3) Å] is also in the
range expected for a double bond. The atoms Cl(1), Zr-
(1), N(1), and C(23) are coplanar with a Z orientation
of the Zr-NdC moiety (Cl and PHCy group are cis).
The zirconocene products obtained by decomposition
of 1 have a bridging butane-2,3-diimino(2-)-N,N′ ligand
with a trans or cis arrangement of the C-N double
bonds. We carried out a crystal stucture determination
on the trans isomer (2a , Figure 2, Table 3). The molecule
is located on an inversion center which bisects the C-C
bond of the butane-2,3-diimino(2-)-N,N′ ligand. As in 1a ,
the short Zr-N bond of 2.018(3) Å and the almost linear
Zr-N-C arrangement [177.9(3)°] in 2a indicate the
presence of a Zr-N multiple bond. The related complex
[(Cp2TiCl)2{µ-NdC(Bz)-C(Bz)dN}] [Ti-N-C 168.3(4)°,
C-N 1.260(5) Å, C-C 1.519(6) Å]20 exhibits bond
lengths and angles for the M-NdC-CdN-M fragment
similar to those of 2a . In [{LW(CO)2}2{µ-NdCMe-
CMedN}] [L ) HB(Me2pz)3], a bridging butane-2,3-
(19) Young, C. G.; Philipp, C. C.; White, P. S.; Templeton, J . L. Inorg.
Chem. 1995, 34, 6412.
(20) Rehbaum, F.; Thiele, K.-H.; Trojanov, S. I. J . Organomet. Chem.
1991, 410, 327.
(21) De Boer, E. J . M.; Teuben, J . H. J . Organomet. Chem. 1978,
153, 53.
(22) Redshaw, C.; Wilkinson, G.; Hussain-Bates, B.; Hursthouse, M.
B. J . Chem. Soc., Dalton Trans. 1992, 555.
(23) Finn, P. A.; Schaefer King, M.; Kilty, P. A.; McCarley, R. E. J .
Am. Chem. Soc. 1975, 97, 220.

Insertion of Acetonitrile into the Zr-P Bond
Organometallics, Vol. 18, No. 15, 1999 2841
1.0-1.8 (br, 11H, Cy), 1.837 (s, 3H, C4CH3CEt), 1.845 (s, 3H,
C4CH3CEt), 1.85 (s, 3H, C4CH3CEt), 1.86 (s, 3H, C4CH3CEt),
1.89 (s, 3H, C4CH3CEt), 1.90 (s, 3H, C4CH3CEt), 1.905 (s, 3H,
3
C4CH3CEt), 1.91 (s, 3H, C4CH3CEt), 1.96 (d, J P-H ) 6.0 Hz,
3H, CH3CP), 2.380 (q, 3J H-H ) 7.6 Hz, 2H, CH2CH3), 2.384 (q,
1
3J H-H ) 7.6 Hz, 2H, CH2CH3), 4.00 (d/d, J P-H ) 208.9 Hz,
2J P-H ) 5.1 Hz, 1H, P-H). 31P NMR (162 MHz, C6D6): δ -17.3
1
ppm (d, J P-H ) 208.9 Hz, P-H). 13C NMR (100.6 MHz, C6D6):
1
δ 177.10 (d, J P-C ) 26.6 Hz, CH3CN), 124.86 (s, C4Me4CEt),
124.63 (s, C4Me4CEt), 119.86 (s, C4Me4CEt), 119.74 (s, C4Me4-
CEt), 119.68 (s, C4Me4CEt), 119.05 (s, C4Me4CEt), 118.91 (s,
1
C4Me4CEt), 118.20 (s, C4CH3CEt), 36.18 (d, J P-C ) 4.5 Hz,
2
3
C1), 34.09 (d, J P-C ) 9.3 Hz, CH3CN), 30.74 (d, J P-C ) 7.8
Hz, C3/C5), 28.39 (d, 2J P-C ) 20 Hz, C2/C6), 27.04 (s, C4), 20.91
(s, CH2CH3), 20.79 (s, CH2CH3), 15.60 (s, CH2CH3), 15.50 (s,
CH2CH3), 12.56 (s, C4CH3CEt), 12.50 (s, C4CH3CEt), 12.45 (s,
C4CH3CEt), 12.32 (s, C4CH3CEt), 12.30 (s, C4CH3CEt), 12.26
(s, C4CH3CEt). Mass (EI, 70 eV): m/z 459 (M+ - Cl - 2C2H5
- 2CH3, 10), 439 [M+ - C(CH3)PHCy, 16], 290 [Cp°Zr(Cl)N+,
100], 254 (Cp°ZrN+, 16), 149 (Cp°+, 35), 134 [(Cp° - CH3)+,
36], 119 (C5Me4+, 41), 105 (C5Me3+, 15), 91 (Zr+, 22), 83 (Cy+,
35), 70 [NC(CH3)P+, 24], 41 (NCCH3+, 44), and fragmentation
F igu r e 2. Molecular structure of [Cp°2(Cl)Zr(µ-NdCMe-
CMedN)Zr(Cl)Cp°2] (2a ) showing the atom-numbering
scheme employed (SHELXTL PLUS; XP).24 Hydrogen
atoms are omitted for clarity.
diimino(2-)-N,N′ ligand with a trans arrangement com-
parable to that in 2a is present.19 Here the C-C
distance [1.40(4) Å]19 is shorter than expected for a
single bond, while in 2a , the C(23)-C(23a) bond length
of 1.524(8) Å and the CdN distance [N-C(23) 1.266(5)
Å] are as expected for a NdC-CdN fragment. The
binuclear complex [{WCl3[1-NH-2-(H2N)C6H4]}2(µ-1,2-
N2C6H4)] has a cis configuration of the CdN double
bonds due to geometric requirements.22 Here, the CdN
bond length [1.316(20) Å] is larger, and the C-C
distance [1.415(33) Å] smaller than in 2a .22 Comparable
bond lengths and angles were observed for the Zr-N-C
fragment in zirconocene alkylideneamido complexes, in
which the Zr-N bond lengths range from 2.013 to 2.063
Å, CdN ranges from 1.259(1) to 1.266(4) Å, and the Zr-
N-C linkages are almost linear (164-174°).13 For the
structurally characterized complex [{NbCl4(CH3CN)}2-
{µ-NdCMe-CMedN}]2-, the data suggest that the π
bonding is delocalized over the Nb(NCMeCMeN)Nb
fragment.23
products thereof. IR: ν(P-H) 2270 (m), ν(CdN) 1651 (st) cm-1
.
P r ep a r a tion of [Cp °2(Cl)Zr (µ-NdCMe-CMedN)Zr (Cl)-
Cp °2] (2). Acetonitrile (0.2 mL, 0.16 g, 3.80 mmol) was added
to a solution of [Cp°2ZrCl(PHCy)] (1.53 g, 2.84 mmol) in toluene
(20 mL). After 20 min the color of the solution changed from
red to orange. A 31P NMR spectrum showed two products [1a
(Z isomer) and 1b (E isomer), vide supra]. The solution was
concentrated and kept at room temperature for 1 month, after
which a small amount of yellow crystals of 2a (trans-2) had
formed and were isolated. The solution was concentrated until
a yellow solid precipitated. This was shown to consist of a
mixture of 2a and 2b (ca. 0.85 g, ca. 64%) by 1H NMR
spectroscopy. Repeated recrystallization from pentane/toluene
gave pure 2b (cis-2) as orange microcrystals.
2a : Mp: 179 °C. C48H74Cl2N2Zr2 (932.44): calcd. C 61.83,
H 8.00, N 3.00, Cl 7.60; found C 61.93, H 8.65, N 3.21, Cl 7.59.
2b: Mp: >300 °C, >55 °C dec. C48H74Cl2N2Zr2 (932.44):
calcd. C 61.83, H 8.00, N 3.00, Cl 7.60; found C 62.03, H 8.99,
N 3.33, Cl 7.66.
3
2a : 1H NMR (400 MHz, C6D6) δ 0.84 (t, J H-H ) 7.5 Hz,
6H, C5Me4CH2CH3), 1.87 (s, 12H, C4CH3CEt), 1.92 (s, 12H,
C4CH3CEt), 2.11 (s, 3H, CH3CN), 2.44 (q, 3J H-H ) 7.5 Hz, 4H,
CH2CH3). Additionally, a singlet at 0.59 ppm is observed,
which could not be asigned. 13C NMR (100.6 MHz, C6D6): δ
ca. 129.9, s, signal is obscured by signals of solvent (Nd
CMeCMedN ?), 126.3 (s, C4Me4CEt), 124.6 (s, C4Me4Et), 123.2
(s, C4Me4Et), 22.1 (s, CH3CN), 21.1 (s, CH2CH3), 15.0 (s,
CH2CH3), 12.8 [s, C4(CH3)4CEt], 12.6 [s, C4(CH3)4CEt]. Mass
(EI, 70 eV): m/z 465.5 (M+/2, 23.7), 421 (M+/2 - C2H5 - CH3,
Exp er im en ta l Section
Gen er a l Rem a r k s. All experiments were carried out under
purified dry argon. Solvents were dried and freshly distilled
under argon. The NMR spectra were recorded with an AVANCE
1
DRX 400 spectrometer (Bruker). H NMR: internal standard
solvent (benzene), external standard TMS. 13C NMR: external
standard TMS, internal standard solvent. 31P NMR: external
standard 85% H3PO4. The IR spectra were recorded on a
Perkin-Elmer System 2000 FT-IR spectrometer in the range
350-4000 cm-1. X-ray structural analyses: Siemens SMART
CCD diffractometer. The melting points were determined in
sealed capillaries under argon and are uncorrected. [Cp°2ZrCl-
(PHCy)]5 was prepared by literature procedures.
100), 316 (M+/2 - Cp°, 13.6), 275 (Cp°ZrCl+, 8.5), 149 (Cp°+,
10.2), 134 [(Cp° - CH3)+, 10.3], 120 (C5Me4+, 7.6), 105 (C5Me3
,
+
3.4), 91 (Zr+, 3.7), 41 (NCCH3+, 5.1), and fragmentation
products thereof.
3
2b: 1H NMR (400 MHz, C6D6) δ 0.96 (t, J H-H ) 7.5 Hz,
6H, C5Me4CH2CH3), 1.89 (s, 12H, C4CH3CEt), 1.93 (s, 6H,
C4CH3CEt), 1.96 (s, 6H, C4CH3CEt), 2.14 (s, 3H, CH3CN), 2.40
P r ep a r a tion of [Cp °2Zr Cl{NdC(Me)(P HCy)}] (1). Ace-
tonitrile (0.2 mL, 0.16 g, 3.80 mmol) was added to a solution
of [Cp°2ZrCl(PHCy)] (1.53 g, 2.84 mmol) in toluene (20 mL).
After 20 min the color of the solution changed from red to
orange. A 31P NMR spectrum showed two products [1a (Z
isomer, -17.3 ppm, 208.9 Hz) and 1b (E isomer, -11.3 ppm,
217.0 Hz), ratio 13:1]. The solution was concentrated and
cooled to -28 °C. After several days, pale yellow-green crystals
3
3
(q, J H-H ) 7.5 Hz, 2H, CH2CH3), 2.41 (q, J H-H ) 7.5 Hz, 2H,
CH2CH3). 13C NMR (100.6 MHz, C6D6): δ 173.0 (s, ?), 124.0
(s, C4Me4CEt), 119.3 (s, C4Me4Et), 119.2 (s, C4Me4Et), 118.7
(s, C4Me4Et), 118.0 (s, C4Me4Et), 29.7 (s, CH3CN), 20.9 (s, CH2-
CH3), 15.5 (s, CH2CH3), 12.5 [s, C4(CH3)4CEt], 12.4 [s, C4(CH3)4-
CEt], 12.2 [s, C4(CH3)4CEt]; apparently, the CN signal is
obscured by signals of solvent. Mass (EI, 70 eV): m/z 466 (M+/
of 1a had formed. Yield: ca. 1.2 g (ca. 73%). Mp: 89 °C. C30H49
-
2, 20.7), 423 (M+/2 - C2H5 - CH3, 100), 387 (M+/2 - C2H5
-
ClNPZr (581.34): calcd C 62.09, H 8.51, N 2.41, Cl 6.11; found
C 61.81, H 8.63, N 2.50, Cl 6.19.
CH3 - Cl, 17.5), 275 (Cp°ZrCl+, 35.7), 258 (Cp°ZrCl+ - CH3,
+
1a decomposes in solution at room temperature.
22.1), 149 (Cp°+, 16.4), 134 [(Cp° - CH3)+, 22.1], 119 (C5Me4
,
17.1), 105 (C5Me3 and ZrN+, 15.7), 91 (Zr+, 16.1), and
3
+
1H NMR (400 MHz, C6D6): δ 0.92 (t, J H-H ) 7.6 Hz, 3H,
3
C5Me4CH2CH3), 0.95 (t, J H-H ) 7.6 Hz, 3H, C5Me4CH2CH3),
fragmentation products thereof. IR: ν(CdN) 1667 (st) cm-1
.

2842 Organometallics, Vol. 18, No. 15, 1999
Segerer et al.
X-r a y Str u ctu r e Deter m in a tion s. Data of 1a and 2a (Mo
KR, λ ) 0.71073 Å) were collected with a Siemens CCD
(SMART). All observed reflections were used for determination
of the unit cell parameters. The structures were solved by
direct methods (SHELXTL PLUS24) and subsequent difference
Fourier syntheses and refined by full-matrix least-squares on
F2 (SHELXTL PLUS24). Restrictions for 1a : C, Cl, N, P, and
Zr atoms anisotropic, H atoms located and refined isotropically.
Absorption correction with SADABS. Restrictions for 2a : C,
Cl, N, and Zr atoms anisotropic, H atoms of Cp° ring C(17) -
C(22) refined in fixed positions, other H atoms located and
refined isotropically. Absorption correction with SADABS.
The methyl and ethyl groups of one of the Cp° rings (atoms
C(12)-C(22)) in 2a have large thermal parameters. While the
program SHELX97 gives splitting positions for the methyl and
ethyl groups (C(17)-C(21)), no splitting positions were given
for the cyclopentadienyl ring C atoms C(12)-C(16), as the
anisotropic displacement parameters were not large enough.
Although refinement of the atoms C(17)-C(21) in splitting
positions results in a lower R value (wR2 decreases from 0.11
to 0.08), this approach results in meaningless bond angles.
Ack n ow led gm en t. We gratefully acknowledge sup-
port of this work by the Deutsche Forschungsgemein-
schaft, the Landesgraduiertenfo¨rderung Sachsen (S.B.),
and the Fonds der Chemischen Industrie, and we thank
the company Chemetall for a generous donation of
lithium alkyls.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, atomic coordinates, anisotropic displacement parameters,
and bond lengths and angles for 1a and 2a . This material is
available free of charge via the Internet at http://pubs.acs.org.
(24) SHELXTL PLUS; Siemens Analyt. X-ray Inst. Inc., 1990. XS:
Program for Crystal Structure Solution, XL: Program for Crystal
Structure Determination, XP: Interactiv Molecular Graphics.
OM9901271