Reactivity of electrophilic μ-phosphinidene complexes with heterocumulenes: Formation of the first σ-π-aminophosphaimine complexes [Mn2(CO)8{μ-η1,η2- P(NiPr2)=NR}] and diazoalkane insertions into metal-phosphorus bonds

Article abstract of DOI:10.1039/b505472a

The bridging phosphinidene complexes [Mn₂(CO) ₈(μ-PNⁱPr₂)] and [Co₂(CO) ₄(μ-dppm)(μ-PNR₂)] (NR₂ = N ⁱPr₂, TMP) react with heterocumulenes RN₃, CH₂N₂ and Ph₂C=N=N to form complexes with μ-η¹,η²-aminophosphaimine, μ- η¹,η²-amino-phosphaalkene and μ- η¹,η²-aminophosphadiphenylmethylazaimine ligands, respectively. The Royal Society of Chemistry 2005.

Full text of DOI:10.1039/b505472a

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COMMUNICATION
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Reactivity of electrophilic m-phosphinidene complexes with
heterocumulenes: formation of the first s-p-aminophosphaimine
complexes [Mn2(CO)8{m-g1,g2-P(NiPr2)LNR}] and diazoalkane
insertions into metal–phosphorus bonds{
Todd W. Graham,ab Konstantin A. Udachina and Arthur J. Carty*ab
Received (in Berkeley, CA, USA) 18th April 2005, Accepted 24th June 2005
First published as an Advance Article on the web 29th July 2005
DOI: 10.1039/b505472a
The bridging phosphinidene complexes [Mn2(CO)8(m-PNiPr2)]
Ph2CLNLN) which afford the first complexes of s,p-bound
aminophosphaimines [Mn2(CO)8{m-g1,g2-P(NiPr2)LNR}] (3a–d)
and rare s-p-aminophosphaalkene ligands [Co2(CO)4(m-dppm)(m-
and [Co2(CO)4(m-dppm)( m-PNR2)] (NR2 5 NiPr2, TMP) react
with heterocumulenes RN3, CH2N2 and Ph2CLNLN to form
complexes with m-g1,g2-aminophosphaimine, m-g1,g2-amino-
phosphaalkene and m-g1,g2-aminophosphadiphenylmethylazai-
mine ligands, respectively.
g1,g2-PNR2LCH2)] (NR2
5
NiPr2 (4a), TMP (4b)).
Diphenyldiazomethane Ph2CLNLN also inserts into one arm of
the phosphinidene bridge in 1 without loss of dinitrogen to yield
the novel complex [Mn2(CO)8{m-P(NiPr2)LN–N(LCPh2)}] (5)
which contains a Mn2PN2 five-membered ring.
Carbene (CX2) and phosphinidene (PX) ligands are isolobal1 and
there are now well-established structure, bonding, and reactivity
similarities1,2 between, for example, Schrock type carbene com-
plexes and their nucleophilic g1-phosphinidene counterparts.3
More recently the isolation of thermally stable, terminal electro-
philic phosphinidenes of the mid4 to late5 transition metals has
stimulated interest in the chemistry of these Fischer type molecules
to complement the extensive knowledge of the reaction manifolds
for transient phosphinidenes.6
Although bridging carbenes (m-alkylidenes)7 comprise an
important and diverse class of organometallic molecules and
intermediates, their m-PX counterparts are relatively rare and their
chemistry is virtually unexplored.8,9 There are also structural and
electronic differences between m-CX2 and m-PX complexes:
whereas bridging carbenes are formally saturated with tetrahedral
stereochemistry at carbon as in I, in the latter, II, the phosphorus
centre is planar and unsaturated,10 and reactivity may be initiated
by attack at the electrophilic phosphorus atom.
The complex [Mn2(CO)8(m-PNiPr2)] (1) was readily prepared by
the reaction of K[Mn(CO)5] with Cl2PNiPr2. This compound is
surprisingly stable and persists for days in THF solution, whereas
the related complexes [Co2(CO)6(m-CO)(m-PNR2)] (NR2 5 NiPr2,
TMP) readily lose carbonyl ligands and undergo condensation
reactions to form the cluster complexes [Co4(CO)8(m-CO){m3-
PNR2}2] (NR2 5 TMP, NiPr2).8 Complex 1 has a 31P NMR
resonance at d 731, the downfield chemical shift of which is typical
for bridging phosphinidene ligands.8 The X-ray structure{ shows a
pseudooctahedral ligand arrangement about each manganese
centre and a bridging aminophosphinidene ligand across the two
˚
metal centres (Mn(1)–Mn(2) 5 2.9193(4) A).
The reaction of 1 with organic azides RN3 (R 5 Me3Si, Me3Sn,
Ph, adamantyl) readily affords the complexes [Mn2(CO)8{m-g1,g2-
P(NiPr2)LNR}] (R 5 Me3Si (3a), Me3Sn (3b), Ph (3c), adamantyl
(3d)). The 31P NMR spectrum of 3a has a resonance at d 216 and
the 1H NMR spectrum shows the presence of both iPr and Me3Si
groups. The X-ray structure of 3a{ (Fig. 1) shows that oxidation
of the phosphinidene phosphorus has occurred with the formation
of a novel m-g1,g2-aminophosphaimine ligand. The phosphorus
atom of the phosphaimine is bonded to Mn(2) (Mn(2)–P(1) 5
˚
2.1857(3) A) with an elongated PLN bond (P(1)–N(2) 5
˚
1.5756(9) A) coordinated in p-fashion to Mn(1) (Mn(1)–
˚
˚
P(1) 5 2.4084(3) A, Mn(1)–N(2) 5 2.1717(9) A). To our
knowledge this is the first example of a phosphaimine bound in
typical m-alkenyl fashion in a binuclear complex, although free
phosphaimines have been previously characterised.12
In this communication we describe the synthesis of two new
examples of the class of m-phosphinidene complexes,
[Mn2(CO)8(m-PNiPr2)] (1) and [Co2(CO)4(m-dppm)(m-PNiPr2)]
(2a) and their novel reactions with heterocumulenes RN3
(R 5 Me3Si, Me3Sn, Ph, adamantyl) and diazoalkanes (CH2N2,
Complexes that are isoelectronic to 3a–d were produced in the
reaction of [Co2(CO)6(m-dppm)(m-PNR2)] (NR2 5 NiPr2 (2a),
TMP (2b)) with CH2N2. The 31P NMR spectrum of the product
(NR2 5 NiPr2 (4a)) shows a new resonance at d 247 and two
resonances for the m-dppm group at d 46 and 38. The 13C NMR
spectrum of 4a shows a resonance for the CH2 fragment of the
phosphaalkene ligand appearing as a broad signal at d 24. The
X-ray structure of 4b{ (Fig. 1) shows that insertion of methylene
into a Co–P bond of 2b has occurred with loss of N2 and the
aSteacie Institute for Molecular Sciences, National Research Council of
Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6
bThe Ottawa-Carleton Chemistry Institute, University of Ottawa,
Ottawa, Ontario, Canada K1N 6N5. E-mail: acarty@pco-bcp.gc.ca;
Fax: 001 613 948 6667; Tel: 001 613 948 6672
{ Electronic supplementary information (ESI) available: Synthetic and
spectroscopic data for compounds 1, 3a–d, 4a–b, 5; crystallographic details
for compounds 1, 3a, 3c, 4b, and 5. See http://dx.doi.org/10.1039/b505472a
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Chem. Commun., 2005, 4441–4443 | 4441

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Fig. 1 ORTEP diagrams of compounds 3a, 4b and 5. Selected hydrogen atoms have been eliminated for clarity and thermal ellipsoids are shown at the
˚
50% probability level. Selected bond lengths (A) and angles (u): 3a: Mn(1)–Mn(2) 2.8888(3), Mn(1)–P(1) 2.4084(3), Mn(1)–N(2) 2.1717(9), Mn(2)–P(1)
2.1857(3), P(1)–N(1) 1.6512(9), P(1)–N(2) 1.5756(9), N(2)–Si(1) 1.7297(9), Mn(2)–P(1)–N(1) 128.69(3), Mn(2)–P(1)–N(2) 118.04(4), Mn(1)–P(1)–Mn(2)
77.76(1), Mn(1)–P(1)–N(1) 126.23(4), Mn(1)–P(1)–N(2) 61.97(3), N(2)–P(1)–N(1) 113.15(5); 4b: Co(1)–Co(2) 2.7143(5), Co(1)–P(1) 2.2135(6), Co(1)–P(3)
2.1321(6), Co(2)–P(2) 2.1948(6), Co(2)–P(3) 2.1232(6), Co(1)–C(2a) 2.105(2), N(1)–P(3) 1.669(2), P(3)–C(2a) 1.737(2), Co(1)–P(3)–Co(2) 79.27(2), Co(2)–
P(3)–C(2a) 108.92(8), Co(1)–P(3)–C(2a) 64.98(7); 5: Mn(1)–Mn(2) 2.8945(4), Mn(1)–P(1) 2.1845(5), Mn(2)–N(3) 2.103(1), P(1)–N(1) 1.631(1), P(1)–N(2)
1.593(1), N(2)–N(3) 1.418(2), Mn(1)–P(1)–N(1) 127.71(5), Mn(1)–P(1)–N(2) 125.49(5), N(1)–P(1)–N(2) 106.69(7).
formation of a new m-g1,g2-coordinated aminophosphaalkene
complex. The principal structural features are a short Co–Co bond
˚
(Co(1)–Co(2) 2.7143(5) A) and a coordinated phosphaalkene
(TMP)PLCH2 bound to Co(2) via phosphorus and to Co(1) in
˚
p-fashion via the PLC bond (P(3)–C(2a) 5 1.737(2) A). The PLC
bond length is comparable to that in [Cp2Mo2(CO)4(m,g1,g2–
P(Ph)LCHMe)], a similar phosphaalkene complex synthesized via
an entirely different route by Mays and co-workers.11 The methine
carbon resonance of the CHMe group in [Cp2Mo2(CO)4(m-g1,g2-
P(Ph)LCHMe)] appears at d 42 and is similar to the LCH2
resonance in 4a. Although the 13C chemical shift of C(2a) is more
indicative of an sp3 hybridized carbon atom, the short P(3)–C(2a)
bond length is consistent with a metal coordinated phosphaalkene.
We are unaware of any other examples of this class of molecule.
The reaction of 1 with diphenyldiazomethane (Scheme 1)
affords a species with a 31P NMR resonance at d 285. Although
the 1H NMR spectrum of 5 shows the presence of both Ph and iPr
groups, it was necessary to carry out an X-ray crystallographic
study to determine if the N2 fragment of the diazoalkane was
retained.{ The structure (Fig. 1) shows that the diazoalkane has
inserted into one Mn–P bond without N2 extrusion to form a five-
membered Mn2PN2 ring. The dimetallacycle has a puckered
conformation which results in a staggered arrangement for the
three carbonyl ligands on each metal that are perpendicular to the
metal–metal bond. The geometry about each metal centre is
Scheme 1
˚
pseudooctahedral with a Mn(1)–P(1) separation of 2.1845(5) A
and a Mn(2)–N(3) bond length of 2.103(1) A. While the
bond length in the nickel cluster [Ni4(CNtBu)4(m3-g2-CNtBu)(m3-
g2-(Me3Si)2NPLNSiMe3)2].13
˚
stereochemistry about P(1) is trigonal planar, the P(1)–N(1)
˚
distance to the diisopropylamino group (1.630(1) A) is distinctly
˚
longer than P(1)–N(2) (1.593(1) A) and together with the short
While the reaction of 2 with CH2N2 and 1 with Ph2CN2 both
lead to insertion into the phosphinidene bridge, complex 5 is
formed without extrusion of N2 from the diazoalkane whereas in
4b loss of N2 has afforded a phosphaethene ligand. Attempts to
convert 5 thermally to the corresponding phosphadiphenylethylene
complex (80 uC, C6D6, overnight) resulted in decomposition.
˚
N(2)–N(3) bond (1.418(2) A) indicates a significant p-character in
the PN2 portion of the metallacycle. However the P(1)–N(2) bond
˚
12
is slightly longer than the PLN separation of 1.545(2) A in the free
phosphaimine (Me3Si)2NPLNSiMe3 but is similar to the PN
4442 | Chem. Commun., 2005, 4441–4443
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Soc., 1995, 117, 11914; A. T. Termaten, T. Nijbacker, M. Schakel,
M. Lutz, A. L. Spek and K. Lammertsma, Chem. Eur. J., 2003, 9, 2200;
A. H. Cowley, Acc. Chem. Res., 1997, 30, 445; C. C. Cummins,
R. R. Schrock and W. M. Davis, Angew. Chem., 1993, 105, 758;
J. B. Bonanno, P. T. Wolczanski and E. B. Lobkovsky, J. Am. Chem.
Soc., 1994, 116, 11159; D. S. J. Arney, R. C. Schnabel, B. C. Scott and
C. J. Burns, J. Am. Chem. Soc., 1996, 118, 6780.
4 B. T. Sterenberg, K. A. Udachin and A. J. Carty, Organometallics, 2001,
21, 2657; B. T. Sterenberg, K. A. Udachin and A. J. Carty,
Organometallics, 2003, 22, 3927.
5 J. Sa´nchez-Nieves, B. T. Sterenberg, K. A. Udachin and A. J. Carty,
J. Am. Chem. Soc., 2003, 125, 2404; R. Melenkivitz, D. J. Mindiola and
G. L. Hillhouse, J. Am. Chem. Soc., 2002, 124, 3846; R. Waterman and
G. L. Hillhouse, J. Am. Chem. Soc, 2003, 125, 13350; A. J. Termaten,
H. Aktas, M. Schakel, A. W. Ehlers, M. Lutz, A. L. Spek and
K. Lammertsma, Organometallics, 2003, 22, 1827.
6 J. B. M. Wit, G. T. van Eijkel, M. Schakel and K. Lammertsma,
Tetrahedron, 2000, 56, 137; J. B. M. Wit, G. T. van Eijkel, F. J. J. de
Kanter, M. Schakel, A. W. Ehlers, M. Lutz, A. L. Spek and
K. Lammertsma, Angew. Chem., Int. Ed., 1999, 38, 2596; A. Marinetti
and F. Mathey, Organometallics, 1984, 3, 456; A. Marinetti and
F. Mathey, J. Am. Chem. Soc., 1982, 104, 4484; N. H. T. Huy and
F. Mathey, J. Org. Chem., 2000, 65, 652.
In conclusion, these results confirm that doubly bridging
phosphinidene complexes, like their m-alkylidene counterparts14
are highly susceptible to insertion reactions with unsaturated
substrates. The electrophilic, unsaturated nature of the m-PR
bridge appears to be only partially alleviated by the presence of the
electron donating NR2 group and through back donation from the
metal centres. The reactivity of the PR bridge presents a wealth of
new opportunities for the synthesis of novel phosphorus ligands.
This work was supported by the National Research Council of
Canada and the Natural Sciences and Engineering Research
Council of Canada (to A.J.C.).
Notes and references
{ Crystallographic data for: 1 [C14H14Mn2NO8P], M 5 465.11, triclinic,
¯
˚
˚
˚
P1, a 5 6.6736(7) A, b 5 9.5035(9) A, c 5 15.4285(15) A, a 5 104.344(2)u,
3
˚
b 5 96.656(2)u, c 5 97.440(2)u, V 5 928.81(16) A , T 5 125(2) K, Z 5 2,
m 5 1.486, 5109 unique, R1[I . 2s(I)] 5 0.0232, Rw (all data) 5 0.0633.
CCDC 275485. 3a: [C17H23Mn2N2O8PSi], M 5 552.31, monoclinic, P21/c,
˚
˚
˚
a 5 15.7307(13) A, b 5 10.5029(8) A, c 5 15.5917(13) A, a 5 90u,
3
7 J. Holton, M. F. Lappert, R. Pearce and P. I. W. Yarrow, Chem. Rev.,
1983, 83, 135; W. A. Herrmann, Pure Appl. Chem., 1982, 54, 65;
S. A. R. Knox, J. Organomet. Chem., 1990, 400, 255; K. H. Theopold
and R. G. Bergman, J. Am. Chem. Soc., 1981, 103, 2489.
˚
b 5 113.0100(10)u, c 5 90u, V 5 2371.1(3) A , T 5 125(2) K, Z 5 4,
m 5 1.226, 5835 unique, R1[I . 2s(I)] 5 0.0198, Rw (all data) 5 0.0543.
CCDC 275484. 3c: [C20H19Mn2N2O8P], M 5 556.22, monoclinic, P21/c,
˚
˚
˚
a 5 8.8228(11) A, b 5 9.7766(12) A, c 5 28.072(3) A, a 5 90u,
3
˚
8 J. Sa´nchez-Nieves, B. T. Sterenberg, K. A. Udachin and A. J. Carty,
J. Cluster Sci., 2004, 15, 151; J. Sa´nchez-Nieves, B. T. Sterenberg,
K. A. Udachin and A. J. Carty, Can. J. Chem., 2004, 82, 1507.
9 M. Esther Garc´ıa, V. Riera, M. A. Ruiz, D. Sa´ez, J. Vaissermann and
J. C. Jeffrey, J. Am. Chem. Soc., 2002, 124, 14304; H. Lang, O. Orama
and G. Huttner, J. Organomet. Chem., 1985, 291, 293; G. Huttner and
K. Evertz, Acc. Chem. Res., 1986, 19, 406; A. M. Arif, A. H. Cowley
and M. Pakulski, J. Chem. Soc., Chem. Commun., 1985, 1707; A. H. Arif,
A. H. Cowley, N. C. Norman, A. G. Orpen and M. Pakulski,
Organometallics, 1988, 7, 309.
b 5 97.045(2)u, c 5 90u, V 5 2403.1(5) A , T 5 125(2) K, Z 5 4, m 5 1.164,
6717 unique, R1[I . 2s(I)] 5 0.0236, Rw (all data) 5 0.0634. CCDC
275483. 4b: [C39H42Co2NOP3], M 5 799.51, monoclinic, C2/c, a 5
˚
˚
˚
30.170(6) A, b 5 10.6655(19) A, c 5 23.493(4) A, a 5 90u, b 5 102.347(3)u,
3
˚
c 5 90u, V 5 7385(2) A , T 5 125(2) K, Z 5 8, m 5 1.070, 10308 unique,
R1[I . 2s(I)] 5 0.0347, Rw (all data) 5 0.0914. CCDC 269680. 5:
˚
[C29H29Mn2N3O8.5P], M 5 696.40, monoclinic, P21/c, a 5 12.1027(16) A,
˚
˚
b 5 20.563(3) A , c 5 13.6644(18) A , a 5 90u, b 5 111.888(2)u, c 5 90u,
3
V 5 3155.5(7) A , T 5 125(2) K, Z 5 4, m 5 0.905, 7871 unique, R1[I .
˚
2s(I)] 5 0.0322, Rw (all data) 5 0.0887. CCDC 269679. See http://
dx.doi.org/10.1039/b505472a for crystallographic data in CIF or other
electronic format.
10 K. Lammertsma, Top. Curr. Chem., 2003, 229, 119.
11 J. E. Davies, M. J. Mays, P. R. Raithby and A. D. Woods, Chem.
Commun., 1999, 2455.
12 S. Pohl, Chem. Ber., 1979, 112, 3159.
13 O. J. Scherer, R. Walter and W. S. Sheldrick, Angew. Chem., Int. Ed.
Engl., 1985, 24, 115.
14 M. Akita, R. Hua, S. A. R. Knox, Y. Moro-oka, S. Nakanishi and
M. I. Yates, Chem. Commun., 1997, 51; P. M. Maitlis, H. C. Long,
R. Quyoum, M. L. Turner and Z.-Q. Wang, Chem. Commun., 1996, 1;
C. E. Sumner, Jr., P. E. Riley, R. E. Davis and R. Pettit, J. Am. Chem.
Soc., 1980, 102, 1752.
1 K. B. Dillon, F. Mathey and J. F. Nixon, Phosphorus, The Carbon
Copy, John Wiley & Sons Ltd., Chichester, 1998.
2 Multiple Bonds and Low Coordination in Phosphorus Chemistry, ed.
M. Regitz and O. J. Scherer, Georg Thieme Verlag, Stuttgart, 1991;
A. T. Termaten, M. Schakel, A. W. Ehlers, M. Lutz, A. L. Spek and
K. Lammertsma, Chem. Eur. J., 2003, 9, 3577.
3 P. B. Hitchcock, M. F. Lappert and W.-P. Leung, J. Chem. Soc., Chem.
Commun., 1987, 1282; T. L. Breen and D. W. Stephan, J. Am. Chem.
This journal is ß The Royal Society of Chemistry 2005
Chem. Commun., 2005, 4441–4443 | 4443