N-N bond cleavage of organohydrazines by molybdenum(II) and tungsten(II) complexes containing a linear tetraphosphine ligand. Formation of nitrido or imido complexes and their reactivities

Article abstract of DOI:10.1021/om7005485

The Mo(II) tetraphosphine-dihalide complexes [MoX₂(κ ⁴-P4)] (X = Cl (2a), Br (2b); P4 = mesoo-C₆H ₄(PPhCH₂CH₂PPh₂)₂) having uncommon trigonal-prismatic geometry cleaved the N-N bond in Me ₂NNH₂ and PhNHNH₂ at room temperature to form the nitrido complexes trans-[MoX(N)(κ⁴-P4)] (X = Cl (3a), Br (3b)). In contrast, similar reactions of the W(II) congener [WBr ₂(κ⁴-P4)] afforded the imido complex trans-[WBr(NH)(κ-P4)]⁺ (4c⁺), which was isolated as a PF₆ or BPh₄ salt. Addition of HBF₄ converted 3 into the imido complexes trans-[MoX(NH)(κ⁴-P4)][BF ₄] (X = Cl (4a[BF₄]), Br (4b[BF₄])), while deprotonation of 4a⁺ and 4b⁺ by NEt₃ readily regenerated 3a and 3b. At elevated temperatures, 2a also reacted with RNHNHR (R = Me, Ph), giving the corresponding organoimido complexes trans-[MoCl(NR) (κ⁴-P4)][PF₆] (6[PF₆]) after anion metathesis with K[PF₆]. The mechanism has been proposed for the N-N bond cleavage, which involves the proton shift in the end-on coordinated organohydrazine followed by the two-electron reduction by the M(II) center to give the M(IV) imido complex and the amine. The nitrido ligand in 3a is susceptible to electrophilic attack by methyl trifluoromethanesulfonate to form 6[CF₃SO₃] (R = Me), while reactions of 3a with acid chlorides RCOCl (R = Me, Ph, p-tolyl (Tol)) afforded the neutral acylimido complexes cis,mer-[MoCl₂(NCOR)(κ³-P4)] (7). Treatment of 7 with K[PF₆] yielded the cationic complexes trans-[MoCl(NCOR)(κ⁴-P4)][PF₆] (8[PF₆]). On the other hand, imido complex 4a[BF₄] smoothly reacted with isocyanates RNCO (R = Ph, Tol) in the presence of a catalytic amount of Et ₃N to give the carbamoylimido complexes trans-[MoCl(NCONHR)- (κ⁴-P4)][BF₄] (9[BF₄]), and the thiocarbamoyl analogue trans-[MoCl(NCSNHPh)(κ⁴-P4)][PF ₆] (10[PF₆]) was also obtained from 4a[PF₆] and PhNCS. Although hydrolysis of 7 (R = Tol) in a THF/aqueous KOH mixture resulted in the formation of p-toluamide only in low yield, reduction of the same complex with NaBH₄ and LiAlH₄ generated p-toluamide and 4-methylbenzylamine, respectively, in moderate yields. Molecular structures of 3a, 4a[BF₄], 4c[BPh₄], 6[PF₆] (R = Me), 6[BF₄] (R = Ph), 7 (R = Me), 8[PF₆] (R = Me), and 9[BF₄] (R = Tol) were determined crystallographically.

Full text of DOI:10.1021/om7005485

Organometallics 2007, 26, 4909-4920
4909
N-N Bond Cleavage of Organohydrazines by Molybdenum(II) and
Tungsten(II) Complexes Containing a Linear Tetraphosphine
Ligand. Formation of Nitrido or Imido Complexes and Their
Reactivities
Daisuke Watanabe, Sumie Gondo, Hidetake Seino, and Yasushi Mizobe*
Institute of Industrial Science, The UniVersity of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505, Japan
ReceiVed June 4, 2007
The Mo(II) tetraphosphine-dihalide complexes [MoX2(κ4-P4)] (X ) Cl (2a), Br (2b); P4 ) meso-
o-C6H4(PPhCH2CH2PPh2)2) having uncommon trigonal-prismatic geometry cleaved the N-N bond in
Me2NNH2 and PhNHNH2 at room temperature to form the nitrido complexes trans-[MoX(N)(κ4-P4)] (X
) Cl (3a), Br (3b)). In contrast, similar reactions of the W(II) congener [WBr2(κ4-P4)] afforded the
imido complex trans-[WBr(NH)(κ4-P4)]+ (4c+), which was isolated as a PF6 or BPh4 salt. Addition of
HBF4 converted 3 into the imido complexes trans-[MoX(NH)(κ4-P4)][BF4] (X ) Cl (4a[BF4]), Br
(4b[BF4])), while deprotonation of 4a+ and 4b+ by NEt3 readily regenerated 3a and 3b. At elevated
temperatures, 2a also reacted with RNHNHR (R ) Me, Ph), giving the corresponding organoimido
complexes trans-[MoCl(NR)(κ4-P4)][PF6] (6[PF6]) after anion metathesis with K[PF6]. The mechanism
has been proposed for the N-N bond cleavage, which involves the proton shift in the end-on coordinated
organohydrazine followed by the two-electron reduction by the M(II) center to give the M(IV) imido
complex and the amine. The nitrido ligand in 3a is susceptible to electrophilic attack by methyl
trifluoromethanesulfonate to form 6[CF3SO3] (R ) Me), while reactions of 3a with acid chlorides RCOCl
(R ) Me, Ph, p-tolyl (Tol)) afforded the neutral acylimido complexes cis,mer-[MoCl2(NCOR)(κ3-P4)]
(7). Treatment of 7 with K[PF6] yielded the cationic complexes trans-[MoCl(NCOR)(κ4-P4)][PF6] (8[PF6]).
On the other hand, imido complex 4a[BF4] smoothly reacted with isocyanates RNCO (R ) Ph, Tol) in
the presence of a catalytic amount of Et3N to give the carbamoylimido complexes trans-[MoCl(NCONHR)-
(κ4-P4)][BF4] (9[BF4]), and the thiocarbamoyl analogue trans-[MoCl(NCSNHPh)(κ4-P4)][PF6] (10[PF6])
was also obtained from 4a[PF6] and PhNCS. Although hydrolysis of 7 (R ) Tol) in a THF/aqueous
KOH mixture resulted in the formation of p-toluamide only in low yield, reduction of the same complex
with NaBH4 and LiAlH4 generated p-toluamide and 4-methylbenzylamine, respectively, in moderate yields.
Molecular structures of 3a, 4a[BF4], 4c[BPh4], 6[PF6] (R ) Me), 6[BF4] (R ) Ph), 7 (R ) Me), 8[PF6]
(R ) Me), and 9[BF4] (R ) Tol) were determined crystallographically.
series of protonated nitrogenous ligands as well as free ammonia.
These reactions involve the step in which the N-N single bond
of intermediary hydrazidium ligand MdN-NH3+ is cleaved to
give ammonia and the nitrido species MtN. In relation to these
and biological N2-fixing systems, reductive cleavage of the N-N
bonds in hydrazines has also been investigated previously, and
several transition metal complexes are known to promote this
transformation stoichiometrically5,6 or catalytically,7,8 in certain
cases of which the metal species catalyze the disproportionation
of hydrazine into ammonia and N2. As for many stoichiometric
reaction systems, formation of not only the nitrido but also the
Introduction
Reduction of dinitrogen into ammonia under mild conditions
by the use of transition metal complexes has been attracting
much attention in relation to biological and industrial nitrogen
fixation. Extensive studies for more than 40 years have
demonstrated that ligating N2 can readily be converted into
ammonia for a considerable number of N2 complexes.1,2
However, the complexes for which the reduction mechanism is
rationally demonstrated by isolating the fully characterized
intermediate stages are still limited. Molybdenum and tungsten
complexes with tertiary phosphine co-ligands3 and those with
triamidoamine co-ligands4 are quite noteworthy in that these
can readily undergo protonation at their N2 ligand to give a
(5) Reactions on monometallic sites: (a) Le Floc’h, C.; Henderson, R.
A.; Hughes, D. L.; Richards, R. L. J. Chem. Soc., Chem. Commun. 1993,
175. (b) Zambrano, C. H.; Fanwick, P. E.; Rothwell, I. P. Organometallics
1994, 13, 1174. (c) Arney, D. S. J.; Burns, C. J. J. Am. Chem. Soc. 1995,
117, 9448.
(6) Reactions on multimetallic sites: (a) Schollhammer, P.; Pe´tillon, F.
Y.; Poder-Guillou, S.; Saillard, J. Y.; Talarmin, J.; Muir, K. W. Chem.
Commun. 1996, 2633. (b) Pe´tillon, F. Y.; Schollhammer, P.; Talarmin, J.;
Muir, K. W. Inorg. Chem. 1999, 38, 1954. (c) Verma, A. K.; Lee, S. C. J.
Am. Chem. Soc. 1999, 121, 10838. (d) Nakajima, Y.; Suzuki, H. Organo-
metallics 2003, 22, 959. (e) Nakajima, Y.; Inagaki, A.; Suzuki, H.
Organometallics 2004, 23, 4040. (f) Vela, J.; Stoian, S.; Flaschenriem, C.
J.; Mu¨nck, E.; Holland, P. L. J. Am. Chem. Soc. 2004, 126, 4522. (g) Shaver,
M. P.; Fryzuk, M. D. J. Am. Chem. Soc. 2005, 127, 500. (h) Ohki, Y.;
Takikawa, Y.; Hatanaka, T.; Tatsumi, K. Organometallics 2006, 25, 3111.
(1) For reviews, see: (a) Allen, A. D.; Harris, R. O.; Loescher, B. R.;
Stevens, J. R.; Whiteley, R. N. Chem. ReV. 1973, 73, 11. (b) Chatt, J.;
Dilworth, J. R.; Richards, R. L. Chem. ReV. 1978, 78, 589. (c) Hidai, M.;
Mizobe, Y. Chem. ReV. 1995, 95, 1115. (d) MacKay, B. A.; Fryzuk, M. D.
Chem. ReV. 2004, 104, 385.
(2) For a summary of recent examples, see: (a) Schrock, R. R. Acc.
Chem. Res. 2005, 38, 955. (b) MacLachlan, E. A.; Fryzuk, M. D.
Organometallics 2006, 25, 1530. (c) Chirik, P. J. Dalton Trans. 2007, 16.
(3) Henderson, R. A.; Leigh, G. J.; Pickett, C. J. AdV. Inorg. Chem.
Radiochem. 1983, 27, 197.
(4) Weare, W. W.; Dai, X.; Byrnes, M. J.; Chin, J. M.; Schrock, R. R.;
Mu¨ller, P. Proc. Natl. Acad. Sci. 2006, 103, 17099, and references therein.
10.1021/om7005485 CCC: $37.00 © 2007 American Chemical Society
Publication on Web 08/21/2007

4910 Organometallics, Vol. 26, No. 20, 2007
Watanabe et al.
imido and amido complexes has also been confirmed. However,
the well-defined bond cleavage reactions of organohydrazines
by Mo and W phosphine complexes have not yet been
documented.
nitrido complex trans-[MoCl(N)(κ4-P4)] (3a), which was ex-
tracted from the evaporated reaction mixture residue with
benzene and isolated from benzene/hexane as orange-red crystals
in 92% yield (eq 2). A similar procedure using the dibromo
We have reported previously the synthesis of new Mo(0) and
W(0) complexes with the linear tetraphosphine ligand meso-o-
C6H4(PPhCH2CH2PPh2)2 (P4), [M(dppe)(κ4-P4)] (1; M ) Mo,
W; dppe ) Ph2PCH2CH2PPh2),9 and recent studies have
disclosed the conversion of 1 into a series of complexes
containing the P4 ligand. Interestingly, the P4 ligand in these
complexes has turned out to display the binding features
characteristic of its unique structure. Thus, coordination by three
five-membered chelate rings is highly strained with the P-M-P
angles much smaller than 90°, resulting in the facile dissociation
of one or two outer P atoms to take a κ3- or κ2-coordination
mode.10 Furthermore, uncommon geometry around the metal
center sometimes emerges. For example, M(II) dihalide com-
plexes [MX2(κ4-P4)] (2; MX ) MoCl (2a), MoBr (2b), WBr
(2c)) obtained from the reaction of 1 with 2 equiv of PhCH2X
have a trigonal-prismatic structure with one of three side
rectangles capped by the κ4-P4 ligand (eq 1),11 which presents
analogue 2b instead of 2a also afforded the nitrido complex
trans-[MoBr(N)(κ4-P4)] (3b) in satisfactory yield. By contrast,
analogous reaction of the W complex 2c with Me2NNH2 did
not give the corresponding nitrido complex but a pink precipitate
insoluble in benzene or THF. Although further purification of
this crude solid was also hampered by its low solubility in other
common solvents including CH2Cl2 and MeCN, crystallization
from CH2Cl2/ether became possible after treatment of this solid
with K[PF6], leading to successful isolation of the W(IV) imido
complex trans-[WBr(NH)(κ4-P4)][PF6] (4c[PF6]) as purple
crystals in 59% yield (eq 3). The initial precipitate was identified
as the Br salt 4cBr from its NMR spectra, comparable to those
of 4c[PF6]. Reactions of 2a and 2c with excess PhNHNH2 also
afforded 3a and 4c+, respectively, and GLC analysis confirmed
the concurrent formation of PhNH2 (∼1.0 mol per mol of 2).
These results might suggest that one metal center cleaves the
N-N bond of hydrazine stoichiometrically and that the nitrido
and imido ligands originate from the NH2 group in organohy-
drazines.
We have also examined the reactions of 2 with unsubstituted
hydrazine, but these appeared to proceed in a different way.
The nitrido or imido complexes above were scarcely formed,
and a much larger than a stoichiometric amount of N2H4 was
consumed in these reactions. For instance, when 2a was allowed
to react with 10 equiv of N2H4 in THF at room temperature for
24 h, formation of 12.1 equiv of NH3 and 3.0 equiv of N2 was
observed. It is likely that certain metal species catalyze
disproportionation of N2H4 to form NH3 and N2 in a 4:1 molar
ratio, but we have not yet been able to fully characterize the
complexes present in this reaction system.
The Mo nitrido complexes 3a and 3b readily underwent
protonation by HBF4 at the N atoms to form the corresponding
Mo(IV) imido complexes trans-[MoX(NH)(κ4-P4)][BF4] (X )
Cl (4a+), Br (4b+)) (Scheme 1). It was also confirmed that
treatment of these imido complexes with bases (e.g., Et3N,
Me2NNH2) regenerated the parent nitrido complexes. In sharp
contrast, deprotonation from the W complex 4c+ did not take
place by amines or hydrazines, and reactions with stronger bases
such as KN(SiMe3)2 or n-BuLi did not proceed cleanly. These
a sharp contrast to an octahedral geometry observed for all the
other known trans-[MX2(tertiary phosphine)4] (M ) Mo, W;
X ) halogen). Probably due to this unusual structure and/or
facile dissociation of P atom(s), complexes 2 have been found
to show much higher reactivities toward diazoalkanes than the
related complexes trans-[MX2(dppe)2]. We have therefore
investigated further the reactions of these dihalide complexes
2 with organo-nitrogenous compounds, viz., organohydrazines.
Results and Discussion
1. Formation of Nitrido and Imido Complexes via N-N
Bond Cleavage of Mono- or 1,1-Disubstituted Hydrazines.
The Mo(II) dichloro complex 2a smoothly reacted with
Me2NNH2 at room temperature in THF to form the Mo(IV)
(7) Reactions on monometallic sites: (a) Schrock, R. R.; Glassman, T.
E.; Vale, M. G.; Kol, M. J. Am. Chem. Soc. 1993, 115, 1760. (b) Vale, M.
G.; Schrock, R. R. Inorg. Chem. 1993, 32, 2767. (c) Ramachandraiah, G.
J. Am. Chem. Soc. 1994, 116, 6733. (d) Hitchcock, P. B.; Hughes, D. L.;
Maguire, M. J.; Marjani, K.; Richards, R. L. J. Chem. Soc., Dalton Trans.
1997, 4747. (e) Chu, W.-C.; Wu, C.-C.; Hsu, H.-F. Inorg. Chem. 2006, 45,
3164.
(8) Reactions on multimetallic sites: (a) Hozumi, Y.; Imasaka, Y.;
Tanaka, K.; Tanaka, T. Chem. Lett. 1983, 12, 897. (b) Block, E.; Ofori-
Okai, G.; Kang, H.; Zubieta, J. J. Am. Chem. Soc. 1992, 114, 758. (c)
Kuwata, S.; Mizobe, Y.; Hidai, M. Inorg. Chem. 1994, 33, 3619. (d)
Coucouvanis, D.; Demadis, K. D.; Malinak, S. M.; Mosier, P. E.; Tyson,
M. A.; Laughlin, L. J. In Transition Metal Sulfur Chemistry; Stiefel, E. I.,
Matsumoto, K., Eds.; ACS Symposium Series 653; American Chemical
Society: Washington, DC, 1996; Chapter 6. (e) Seino, H.; Masumori, T.;
Hidai, M.; Mizobe, Y. Organometallics 2003, 22, 3424. (f) Nakajima, Y.;
Suzuki, H. Organometallics 2005, 24, 1860. (g) Takei, I.; Dohki, K.;
Kobayashi, K.; Suzuki, T.; Hidai, M. Inorg. Chem. 2005, 44, 3768.
(9) (a) Arita, C.; Seino, H.; Mizobe, Y.; Hidai, M. Chem. Lett. 1999,
28, 611. (b) Arita, C.; Seino, H.; Mizobe, Y.; Hidai, M. Bull. Chem. Soc.
Jpn. 2001, 74, 561.
(10) (a) Seino, H.; Arita, C.; Hidai, M.; Mizobe, Y. J. Organomet. Chem.
2002, 658, 106. (b) Ohnishi, T.; Seino, H.; Hidai, M.; Mizobe, Y. J.
Organomet. Chem. 2005, 690, 1140.
(11) Seino, H.; Watanabe, D.; Ohnishi, T.; Arita, C.; Mizobe, Y. Inorg.
Chem. 2007, 46, 4784.

N-N CleaVage of Organohydrazines by Mo(II) and W(II) Complexes
Scheme 1
Organometallics, Vol. 26, No. 20, 2007 4911
results may be explained by the lower acidity of the imido ligand
bound to the less-electron-withdrawing W(IV) center as com-
pared to that in the Mo(IV) complex. In the reactions of 2 (M
) Mo) with organohydrazines, due to the presence of concomi-
tantly formed amine and/or excess hydrazine, the deprotonation
products, viz., nitrido complexes, presumably become the major
product. Hence the reactions using stoichiometric amounts of
organohydrazines, which are converted to less basic products
after N-N cleavage, might lead to the direct isolation of imido
complexes even in the case of Mo. Indeed, reactions of 2a and
2b with 1.1 equiv of N-aminophthalimide proceeded very slowly
(over ∼10 days) in THF at room temperature, from which were
obtained the salts of cationic imido complexes 4a+ and 4b+
after anion metathesis with K[PF6] or Na[BPh4].
2. Characterization of the Nitrido and Imido Complexes.
Single-crystal X-ray diffraction studies were carried out to
determine the structural details. Molecular structures of the
nitrido complex 3a and the imido complex 4a[BF4] are depicted
in Figures 1 and 2, respectively. In both complexes, the Mo
centers adopt severely distorted octahedral geometry with
mutually trans N and Cl atoms, and four P atoms of the P4
ligand occupy the remaining equatorial sites. The phenyl groups
attached to the inner P atoms are directed syn to the nitrogenous
ligand. The Mo-N distance in the nitrido complex 3a at 1.667-
(3) Å is characteristic of a Mo-N triple bond and somewhat
shorter than those in trans-[MoCl(N)(depe)2] (depe ) Et2PCH2-
CH2PEt2), at 1.684(5)-1.722(5) Å,12 and trans-[Mo(L)(N)-
(dppe)2] (L ) N3,13 NCCHdCOPh,14 NCC(CN)COMe15), at
1.70-1.79 Å. The ν(MotN) values at 994 and 997 cm-1 for
3a and 3b, respectively, are almost comparable to those at 970-
1000 cm-1 for the other precedent Mo(IV)-nitrido com-
plexes.12,14-17 In the cationic imido complex 4a+, the Mo-N
bond is elongated to 1.712(4) Å from that of the nitrido complex
3a, which is a value typical of the 2σ- and 4π-electron-donating
imido ligand.13,17,18 This assignment is consistent with the
finding that the imido group has an almost linear Mo-N-H
bond (176(1)°). The N-Mo-Cl linkages in both 3a and 4a+
are essentially linear. However, their Mo-Cl distances at
2.7851(9) Å for 3a and 2.523(1) Å for 4a+ differ significantly,
indicating that trans influence of the nitrido ligand is much
stronger than that of the imido ligand. Bonding parameters
associated with the P4 ligand are essentially identical between
3a and 4a+. Thus, in each structure the Mo-P distances for
the inner P atoms are much shorter than those for the outer
ones. Since the P-Mo-P angles in the five-membered chelate
rings are in the range 78-81°, the remaining cisoid P(1)-Mo-
P(4) angles of 118.9(2)° for 3a and 112.71(4)° for 4a+ are
widened considerably from ideal 90°. To compress the P(1)-
Mo-P(4) angles, all Mo-P bonds in 3a and 4a+ are tilted away
from the N atoms, as shown by the obtuse N-Mo-P angles.
For instance, average values of the four N-Mo-P angles are
98.7(1)° for 3a as compared to 90.2(6)-95.2(2)° for the above
trans-[Mo(L)(N)(dppe)2].
As depicted in Figure 3, the crystal strucuture of the cation
in 4c[BPh4] is quite similar to that of 4a+. Bonding parameters
of the imido ligand are not exceptional in comparison with other
W(IV) complexes.13,19 It has been found that one of the phenyl
groups in the BPh4 anion is interacting with the imido hydrogen
in a NH-π fashion, with the shortest H‚‚‚C distance being 2.60-
(9) Å.
As is consistent with the crystal structures of pseudo-Cs
symmetry, each of 3 and 4+ exhibits two 31P{1H} signals
assignable to the outer and inner P atoms. These are mutually
coupling in an AA′XX′ pattern (see Experimental Section for
(12) Cugny, J.; Schmalle, H. W.; Fox, T.; Blacque, O.; Alfonso, M.;
Berke, H. Eur. J. Inorg. Chem. 2006, 540.
(13) Dilworth, J. R.; Dahlstrom, P. L.; Hyde, J. R.; Zubieta, J. Inorg.
Chim. Acta 1983, 71, 21.
(14) Seino, H.; Tanabe, Y.; Ishii, Y.; Hidai, M. Inorg. Chim. Acta 1998,
280, 163.
(15) Tanabe, Y.; Ishii, Y.; Seino, H.; Hidai, M. J. Am. Chem. Soc. 2000,
122, 1690.
(16) (a) Chatt, J.; Dilworth, J. R. J. Chem. Soc., Chem. Commun. 1975,
983. (b) Chatt, J.; Dilworth, J. R. J. Indian Chem. Soc. 1977, 54, 13. (c)
Hughes, D. L.; Mohammed, M. Y.; Pickett, C. J. J. Chem. Soc., Dalton
Trans. 1990, 2013. (d) Henderson, R. A.; Leigh, G. J.; Pickett, C. J. J.
Chem. Soc., Dalton Trans. 1989, 425.
(17) Yoshida, T.; Adachi, T.; Yabunouchi, N.; Ueda, T.; Okamoto, S. J.
Chem. Soc., Chem. Commun. 1994, 151.
(18) For reviews, see: (a) Dehnicke, K.; Stra¨hle, J. Angew. Chem., Int.
Ed. Engl. 1981, 20, 413. (b) Nugent, W. A.; Mayer, J. M. Metal-Ligand
Multiple Bonds; Wiley-Interscience: New York, 1988. (c) Eikey, R. A.;
Abu-Omar, M. M. Coord. Chem. ReV. 2003, 243, 83.
(19) Ishino, H.; Tokunaga, S.; Seino, H.; Ishii, Y.; Hidai, M. Inorg. Chem.
1999, 38, 2489.
Figure 1. Molecular structure of 3a. Hydrogen atoms and the minor
components of the disordered groups are omitted for clarity.
Thermal ellipsoids are drawn at the 30% probability level. Selected
bond lengths (Å) and angles (deg) (P* ) P(1)-P(4)): Mo-Cl,
2.7851(9); Mo-P(1), 2.518(1); Mo-P(2), 2.4388(9); Mo-P(3),
2.432(1); Mo-P(4), 2.525(7); Mo-N, 1.667(3); N-Mo-Cl, 177.9-
(1); Cl-Mo-P*, 80.80(3)-82.8(1); N-Mo-P*, 95.5(2)-100.61-
(9); P(1)-Mo-P(2), 78.38(3); P(2)-Mo-P(3), 78.05(3); P(3)-
Mo(1)-P(4), 79.6(2); P(1)-Mo-P(3), 152.18(3); P(2)-Mo-P(4),
154.3(2); P(1)-Mo-P(4), 118.9(2).

4912 Organometallics, Vol. 26, No. 20, 2007
Watanabe et al.
Figure 2. Molecular structure of 4a[BF4]. Hydrogen atoms in the
P4 ligand are omitted for clarity. Thermal ellipsoids of non-
hydrogen atoms are drawn at the 30% probability level. Selected
bond lengths (Å) and angles (deg): Mo-Cl(1), 2.523(1); Mo-
P(1), 2.533(1); Mo-P(2), 2.453(1); Mo-P(3), 2.455(1); Mo-P(4),
2.535(1); Mo-N, 1.712(4); N-H(43), 0.77(4); F(1)‚‚‚H(43), 2.13-
(4); N-Mo-Cl(1), 175.8(1); Cl(1)-Mo-P, 78.76(4)-80.78(4);
N-Mo-P, 98.1(1)-103.7(1); P(1)-Mo-P(2), 80.60(4); P(2)-
Mo-P(3), 79.16(4); P(3)-Mo-P(4), 79.91(3); P(1)-Mo-P(3),
153.01(4); P(2)-Mo-P(4), 153.13(3); P(1)-Mo-P(4), 112.71(4);
Mo-N-H(43), 176(1).
Figure 3. Molecular structure of 4c[BPh4]. Hydrogen atoms except
for the imido N-H and the minor components of the disordered
groups are omitted for clarity. Thermal ellipsoids of non-hydrogen
atoms are drawn at the 30% probability level. Selected bond lengths
(Å) and angles (deg): W-Br, 2.6994(8); W-P(1), 2.520(1);
W-P(2), 2.433(1); W-P(3), 2.445(1); W-P(4), 2.523(2); W-N,
1.725(5); N-H(43), 0.82(9); N-W-Br, 178.2(2); Br-W-P,
78.91(4)-80.94(4); N-W-P, 99.3(2)-101.5(2); P(1)-W-P(2),
78.64(4); P(2)-W-P(3), 79.92(4); P(3)-W-P(4), 78.02(4); P(1)-
W-P(3), 153.36(5); P(2)-W-P(4), 151.70(4); P(1)-W-P(4),
116.04(5); W-N-H(43), 166(5). The nearest N-H‚‚‚C contact to
the BPh4 anion is 2.60(9) Å.
details), and the signal at larger δ value is attributable to the
inner P atoms.20 In the 1H NMR spectrum, a broad peak
observed in the range δ 4.0-4.7 for the Mo complexes 4a+
and 4b+ and δ 6.2-6.4 for the W complex 4c+ is assignable to
the imido proton. These chemical shifts are slightly affected
by the nature of the counteranion. It is noteworthy that most
imido NH signals of the previously reported Mo(IV) and W(IV)
complexes are obscured or appear at δ 7-1017,21,22 except
for that at δ 5.53 for cis,trans-[WCl2(NH)(PMe2Ph)2(C2H2)].19
In the IR spectra of the solid samples of 4+, the ν(N-H)
imido ligands in 3 and 4+ originate from the NH2 group in
mono- and 1,1-disubstituted hydrazines, reactions of 2 with 1,2-
disubstituted hydrazines may provide N-substituted imido
complexes. It has turned out that in contrast to mono- and 1,1-
disubstituted hydrazines, which smoothly reacted with 2 at room
temperature, the reaction of PhNHNHPh with the Mo complex
2a required much more severe conditions, viz., in toluene at
reflux. The major product present in the resulting blue-green
solution was characterized as the neutral phenylimido complex
values are in the ordinary range 3100-3400 cm-1 16a-c,17,19,21
,
where the influence of the counteranion is clearly observed:
the ν(N-H) frequencies decrease in the order of the anion
PF6 > BPh4 > BF4 (e.g., 3292, 3235, and 3203 cm-1
,
1
cis,mer-[MoCl2(NPh)(κ3-P4)] (5y) by H and 31P{1H} NMR
respectively, for 4a+). This tendency may be ascribed to the
interaction of the imido hydrogen with the counteranion.
Hydrogen bonding is apparently present in the X-ray structure
of 4a[BF4] ((N-)H‚‚‚F ) 2.13(4) Å), and some contact exists
in 4c[BPh4] as described above, which is also the case in the
isomorphous 4a[BPh4].23 In addition, preliminary crystal-
lographic analysis of 4c[PF6] indicates the absence of any
interaction between the imido ligand and the PF6 anion.23 In
these series, the ν(N-H) values of the W complexes are higher
by >40 cm-1 than those of the Mo complexes, which is
consistent with the less protic nature of the former.
spectra (Scheme 2). Thus, the latter spectrum showed four
resonances due to four inequivalent P nuclei, including one
signal at δ -10.2, which is characteristic of a dissociated outer
(22) (a) Pe´rez, P. J.; Luan, L.; White, P. S.; Brookhart, M.; Templeton,
J. L. J. Am. Chem. Soc. 1992, 114, 7928. (b) Powell, K. R.; Pe´rez, P. J.;
Luan, L.; Feng, S. G.; White, P. S.; Brookhart, M.; Templeton, J. L.
Organometallics 1994, 13, 1851.
(23) Crystallographic data for 4a[BPh4]‚0.4(CH2Cl2)‚0.5(Et2O): C72.4H68.8
-
BCl1.8NMoO0.5P4, fw ) 1255.41, space group P21/a (no. 14), a ) 21.084-
(5) Å, b ) 13.910(3) Å, c ) 23.044(5) Å, â ) 107.850(1)°, V ) 6433(3)
Å3, Z ) 4, Fcalcd ) 1.296 g cm-3, µ ) 0.421 mm-1, R1 ) 0.075 (5478
2
2
reflections with Fo > 2σ(Fo )) and wR2 ) 0.226 (15 127 all unique
3. N-N Bond Cleavage of 1,2-Disubstituted Hydrazines
to Form the Organoimido Complexes. Since the nitrido and
reflections) for 837 parameters. For 4c[PF6]‚0.6(CH2Cl2): C46.6H44.2
-
BrCl1.4F6NP5W, fw ) 1200.52, space group P21/c (no. 14), a ) 14.514(3)
Å, b ) 15.950(3) Å, c ) 22.629(5) Å, â ) 108.174(1)°, V ) 4977(2) Å3,
Z ) 4, Fcalcd ) 1.602 g cm-3, µ ) 3.420 mm-1, R1 ) 0.053 (6237 reflections
(20) Garrou, P. E. Chem. ReV. 1981, 81, 229.
(21) Bevan, P. C.; Chatt, J.; Dilworth, J. R.; Henderson, R. A.; Leigh,
G. J. J. Chem. Soc., Dalton Trans. 1982, 821.
2
2
with Fo > 2σ(Fo )) and wR2 ) 0.159 (11 478 all unique reflections) for
624 parameters.

N-N CleaVage of Organohydrazines by Mo(II) and W(II) Complexes
Organometallics, Vol. 26, No. 20, 2007 4913
Scheme 2
P atom. Although purification of 5y was unsuccessful, treatment
with K[PF6] transformed 5y into the cationic complex trans-
[MoCl(NPh)(κ4-P4)][PF6] (6y[PF6]), which was isolated as pure
brown crystals in 38% yield. The reaction of 2a with
MeNHNHMe, which was generated in situ from its bis(hydro-
chloride) salt and Et3N, proceeded at 60 °C to form the methyl-
imido complex cis,mer-[MoCl2(NMe)(κ3-P4)] (5x) and after
analogous anion metathesis with K[PF6] trans-[MoCl(NMe)-
(κ4-P4)][PF6] (6x[PF6]) was obtained as red crystals in 63%
yield. Reactions of the W complex 2c with 1,2-disubstituted
hydrazines were also examined under forcing conditions but
resulted in the formation of an intractable mixture containing
only a small amount of the expected W organoimido complexes,
if any.
Molecular structures of both 6x[PF6] and 6y[BF4] have been
fully determined by X-ray crystallography as shown in Figures
4 and 5, respectively. Coordination geometries of both com-
plexes are esssentially identical with that of 4a+ except for the
organic substituents bound to the N atom. The Mo-N-C
linkages are bent slightly by 10.2(3)° and 12.5(3)° toward the
direction of the o-phenylene group in P4 probably due to
intramolecular steric repulsion against the phenyl groups bound
to the outer P atoms in P4. The Mo-N distances are comparable
to that of 4a+ and other reported values for organoimido ligands
bound to Mo(IV).15,24-27
Figure 5. Molecular structure of the cationic part of 6y[BF4].
Hydrogen atoms are omitted for clarity. Thermal ellipsoids are
drawn at the 30% probability level. Selected bond lengths (Å) and
angles (deg): Mo-Cl, 2.553(1); Mo-P(1), 2.531(2); Mo-P(2),
2.435(2); Mo-P(3), 2.430(1); Mo-P(4), 2.524(2); Mo-N, 1.733-
(3); N-C(47), 1.426(5); N-Mo-Cl, 172.5(1); Cl-Mo-P, 75.86-
(4)-78.58(5); N-Mo-P, 97.2(1)-106.2(1); P(1)-Mo-P(2), 79.71-
(6); P(2)-Mo-P(3), 80.91(5); P(3)-Mo-P(4), 79.81(5); P(1)-
Mo-P(3), 150.77(5); P(2)-Mo-P(4), 151.59(4); P(1)-Mo-P(4),
108.61(4); Mo-N-C(47), 167.5(3).
On the basis of the above results, plausible mechanisms for
the N-N bond cleavage of organohydrazines by 2 are illustrated
in Scheme 3. At first, the 16-electron M(II) center undergoes
coordination of hydrazine by the sterically less hindered N atom.
Hydrazidium ligand is formed via intramolecular 1,2-H shift
accompanied by dissociation of X or one of the PPh2 groups in
P4. Then, electron donation from the M(II) center causes
reductive N-N bond cleavage to generate 1 equiv of the amine
and M-N multiple bond formation, affording the M(IV) imido
complex such as 4+, 6+, and 5. Deprotonation of the imido
ligand in 4+ (R3 ) H) may provide the nitrido complex 3, but
the equilibrium exists in this step between 4+ and coexisting
amine or excess hydrazine as described above. Such intercon-
versions between nitrido and imido ligands by proton tranfer
are well precedented.12,16a-c,17,21,22,28
The above pathways of N-N bond cleavage are quite parallel
to what proceeds on the dialkylhydrazido(2-) complexes trans-
[MIVBr(NNR2)(dppe)2]+ (M ) Mo, W; R ) alkyl) derived
from the dinitrogen complexes trans-[M(N2)2(dppe)2].29,30
Two-electron reduction of these affords the neutral complexes
[MII(NNR2)(dppe)2], which causes N-N bond cleavage upon
(24) (a) Hughes, D. L.; Lowe, D. J.; Mohammed, M. Y.; Pickett, C. J.;
Pinhal, N. M. J. Chem. Soc., Dalton Trans. 1990, 2021. (b) Hughes, D. L.;
Ibrahim, S. K.; Macdonald, C. J.; Ali, H. M.; Pickett, C. J. J. Chem. Soc.,
Chem. Commun. 1992, 1762. (c) Fairhurst, S. A.; Hughes, D. L.; Ibrahim,
S. K.; Abasq, M.-L.; Talarmin, J.; Queiros, M. A.; Fonseca, A.; Pickett, C.
J. J. Chem. Soc., Dalton Trans. 1995, 1973.
(25) Chou, C. Y.; Devore, D. D.; Huckett, S. C.; Maatta, E. A.; Huffman,
J. C.; Takusagawa, F. Polyhedron 1986, 5, 301.
(26) Montilla, F.; Galindo, A.; Carmona, E.; Gutie´rrez-Puebla, E.; Monge,
A. J. Chem. Soc., Dalton Trans. 1998, 1299.
(27) Cameron, T. M.; Ortiz, C. G.; Ghiviriga, I.; Abboud, K. A.; Boncella,
J. M. J. Am. Chem. Soc. 2002, 124, 922.
(28) Adachi, T.; Hughes, D. L.; Ibrahim, S. K.; Okamoto, S.; Pickett,
C. J.; Yabanouchi, N.; Yoshida, T. J. Chem. Soc., Chem. Commun. 1995,
1081.
(29) (a) Hussain, W.; Leigh, G. J.; Pickett, C. J. J. Chem. Soc., Chem.
Commun. 1982, 747. (b) Henderson, R. A.; Leigh, G. J.; Pickett, C. J. J.
Chem. Soc., Dalton Trans. 1989, 425.
Figure 4. Molecular structure of the cationic part of 6x[PF6].
Hydrogen atoms are omitted for clarity. Thermal ellipsoids are
drawn at the 30% probability level. Selected bond lengths (Å) and
angles (deg): Mo-Cl(1), 2.5414(7); Mo-P(1), 2.5423(8); Mo-
P(2), 2.4377(7); Mo-P(3), 2.4341(7); Mo-P(4), 2.5384(7); Mo-
N, 1.710(3); N-C(47), 1.436(5); N-Mo-Cl(1), 173.65(9); Cl(1)-
Mo-P, 79.18(3)-80.03(3); N-Mo-P, 95.57(8)-103.80(8); P(1)-
Mo-P(2), 78.74(2); P(2)-Mo-P(3), 80.53(2); P(3)-Mo-P(4),
79.05(2); P(1)-Mo-P(3), 152.98(3); P(2)-Mo-P(4), 152.79(3);
P(1)-Mo-P(4), 113.77(3); Mo-N-C(47), 169.8(3).
(30) Horn, K. H.; Bo¨res, N.; Lehnert, N.; Mersmann, K.; Na¨ther, C.;
Peters, G.; Tuczek, F. Inorg. Chem. 2005, 44, 3016.

4914 Organometallics, Vol. 26, No. 20, 2007
Watanabe et al.
Scheme 3a
a “P4” represents the κ3-coordination mode.
Scheme 4
protonation to produce the M(IV) imido complexes and NHR2.
The hydrazidium complexes [MII(L)(NNHR2)(dppe)2]+ as the
intermediate stage have been detected. In a similar way,
chemical reduction of the (1-pyridinio)imido complexes cis,trans-
[WCl2(NNC5H5-nRn)(PMe2Ph)2(L)] (R ) alkyl; L ) CO, C2H2)
in the presence of proton source is known to yield smoothly
the imido complexes cis,trans-[WCl2(NH)(PMe2Ph)2(L)] and
pyridines NC5H5-nRn.19 With respect to the formation of
the organoimido ligand via cleavage of the N-N bond on the
single metal center, it has been reported that decomposition31
or halogenation32 of [(CO)5W{NPhNPhC(OMe)Me}] gives
[(CO)5W(NPh)] or [(CO)2W(NPh)X2]2, respectively, together
with PhNdC(OMe)Me. Disproportionation of two RCONHNHR′
into a NR′ and a R′NdNCOR ligand on Mo(IV) complexes
has also been precedented.33
Finally, it should be emphasized that the closely related trans-
[MoBr2(dppe)2] did not show any reactivities toward hydrazine
compounds. The remarkably higher reactivity of 2 is presumably
ascribable to the presence of the electronically less stable metal
center with the sterically less congested reaction site arising
from their unusual trigonal-prismatic structure.
4. Preparation of the Organoimido Complexes by the
Reactions with Electrophiles. The terminal nitrido ligand is
presumed to be susceptible to electrophilic attack due to the
presence of lone-pair electrons, and reactivities toward not only
proton but also carbon electrophiles have been widely in-
vestigated.16c,22,24b,c,34-40 Since the nitrido ligand in 3 is readily
protonated to form the imido ligand, the N atom in 3 is assumed
to be of significantly nucleophilic character. As expected, 3a
rapidly reacted with methyl triflate at room temperature to give
the methylimido complex 6x[CF3SO3] in 71% yield. However,
reactions of 3 with alkyl halides afforded only mixtures of
several uncharacterized products.
On the other hand, reactions of 3 with various acid chlorides
RCOCl proceeded smoothly at room temperature, yielding the
acylimido complexes cis,mer-[MoCl2(NCOR)(κ3-P4)] (R ) Me
(7x), Ph (7y), Tol (7z); Tol ) p-tolyl) in satisfactory yields
(Scheme 4). As observed for 5, treatment with KPF6 in CH2Cl2
at room temperature converted 7 into the corresponding cationic
complexes trans-[MoCl(NCOR)(κ4-P4)][PF6] (8[PF6]). IR spec-
tra of both 7 and 8[PF6] show strong ν(CdO) bands at 1640-
1700 cm-1, which are comparable to those of previously
reported acylimido complexes.22,36-39,40d,41
(31) (a) Sleiman, H. F.; McElwee-White, L. J. Am. Chem. Soc. 1988,
110, 8700. (b) Maxey, C. T.; Sleiman, H. F.; Massey, S. T.; McElwee-
White, L. J. Am. Chem. Soc. 1992, 114, 5153, and references therein.
(32) (a) McGowan, P. C.; Massey, S. T.; Abboud, K. A.; McElwee-
White, L. J. Am. Chem. Soc. 1994, 116, 7419. (b) He, Y.; McGowan, P.
C.; Abboud, K. A.; McElwee-White, L. J. Chem. Soc., Dalton Trans. 1998,
3373, and references therein.
(33) (a) Chatt, J.; Dilworth, J. R. J. Chem. Soc., Chem. Commun. 1972,
549. (b) Bishop, M. W.; Chatt, J.; Dilworth, J. R.; Hursthouse, M. B.;
Jayaweera, S. A. A.; Quick, A. J. Chem. Soc., Dalton Trans. 1979, 914.
(34) Bishop, M. W.; Chatt, J.; Dilworth, J. R.; Neaves, B. D.; Dahlstrom,
P.; Hyde, J.; Zubieta, J. J. Organomet. Chem. 1981, 213, 109.
(35) Sellmann, D.; Wemple, M. W.; Donaubauer, W.; Heinemann, F.
W. Inorg. Chem. 1997, 36, 1397.
X-ray crystallography has been undertaken to compare the
structures of acetylimido complexes 7x and 8x[PF6]. As depicted
in Figures 6 and 7, respectively, there is no significant difference
between the structures of acetylimido ligands in these two, which
are featured by a linear Mo-N-C array and a trigonal planar,
(36) Groves, J. T.; Takahashi, T. J. Am. Chem. Soc. 1983, 105, 2073.
(37) (a) Che, C.-M.; Lam, M. H.-W.; Mak, T. C. W. J. Chem. Soc.,
Chem. Commun. 1989, 1529. (b) Li, Z.-Y.; Yu, W.-Y.; Che, C.-M.; Poon,
C.-K.; Wang, R.-J.; Mak, T. C. W. J. Chem. Soc., Dalton Trans. 1992,
1657.
(38) (a) Bottomley, L. A.; Neely, F. L. Inorg. Chem. 1990, 29, 1860.
(b) Tong, C.; Bottomley, L. A. J. Porphyrins Phthalocyanines 1998, 2,
261.
(40) (a) Brask, J. K.; Dura`-Vila`, V.; Diaconescu, P. L.; Cummins, C. C.
Chem. Commun. 2002, 902. (b) Sceats, E. L.; Figueroa, J. S.; Cummins, C.
C.; Loening, N. M.; Van der Wel, P.; Griffin, R. G. Polyhedron 2004, 23,
2751. (c) Clough, C. R.; Greco, J. B.; Figueroa, J. S.; Diaconescu, P. L.;
Davis, W. M.; Cummins, C. C. J. Am. Chem. Soc. 2004, 126, 7742. (d)
Figueroa, J. S.; Piro, N. A.; Clough, C. R.; Cummins, C. C. J. Am. Chem.
Soc. 2006, 128, 940. (e) Curley, J. J.; Sceats, E. L.; Cummins, C. C. J. Am.
Chem. Soc. 2006, 128, 14036.
(39) Leung, W.-H.; Chim, J. L. C.; Williams, I. D.; Wong, W.-T. Inorg.
Chem. 1999, 38, 3000.
(41) Thomas, S.; Lim, P. J.; Gable, R. W.; Young, C. G. Inorg. Chem.
1998, 37, 590.

N-N CleaVage of Organohydrazines by Mo(II) and W(II) Complexes
Organometallics, Vol. 26, No. 20, 2007 4915
a tridentate fashion to the octahedral Mo center in a meridional
fashion with one of the outer P atoms dissociated. The
acetylimido and one of two chlorido ligands are mutually trans,
and the former resides at the same side with the phenyl groups
bound to the inner P atoms. The cis N-Mo-P angles are
widened to 96.2(1)-105.3(1)° as observed in 3, 4+, and 6+ (vide
supra). The coordination geometry of 8x+ is essentially the same
as those of the trans-κ4-P4 imido complexes 4+ and 6+. In the
1H NMR spectra, a considerable high-field shift of the acetyl
signals is observed for 7x (δ 0.48) and especially for 8x+ (δ
-0.12) probably due to the shielding effect by the phenyl groups
in P4, which are surrounding the acetylimido ligand.
Although treatment of 3a with organic isocyanates resulted
in recovery of 3a, imido complex 4a[BF4] did react with RNCO
to give the carbamoylimido complexes trans-[MoCl(NCONHR)-
(κ4-P4)][BF4] (R ) Ph (9y[BF4]), Tol (9z[BF4])) in moderate
yields (eq 4). These reactions did take place at room temperature
Figure 6. Molecular structure of 7x. Hydrogen atoms are omitted
for clarity. Thermal ellipsoids are drawn at the 30% probability
level. Selected bond lengths (Å) and angles (deg): Mo-Cl(1),
2.484(1); Mo-Cl(2), 2.512(1); Mo-P(1); 2.490(1); Mo-P(2),
2.408(1); Mo-P(3), 2.5115(9); Mo-N, 1.749(3); N-C(47), 1.382-
(6); O(1)-C(47), 1.189(7); C(47)-C(48), 1.488(7); Cl(1)-Mo-
Cl(2), 90.18(4); N-Mo-Cl(1), 174.1(1); N-Mo-Cl(2), 93.4(1);
Cl(1)-Mo-P(1), 77.81(3); Cl(1)-Mo-P(2), 80.44(4); Cl(1)-Mo-
P(3), 79.08(3); Cl(2)-Mo-P(1), 101.66(4); Cl(2)-Mo-P(2),
169.91(4); Cl(2)-Mo-P(3), 93.95(3); N-Mo-P(1), 96.9(1);
N-Mo-P(2), 96.2(1); N-Mo-P(3), 105.3(1); P(1)-Mo-P(2),
80.12(4); P(2)-Mo-P(3), 80.70(3); P(1)-Mo-P(3), 152.03(3);
Mo-N-C(47), 171.3(3); O(1)-C(47)-N, 122.5(4); O(1)-C(47)-
C(48), 122.8(5); N-C(47)-C(48), 114.6(4).
in CH2Cl2 but were much accelerated by addition of a catalytic
amount of Et3N (∼20 mol %). Since the imido N atom in 4a+
lacks the lone-pair electrons as a result of their donation to the
Mo center, it is assumed that the nitrido complex 3a generated
in situ might be the active species also in this reaction, and
here its adduct with RNCO undergoes rapid protonation to form
stable 9+. Under similar conditions, 4a[PF6] also reacted with
isothiocyanate PhNCS, yielding trans-[MoCl(NCSNHPh)-
(κ4-P4)][PF6] (10y[PF6]). For 9y[BF4], the IR spectrum exhibits
the characteristic bands for the -C(O)NH- moiety (ν(N-H)
at 3381, amide I at 1681, and amide II at 1511 cm-1), and the
1H NMR signal of the amide proton appears at δ 3.62 as a broad
peak. Thiocarbamoylimido complex 10y[PF6] shows ν(CdS)
at 1096 cm-1
.
The molecular structure of 9z[BF4] has been determined
unambiguously by X-ray crystallography as shown in Figure
8. The structure of the {MoCl(κ4-P4)} chromophore is not
exceptional in comparison with other imido complexes described
above. The carbamoylimido ligand is almost planar, in which
the Mo-N distance of 1.746(3) Å and the Mo-N-C angle of
177.1(3)° are comparable to those of the above imido ligands.
With respect to the C(47)-N(2) bond, the p-tolyl group bound
to N(2) is located trans to the imido N(1) atom, avoiding
repulsion against the P4 ligand. The short C(47)-N(2) bond
length of 1.345(5) Å indicates the existence of π-bonding to
some extent by contribution of the resonance structure I in Chart
1. In contrast, the long C(47)-N(1) distance, at 1.411(5) Å,
reflects the absence of π-donation from the imido N atom to
the carbonyl C atom represented by II.
Figure 7. Molecular structure of the cationic part of 8x[PF6].
Hydrogen atoms are omitted for clarity. Thermal ellipsoids are
drawn at the 30% probability level. Selected bond lengths (Å) and
angles (deg): Mo-Cl(1), 2.5298(9); Mo-P(1), 2.5434(8); Mo-
P(2), 2.4447(8); Mo-P(3), 2.4469(8); Mo-P(4), 2.5425(8); Mo-
N, 1.737(3); N-C(47), 1.414(5); O-C(47), 1.209(5); C(47)-C(48),
1.456(6); N-Mo-Cl(1), 176.37(9); Cl(1)-Mo-P, 78.43(3)-79.17-
(3); N-Mo-P, 98.20(9)-103.20(8); P(1)-Mo-P(2), 78.94(3);
P(2)-Mo-P(3), 80.36(3); P(3)-Mo-P(4), 79.06(3); P(1)-Mo-
P(3), 151.67(3); P(2)-Mo-P(4), 152.62(3); P(1)-Mo-P(4), 112.84-
(3); Mo-N-C(47), 177.2(3); N-C(47)-O, 118.3(4); N-C(47)-
C(48), 116.8(4); O-C(47)-C(48), 124.9(4).
5. Liberation of Organonitrogen Compounds from the
Organoimido Complex. Nitrido and imido complexes not only
(42) Nielson, A. J.; Hunt, P. A.; Rickard, C. E. F.; Schwerdtfeger, P. J.
Chem. Soc., Dalton Trans. 1997, 3311.
(43) Cross, J. L.; Garrett, A. D.; Crane, T. W.; White, P. S.; Templeton,
J. L. Polyhedron 2004, 23, 2831.
sp2-hybridized C(47).40b-d,41-43 The Mo-N and N-C bond
lengths are almost comparable to those in the methyl- and
phenylimido complexes 6+. In 7x, the P4 ligand coordinates in

4916 Organometallics, Vol. 26, No. 20, 2007
Watanabe et al.
Scheme 5a
a Yields of the organic compounds are presented in parentheses.
gives primary amines or nitriles, respectively. To demonstrate
a utility for the nitrido complex 3 in organic synthesis, we have
examined liberation of organonitrogen compounds from the
toluoylimido complex 7z.
In contrast to the above d0 acylimido-amido complexes
liberating nitriles readily, 7z was stable even under refluxing
conditions in toluene. However, when 7z was treated with
aqueous KOH in THF to hydrolyze the Mo-N bond, Tol-
CONH2 was produced although the yield was not satisfactory
(24% after 1 h; Scheme 5). Since all the starting complex was
consumed, the low yield of amide is probably due to the
hydrolysis of the amide group, which was implied by the finding
that a similar reaction conducted in EtOH generated a significant
amount of TolCOOEt.
Versatility of hydride reagents in the cleavage of the Mo-N
multiple bond has previously been demonstrated in the reactions
of the pyrrolylimido complex trans-[MoF{N(1-pyrrolyl)}-
(dppe)2]+ to yield N-aminopyrrole, pyrrole, and ammonia.48 As
expected, treatment of 7z with an excess amount of NaBH4 in
EtOH at room temperature improved the yield of TolCONH2
to 52%, and neither TolCOOEt nor TolCH2NH2 was detected
in the reaction mixtures. On the other hand, reaction of 7z
with excess LiAlH4 in THF gave TolCH2NH2 in 64% yield
after quenching by EtOH. In both reaction mixtures, several
Mo-P4 complexes were present, but their isolation and char-
acterization were not successful.
Figure 8. Molecular structure of the cationic part of 9z[BF4].
Hydrogen atoms except for the N-H moiety are omitted for clarity.
Thermal ellipsoids of non-hydrogen atoms are drawn at the 30%
probability level. Selected bond lengths (Å) and angles (deg):
Mo-Cl, 2.529(1); Mo-P(1), 2.525(1); Mo-P(2), 2.428(1),
Mo-P(3), 2.440(1); Mo-P(4), 2.529(1); Mo-N(1), 1.746(3);
N(1)-C(47), 1.411(5); O-C(47), 1.204(5); N(2)-C(47), 1.345-
(5); N(2)-C(48), 1.409(4); N(2)-H(43), 0.86(4); N(1)-Mo-Cl,
174.88(9); Cl-Mo-P, 77.37(4)-78.89(4); N(1)-Mo-P, 97.9(1)-
104.7(1); P(1)-Mo-P(2), 79.94(4); P(2)-Mo-P(3), 80.87(4);
P(3)-Mo-P(4), 79.72(5); P(1)-Mo-P(3), 151.31(3); P(2)-Mo-
P(4), 152.59(4); P(1)-Mo-P(4), 109.49(4); Mo-N(1)-C(47),
177.1(3); N(1)-C(47)-O, 121.8(4); N(2)-C(47)-O, 126.4(4);
N(1)-C(47)-N(2), 111.9(3); C(47)-N(2)-C(48), 127.3(3); C(47)-
N(2)-H(43), 108(2); C(48)-N(2)-H(43), 118(2).
Chart 1
Experimental Section
General Comments. All manipulations were performed under
nitrogen atmosphere using standard Schlenk techniques. Solvents
were dried by common procedures and distilled under nitrogen
before use. Complexes 2 were prepared according to literature
methods.11 Other reagents were commercially available and used
as received.
1H and 31P{1H} NMR spectra (400 MHz) were recorded on a
JEOL alpha-400 spectrometer at 20 °C, and chemical shifts were
referenced to those of residual solvent impurity resonances for 1H
(C6D6 at 7.16, CD2Cl2 at 5.32, and acetone-d6 at 2.09) or external
85% H3PO4 for 31P. The coupling systems of 31P{1H} NMR spectra
were analyzed by simulations using the gNMR program package.49
IR spectra were recorded on a JASCO FT/IR-420 spectrometer,
and elemental analyses were done with a Perkin-Elmer 2400 series
II CHN analyzer. GC-MS and GLC measurements were performed
on a Shimadzu GC-MS QP-5050 spectrometer and GC-14B gas
represent the important intermediate stages in the N2-fixing cycle
but are utilizable as nitrogen sources for organic synthesis. For
instance, some nitrido complexes of Mn and Ru serve as N
atom-transfer reagents, attaining aziridination of alkenes or
amination of silyl enol ethers.36,44,45 Recently, it has been shown
that a series of d0 nitrido complexes with amido ancillary ligands
[M(N)(NRAr)3]n- (M ) Nb: n ) 1; Mo and W: n ) 0; R )
alkyl; Ar ) 3,5-C6H3Me2) react with acyl halides to produce
nitriles via transient formation of an acylimido ligand.40c-e
Incorporation of N atoms into organic compounds has also been
investigated in detail by using the nitrido complex trans-[MoCl-
(N)(dppe)2], closely related to 3. Alkylation at the nitrido ligand
in this complex provides various organoimido complexes, and
the following electrolytic reduction24,46 or deprotonation24c,47
(46) Alias, Y.; Ibrahim, S. K.; Queiros, M. A.; Fonseca, A.; Talarmin,
J.; Volant, F.; Pickett, C. J. J. Chem. Soc., Dalton Trans. 1997, 4807.
(47) Henderson, R. A.; Ibrahim, S. K.; Pickett, C. J. J. Chem. Soc., Chem.
Commun. 1993, 392.
(48) Seino, H.; Ishii, Y.; Sasagawa, T.; Hidai, M. J. Am. Chem. Soc.
1995, 117, 12181.
(44) (a) Du Bois, J.; Tomooka, C. S.; Hong, J.; Carreira, E. M. Acc.
Chem. Res. 1997, 30, 364. (b) Minakata, S.; Ando, T.; Nishimura, M.; Ryu,
I.; Komatsu, M. Angew. Chem., Int. Ed. 1998, 37, 3392.
(45) (a) Leung, S. K.-Y.; Huang, J.-S.; Liang, J. L.; Che, C.-M.; Z. Z.-
Y. Angew. Chem., Int. Ed. 2004, 42, 340. (b) Man, W.-L.; Lam, W. W. Y.;
Yiu, S.-M.; Lau, T.-C.; Peng, S.-M. J. Am. Chem. Soc. 2004, 126, 15336.
(49) Budzelaar, P. H. M. gNMR 4.1.0; Charwell Scientific: The
Magdalen Centre, Oxford Science Park, Oxford OX4 4GA, U.K., 1995-
1999.

N-N CleaVage of Organohydrazines by Mo(II) and W(II) Complexes
Organometallics, Vol. 26, No. 20, 2007 4917
chromatographs equipped with CBP1 or CBP10 fused silica
capillary columns (25 m × φ 0.25 mm). HPLC analyses were
carried out on a Shimadzu Prominence system equipped with a
UV-vis detector and a HRC-SIL packed column (15 cm × φ 4.6
mm) using n-hexane/EtOH (85:15) as eluent.
metathesis with Na[BPh4] in CH2Cl2 followed by crystallization
from CH2Cl2/diethyl ether afforded efflorescent purple crystals of
4c[BPh4]‚0.35(CH2Cl2)‚0.65(Et2O), which lost the solvating mol-
ecules under vacuum. 1H NMR (CD2Cl2): δ 2.8-3.2 (m, 6H,
PCH2), 2.4-3.65 (m, 2H, PCH2), 6.22 (br, 1H, NH), 6.80-7.55
(m, 46H, aromatic H), 7.7-8.0 (m, 8H, aromatic H). 31P{1H} NMR
(CD2Cl2): δ 41.5, 82.0 (AA′XX′ pattern: JAX + JAX′ ) 147 Hz).
IR (KBr, cm-1): 3295 (ν(N-H)). Anal. Calcd for C70H63-
BBrNP4W: C, 63.85; H, 4.82; N, 1.06. Found: C, 63.42; H, 4.96;
N, 0.95.
Preparation of trans-[MoCl(N)(κ4-P4)] (3a). To a green
suspension of 2a (740 mg, 0.840 mmol) in THF (50 mL) was added
1,1-dimethylhydrazine (100 µL, 1.32 mmol), and the mixture was
stirred at room temperature for 90 min. Volatiles were removed
from the resulting orange-red solution under reduced pressure, and
the residue was extracted with benzene (40 mL). Addition of hexane
to the concentrated benzene extract afforded orange-red crystals
Formation of trans-[MoCl(NH)(κ4-P4)][BF4] (4a[BF4]) by
Protonation of 3a with HBF4. To a solution of 3a (301 mg, 0.35
mmol) in benzene (25 mL) was added 54% HBF4 in diethyl ether
(58 µL, 0.42 mmol) at room temperature with stirring. After 70
min, the deposited pink solid of 4a[BF4]‚0.25(C6H6) was filtered
off, washed successively with benzene (15 mL) and diethyl ether
1
of 3a‚0.5(C6H6) (664 mg, 92% yield). H NMR (C6D6): δ 2.05-
2.25, 2.35-2.55, 2.75-2.95, 3.35-3.55 (m, 2H each, PCH2), 6.75-
7.15 (m, 20H, aromatic H), 7.45-7.6 (m, 6H, aromatic H), 7.75-
7.85, 8.55-8.65 (m, 4H each, aromatic H). 31P{1H} NMR (C6D6):
δ 66.5, 101.9 (AA′XX′ pattern: JAX ) 6, JAX′ ) 94, JAA′ ) 23,
JXX′ ) 12 Hz). IR (KBr, cm-1): 994 (ν(MotN)). Anal. Calcd for
C49H45ClMoNP4: C, 65.16; H, 5.02; N, 1.55. Found: C, 65.67; H,
5.12; N, 1.37.
1
(15 mL), and then dried under vacuum (309 mg, 91% yield). H
NMR (CD2Cl2): δ 2.85-3.10 (m, 6H, PCH2), 3.25-3.45 (m, 2H,
PCH2), 4.62 (br, 1H, NH), 7.00-7.35 (m, 20H, aromatic H), 7.5-
7.6 (m, 6H, aromatic H), 7.75-7.80 (m, 2H, aromatic H), 7.90-
8.05 (m, 6H, aromatic H), 7.35 (s, 1.5H, 0.25C6H6). 31P{1H} NMR
(CD2Cl2): δ 56.8, 92.3 (AA′XX′ pattern: JAX ) 5, JAX′ ) 129,
JAA′ ) 22, JXX′ ) 9 Hz). IR (KBr, cm-1): 3203 (ν(N-H)). Anal.
Calcd for C47.5H44.5BClF4MoNP4: C, 58.73; H, 4.62; N, 1.44.
Found: C, 58.83; H, 4.63; N, 1.39. Single crystals for X-ray analysis
were obtained by recrystallization from CH2Cl2/Et2O as purple
crystals of 4a[BF4]‚0.25(CH2Cl2)‚0.25(Et2O). Anal. Calcd for
Preparation of trans-[MoBr(N)(κ4-P4)] (3b). This complex was
obtained similarly from 2b (980 mg, 1.00 mmol) and 1,1-
dimethylhydrazine (114 µL, 1.50 mmol) as reddish-orange micro-
crystals (728 mg, 80% yield). 1H NMR (C6D6): δ 2.10-2.3, 2.35-
2.55, 2.8-3.0, 3.45-3.65 (m, 2H each, PCH2), 6.75-7.15 (m, 20H,
aromatic H), 7.5-7.7 (m, 6H, aromatic H), 7.75-7.85, 8.50-8.60
(m, 4H each, aromatic H). 31P{1H} NMR (C6D6): δ 64.1, 101.5
(AA′XX′ pattern: JAX + JAX′ ) 96 Hz). IR (KBr, cm-1): 997
(ν(MotN)). Anal. Calcd for C46H42BrMoNP4: C, 60.81; H, 4.66;
N, 1.54. Found: C, 60.61; H, 4.95; N, 1.47.
C47.25H46BCl1.5F4MoNO0.25P4: C, 57.23; H, 4.68; N, 1.41. Found:
C, 57.63; H, 4.54; N, 1.47.
Preparation of trans-[MoBr(NH)(κ4-P4)][BF4] (4b[BF4]). This
compound was prepared according to a method similar to that for
4a[BF4] by starting from 3b (36 mg, 0.040 mmol) and 54% HBF4
in diethyl ether (6.6 µL, 0.048 mmol) and obtained as a pink solid
of 4b[BF4]‚0.25(C6H6) (12 mg, 29% yield). 1H NMR (CD2Cl2): δ
2.70-3.20 (m, 6H, PCH2), 3.35-3.6 (m, 2H, PCH2), 4.67 (br, 1H,
NH), 6.85-7.30 (m, 20H, aromatic H), 7.5-7.6 (m, 6H, aromatic
H), 7.75-7.8 (m, 2H, aromatic H), 7.9-8.05 (m, 6H, aromatic H),
7.35 (s, 1.5H, 0.25C6H6). 31P{1H} NMR (CD2Cl2): δ 53.8, 91.9
(AA′XX′ pattern: JAX + JAX′ ) 127 Hz). IR (KBr, cm-1): 3197
(ν(N-H)). Anal. Calcd for C47.5H44.5BBrF4MoNP4: C, 56.16; H,
4.42; N, 1.38. Found: C, 56.47; H, 4.39; N, 1.47.
Reaction of 2a with Phenylhydrazine. A mixture of 2a (82
mg, 0.093 mmol) and phenylhydrazine (28 µL, 0.28 mmol) in THF
(5 mL) was stirred at room temperature for 24 h. After evaporation
of solvent from the resulting orange-red solution, extraction with
benzene followed by crystallization by adding hexane to the extract
gave crystals of 3a‚0.5(C6H6) (41 mg, 48% yield). In a different
run using 2a (33 mg, 0.037 mmol) and phenylhydrazine (21 mg,
0.19 mmol), the formation of 103 mol % of aniline per 2a was
confirmed by GC-MS and GLC analyses.
Preparation of trans-[WBr(NH)(κ4-P4)][PF6] (4c[PF6]). 1,1-
Dimethylhydrazine (11 µL, 0.15 mmol) was added to a green
suspension of 2c‚0.5(C6H6) (107 mg, 0.098 mmol) in THF (5 mL).
After the mixture was stirred at room temperature for 60 min, the
resultant pink suspension was evaporated to dryness under reduced
pressure, and then the residual solid was washed with benzene (8
mL). The remaining pink solid was stirred with KPF6 (92 mg, 0.50
mmol) in CH2Cl2 (8 mL) for 24 h at room temperature and then
filtered. Addition of diethyl ether to the concentrated filtrate formed
efflorescent purple crystals, which were filtered off and throughly
dried under vacuum, giving 4c[PF6] (66 mg, 59% yield). 1H NMR
(CD2Cl2): δ 2.85-3.35 (m, 6H, PCH2), 2.35-3.60 (m, 2H, PCH2),
6.37 (br, 1H, NH), 6.95-7.25 (m, 20H, aromatic H), 7.35-7.5 (m,
6H, aromatic H), 7.65-7.75 (m, 2H, aromatic H), 7.80-7.85 (m,
4H, aromatic H), 7.90-8.00 (m, 2H, aromatic H). 31P{1H} NMR
(CD2Cl2): δ 41.6 (JW-P ) 317 Hz), 82.1 (JW-P ) 273 Hz) (AA′XX′
pattern with 183W satellites: JAX ) 26, JAX′ ) 121, JAA′ ) 14, JXX′
) 3 Hz). IR (KBr, cm-1): 3338 (ν(N-H)). Anal. Calcd for C46H43-
BrF6NP5W: C, 48.36; H, 3.79; N, 1.23. Found: C, 48.62; H, 4.21;
N, 0.98.
Reaction of 4a[BF4] with Et3N. Triethylamine (20 µL, 0.14
mmol) was added to a stirred mixture of 4a[BF4] (48 mg, 0.049
mmol) in THF (5 mL) at room temperature. The pink suspension
immediately turned to an orange solution, NMR measurement of
which revealed the formation of 3a.
Reaction of 2a with N-Aminophthalimide. A mixture of 2a
(50 mg, 0.056 mmol) and N-aminophthalimide (10 mg, 0.061 mmol)
in THF (5 mL) was stirred at room temperature for 240 h. The
resulting pink solid was filtered off, washed with THF and diethyl
ether, and then stirred with KPF6 (30 mg, 0.16 mmol) in CH2Cl2
for 24 h. Addition of diethyl ether to the filtered product solution
1
formed purple crystals of 4a[PF6] (19 mg, 34% yield). H NMR
(CD2Cl2): δ 4.28 (br, 1H, NH). 31P{1H} NMR (CD2Cl2): δ 56.7,
92.3 (AA′XX′ pattern: JAX + JAX′ ) 134 Hz). IR (KBr): ν(N-H)
3292 cm-1. Anal. Calcd for C46H43ClF6MoNP5: C, 54.70; H, 4.29;
N, 1.39. Found: C, 54.38; H, 4.17; N, 1.37. By a similar method,
purple crystals of 4a[BPh4] (36 mg, 24% yield) were obtained from
2a (112 mg, 0.126 mmol) and N-aminophthalimide (23 mg, 0.14
1
mmol), using Na[BPh4] (57 mg, 0.52 mmol) instead of KPF6. H
Reaction of 2c with Phenylhydrazine. A mixture of 2c‚0.5-
(C6H6) (49 mg, 0.044 mmol) and phenylhydrazine (14 µL, 0.14
mmol) in THF (4 mL) was stirred at room temperature for 24 h.
GC-MS and GLC analyses of the liquid phase confirmed the
formation of aniline (1.02 equiv to 2c). The deposited pink solid
was filtered off and stirred with KPF6 (25 mg, 0.14 mmol) in
CH2Cl2 (5 mL). Crystals of 4c[PF6] were obtained by addition of
diethyl ether to the filtered solution (10 mg, 20% yield). Anion
NMR (CD2Cl2): δ 4.06 (br, 1H, NH). 31P{1H} NMR (CD2Cl2): δ
56.6, 92.2 (AA′XX′ pattern: JAX + JAX′ ) 134 Hz). IR (KBr, cm-1):
3235 (ν(N-H)). Anal. Calcd for C70H63BClMoNP4: C, 70.99; H,
5.36; N, 1.18. Found: C, 70.63; H, 5.22; N, 1.06.
Preparation of 4b[PF6] and 4b[BPh4]. Each compound was
prepared according to a method similar to that for the corresponding
salt of 4a+ by starting from 2b, N-aminophthalimide, and an

4918 Organometallics, Vol. 26, No. 20, 2007
Watanabe et al.
appropriate source of anion. 4b[PF6]: 32% yield as purple crystals.
1H NMR (CD2Cl2): δ 4.29 (br, 1H, NH). 31P{1H} NMR
(CD2Cl2): δ 53.5, 91.6 (AA′XX′ pattern: JAX + JAX′ ) 127 Hz).
IR (KBr, cm-1): 3279 (ν(N-H)). Anal. Calcd for C46H43ClF6-
MoNP5: C, 52.39; H, 4.11; N, 1.33. Found: C, 52.28; H, 4.06; N,
1.26. 4b[BPh4]: 40% yield as purple crystals. 1H NMR (CD2Cl2):
δ 4.04 (br, 1H, NH). 31P{1H} NMR (CD2Cl2): δ 53.2, 91.5
(AA′XX′ pattern: JAX + JAX′ ) 127 Hz). IR (KBr, cm-1): 3231
(ν(N-H)). Anal. Calcd for C70H63BClMoNP4: C, 68.42; H, 5.17;
N, 1.14. Found: C, 68.34; H, 5.13; N, 1.00.
1265, 1149 (ν(SdO)). Anal. Calcd for C48.5H46Cl2F3MoNO3P4S:
C, 54.41; H, 4.33; N, 1.31. Found: C, 54.40; H, 4.28; N, 1.09.
Preparation of cis,mer-[MoCl2(NCOMe)(κ3-P4)] (7x). To a
solution of 3a‚0.5(C6H6) (86 mg, 0.10 mmol) in THF (5 mL) was
added acetyl chloride (11 µL, 0.15 mmol), and the solution was
stirred at room temperature for 1 h. The color of the solution
changed from reddish-orange to green. Concentration of the solution
in vacuo followed by addition of hexane formed green crystals of
1
7x‚THF (78 mg, 76% yield). H NMR (acetone-d6): δ 0.48 (s,
3H, Me), 2.2-4.1 (m, 8H, PCH2), 6.95-7.25 (m, 7H, aromatic
H), 7.3-7.45 (m, 11H, aromatic H), 7.5-7.7 (m, 7H, aromatic H),
7.85-7.9 (m, 2H, aromatic H), 8.0-8.3 (m, 7H, aromatic H), 1.83,
3.66 (m, 4H each, THF). 31P{1H} NMR (acetone-d6): δ -11.1 (d,
JPP ) 41 Hz), 47.5 (d, JPP ) 182 Hz), 56.2 (ddd, JPP ) 182, 41, 5
Hz), 93.8 (d, JPP ) 5 Hz). IR (KBr, cm-1): 1673 (ν(CdO)). Anal.
Calcd for C52H53Cl2MoNO2P4: C, 61.55; H, 5.26; N, 1.38. Found:
C, 61.91; H, 5.30; N, 1.36.
Preparation of trans-[MoCl(NMe)(κ4-P4)][PF6] (6x[PF6]). To
a mixture of 2a (44 mg, 0.050 mmol) and 1,2-dimethylhydrazine
bis(hydrochloride) (10 mg, 0.075 mmol) were added THF (5 mL)
and Et3N (21 µL, 0.15 mmol), and the mixture was stirred at 60
°C for 90 min. NMR measurement of the resulting brown solution
showed the presence of a single product, whose spectrum is
diagnostic of cis,mer-[MoCl2(NMe)(κ3-P4)] (5x). Volatiles were
removed under reduced pressure, and KPF6 (47 mg, 0.26 mmol)
and CH2Cl2 (5 mL) were added to the residue. After stirring for 48
h at room temperature, the mixture was filtered. Addition of diethyl
ether to the filtrate afforded red crystals of 6x[PF6]‚CH2Cl2 (35
mg, 63% yield). 5x: 1H NMR (C6D6): δ 1.18 (br dt, JPH ) 4.2,
2.9 Hz, 3H, Me). 31P{1H} NMR (C6D6): δ -10.3 (d, JPP ) 32
Hz), 50.3 (d, JPP ) 194 Hz), 53.8 (ddd, JPP ) 194, 32, 5 Hz), 105.5
(d, JPP ) 5 Hz). 6x[PF6]‚CH2Cl2: 1H NMR (CD2Cl2): δ 1.48 (quin,
JPH ) 3.2 Hz, 3H, Me), 3.0-3.35 (m, 8H, PCH2), 6.8-6.9 (m,
4H, aromatic H), 7.0-7.35 (m, 16H, aromatic H), 7.55-7.60, 7.80-
7.85 (m, 6H each, aromatic H), 8.0-8.05 (m, 2H, aromatic H).
Preparation of cis,mer-[MoCl2(NCOR)(κ3-P4)] (R ) Ph (7y),
p-Tol (7z)). These complexes were prepared from 3a‚0.5(C6H6)
and 1.5 equiv of the corresponding acid chlorides according to a
method analogous to that for preparing 7x. 7y‚0.5(THF): 47% yield
1
as yellow-green crystals. H NMR (acetone-d6): δ 2.4-2.55 (m,
1H, PCH2), 2.7-2.9, 3.05-3.15 (m, 2H each, PCH2), 3.8-4.15
(m, 3H, PCH2), 6.95-7.55 (m, 24H, aromatic H), 7.55-7.75 (m,
7H, aromatic H), 7.95-8.1 (m, 6H, aromatic H), 8.2-8.3 (m, 2H,
aromatic H), 1.83, 3.66 (m, 2H each, 0.5THF). 31P{1H} NMR
(acetone-d6): δ -10.9 (d, JPP ) 41 Hz), 49.2 (d, JPP ) 177 Hz),
55.8 (ddd, JPP ) 177, 41, 5 Hz), 95.3 (d, JPP ) 5 Hz). IR (KBr,
cm-1): 1644 (ν(CdO)). Anal. Calcd for C55H51Cl2MoNO1.5P4: C,
63.47; H, 4.94; N, 1.35. Found: C, 63.21; H, 5.09; N, 1.27. 7z‚
0.5(THF): 90% yield as yellow-green crystals. 1H NMR (acetone-
d6): δ 2.36 (s, 3H, Me), 2.4-2.55 (m, 1H, PCH2), 2.7-2.9, 3.0-
3.2 (m, 2H each, PCH2), 3.8-4.15 (m, 3H, PCH2), 6.95-7.45 (m,
23H, aromatic H), 7.55-7.75 (m, 7H, aromatic H), 7.9-8.1 (m,
6H, aromatic H), 8.25-8.35 (m, 2H, aromatic H), 1.83, 3.66 (m,
31P{1H} NMR (CD2Cl2): δ 56.0, 93.8 (AA′XX′ pattern: JAX
JAX′ ) 141 Hz). Anal. Calcd for C48H47Cl3F6MoNP5: C, 51.98; H,
3.72; N, 1.01. Found: C, 52.09; H, 4.24; N, 0.98.
+
Preparation of trans-[MoCl(NPh)(κ4-P4)][PF6] (6y[PF6]). A
mixture of 2a (45 mg, 0.051 mmol) and 1,2-diphenylhydrazine (14
mg, 0.075 mmol) in toluene (5 mL) was refluxed for 90 min. The
sole product in the resulting blue-green solution was characterized
as cis,mer-[MoCl2(NPh)(κ3-P4)] (5y) from the NMR spectra. After
evaporation of the solvent in vacuo, the residue was stirred with
KPF6 (46 mg, 0.25 mmol) in CH2Cl2 (5 mL) at room temperature
for 24 h. The mixture was filtered, and the filtrate was evaporated
to dryness. After addition of THF (5 mL) and Et3N (7 µL, 0.051
mmol), the mixture was stirred for 1 h, evaporated again, and
washed three times with benzene (5 mL). Recrystallization of the
residue from CH2Cl2/diethyl ether gave brown crystals of 6y[PF6]
(21 mg, 38% yield). 5y: 1H NMR (C6D6): δ 5.91 (d, J ) 7.6 Hz,
2H, o-H in NPh), 6.39 (br t, J ) 8.0 Hz, 2H, m-H in NPh).
2H each, 0.5THF). 31P{1H} NMR (acetone-d6): δ -10.9 (d, JPP
)
41 Hz), 49.2 (d, JPP ) 179 Hz), 55.8 (ddd, JPP ) 179, 41, 5 Hz),
95.3 (d, JPP ) 5 Hz). IR (KBr, cm-1): 1642 (ν(CdO)). Anal. Calcd
for C56H53Cl2MoNO1.5P4: C, 63.77; H, 5.06; N, 1.33. Found: C,
63.49; H, 4.98; N, 1.18.
Preparation of trans-[MoCl(NCOMe)(κ4-P4)][PF6] (8x[PF6]).
A mixture of 7x‚THF (28 mg, 0.028 mmol) and KPF6 (29 mg,
0.15 mmol) in CH2Cl2 (5 mL) was stirred at room temperature for
18 h. Filtration followed by addition of diethyl ether to the
concentrated filtrate formed reddish-purple crystals of 8x[PF6]‚
31P{1H} NMR (C6D6): δ -10.2 (d, JPP ) 37 Hz), 52.9 (d, JPP
)
1
CH2Cl2 (18 mg, 57% yield). H NMR (CD2Cl2): δ -0.12 (s, 3H,
196 Hz), 54.4 (ddd, JPP ) 196, 37, 6 Hz), 103.2 (d, JPP ) 6 Hz).
6y[PF6]: 1H NMR (CD2Cl2): δ 3.0-3.5 (m, 8H, PCH2), 5.22 (d,
J ) 7.3 Hz, 2H, o-H in NPh), 6.50 (dd, J ) 8.3, 7.3 Hz, 2H, m-H
in NPh), 6.85-7.6 (m, 27H, aromatic H), 7.8-7.9 (m, 6H, aromatic
H), 8.0-8.1 (m, 2H, aromatic H). 31P{1H} NMR (CD2Cl2): δ 56.0,
93.8 (AA′XX′ pattern: JAX + JAX′ ) 138 Hz). Anal. Calcd for
C52H47ClF6MoNP5: C, 57.50; H, 4.31; N, 1.29. Found: C, 56.87;
H, 4.36; N, 1.23. Single crystals of 6y[BF4] suitable for X-ray
crystallographic study were obtained by anion metathesis with
NaBF4 followed by crystallization from ClCH2CH2Cl/diethyl ether.
Me), 3.0-3.55 (m, 8H, PCH2), 6.95-7.35 (m, 20H, aromatic H),
7.5-7.65 (m, 6H, aromatic H), 7.85-7.9 (m, 2H, aromatic H),
7.95-8.10 (m, 6H, aromatic H). 31P{1H} NMR (CD2Cl2): δ 56.7,
93.5 (AA′XX′ pattern: JAX + JAX′ ) 133 Hz). IR (KBr, cm-1):
1697 (ν(CdO)). Anal. Calcd for C49H47Cl3F6MoNOP5: C, 51.76;
H, 4.17; N, 1.23. Found: C, 51.88; H, 4.08; N, 1.11.
Preparation of trans-[MoCl(NCOR)(κ4-P4)][PF6] (R ) Ph
(8y[PF6]), p-Tol (8z[PF6])). These complexes were obtained in a
manner similar to that for 8x[PF6] from 7y or 7z with excess
1
KPF6. 8y[PF6]: 51% yield as reddish-purple crystals. H NMR
Reaction of 3a with CF3SO3Me. Methyl trifluoromethane-
sulfonate (13 µL, 0.11 mmol) was added to a benzene solution (5
mL) of 3a‚0.5(C6H6) (87 mg, 0.10 mmol) at room temperature.
Stirring the mixture for 20 min formed a pink precipitate, which
was filtered off and recrystallized from CH2Cl2/diethyl ether to give
pink microcrystals of 6x[CF3SO3]‚0.5(CH2Cl2) (78 mg, 71% yield).
1H NMR (CD2Cl2): δ 1.48 (quin, JPH ) 3.2 Hz, 3H, Me), 3.0-
3.35 (m, 8H, PCH2), 6.8-6.9 (m, 4H, aromatic H), 7.0-7.35 (m,
16H, aromatic H), 7.55-7.60, 7.80-7.85 (m, 6H each, aromatic
H), 8.0-8.05 (m, 2H, aromatic H). 31P{1H} NMR (CD2Cl2): δ
56.0, 93.8 (AA′XX′ pattern: JAX + JAX′ ) 141 Hz). IR (KBr, cm-1):
(CD2Cl2): δ 3.0-3.6 (m, 8H, PCH2), 6.43 (dd, J ) 8.3, 1.0 Hz,
2H, o-H of COPh), 6.55 (br t, J ) 7.6 Hz, 2H, m-H of COPh),
6.95-7.3 (m, 21H, aromatic H), 7.4-7.5 (m, 6H, aromatic H), 7.8-
7.9 (m, 2H, aromatic H), 7.95-8.05 (m, 6H, aromatic H). 31P{1H}
NMR (CD2Cl2): δ 55.8, 93.4 (AA′XX′ pattern: JAX + JAX′ ) 129
Hz). IR (KBr, cm-1): 1647 (ν(CdO)). Anal. Calcd for C53H47-
ClF6MoNOP5: C, 57.13; H, 4.25; N, 1.26. Found: C, 56.67; H,
1
4.14; N, 1.02. 8z[PF6]: 71% yield as reddish-purple crystals. H
NMR (CD2Cl2): δ 2.08 (s, 3H, Me), 3.0-3.6 (m, 8H, PCH2), 6.32
(s, 4H, MeC6H4), 6.95-7.3 (m, 20H, aromatic H), 7.4-7.5 (m,
6H, aromatic H), 7.8-7.9 (m, 2H, aromatic H), 7.95-8.05 (m, 6H,

N-N CleaVage of Organohydrazines by Mo(II) and W(II) Complexes
Organometallics, Vol. 26, No. 20, 2007 4919
Table 1. Crystallographic Data for 3a‚0.5(C6H6), 4a[BF4]‚0.25(CH2Cl2)‚0.25(Et2O), 4c[BPh4]‚0.35(CH2Cl2)‚0.65(Et2O), and
6x[PF6]‚CH2Cl2
4a[BF4]‚0.25(CH2Cl2)‚
4c[BPh4]‚0.35(CH2Cl2)‚
3a‚0.5(C6H6)
0.25(Et2O)
0.65(Et2O)
6x[PF6]‚CH2Cl2
formula
fw
space group
a, Å
b, Å
c, Å
C49H45ClNMoP4
903.19
C47.25H46BCl1.5F4NMoO0.25P4
991.71
C72.95H70.2BBrCl0.7NO0.65P4W
C48H47Cl3F6NMoP5
1109.06
P21/n (no. 14)
14.955(2)
21.017(3)
15.553(2)
90
90.036(2)
90
4889(1)
4
1.507
0.653
0.4 × 0.4 × 0.1
0.727-0.937
11 274 (Rint ) 0.029)
7724
1394.64
P21/a (no. 14)
21.378(4)
13.828(2)
23.027(4)
90
107.5212(8)
90
6491(2)
4
1.427
2.570
0.5 × 0.4 × 0.2
0.489-0.598
14 976 (Rint ) 0.038)
9778
C2/c (no. 15)
31.555(7)
14.956(3)
22.808(5)
90
119.6042(7)
90
9359(3)
8
1.282
0.506
0.5 × 0.4 × 0.3
0.629-0.859
10 856 (Rint ) 0.024)
8221
P1h (no. 2)
10.368(3)
10.953(3)
22.328(7)
77.59(1)
86.42(1)
69.16(1)
2314(1)
2
1.423
0.558
0.3 × 0.15 × 0.1
0.744-0.946
10 523 (Rint ) 0.036)
6144
R, deg
â, deg
γ, deg
V, Å3
Z
F
calcd, g cm-3
µ, mm-1
cryst size, mm3
transmn factor
no. of reflns unique
no. of reflns obsda
no. of variables
568
0.049
0.145
1.01
601
0.047
0.138
1.01
873
0.042
0.131
1.02
624
0.036
0.120
1.03
b
R1
c
wR2
gofd
2
2
b
2
2
c
2
2
2
2
2
a Fo > 2σ(Fo ). R1 ) ∑||Fo| - |Fc||/∑|Fo| for Fo > 2σ(Fo ). wR2 ) [∑w(Fo - Fc )2/∑w(Fo )2]1/2 (w ) [σ(Fo ) + aFo + b]-1) for all unique data.
2
2
dgof ) [∑w(Fo - Fc )2/{(no. of reflns obsd) - (no. of variables)}]1/2
.
aromatic H). 31P{1H} NMR (CD2Cl2): δ 55.8, 93.4 (AA′XX′
pattern: JAX + JAX′ ) 130 Hz). IR (KBr, cm-1): 1642 (ν(CdO)).
Anal. Calcd for C54H49ClF6MoNOP5: C, 57.49; H, 4.38; N, 1.24.
Found: C, 57.28; H, 4.29; N, 1.19.
aromatic H). 31P{1H} NMR (CD2Cl2): δ 56.0, 93.7 (AA′XX′
pattern: JAX + JAX′ ) 136 Hz). IR (KBr, cm-1): 3348 (ν(N-H)),
1360 (δ(NH)), 1096 (ν(CdS)). Anal. Calcd for C53H48ClF6-
MoN2P5S: C, 55.58; H, 4.22; N, 2.45. Found: C, 55.44; H, 4.26;
N, 2.37.
Preparation
of
trans-[MoCl(NCONHPh)(κ4-P4)][BF4]
(9y[BF4]). To a solution of 4a[BF4] (38 mg, 0.039 mmol) in
dichloroethane (4 mL) were added phenyl isocyanate (13 µL, 0.12
mmol) and Et3N (1 µL, 7 µmol) at room temperature with stirring.
The color of the solution turned from reddish-purple to brown
during 2 h. Addition of diethyl ether to the concentrated solution
Reaction of 7z with KOH. To a THF (5 mL) solution of 7z‚
0.5THF (53 mg, 0.050 mmol) was added a 0.5 M aqueous KOH
solution (1 mL, 0.5 mmol), and the mixture was stirred vigorously
at room temperature for 1 h. The green solution turned to red during
this period. HPLC analysis of the resultant solution confirmed the
formation of p-TolCONH2 in 24% yield.
1
gave brown crystals of 9y[BF4] (24 mg, 57% yield). H NMR
(CD2Cl2): δ 3.05-3.40 (m, 8H, PCH2), 3.62 (br, 1H, NH), 6.14
(d, J ) 7.6 Hz, 2H, o-H of NPh), 6.9-7.15 (m, 21H, aromatic H),
7.2-7.3 (m, 2H, aromatic H), 7.55-7.6 (m, 6H, aromatic H), 7.95-
8.0 (m, 2H, aromatic H), 8.1-8.2 (m, 6H, aromatic H). 31P{1H}
NMR (CD2Cl2): δ 58.1, 93.5 (AA′XX′ pattern: JAX + JAX′ ) 138
Hz). IR (KBr, cm-1): 3381 (ν(N-H)), 1681 (ν(CdO)), 1511
(δ(NH)). Anal. Calcd for C53H48BClF4MoN2OP4: C, 59.43; H, 4.52;
N, 2.62. Found: C, 58.81; H, 4.47; N, 2.57.
Reaction of 7z with NaBH4. A mixture of 7z‚0.5THF (42 mg,
0.040 mmol) and NaBH4 (66 mg, 1.7 mmol) in EtOH (4 mL) was
stirred at room temperature for 1 h. HPLC analysis of the resulting
reddish-orange solution showed the formation of p-TolCONH2 and
p-TolCN in 52% and <1% yields, respectively.
Reaction of 7z with LiAlH4. A solution of 7z‚0.5THF (42 mg,
0.040 mmol) and LiAlH4 (15 mg, 0.40 mmol) in THF (4 mL) was
stirred at room temperature for 1 h, and then the resulting dark
green suspension was quenched by adding EtOH (4 mL). After
stirring the mixture for 1 h, the liquid phase was analyzed by GLC,
which revealed the formation of p-TolCH2NH2 in 64% yield.
Crystallography. Single crystals of 3a‚0.5(C6H6), 4a[BF4]‚
0.25(CH2Cl2)‚0.25(Et2O), 6x[PF6]‚CH2Cl2, 6y[BF4], 7x‚THF,
8x[PF6]‚CH2Cl2, and 9z[BF4] were obtained by the procedures
stated above, whereas those of 4c[BPh4]‚0.35(CH2Cl2)‚0.65(Et2O)
were used immediately after collecting from the mother liquor.
These were sealed in glass capillaries under argon and mounted
on a Rigaku Mercury CCD diffractometer equipped with a graphite-
monochromatized Mo KR source. Diffraction data were collected
at 20 °C and processed using the CrystalClear program package.50
All data were corrected for absorption (based on multiscans) and
for Lorentz and polarization effects. Details of the X-ray diffraction
study are listed in Tables 1 and 2.
Preparation of trans-[MoCl2(NCONHTol-p)(κ4-P4)][BF4]
(9z[BF4]). This complex was obtained as brown crystals (39 mg,
74% yield) from 4a[BF4] (47 mg, 0.048 mmol) in a fashion
analogous to that for 9y[BF4], where phenyl isocyanate was replaced
1
by p-tolyl isocyanate (19 µL, 0.15 mmol). H NMR (CD2Cl2): δ
2.18 (s, 3H, Me), 3.0-3.4 (m, 8H, PCH2), 3.58 (br, 1H, NH), 6.03
(d, J ) 8.5 Hz, 2H, MeC6H4), 6.8-7.15 (m, 20H, aromatic H),
7.2-7.3 (m, 2H, aromatic H), 7.55-7.6 (m, 6H, aromatic H), 7.9-
8.0 (m, 2H, aromatic H), 8.1-8.2 (m, 6H, aromatic H). 31P{1H}
NMR (CD2Cl2): δ 57.9, 93.4 (AA′XX′ pattern: JAX + JAX′ ) 138
Hz). IR (KBr, cm-1): 3391 (ν(N-H)), 1678 (ν(CdO)), 1513
(δ(NH)). Anal. Calcd for C54H50BClF4MoN2OP4: C, 59.77; H, 4.64;
N, 2.58. Found: C, 59.70; H, 4.68; N, 2.44.
Preparation of trans-[MoCl(NCSNHPh)(κ4-P4)][PF6] (10y-
[PF6]). Phenyl isothiocyanate (15 µL, 0.12 mmol) and Et3N (1 µL,
7 µmol) were added to 4a[PF6] (40 mg, 0.040 mmol) dissolved in
CH2Cl2 (4 mL), and the solution was stirred at room temperature
for 24 h. The resulting red solution was concentrated, and diethyl
ether was added to deposit a brown solid of 10y[PF6] (32 mg, 69%
yield). 1H NMR (CD2Cl2): δ 3.05-3.5 (m, 8H, PCH2), 5.24 (br s,
1H, NH), 6.21 (br d, J ) 6 Hz, 2H, o-H of NPh), 6.95-7.15 (m,
21H, aromatic H), 7.2-7.3 (m, 2H, aromatic H), 7.55-7.6 (m, 6H,
aromatic H), 7.9-7.95 (m, 2H, aromatic H), 8.05-8.2 (m, 6H,
Structure solution and refinements were carried out by using the
CrystalStructure program package.51 The positions of the non-
hydrogen atoms were determined by Patterson methods (PATTY)52
(50) CrystalClear 1.3.5; Rigaku Corporation, 1998-2003.
(51) CrystalStructure 3.6.0, Crystal structure analysis package; Rigaku
and Rigaku/MSC: 9009 New Trails Dr., The Woodlands, TX 77381, 2000-
2004.

4920 Organometallics, Vol. 26, No. 20, 2007
Table 2. Crystallographic Data for 6y[BF4], 7x‚THF, 8x[PF6]‚CH2Cl2, and 9z[BF4]
Watanabe et al.
6y[BF4]
7x‚THF
8x[PF6]‚CH2Cl2
9z[BF4]
formula
fw
space group
a, Å
b, Å
c, Å
C52H47BClF4NMoP4
1028.04
Pna21 (no. 33)
19.402(2)
17.427(2)
14.257(2)
90
90
90
4821(1)
4
1.416
0.512
C52H53Cl2NMoO2P4
1014.74
C49H47Cl3F6NMoOP5
C54H50BClF4N2MoOP4
1085.09
Pna21 (no. 33)
19.422(3)
18.184(2)
14.219(2)
90
90
90
5022(1)
4
1.435
0.498
1137.07
P21/n (no. 14)
14.935(2)
21.363(4)
15.569(3)
90
90.9925(7)
90
4967(1)
4
1.521
0.647
0.35 × 0.15 × 0.1
0.714-0.937
11 624 (Rint ) 0.039)
7518
P1h (no. 2)
9.602(3)
14.550(4)
17.553(5)
98.444(5)
92.608(4)
93.140(4)
2418(1)
R, deg
â, deg
γ, deg
V, Å3
Z
2
F
calcd, g cm-3
1.393
0.554
0.3 × 0.2 × 0.1
0.715-0.946
11 012 (Rint ) 0.035)
6109
612
0.044
0.140
1.01
µ, mm-1
cryst size, mm3
transmn factor
no. of reflns unique
no. of reflns obsda
no. of variables
0.4 × 0.3 × 0.3
0.25 × 0.25 × 0.2
0.690-0.858
0.882-0.905
10 706 (Rint ) 0.032)
11 853 (Rint ) 0.038)
7568
661
0.033
0.109
1.03
7493
667
0.034
0.116
1.03
642
0.042
0.126
1.01
b
R1
c
wR2
gofd
2
2
b
2
2
c
2
2
2
2
2
a Fo > 2σ(Fo ). R1 ) ∑||Fo| - |Fc||/∑|Fo| for Fo > 2σ(Fo ). wR2 ) [∑w(Fo - Fc )2/∑w(Fo )2]1/2 (w ) [σ(Fo ) + aFo + b]-1) for all unique data.
2
2
dgof ) [∑w(Fo - Fc )2/{(no. of reflns obsd) - (no. of variables)}]1/2
.
and subsequent Fourier synthesis (DIRDIF 99).53 These were refined
by full-matrix least-squares techniques with anisotropic thermal
parameters except for those stated otherwise below. Thermal
ellipsoids of non-hydrogen atoms are drawn at the 30% probability
level in all figures. The C-H hydrogen atoms were placed at the
calculated positions and included in the final stages of the
refinements with fixed parameters, while the N-H hydrogen atoms
were found in difference Fourier maps and refined with isotropic
parameters. The absolute structures of 6y[BF4] and 9z[BF4] were
determined by refinement of Flack parameters (x ) 0.26(3) and
0.15(3), respectively).54 As for 3a‚0.5(C6H6), atoms in the
CH2-P(4)-Ph moiety were found in the two disordered positions
with occupancies of 0.5 each, while another phenyl group was also
disordered toward two orientations but with occupancies of 0.7 and
0.3. The phenyl groups of 0.5 and 0.3 occupancies in this solution
were refined isotropically. In each of 4a[BF4]‚0.25(CH2Cl2)‚0.25-
(Et2O) and 4c[BPh4]‚0.35(CH2Cl2)‚0.65(Et2O), the solvent mol-
ecules were found overlapping at the same site in the crystal, and
these were refined isotropically with the restraints of the bond
lengths and angles. Three phenyl groups in the cationic part of
4c[BPh4]‚0.35(CH2Cl2)‚0.65(Et2O) were located at the disordered
positions in 0.55/0.45, 0.75/0.25, and 0.75/0.25 ratios, among which
the C atoms of 0.25 occupancy were refined isotropically. In
addition, the BF4 anion in 6y[BF4] was disordered in two orienta-
tions in a 0.7/0.3 ratio.
Acknowledgment. This work was supported by a Grant-
in-Aid for Scientific Research on Priority Area (No. 18065005,
“Chemistry of Concerto Catalysis”) from the Ministry of
Education, Culture, Sports, Science, and Technology, Japan, and
by CREST of JST (Japan Science and Technology Agency).
Supporting Information Available: Crystallographic data of
3a‚0.5(C6H6),4a[BF4]‚0.25(CH2Cl2)‚0.25(Et2O),4c[BPh4]‚0.35(CH2Cl2)‚
0.65(Et2O), 6x[PF6]‚CH2Cl2, 6y[BF4], 7x‚THF, 8x[PF6]‚CH2Cl2,
and 9z[BF4] in CIF format and detailed experimental information.
This material is available free of charge via the Internet at
http://pubs.acs.org.
(52) PATTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman,
W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J. M. M.; Smykall, C. The
DIRDIF program system; Technical Report of the Crystallography Labora-
tory: University of Nijmegen, The Netherlands, 1992.
(53) DIRDIF99: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman,
W. P.; de Gelder, R.; Israel, R.; Smits, J. M. M. The DIRDIF-99 program
system; Technical Report of the Crystallography Laboratory: University
of Nijmegen, The Netherlands, 1999.
(54) Flack, H. D. Acta Crystallogr. Sect. A 1983, A39, 876.
OM7005485