Protonation and methylation of zerovalent molybdenum complexes of the type trans-[Mo(CNR)(L)(Ph2PCH2CH2PPh 2)2](R = Ph or Bun; L= N2, CO, or Nitrile) and trans-[Mo(CO)(L′)(Ph<sub

Article abstract of DOI:10.1021/om000049d

Treatment of trans-[Mo(CNPh)(N₂)(dppe)₂] with aqueous HBF₄ afforded an aminocarbyne complex, which was isolated as trans-[Mo(≡CNHPh)(O=CMe₂)(dppe)₂][BF₄] (7) after crystallization of the cr

Full text of DOI:10.1021/om000049d

2002
Organometallics 2000, 19, 2002-2011
P r oton a tion a n d Meth yla tion of Zer ova len t Molybd en u m
Com p lexes of th e Typ es
tr a n s-[Mo(CNR)(L)(P h 2P CH2CH2P P h 2)2] (R ) P h or Bu n ;
L ) N2, CO, or Nitr ile) a n d
tr a n s-[Mo(CO)(L′)(P h 2P CH2CH2P P h 2)2] (L′ ) N2 or
Nitr ile) To Give Ca r byn e or Hyd r id o Com p lexes1
Hidetake Seino,† Daigo Nonokawa,† Goh Nakamura,†,‡ Yasushi Mizobe,*,†,§ and
Masanobu Hidai*,‡
Institute of Industrial Science, The University of Tokyo, Roppongi, Minato-ku, Tokyo 106-8558,
J apan, Department of Chemistry and Biotechnology, Graduate School of Engineering,
The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, J apan, and Institute for
Molecular Science, Myodaiji, Okazaki 444-8585, J apan
Received J anuary 20, 2000
Treatment of trans-[Mo(CNPh)(N2)(dppe)2] with aqueous HBF4 afforded an aminocarbyne
complex, which was isolated as trans-[Mo(tCNHPh)(OdCMe2)(dppe)2][BF4] (7) after crystal-
lization of the crude product from acetone-hexane, whereas the reaction of trans-[Mo-
(CNBun)(N2)(dppe)2] with [Me2OH][BF4] resulted in the formation of the aminocarbene
complex with an agostic R-C-H bond, trans-[MoF(CHNHBun)(dppe)2][BF4]. Analogous
treatment of trans-[Mo(CNR)(L)(dppe)2] (R ) Ph, Bun; L ) p-MeOC6H4CN, CO (4)) with
[Me2OH][BF4] gave aminocarbyne complexes trans-[Mo(tCNHR)(NCC6H4OMe-p)(dppe)2]-
[BF4] and cis-[Mo(tCNHR)(CO)(dppe)2][BF4] (10). In solution at room temperature, the latter
complexes gradually isomerized to the hydrido complexes [MoH(CNR)(CO)(dppe)2][BF4] (12).
Related aminocarbyne complexes cis-[Mo(tCNMeR)(CO)(dppe)2][BF4] (13) were obtained
from the reactions of 4 with [Me3O][BF4]. For comparison, carbonyl complexes trans-[Mo-
(CO)(N2)(dppe)2] and trans-[Mo(CO)(p-MeOC6H4CN)(dppe)2] were allowed to react with
aqueous HBF4, which revealed the formation of the hydrido complexes [MoH(CO)(H2O)-
(dppe)2][BF4] (14) and [MoH(CO)(p-MeOC6H4CN)(dppe)2][BF4] (15), respectively. The X-ray
analyses were undertaken to determine the detailed structures for 7, 10a (R ) Ph), 12a (R
) Ph), 13b (R ) Bun), 14‚THF, and 15‚Et2O.
In tr od u ction
nitrogenase substrates such as isocyanides and nitriles
bound to the {M(P )4} chromophore have also been
attracting considerable interest. In contrast to the
biological catalysis of nitrogenase, which reduces MeNC
into methane, methylamine, and dimethylamine to-
gether with a small amount of ethylene and ethane3b
and transforms the nitriles RCN (R ) Me, Et, Prn) into
the alkanes RCH3 and ammonia,4 the reactions of the
isocyanide complexes trans-[M(CNMe)2(dppe)2] (dppe )
Ph2PCH2CH2PPh2) with 2 equiv of acid such as [Et2-
OH][BF4] and HCl have been shown to give the alkyne
complexes trans-[MX(η2-MeHNCtCNHMe)(dppe)2]+ (X
) F, Cl) via the aminocarbyne species trans-[M(tC-
NHMe)2(dppe)2]2+ generated by the protonation at the
isocyanide N atoms,5 while the protonation of the
dinitrogen-nitrile complexes trans-[M(N2)(NCR)(dppe)2]
Previous studies in this and other laboratories about
the reactivities of Mo and W dinitrogen complexes of
the type [M(N2)2(P )4] (M ) Mo, W; P ) tertiary
phosphine) have shown that the coordinated N2 in these
complexes is susceptible to the electrophilic attack by
protons to be converted into a hydrazido(2-) ligand
(NNH2) and/or nitrogen hydrides, i.e., NH3 and less
commonly N2H4, depending on the nature of the proton
source and the ancillary ligand P along with the
reaction conditions.2 These findings are of great impor-
tance owing to their possible relevance to the mecha-
nism for a biological N2 fixation in nitrogenase that still
remains to be elucidated.3 Hence, reactivities of other
† Institute of Industrial Science.
‡ Department of Chemistry and Biotechnology.
§ Institute for Molecular Science.
(4) Burgess, B. K. In Molybdenum Enzymes; Spiro, T. G., Ed.; J ohn
Wiley & Sons: New York, 1985; p 161.
(1) Preparation and Properties of Molybdenum and Tungsten Dini-
trogen Complexes. 67. Part 66: Seino, H.; Mizobe, Y.; Hidai, M. Bull.
Chem. Soc. J pn. 2000, 73, 631.
(2) (a) Hidai, M.; Mizobe, Y. Chem. Rev. 1995, 95, 1115. (b)
Bazhenova, T. A.; Shilov, A. E. Coord. Chem. Rev. 1995, 144, 69. (c)
Leigh, G. J . Acc. Chem. Res. 1992, 25, 178, and references therein.
(3) (a) Howard, J . B.; Rees, D. C. Chem. Rev. 1996, 96, 2965. (b)
Burgess, B. K.; Lowe, D. J . Chem. Rev. 1996, 96, 2983. (c) Eady, R. R.
Chem. Rev. 1996, 96, 3013, and references therein.
(5) (a) Wang, Y.: Frau´sto da Silva, J . J . R.; Pombeiro, A. J . L.;
Pellinghelli, M. A.; Tiripicchio, A.; Henderson, R. A.; Richards, R. L.
J . Chem. Soc., Dalton Trans. 1995, 1183. See also to refer to the
protonation on the related isocyanide complexes: Henderson, R. A.;
Pombeiro, A. J . L.; Richards, R. L.; Frau´sto da Silva, J . J . R.; Wang,
Y. J . Chem. Soc., Dalton Trans. 1995, 1193. (b) Formation of the
aminocarbyne ligand has also been observed for the protonation
reactions of a wider range of isocyanide complexes. See ref 16.
10.1021/om000049d CCC: $19.00 © 2000 American Chemical Society
Publication on Web 04/20/2000

Protonation of Zerovalent Mo Complexes
Organometallics, Vol. 19, No. 10, 2000 2003
Sch em e 1
(R ) Me, aryl) with excess amounts of aqueous HCl and
HBF4 has turned out to occur at the nitrile carbon to
give the imido complexes trans-[MX(tNCH2R)(dppe)2]+
(X ) Cl, F).6 However, reactions of protic acids with
these M(0) complexes tend to be significantly affected
by subtle factors, which result in the formation of more
diversified products. Thus, treatment of trans-[M(N2)-
(NCPrn)(dppe)2] with H2SO4 in THF at 0 °C was
reported to cause the protonation at the N2 ligand,
affording [M(NNH2)(NCPrn)(dppe)2]2+ 7
. On the other
hand, it has been observed that hydrido complexes [MH-
(CNR)2(dppe)2]+ and hydridoaminocarbyne complexes
[MH(tCNHR)(CNR)(dppe)2]2+ are formed from the
reactions of trans-[M(CNR)2(dppe)2] with acids under
certain controlled conditions.8 Formation of the former
hydridobis(isocyanide) complexes is reminiscent of the
reaction of trans-[W(N2)2(dppe)2] with HCl in THF
giving the hydridobis(dinitrogen) complex [WH(N2)2-
(dppe)2]+.9 Interestingly, the reactions of the dinitro-
gen-nitrile complexes with the other electrophiles such
as PhCOCl10 and Me3SiI11 occur rather at the N2 ligand
to give the diazenido (MNNCOPh, MNNSiMe3) com-
plexes or the hydrazido(2-) (MNNHCOPh, MNNH-
SiMe3) complexes resulting from the successive proto-
nation of the produced diazenido species by adventitious
HX (X ) Cl, I).
In the preceding papers,12 we have reported that a
range of isocyanide-dinitrogen complexes trans-[Mo-
(CNR)(N2)(dppe)2] (1; R ) alkyl, aryl) can readily be
prepared from the reactions of trans-[Mo(N2)2(dppe)2]
(2) with corresponding benzaldehyde imines PhCHdNR.
Furthermore, a series of isocyanide complexes trans-
[Mo(CNR)(L)(dppe)2] (L ) nitrile (3), CO(4), isocyanide,
and H2) are available from 1 through subsequent
replacement of the N2 ligand by L. Now we have
investigated the protonation reactions of a series of Mo-
(0) complexes containing one or two nitrogenase sub-
strates as the ligand. In this paper, we wish to sum-
marize the results of this study, demonstrating which
site in complexes 3 and 4 as well as the previously
reported carbonyl complexes trans-[Mo(CO)(L′)(dppe)2]
(L′ ) N2 (5),13 nitrile (6)14) is more susceptible to
protonation.
by aqueous HBF4 in THF has already been reported by
this group to proceed at the terminal N atom of one N2
ligand, affording the doubly protonated product trans-
[MoF(NNH2)(dppe)2][BF4].15 Now we have found that
the analogous treatment of the isocyanide-dinitrogen
complex 1a (R ) Ph) results in the formation of an
aminocarbyne complex; that is, monoprotonation occurs
not at the N2 ligand but at the isocyanide N atom. There
is precedent that the addition of electrophiles to electron-
rich isocyanide complexes results in the formation of
aminocarbyne complexes.16 Molecular orbital calcula-
tions on the related d6 electron-rich Re isocyanide
complex [ReCl(CNH)(H2PCH2CH2PH2)2] were carried
out previously, which demonstrated that a negative
charge is accumulated on the Cl and N atoms and the
reaction with the electrophile gives the product of N
attack, that is, the thermodynamically favored ami-
nocarbyne complex.17 The product was isolated as the
acetone adduct trans-[Mo(tCNHPh)(Me2CO)(dppe)2]-
[BF4] (7) after recrystallization of the yet uncharacter-
izable crude product18 from acetone/hexane (Scheme 1).
The IR spectrum of 7 shows a weak band at 3308 cm-1
attributable to ν(NH), which shifted to 2427 cm-1 for
the deuterium analogue. In the 1H NMR spectrum,
however, the resonance due to the amino proton was
not assignable presumably because of its overlapping
with the phenyl resonances. The trans geometry around
the Mo was implicated by its 31P NMR spectrum
exhibiting only one singlet at 60.5 ppm.
Resu lts a n d Discu ssion
P r ot on a t ion of Isocya n id e-Din it r ogen Com -
p lexes 1. Protonation of the bis(dinitrogen) complex 2
Detailed structure of 7 has been determined by the
X-ray crystallography. An ORTEP drawing and the
important bond distances and angles are shown in
Figure 1 and Table 1, respectively. Complex 7 has an
octahedral configuration with the aminocarbyne and
acetone ligands in mutually trans positions. For the
aminocarbyne ligand, the Mo-C-N linkage is es-
sentially linear (176.8(3)°). The short Mo-C distance
(6) Seino, H.; Tanabe, Y.; Ishii, Y.; Hidai, M. Inorg. Chim. Acta 1998,
280, 163.
(7) Chatt, J .; Leigh, G. J .; Neukomm, H.; Pickett, C. J .; Stanley, D.
R. J . Chem. Soc., Dalton Trans. 1980, 121.
(8) (a) Pombeiro, A. J . L.; Richards, R. L. Transition Met. Chem.
1980, 5, 55. (b) Chatt, J .; Pombeiro, A. J . L.; Richards, R. L. J . Chem.
Soc., Dalton Trans. 1979, 1585.
(9) Chatt, J .; Heath, G. A.; Richards, R. L. J . Chem. Soc., Dalton
Trans. 1974, 2074.
(10) Tatsumi, T.; Hidai, M.; Uchida, Y. Inorg. Chem. 1975, 14, 2530.
(11) Hidai, M.; Komori, K.; Kodama, T.; J in, D.-M.; Takahashi, T.;
Sugiura, S.; Uchida, Y.; Mizobe, Y. J . Organomet. Chem. 1984, 272,
155.
(12) (a) Seino, H.; Arita, C.; Nonokawa, D.; Nakamura, G.; Harada,
Y.; Mizobe, Y.; Hidai, M. Organometallics 1999, 18, 4165. (b) Naka-
mura, G.; Harada, Y.; Arita, C.; Seino, H.; Mizobe, Y.; Hidai, M.
Organometallics 1998, 17, 1010.
(13) Sato, M.; Tatsumi, T.; Kodama, T.; Hidai, M.; Uchida, T.;
Uchida, Y. J . Am. Chem. Soc. 1978, 100, 4447.
(14) Tatsumi, T.; Tominaga, H.; Hidai, M.; Uchida, Y. J . Organomet.
Chem. 1980, 199, 63.
(15) Hidai, M.; Kodama, T.; Sato, M.; Harakawa, M.; Uchida, Y.
Inorg. Chem. 1976, 15, 2694.
(16) (a) Mayr, A.; Hoffmeister, H. Adv. Organomet. Chem. 1991, 32,
227. (b) Mayr, A.; Bastos, C. M. Prog. Inorg. Chem. 1992, 40, 1. (c)
Filippou, A. C. In Organic Synthesis via Organometallics; Helmchen,
G., Dibo, J ., Flubacher, D., Wiese, B., Eds.; F. Vieweg & Sohn:
Braunschweg, 1997; p 97.
(17) Carvalho, M. F. N. N.; Pombeiro, A. J . L.; Bakalbassis, E. G.;
Tsipis, C. A. J . Organomet. Chem. 1989, 371, C26.
(18) The crude product probably contains a H2O molecule at the site
trans to the aminocarbyne ligands, although full characterization was
unsuccessful.

2004 Organometallics, Vol. 19, No. 10, 2000
Seino et al.
Ch a r t 1
The C-O distance at 1.226(5) Å is typical of that of the
CdO double bond and comparable to those in the
other σ-bound acetone ligands for, for example, [Rh-
(dCdCdCPh2)(Me2CO)(PPri ) ][PF6] (1.216(3) Å)22 and
3 2
[Ru{C(dCHPh)OCMeO}(Me2CO)(CO)(PPri ) ][BF4]
3 2
(1.235(10) Å).23
Protonation of the BunNC complex 1b with aqueous
HBF4 under the conditions employed above did not give
any characterizable products. However, protonation by
the use of [Me2OH][BF4] at 0 °C proceeded cleanly,
leading to the formation of the product protonated at
both the N and C atoms, trans-[MoF(CHNHBun)(dppe)2]-
[BF4] (8) (Scheme 1). Differences in the reactivity
between 1a and 1b are well comparable to those in
PhNH2 and BunNH2 arising from the stronger electron-
donating ability of the Bun group than the Ph group. In
this reaction, the second protonation seems to be so
rapid that the monoprotonated product could not be
F igu r e 1. ORTEP drawing of 7. Hydrogen atoms are
omitted for clarity except for the amino proton H(1), having
hydrogen-bonding interaction with F(1).
Ta ble 1. Selected Bon d Dista n ces a n d An gles in 7
(a) Bond Distances (Å)
Mo-P(1)
Mo-P(3)
Mo-O
O-C(8)
N-H(1)
2.520(1)
2.522(1)
2.310(3)
1.226(5)
0.90
Mo-P(2)
Mo-P(4)
Mo-C(1)
C(1)-N
2.473(1)
2.526(1)
1.808(4)
1.345(5)
2.12
1
detected; the H NMR spectrum of the reaction mixture
of 1b with an equimolar amount of [Me2OH][BF4]
showed the presence of only 8 and unreacted 1b. In
contrast, the reaction of 1a with [Me2OH][BF4] was
somehow elusive, and no tractable compounds were
obtained from the reaction mixture.
F(1)-H(1)
(b) Bond Angles (deg)
P(1)-Mo-P(2)
P(1)-Mo-P(4)
P(1)-Mo-C(1)
P(2)-Mo-P(4)
P(2)-Mo-C(1)
P(3)-Mo-O
80.70(4)
100.16(4)
89.2(1)
177.63(6)
87.4(1)
85.45(9)
83.12(7)
177.3(2)
176.8(3)
126.0
P(1)-Mo-P(3)
178.32(5)
92.94(9)
98.92(4)
94.64(8)
80.16(4)
92.5(1)
P(1)-Mo-O
Appearance of the four P atoms as one doublet in the
31P{1H} NMR spectrum is indicative of the trans
structure for 8, where the observed J P-F value of 30 Hz
is in good agreement with those of related Mo complexes
of the type trans-[MoF(E)(dppe)2]+ (E ) NNH2, 30 Hz;15
E ) NNdCHEt, 30 Hz24). In the 1H NMR spectrum, two
new resonances each integrating for one proton ap-
peared. One of these signals observed as a broad singlet
at 3.15 ppm may be assigned to the NH proton. The
other peak at -7.25 ppm, at a glance, seems to be
attributable to the hydride (MoH) rather than the
carbene proton (ModCH-), since the carbene proton is
expected to resonate generally in a much lower field,
e.g., 10-18 ppm.25 However, the observed peak is
correlated to the NH proton with the coupling constant
of as large as 7.8 Hz, and furthermore the coupling of
this resonance with the P atoms by J P-H ) 10.7 Hz
seems to be too small to be assigned as that of the
hydride bound to the Mo center (vide supra). In addition,
the 13C NMR spectrum showed the R-C resonance at
203.2 ppm, which split into a doublet with J C-H ) 61
Hz in the coupled spectrum. From these NMR data, it
may be concluded that 1b has a carbene ligand with an
R-C-H agostic bond, as demonstrated for, for example,
P(2)-Mo-P(3)
P(2)-Mo-O
P(3)-Mo-P(4)
P(3)-Mo-C(1)
P(4)-Mo-C(1)
Mo-O-C(8)
P(4)-Mo-O
94.8(1)
O-Mo-C(1)
Mo-C(1)-N
C(1)-N-H(1)
F(1)-H(1)-N
152.0(3)
125.3(4)
108.0
C(1)-N-C(2)
C(2)-N-H(1)
149.0
at 1.808(4) Å is diagnostic of the Mo-C multiple
bonding, which is comparable to those in the other
carbyne complexes,16a e.g., [Mo(tCNEt2)(CO)3(µ-I)]2
(1.80(2) Å)19 and [CpMo(tCCH2CMe3)(P(OMe)3)2]
(1.796(2) Å; Cp ) η5-C5H5).20 The bond angles around
the N atom (125.3(4)°, 126°, and 108°) are indicative of
its sp2 character, which is consistent with the C(1)-N
bond length at 1.345(5) Å, being much shorter than the
typical C-N single bond distance of 1.47 Å. These
structural features of the aminocarbyne ligand may be
interpreted in terms of the delocalization of electron
density from the N p orbital by interaction with a p
orbital on the carbyne C atom as described by the two
extreme structures i and ii shown in Chart 1.21
The acetone ligand is bound to the Mo atom in an η1
manner as commonly observed for the ketone complexes.
(22) Windmu¨ller, B.; Nu¨rnberg, O.; Wolf, J .; Werner, H. Eur. J .
Inorg. Chem. 1999, 613.
(23) Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, A. M.; On˜ate, E.; Oro,
L. A. Organometallics 1994, 13, 1669.
(24) Hidai, M.; Mizobe, Y.; Sato, M.; Kodama, T.; Uchida, Y. J . Am.
Chem. Soc. 1978, 100, 5740.
(25) Torraca, K. E.; Ghiviriga, I.; McElwee-White, L. Organometal-
lics 1999, 18, 2262.
(19) Fischer, E. O.; Wittman, D.; Himmelreich, D.; Cai, R.; Acker-
mann, K.; Neugebauer, D. Chem. Ber. 1982, 115, 3152.
(20) Allen, S. R.; Beevor, R. G.; Green, M.; Orpen, A. G.; Paddick,
K. E.; Williams, I. D. J . Chem. Soc., Dalton Trans. 1987, 591.
(21) (a) Kim, H. P.; Angelici, R. J . Adv. Organomet. Chem. 1987,
27, 51. (b) Gallop, M. A.; Roper, W. R. Adv. Organomet. Chem. 1986,
25, 121.

Protonation of Zerovalent Mo Complexes
Organometallics, Vol. 19, No. 10, 2000 2005
Sch em e 2
[CpMo(CHBun)(CO)(P(OPh)3)]+,25 cis,trans-[W(CHR)Cl2-
(CO)(PMe3)2] (R ) Ph,26 But 27), trans-[WCl(CHBut)-
(PMe3)4]+,28 and trans-[WMe(CHC6H4Me){PPh(CH2CH2-
PPh2)2}(CO)]+.29 The J C-H values for such protons are
reported to fall in the range 45-90 Hz, which are
significantly smaller than those for the common, nona-
gostic methylidene protons (110-130 Hz).29
Formation of an aminocarbene complex from the
reaction of an isocyanide complex with excess acid is
precedented. For example, [Mo(CNBut)6] reacts with an
excess of CF3COOH at -78 °C to give [Mo(dCHNHBut)-
(CNBut)5][OCOCF3]2. However, the NMR data for this
complex clearly showed the absence of any agostic
interaction between the R-C-H bond and the Mo
center.30
P r oton a tion of Isocya n id e-Nitr ile Com p lexes
tr a n s-[Mo(CNR)(NCC6H4OMe-p)(d p p e)2] (3). The
reactions of 3 with [Me2OH][BF4] in THF at 0 °C gave
the monoprotonated products trans-[Mo(tCNHR)(NC-
C6H4OMe-p)(dppe)2][BF4] (R ) Ph (9a ), Bun (9b)) (eq
1). Only one singlet was observed in the 31P NMR
F igu r e 2. ORTEP drawing of 10a . Hydrogen atoms are
omitted for clarity except for the amino proton H(1), having
hydrogen-bonding interaction with F(1) and F(2).
Ta ble 2. Selected Bon d Dista n ces a n d An gles in
10a
(a) Bond Distances (Å)
Mo-P(1)
Mo-P(3)
Mo-C(1)
C(8)-O
2.664(3)
2.589(3)
1.812(10)
1.154(10)
1.0(1)
Mo-P(2)
Mo-P(4)
Mo-C(8)
C(1)-N
2.478(3)
2.474(3)
1.95(1)
1.32(1)
2.2(1)
N-H(1)
F(1)-H(1)
F(2)-H(1)
2.3(1)
(b) Bond Angles (deg)
P(1)-Mo-P(2)
P(1)-Mo-P(4)
P(1)-Mo-C(8)
P(2)-Mo-P(4)
P(2)-Mo-C(8)
P(3)-Mo-C(1)
P(4)-Mo-C(1)
C(1)-Mo-C(8)
Mo-C(8)-O
78.66(9)
105.86(9)
82.2(3)
174.90(10)
92.1(3)
99.9(3)
83.4(3)
88.0(4)
P(1)-Mo-P(3)
91.53(9)
166.6(3)
98.53(10)
92.6(3)
79.16(9)
166.4(3)
90.9(3)
173.3(8)
124.1(10)
157.0(10)
P(1)-Mo-C(1)
P(2)-Mo-P(3)
P(2)-Mo-C(1)
P(3)-Mo-P(4)
P(3)-Mo-C(8)
P(4)-Mo-C(8)
Mo-C(1)-N
spectra, while two characteristic bands appeared in the
IR spectra, one being assignable to ν(CtN) of the
coordinated nitrile and the other to ν(NH). These data
indicate that the protonation takes place at the isocya-
nide N atom to give the aminocarbyne ligand, which
occupies the site trans to the nitrile ligand still intact
after the reaction. The ν(CtN) values of 2225 and 2226
cm-1 observed for 9a and 9b, respectively, are slightly
higher than that of a free p-MeOC6H4CN (2217 cm-1).
P r oton a tion of Isocya n id e-Ca r bon yl Com p lexes
4. Protonation reactions of 4a (R ) Ph) and 4b (R )
Bun) with [Me2OH][BF4] in THF at 0 °C both afforded
the aminocarbyne complexes cis-[Mo(tCNHR)(CO)-
(dppe)2][BF4] (10) in moderate yields (Scheme 2). In the
178.6(10)
110.0(7)
134.0(9)
C(1)-N-C(2)
F(1)-H(1)-N
C(1)-N-H(1)
F(2)-H(1)-N
IR spectra of 10, the intense bands assignable to
ν(CtO) appeared together with the weak ν(NH) bands,
indicating that the protonation occurs on the isocyanide
N atom with the CO ligand intact. On the basis of the
31P NMR spectra exhibiting four resonances with the
same intensities, the cis structure has been implicated
for 10.
The structure of 10a (R ) Ph) has been fully charac-
terized by the X-ray analysis. An ORTEP drawing is
depicted in Figure 2, while the important bond distances
and angles are summarized in Table 2. For the ami-
nocarbyne ligand in 10a , the Mo-C-N linkage is
essentially linear (173.3(8)°), and the Mo-C and C-N
distances at 1.812(10) and 1.32(1) Å are comparable to
those in 7. It is to be noted that in the closely related
alkylidyne complex cis-[Mo(tCCH2Ph)(CO)(dppe)2]-
(26) Mayr, A.; Asaro, M. F.; Kjelsberg, M. A.; Lee, K. S.; Van Eugen,
D. Organometallics 1987, 6, 432.
(27) Wengrovius, J . H.; Schrock, R. R.; Churchill, M. R.; Wasserman,
H. J . J . Am. Chem. Soc. 1982, 104, 1739.
(28) Holmes, S. J .; Clark, D. N.; Turner, H. W.; Schrock, R. R. J .
Am. Chem. Soc. 1982, 104, 6322.
(29) J effery, J . C.; Weller, A. S. J . Organomet. Chem. 1997, 548,
195.
(30) Carnahan, E. M.; Lippard, S. J . J . Chem. Soc., Dalton Trans.
1991, 699.

2006 Organometallics, Vol. 19, No. 10, 2000
Seino et al.
Ta ble 3. Selected Bon d Dista n ces a n d An gles in
12a
(a) Bond Distances (Å)
Mo-P(1)
Mo-P(3)
Mo-C(1)
C(8)-O
2.475(2)
2.570(2)
2.094(6)
1.157(7)
1.63(7)
Mo-P(2)
Mo-P(4)
Mo-C(8)
C(1)-N
2.565(2)
2.471(2)
1.977(7)
1.163(7)
Mo-H(1)
(b) Bond Angles (deg)
P(1)-Mo-P(2)
P(1)-Mo-P(4)
P(1)-Mo-C(8)
P(2)-Mo-P(4)
P(2)-Mo-C(8)
P(3)-Mo-C(1)
P(4)-Mo-C(1)
C(1)-Mo-C(8)
Mo-C(8)-O
78.70(6)
112.12(6)
88.9(2)
168.38(6)
87.5(2)
87.2(2)
91.2(2)
176.3(3)
178.6(6)
50.0(2)
P(1)-Mo-P(3)
168.60(6)
87.8(2)
91.35(6)
93.5(2)
78.28(6)
96.3(2)
88.4(2)
178.4(6)
177.5(7)
61.0(2)
P(1)-Mo-C(1)
P(2)-Mo-P(3)
P(2)-Mo-C(1)
P(3)-Mo-P(4)
P(3)-Mo-C(8)
P(4)-Mo-C(8)
Mo-C(1)-N
C(1)-N-C(2)
P(4)-Mo-H(1)
P(1)-Mo-H(1)
broad resonances with the same intensities, while the
1H NMR spectrum shows a high-field resonance char-
acteristic of the hydride proton, which splits into a
triplet of triplets at low temperatures. These spectral
data are consistent with the solid structure clarified by
the X-ray diffraction. Complex 12b also exhibited the
analogous spectral feature.
F igu r e 3. ORTEP drawing of the cation in12a . Hydrogen
atoms are omitted for clarity except for the hydride H(1).
Meth yla tion of Isocya n id e-Ca r bon yl Com p lexes
4. Complexes 4 reacted with [Me3O][BF4] in CH2Cl2 at
room temperature to give the aminocarbyne complexes
cis-[Mo(tCNMeR)(CO)(dppe)2][BF4] (13) in moderate
yields (eq 2). Isolation of any characterizable products
[BF4] (11)31 the Mo-Ccarbyne distance (1.768(8) Å) is
considerably shorter than that in 10a . This may be
explained by the significant contribution of the reso-
nance structure ii shown in Chart 1 for the aminocar-
byne complex 10a . The fact that the ν(CtO) bands
appeared at 1893 and 1910 cm-1 for 10a and 11,
respectively, indicates the stronger electron-donating
ability of the Mo center toward the CO ligand in 10a
than that in 11. This is also consistent with the
significant contribution of structure ii, where the dona-
tion of lone-pair electron density occurs from the N atom
toward the metal center.
Complexes 10 have proved to be unstable in solution
at room temperature. Thus, 10 dissolved in CDCl3 are
gradually converted into hydridoisocyanide complexes
[MoH(CNR)(CO)(dppe)2][BF4] (12) (Scheme 2). As ex-
pected, this isomerization turned out to be much en-
hanced by the addition of [Me2OH][BF4]. Migration of
the proton from the aminocarbyne ligand to the metal
center was invoked previously to explain the formation
of [MH(CNMe)2(dppe)2]+ from the reaction of trans-
[M(CNMe)2(dppe)2] and [Et2OH][BF4] via the presumed
intermediate trans-[M(tCNHMe)(CNMe)(dppe)2]+.8a
The structure of 12a (R ) Ph) has been determined
in detail by X-ray analysis (Figure 3 and Table 3).
Complex 12a has a pentagonal bypyramidal structure
with the CO and PhNC ligands occupying the apical
positions. The hydride was unequivocally found in the
Fourier map, which lies on the basal plane between the
P(1) and P(4) atoms (d(Mo-H) ) 1.63(7) Å). Bonding
parameters in the CO and PhNC ligands are unexcep-
tional. The IR spectrum of 12a shows the intense bands
at 2061 and 1861 cm-1 assignable to ν(CtN) and
ν(CtO), respectively, which are shifted to the consider-
ably higher region than those of the parent Mo(0)
complex 4a (ν(CtN), 2017 and 1991; ν(CtO), 1812
cm-1).12a The 31P NMR spectrum of 12a exhibits two
failed by the analogous treatment of 1 with [Me3O][BF4].
It is interesting to note that [Mo(CNBut)6] is susceptible
to electrophilic attack by MeOTf 29 and alkyl halides32
at the R-carbon atom to give η2-iminoacyl complexes
[Mo(η2-ButNCR)(CNBut)5]+ (R ) Me, PhCH2). Spectro-
scopic data for 13 are indicative of the cis structure, as
manifested for the related CNHR complexes 10, which
has been confirmed by X-ray analysis of the Bun complex
13b.
An ORTEP drawing of the cation in 13b is shown in
Figure 4, while selected bond distances and angles are
listed in Table 4. The structure of 13b is quite analogous
to that of 10a . Thus, the aminocarbyne and CO ligands
occupy the mutually cis positions, and in the amino-
carbyne ligand the Mo-C-N linkage is almost linear
(173.7(6)°). However, the Mo-C distance at 1.843(7) Å
is slightly longer and the Ccarbyne-N distance at
1.305(8) Å is a little shorter than the corresponding bond
distances of 1.812(10) and 1.32(1) Å, respectively, in 10a .
These differences may be explained by the greater
contribution of the structure ii for 13b with the strongly
electron-donating NBunMe group than for 10a with the
NHPh moiety. The almost planar geometry around the
(31) Nakamura, G.; Harada, Y.; Mizobe, Y.; Hidai, M. Bull. Chem.
Soc. J pn. 1996, 69, 3305.
(32) Yoshida, T.; Hirotsu, K.; Higuchi, T.; Otsuka, S. Chem. Lett.
1982, 1017.

Protonation of Zerovalent Mo Complexes
Organometallics, Vol. 19, No. 10, 2000 2007
F igu r e 5. ORTEP drawing of 14. Hydrogen atoms are
omitted for clarity except for the hydride H(1).
F igu r e 4. ORTEP drawing of the cation in 13b. Hydrogen
atoms are omitted for clarity.
Ta ble 5. Selected Bon d Dista n ces a n d An gles in 14
Ta ble 4. Selected Bon d Dista n ces a n d An gles in
13b
(a) Bond Distances (Å)
Mo-P(1)
Mo-P(3)
Mo-O(2)
C(1)-O(1)
2.453(1)
2.516(1)
2.330(6)
1.175(5)
Mo-P(2)
Mo-P(4)
Mo-C(1)
Mo-H(1)
2.575(2)
2.426(1)
1.857(5)
1.63(5)
(a) Bond Distances (Å)
Mo-P(1)
Mo-P(3)
Mo-C(1)
C(7)-O
2.664(2)
2.589(2)
1.843(7)
1.169(7)
Mo-P(2)
Mo-P(4)
Mo-C(7)
C(1)-N
2.501(2)
2.502(2)
1.950(7)
1.305(8)
(b) Bond Angles (deg)
P(1)-Mo-P(2)
P(1)-Mo-P(4)
P(1)-Mo-C(1)
P(2)-Mo-P(4)
P(2)-Mo-C(1)
P(3)-Mo-O(2)
P(4)-Mo-O(2)
O(2)-Mo-C(1)
P(1)-Mo-H(1)
77.47(5)
114.33(5)
93.1(2)
168.10(5)
97.5(2)
90.63(9)
95.3(1)
178.2(2)
53.0(1)
P(1)-Mo-P(3)
167.61(5)
88.68(9)
90.17(4)
83.0(1)
78.05(4)
87.7(2)
83.9(2)
176.5(4)
60.0(1)
P(1)-Mo-O(2)
P(2)-Mo-P(3)
P(2)-Mo-O(2)
P(3)-Mo-P(4)
P(3)-Mo-C(1)
P(4)-Mo-C(1)
Mo-C(1)-O(1)
P(4)-Mo-H(1)
(b) Bond Angles (deg)
P(1)-Mo-P(2)
P(1)-Mo-P(4)
P(1)-Mo-C(7)
P(2)-Mo-P(4)
P(2)-Mo-C(7)
P(3)-Mo-C(1)
P(4)-Mo-C(1)
C(1)-Mo-C(7)
Mo-C(7)-O
78.82(6)
102.32(7)
83.9(2)
177.92(7)
91.2(2)
95.2(2)
89.7(2)
87.6(3)
177.5(6)
121.0(8)
P(1)-Mo-P(3)
95.36(6)
165.3(2)
99.15(6)
89.4(2)
79.05(6)
169.3(2)
90.7(2)
173.7(6)
129.5(8)
106.3(9)
P(1)-Mo-C(1)
P(2)-Mo-P(3)
P(2)-Mo-C(1)
P(3)-Mo-P(4)
P(3)-Mo-C(7)
P(4)-Mo-C(7)
Mo-C(1)-N
C(1)-N-C(2)
C(2)-N-C(6)
(Figure 5 and Table 5). No intermediate stages, e.g., a
hydroxycarbyne complex, were detected. Complex 14
C(1)-N-C(6)
N atom is observed also in 13b, with C-N-C angles of
129.5(8)°, 121.0(8)°, and 106.3(9)°.
P r oton a tion of Ca r bon yl-Din itr ogen Com p lex
5 a n d Ca r bon yl-Nitr ile Com p lex 6. Relevant to the
reaction of isocyanide-carbonyl complexes 4 with [Me2-
OH][BF4], our study has been extended further to clarify
the details of the protonation reactions of other Mo(0)
carbonyl complexes. As for the related reaction of cis-
[Mo(CO)2(dppe)2] with acids, the hydrido complex [MoH-
(CO)2(dppe)2][SO3F], having a monocapped octahedral
structure, was formed by treatment with HSO3F,33
whereas the paramagnetic complexes trans-[Mo(CO)2-
(dppe)2]X (X ) BF4, HSO4) were obtained from the
reaction with [Et2OH][BF4] and H2SO4.34
Now we have found that treatment of 5 with aqueous
HBF4 in THF at room temperature results in the loss
of the coordinated N2 to give the hydrido complex [MoH-
(CO)(OH2)(dppe)2][BF4] (14) (eq 3), whose structure has
been determined unambiguously by X-ray analysis
has a pentagonal bipyramidal geometry with the CO
and H2O ligands in the apical positions. The hydride
was located between the P(1) and P(4) atoms, with the
Mo-H distance at 1.63(5) Å. Complex 14 shows a strong
ν(CtO) band at 1776 cm-1 in its IR spectrum, which is
lower than the values for [Mo(CO)(dppe)2] (1807 cm-1
)
and 5 (1812 and 1789 cm-1).13 The exceptionally low
ν(CtO) value observed for the CO ligand in 14 suggests
the extremely electron-donating nature of the [MoH-
(OH2)(dppe)2]+ moiety toward the CO ligand, having no
other π-acidic ligands but the good donor ligand H2O
in the trans position.
Treatment of the carbonyl-nitrile complex trans-[Mo-
(CO)(NCC6H4OMe-p)(dppe)2] (6) with aqueous HBF4
also afforded the hydrido complex [MoH(CO)(NCC6H4-
OMe-p)(dppe)2][BF4] (15) in high yield (eq 4). In contrast
(33) Datta, S.; Dezube, B.; Kouba, J . K.; Wreford, S. S. J . Am. Chem.
Soc. 1978, 100, 4404.
(34) Chatt, J .; Pombeiro, A. J . L.; Richards, R. L. J . Chem. Soc.,
Dalton Trans. 1980, 492.

2008 Organometallics, Vol. 19, No. 10, 2000
Seino et al.
exhibiting two characteristic bands at 2217 and 1796
cm-1 due to ν(NtC) and ν(CtO) are in agreement with
the structure determined by the X-ray analysis. It is to
be noted that 6 shows ν(NtC) and ν(CtO) bands at
2155 and 1767 cm-1 14
.
Con clu d in g Rem a r k s
The present study on the protonation reaction of the
Mo(0) complexes containing one or two nitrogenase
substrates as the ligand has disclosed that on treatment
with either [Me2OH][BF4] or aqueous HBF4, a series of
isocyanide complexes trans-[Mo(CNR)(L)(dppe)2] with
L ) N2, p-MeOC6H4CN, and CO undergoes protonation
at the isocyanide N atom to give the aminocarbyne
complexes except for 1b (R ) Bun, L ) N2), the latter of
which is susceptible to attack at both the R-C and N
atom in the n-butylisocyanide ligand, affording the
carbene complex with an agostic R-C-H bond, 8. In the
aminocarbyne and carbene complexes obtained here,
both the nitrile and CO ligands are still intact for 9 and
10, whereas the coordinated N2 in 1 is lost in the
products 7 and 8. However, the aminocarbyne complexes
10 with the CO ligand are unstable in a solution state
at room temperature and are converted into the hydri-
doisocyanide complexes 12. The methylation of the
isocaynide-carbonyl complexes 4 with [Me3O][BF4]
proceeds similarly to give the stable aminocarbyne
complexes 13. By contrast, the carbonyl complexes
trans-[Mo(CO)(L)(dppe)2] (L ) N2, p-MeOC6H4CN) re-
acted with aqueous HBF4 to afford the hydrido com-
plexes 14 and 15, with a loss of the N2 ligand for the
former and a retention of the nitrile ligand for the latter,
respectively.
F igu r e 6. ORTEP drawing of the cation in 15. Hydrogen
atoms are omitted for clarity except for the hydride H(1).
Ta ble 6. Selected Bon d Dista n ces a n d An gles in 15
(a) Bond Distances (Å)
Mo-P(1)
Mo-P(3)
Mo-N
C(1)-O(1)
Mo-H(1)
2.464(2)
2.550(2)
2.190(4)
1.181(6)
1.64(3)
Mo-P(2)
Mo-P(4)
Mo-C(1)
N-C(2)
2.567(2)
2.438(2)
1.892(5)
1.131(6)
(b) Bond Angles (deg)
P(1)-Mo-P(2)
P(1)-Mo-P(4)
P(1)-Mo-C(1)
P(2)-Mo-P(4)
P(2)-Mo-C(1)
P(3)-Mo-N
77.61(5)
114.49(5)
91.2(2)
167.49(5)
96.8(2)
91.7(1)
91.3(1)
177.6(2)
175.8(5)
59.0(1)
P(1)-Mo-P(3)
167.94(5)
90.4(1)
90.73(5)
85.2(1)
77.34(5)
87.0(2)
86.5(2)
177.7(5)
176.0(6)
55.0(1)
P(1)-Mo-N
P(2)-Mo-P(3)
P(2)-Mo-N
Exp er im en ta l Section
P(3)-Mo-P(4)
P(3)-Mo-C(1)
P(4)-Mo-C(1)
Mo-N-C(2)
Gen er a l Con sid er a tion s. All manipulations were done
under an atmosphere of N2 except for those stated otherwise.
IR and NMR spectra were recorded on a J ASCO FT/IR-420
spectrometer at room temperature and on J EOL EX-270 or
LA-400 spectrometers at 20 °C, respectively. The signals due
to the aromatic protons are omitted from the 1H NMR data
shown below. Elemental analyses were carried out with a
Perkin-Elmer 2400 series II CHN analyzer. Amounts of
solvating molecules in the products were determined by X-ray
crystallography, NMR measurements, and/or GLC analysis.
Complexes 1, 3, 4,12 5,13 and 614 were prepared according to
the literature methods, whereas aqueous HBF4, [Me2OH][BF4],
and [Me3O][BF4] were commercially obtained and used as
received.
P(4)-Mo-N
N-Mo-C(1)
Mo-C(1)-O(1)
P(1)-Mo-H(1)
N-C(2)-C(3)
P(4)-Mo-H(1)
to the reaction of the dinitrogen-nitrile complex trans-
[Mo(N2)(NCR)(dppe)2] with HBF4, giving trans-[MoF-
(NCH2R)(dppe)2]+ (vide supra), the protonation of 6
occurs at the metal center without loss of both the CO
and nitrile ligands. The structure of 15 has also been
P r ep a r a tion of 7. To a suspension of 1a ‚2C6H6 (223 mg,
0.217 mmol) in THF (2 mL) was added an aqueous HBF4
solution (42%, 0.3 mL). A yellow solid immediately precipi-
tated, which was filtered off and redissolved in acetone.
Addition of hexane to the solution afforded orange crystals of
7 (162 mg, 65% yield). Anal. Calcd for C62H60NOBF4P4Mo: C,
65.22; H, 5.30; N, 1.23. Found: C, 65.26; H, 5.44; N, 1.15. IR
(KBr): ν(NH), 3308; ν(CdO), 1673; ν(CN), 1495 cm-1. 1H NMR
(acetone-d6): δ 2.8-3.0 (m, 8H, PCH2), 2.04 (s, 6H, Me2CdO).
31P{1H} NMR (acetone-d6): δ 60.5 (s).
P r ep a r a tion of 8. A suspension of 1b (77 mg, 0.075 mmol)
in THF (3 mL) was treated with [Me2OH][BF4] (18 µL, 0.15
mmol) at 0 °C. After stirring for 2 h, ether was added to the
reaction mixture. A yellow solid deposited, which was filtered
off and crystallized from CH2Cl2-ether at 0 °C to give orange
crystals of 8 (41 mg, 49% yield). Anal. Calcd for C57H59NBF5P4-
Mo: C, 63.17; H, 5.49; N, 1.29. Found: C, 63.09; H, 5.38; N,
characterized by X-ray crystallography, which is de-
picted in Figure 6 and Table 6. The geometry around
the Mo in 15 is also a pentagonal bipyramid, with the
CO and nitrile ligands occupying the apical positions.
The hydride was found on the basal plane between the
P(1) and P(4) atoms, which is consistent with the low-
1
temperature H and 31P NMR spectra showing a triplet
of triplets at -4.45 ppm due to the hydride proton and
two broad signals with the same intensities assigned
to the dppe ligands, respectively. The IR spectrum

Protonation of Zerovalent Mo Complexes
Organometallics, Vol. 19, No. 10, 2000 2009
1.54. IR (KBr): ν(NH), 3360 and 3300; ν(CN), 1526 cm-1. H
NMR (CD2Cl2): δ -7.25 (d quin, J H-H ) 7.8 Hz, J H-P ) 10.7
Hz, 1H, MoCH), 0.50 (m, 2H, NCH2CH2), 0.55-0.7 (m, 5H,
CH2CH3), 1.91 (br quar, 2H, J ) 6.8 Hz, NCH2), 3.15 (br, 1H,
NH), 2.5-2.8 (m, 8H, PCH2). 31P{1H} NMR (CD2Cl2): δ 48.6
(d, J P-F ) 30 Hz). 13C NMR (CD2Cl2): δ 203.2 (J C-P ) 13 Hz
(quin), J C-F ) 67 Hz (d), J C-H ) 61 Hz (d), MoC).
P r ep a r a tion of 9a ‚1/2CH2Cl2. Into a solution of 3a ‚1/
2C6H6 (80 mg, 0.068 mmol) in THF (3 mL) was added [Me2-
OH][BF4] (18 µL, 0.148 mmol) at -30 °C under Ar. After
stirring for 2 h at 0 °C, ether was added to precipitate a solid,
which was filtered off and recrystallized from CH2Cl2-ether
to give 9a ‚1/2CH2Cl2 as orange crystals (62 mg, 73% yield).
Anal. Calcd for C67.5H62N2OBClF4P4Mo: C, 64.38; H, 4.96; N,
2.22. Found: C, 64.28; H, 5.10; N, 2.24. IR (KBr): ν(CtN),
2225; ν(NH), 3282 cm-1. 1H NMR (CDCl3): δ 3.90 (s, 3H, MeO),
5.05 (br, 1H, NH), 2.3-2.7 (m, 8H, PCH2). 31P{1H} NMR
(CDCl3): δ 65.0 (s).
P r ep a r a tion of 9b. This complex was obtained in 61% yield
as orange crystals from 3b by a method similar to that for
preparing 9a . Anal. Calcd for C65H65N2OBF4P4Mo: C, 65.23;
H, 5.47; N, 2.34. Found: C, 64.60; H, 5.43; N, 2.30. IR (KBr):
ν(CtN), 2226; ν(NH), 3294 cm-1. 1H NMR (CD2Cl2): δ 0.7 (m,
3H, CH3), 0.8-0.9 (m, 4H, CH2CH2CH3), 2.3-2.7 (m, 10H,
NHCH2 and PCH2), 3.83 (s, 3H, MeO), 3.65 (br, 1H, NH). 31P-
{1H} NMR (CD2Cl2): δ 66.8 (s).
C61H56NOBF4P4Mo: C, 65.08; H, 5.01; N, 1.24. Found: C,
64.63; H, 5.07; N, 1.23. IR (KBr): ν(CtO), 1859; ν(CN), 1506
cm-1. 1H NMR (CDCl3): δ 1.6-1.8 (m, 3H, PCH2), 1.86 (s, 3H,
NMe), 2.1-2.4 (m, 3H, PCH2), 2.85 and 3.55 (m, 1H each,
PCH2). 31P{1H} NMR (CDCl3): δ 22.1 (br t, J ) 22 Hz, 1P),
34.2 (br td, J ) 21 and 5 Hz, 1P), 50.5 (ddd, J ) 84, 23, and
5 Hz, 1P), and 56.8 (dd, J ) 84 and 20 Hz, 1P).
1
P r ep r a tion of 13b. This complex was prepared by a
method essentially similar to that of 13a : pale brown crystals,
yield 55%. Anal. Calcd for C59H60NOBF4P4Mo: C, 64.09; H,
5.47; N, 1.27. Found: C, 63.92; H, 5.48; N, 1.28. IR (KBr):
ν(CtO), 1858; ν(CN), 1550 cm-1. 1H NMR (CDCl3): δ 0.7-1.2
(m, 7H, CH2CH2CH3), 2.0-3.2 (m, 10H, NCH2 and PCH2), 2.06
(s, 3H, NMe). 31P{1H} NMR (CDCl3): δ 25.1 (ddd, J ) 3, 15
and 24 Hz, 1P), 37.9 (dd, J ) 23 and 15, 1P), 50.3 (dd, J ) 85
and 24 Hz, 1P), and 58.8 (ddd, J ) 3, 85 and 23 Hz, 1P).
P r ep a r a tion of 14‚THF . To a THF solution of 5‚1/2C6H6
(102 mg, 0.102 mmol) was added aqueous HBF4 (42%, 61 mg,
0.29 mmol) at room temperature. After stirring for 0.5 h, the
resultant pale yellow solution was concentrated to ca. 2.5 mL.
Addition of ether gave yellow crystals of 14‚THF (88 mg, 78%
yield). Anal. Calcd for C57H59O3BF4P4Mo: C, 62.31; H, 5.41.
Found: C, 62.37; H, 5.44. IR (KBr): ν(CtO), 1776 cm-1 1H
.
NMR (THF-d8, 20 °C): δ -3.7 to -2.5 (v br, 1H, MoH), 2.6-
3.0 (m, 8H, PCH2). 1H NMR (THF-d8, -73 °C): δ -3.39 (quin,
J P-H ) 41 Hz, 1H, MoH). 31P{1H} NMR (THF-d8): δ 65-69
(br).
P r ep a r a tion of 10a . To a suspension of 4a (86 mg, 0.084
mmol) in THF (3 mL) was added [Me2OH][BF4] (21 µL, 0.17
mmol) at 0 °C. After stirring for 2 h at this temperature, ether
was added to deposit the orange solid, which was filtered off
and recrystallized from CH2Cl2-ether at -20 °C, affording
P r ep a r a tion of 15‚Et2O. To a suspension of 6 (95 mg, 0.090
mmol) in THF (3 mL) was added aqueous HBF4 (42%, 39 mg,
0.19 mmol) under Ar, and the mixture was stirred for 2 h. By
addition of ether to the resultant solution, yellow crystals of
15‚Et2O precipitated (100 mg, 91% yield). Anal. Calcd for
orange crystals of 10a (38 mg, 42%). Anal. Calcd for C60H54
-
NOBF4P4Mo: C, 64.82; H, 4.90; N, 1.26. Found: C, 64.22; H,
C
65H66NO3BF4P4Mo: C, 64.21; H, 5.47; N, 1.15. Found: C,
4.88; N, 1.42. IR (KBr): ν(NH), 3239; ν(CtO), 1893; ν(CN),
64.31; H, 5.58; N, 1.08. IR (KBr): ν(CtN), 2217; ν(CtO), 1796
1
1502 cm-1. H NMR (CDCl3): δ 1.9-3.4 (m, 8H, PCH2), 6.60
1
cm-1. H NMR (THF-d8, 20 °C): δ -4.20 (quin, J P-H ) 42 Hz,
(br s, 1H, NH). 31P{1H} NMR (CDCl3): δ 23.8 (ddd, J ) 23,
15, and 3 Hz, 1P), 40.8 (dd, J ) 24 and 14 Hz, 1P), 50.5 (dd,
J ) 84 and 24 Hz, 1P), 57.7 (ddd, J ) 84, 23, and 3 Hz, 1P).
P r ep a r a tion of 10b‚1/2CH2Cl2.This complex was obtained
as yellow crystals in 62% yield from 4b by a method similar
to that for 10a . Anal. Calcd for C58.5H59NOBClF4P4Mo: C,
61.95; H, 5.24; N, 1.23. Found: C, 62.35; H, 5.21; N, 1.16. IR
(KBr): ν(NH), 3253; ν(CtO), 1854; ν(CN), 1533 cm-1. 1H NMR
(CDCl3): δ 0.64 (t, 3H, J ) 7.1 Hz, CH3), 0.78 (sex, J ) 7.1
Hz, 2H, CH2CH3), 0.85-1.05 (m, 2H, NCH2CH2), 1.8-3.2 (m,
10H, NCH2 and PCH2), 6.35 (br s, 1H, NH). 31P{1H} NMR
(CDCl3): δ 26.6 (ddd, J ) 24, 12, and 3 Hz), 39.6 (ddd, J ) 24,
12, and 3 Hz), 55.4 (ddd, J ) 87, 24, and 3 Hz), 59.7 (ddd, J )
87, 24, and 3 Hz).
1H, MoH), 2.45-2.7 and 2.8-3.05 (m, 4H each, PCH2), 3.83
1
(s, 3H, MeO). H NMR (THF-d8, -90 °C): δ -4.45 (tt, J P-H
)
70.3 and 11.2 Hz, 1H, MoH). 31P{1H} NMR (THF-d8): δ 66-
70 (br). 31P{1H} NMR (THF-d8, -90 °C): δ 53-56 and 83-86
(br).
X-r a y Cr ysta llogr a p h ic Stu d ies. Single crystals of 7, 10a ,
12a , 13b, 14‚THF, and 15‚Et2O were sealed in glass capillaries
under Ar and transferred to a Rigaku AFC7R diffractometer
equipped with a graphite-monochromatized Mo KR source.
Diffraction studies were done at room temperature. Orienta-
tion matrixes and unit cell parameters were determined by
least-squares treatment of 25 reflections with 35° < 2θ < 40°.
The intensities of three check reflections were monitored every
150 reflections during data collection, which revealed no
significant decay for 10a , 12a , 13b, 14‚THF, and 15‚Et2O, but
an almost linear decay for 7, with an average 6.3% loss in
intensities at the end of the data collection. Intensity data were
corrected for Lorentz and polarization effects and for absorp-
tion (ψ scans), and for 7 decay correction was also applied.
Details of crystal and data collection parameters are listed in
Table 7.
Structure solution and refinements were carried out by
using the teXsan program package.35 The positions of the non-
hydrogen atoms were determined by Patterson methods and
subsequent Fourier syntheses (DIRDIF PATTY),36 which were
refined anisotropically by full-matrix least-squares techniques.
The hydrogen atoms attached to the amino N in 7 and 10a as
well as those bound to the Mo atom in 12a , 14, and 15 were
found from the Fourier maps, which were refined isotropically,
except for the amino hydrogen in 7. Other hydrogens were
P r ep a r a tion of 12a . A CH2Cl2 solution of 10a (27 mg, 9.925
mmol) was left for 31 h at 20 °C. Addition of ether to the
resulting solution gave pale yellow crystals of 12a (15 mg, 56%
yield). Anal. Calcd for C60H54NOBF4P4Mo: C, 64.82; H, 4.90;
N, 1.26. Found: C, 64.69; H, 5.31; N, 1.33. IR (KBr): ν(NtC),
2061; ν(CtO), 1861 cm-1 1H NMR (CDCl3, 20 °C): δ -5.35
.
(m, 1H, MoH), 2.4-2.8 (m, 8H, PCH2). 1H NMR (THF-d8, -43
°C): δ -5.46 (tt, J P-H ) 70.2 and 12.7 Hz, 1H, MoH). 1H NMR
(THF-d8, 47 °C): δ -5.23 (quin, J P-H ) 42.1 Hz, 1H, MoH).
31P{1H} NMR (CDCl3): δ 54-58 and 79-83 (br, 2P each).
F or m a tion of 12b. Isomerization of 10b into 12b in a
CDCl3 solution was monitored by NMR spectra, which revealed
the formation of 12b in 95% after 8.5 h. IR (KBr): ν(NC), 2113;
ν(CO), 1833 cm-1 1H NMR (CD2Cl2): δ -5.54 (pseudo quin,
.
J H-P ) 42 Hz, 1H, MoH), 0.65 (t, J ) 7.1 Hz, 3H, CH3), 0.7-
0.9 (m, 4H, CH2CH2CH3), 2.4-2.8 (m, 10H, NCH2 and PCH2).
31P{1H} NMR (CDCl3): δ 52-60 and 77-84 (br, 2P each).
P r ep a r a tion of 13a . Complex 4a (61 mg, 0.059 mmol)
dissolved in CH2Cl2 (3 mL) was treated with [Me3O][BF4] (17
mg, 0.12 mmol) at room temperature. After stirring for 20 h,
ether was added to the resulting solution, affording 13a as
pale red microcrystals (29 mg, 43% yield). Anal. Calcd for
(35) teXsan: Crystal Structure Analysis Package; Molecular Struc-
ture Corp.: The Woodlands, TX, 1985 and 1992.
(36) PATTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bos-
man, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla,
C. The DIRDIF program system; Technical Report of the Crystal-
lography Laboratory; University of Nijmegen: The Netherlands, 1992.

Ta ble 7. Cr ysta llogr a p h ic Da ta for 7, 10a , 12a , 13a , 14‚THF , a n d 15‚Et2O
7
10a
12a
13a
14‚THF
15‚Et2O
formula
fw
C
62H60NOBF4P4Mo
C60H54NOBF4P4Mo
1111.73
C60H54NOBF4P4Mo
1111.73
C59H60NOBF4P4Mo
1105.77
C57H59O3BF4P4Mo
1098.73
C65H66NO3BF4P4Mo
1215.88
1141.80
space group
a (Å)
b (Å)
Cc (No. 9)
23.936(3)
12.244(4)
20.348(2)
P21/n (No. 14)
12.073(7)
22.55(2)
19.497(9)
90
104.94(4)
90
5129(5)
P21/n (No. 14)
11.498(4)
27.625(6)
17.059(2)
90
99.95(2)
90
5336(2)
P21/n (No. 14)
12.258(2)
22.932(3)
19.710(2)
P21/n (No. 14)
14.75(1)
17.336(9)
21.587(10)
90
110.20(4)
90
5181(4)
P1h (No. 2)
11.349(5)
14.251(4)
18.731(5)
88.07(2)
86.39(3)
88.87(3)
3021(1)
2
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
90
90
109.520(8)
90
5620(1)
4
1.349
2360
4.02
104.808(8)
90
5356(1)
4
1.371
2288
4.19
4
4
4
F
calc (g cm-3
)
1.440
2288
4.38
1.384
2288
4.21
1.408
2272
4.35
1.336
1260
3.81
F(000)
µ
calc (cm-1
)
cryst size (mm3)
scan type
1.0 × 0.8 × 0.6
0.6 × 0.15 × 0.1
0.6 × 0.15 × 0.05
0.4 × 0.3 × 0.2
0.6 × 0.3 × 0.2
0.8 × 0.2 × 0.15
ω-2θ
ω-2θ
ω
ω-2θ
ω-2θ
ω-2θ
2θ range (deg)
no. measd
no. unique
no. obsd
5-55
5-55
5-55
5-50
5-55
5-50
6905
12 275
12 839
9895
12 325
11 427
6761
5871
11 730
3792
12 242
4716
9426
4545
11 872
6396
10 566
5448
no. var
680
653
666
712
662
743
corrections
Lorentz-polarization;
absorption (ψ scan,
transmn factor:
0.9219-0.9999);
decay (6.3%, linear);
secondary extinction
Lorentz-polarization;
absorption (ψ scan,
transmn factor:
0.9521-0.9965)
Lorentz-polarization
Lorentz-polarization;
absorption (ψ scan,
transmn factor:
0.9447-0.9996)
Lorentz-polarization;
absorption (ψ scan,
transmn factor:
0.9379-0.9988)
Lorentz-polarization;
absorption (ψ scan,
transmn factor:
0.9621-0.9986)
(coeff: 4.763 × 10-8
)
Ra
0.030
0.031
0.058
0.057
0.048
0.045
0.047
0.047
0.047
0.044
0.044
0.037
b
Rw
GOF
1.68
1.57
1.31
1.44
1.60
1.41
residual peaks
0.39, -0.46
0.85, -0.89
0.40, -0.36
0.31, -0.38
0.89, -0.42
0.35, -0.33
(e-/Å-3
)
a
b
2 1/2
R ) ∑||Fo| - |Fc||/∑ |Fo|. Rw ) [∑w(|Fo| - |Fc|)2/∑wFo
] .

Protonation of Zerovalent Mo Complexes
Organometallics, Vol. 19, No. 10, 2000 2011
placed at the calculated positions and included in the final
stages of the refinements with fixed parameters.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and equivalent thermal parameters, anisotropic
thermal parameters, and extensive bond lengths and angles,
together with figures with full atom-numbering schemes, for
7, 10a , 12a , 13b, 14‚THF, and 15‚Et2O. These materials are
available free of charge via the Internet at http://pubs.acs.org.
Ack n ow led gm en t. This work was supported by the
Ministry of Education, Science, Sports, and Culture of
J apan (Grant Nos. 09102004 and 09238103).
OM000049D