Chemistry of Diazaphosphole-Phosphines. 3. Complexation Reactions of Substituted (Fluoro, Dimethylamino, or Trifluoroethoxy)diazaphosphinephospholes with Ru(II), Rh(I), and Rh(III) Precursors: The Crystal and Molecular Structures of Cyclopentadienylbis(κP-4-(difluorophosphino)-2,5-dimethyl-2H-1,2, 3σ2-diazaphosphole Rhodium(I)

Article abstract of DOI:10.1021/om9903590

Metal complexes of a series of diphosphorus ligands, 4-(difluorophosphino)-2,5-dimethyl-2H-1,2,3σ²-diazaphosphole (1), 4-(bis(dimethylaminophosphino)-2,5-dimethyl-2H-1,2,3σ ²-diazaphosphole (2), and 4-bis(1,1,1-trifluoroethoxyphosphino)-2,5-dimethyl-2H-1,2,3σ ²-diazaphosphole (3), were prepared. Ligand 1 reacted with CpRu(PPh₃)₂Cl to give the diastereotopic complex CpRu(PPh₃)(1)Cl (4). With CpRh(CO)₂ this same ligand gave CpRh(1)₂ (5), which was structurally characterized. The Cp-rhodium center carries two difluorophosphinodiazaphole ligands. The P-N bond distances, (1.670(4) and 1.672(3) A?), suggest partial multiple-bond character. [Cp*Rh(Cl)₂] with (1) gave Cp*Rh(Cl)₂(1). Ligand 2 with [Rh(CO)₂Cl]₂ gave trans-Rh(CO)Cl(2)₂ (7), which was structurally characterized. The structure reveals two square-planar isomers in 75:25 ratio differing only in the interchange of Cl and CO. The two diazaphosphole ligands lie trans to each other and the planar diazaphosphole rings are oriented perpendicular to the square plane, stacked so that a mirror plane exists through the Cl-Rh-CO plane. The phosphorus-rhodium distance is 2.33 A?. The average P-N bond distance of the exo-phosphorus center and the dimethylamino groups is 1.683 A?, shorter than the normally accepted single-bond length. The dimethylamino nitrogen atoms on the exo-phosphorus are planar. Similarly, ligand 3 with [Rh(CO)₂Cl]₂ gave trans-[Rh(CO)Cl(3)₂] (8). The ligand action ranges in reactivity from a similarity to phenylphosphines through to PF₃, reflecting the variation in basicity induced by substituent changes on the exo-phosphorus.

Full text of DOI:10.1021/om9903590

3306
Organometallics 1999, 18, 3306-3315
Ch em istr y of Dia za p h osp h ole-P h osp h in es. 3.
Com p lexa tion Rea ction s of Su bstitu ted (F lu or o,
Dim eth yla m in o, or
Tr iflu or oeth oxy)d ia za p h osp h in ep h osp h oles w ith Ru (II),
Rh (I), a n d Rh (III) P r ecu r sor s: Th e Cr ysta l a n d
Molecu la r Str u ctu r es of
Cyclop en ta d ien ylbis(KP -4-(d iflu or op h osp h in o)-
2,5-d im eth yl-2H-1,2,3σ2-d ia za p h osp h ole Rh od iu m (I) a n d
tr a n s-Ch lor oca r bon ylbis(KP -4-(d im eth yla m in op h osp h in o)-
2,5-d im eth yl-2H-1,2,3σ2-d ia za p h osp h ole Rh od iu m (I)
Michael D. Mikoluk, Robert McDonald, and Ronald G. Cavell*
Department of Chemistry, University of Alberta, Edmonton, AB, Canada T6G 2G2
Received May 13, 1999
Metal complexes of a series of diphosphorus ligands, 4-(difluorophosphino)-2,5-dimethyl-
2H-1,2,3σ2-diazaphosphole (1), 4-(bis(dimethylaminophosphino)-2,5-dimethyl-2H-1,2,3σ2-
diazaphosphole (2), and 4-bis(1,1,1-trifluoroethoxyphosphino)-2,5-dimethyl-2H-1,2,3σ2-
diazaphosphole (3), were prepared. Ligand 1 reacted with CpRu(PPh3)2Cl to give the
diastereotopic complex CpRu(PPh3)(1)Cl (4). With CpRh(CO)2 this same ligand gave
CpRh(1)2 (5), which was structurally characterized. The Cp-rhodium center carries
two difluorophosphinodiazaphole ligands. The P-N bond distances, (1.670(4) and
1.672(3) Å), suggest partial multiple-bond character. [Cp*Rh(Cl)2] with (1) gave
Cp*Rh(Cl)2(1). Ligand 2 with [Rh(CO)2Cl]2 gave trans-Rh(CO)Cl(2)2 (7), which was structur-
ally characterized. The structure reveals two square-planar isomers in 75:25 ratio differing
only in the interchange of Cl and CO. The two diazaphosphole ligands lie trans to each
other and the planar diazaphosphole rings are oriented perpendicular to the square plane,
stacked so that a mirror plane exists through the Cl-Rh-CO plane. The phosphorus-
rhodium distance is 2.33 Å. The average P-N bond distance of the exo-phosphorus center
and the dimethylamino groups is 1.683 Å, shorter than the normally accepted single-bond
length. The dimethylamino nitrogen atoms on the exo-phosphorus are planar. Similarly,
ligand 3 with [Rh(CO)2Cl]2 gave trans-[Rh(CO)Cl(3)2] (8). The ligand action ranges in
reactivity from a similarity to phenylphosphines through to PF3, reflecting the variation in
basicity induced by substituent changes on the exo-phosphorus.
In tr od u ction
ent combinations exist with all manner of attachment
types, and a particular ligand (or metal-ligand combi-
nation) can provide vastly improved (and unexpected)
levels of catalytic performance.
Simple phosphines are widely used in support of
homogeneous catalytic processes,4 but development of
the extensive substitutional chemistry and structural
environments demonstrated by phosphorus opens an
enormous potential for the development of hemilabile
ligand chemistry incorporating phosphorus.
The nature of the ligand has a profound effect on the
chemistry of a metal complex, and so design and
“tailoring” of ligand properties can lead to new metal
chemistry. Of particular recent interest in the evolution
of homogeneous catalyst precursor species is the devel-
opment of chelate ligands with multifunctional charac-
ter particularly because such ligands can open reaction
sites of different character while simultaneously main-
taining one stable link to the metal center. In this way,
potentially facile reversibility can be generated. Che-
lated ligands with differential reactivity have been
termed “hemilabile”.1-3 An enormous number of differ-
We have previously described5 a set of 4-phosphino-
diazaphospholes as potential multifunctional ligands
with three possible coordination sites (Scheme 1), either
(3) J effrey, J . C.; Rauchfuss, T. B. Inorg. Chem. 1979, 18, 2658-
2666.
(4) Parshall, G. W.; Ittel, S. D. Homogeneous Catalysis. The
Applications and Chemistry of Catalysis by Soluble Transition
Metal Complexes, 2nd ed.; Wiley: New York, 1992.
(5) Mikoluk, M. D.; Cavell, R. G. Inorg. Chem. 1999, 38, 1971-1981.
* Corresponding author. Phone: (780)-492-5310. Fax: (780)-492-
8231. E-mail: Ron.Cavell@Ualberta.ca.
(1) Sloan, C. S.; Weinberger, D. A.; Mirkin, C. A. Prog. Inorg. Chem.
1999, 48, 233-350.
(2) Bader, A.; Lindner, E. Coord. Chem. Rev. 1991, 108, 27-110.
10.1021/om9903590 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 07/30/1999

Chemistry of Diazaphosphole-Phosphines. 3
Organometallics, Vol. 18, No. 17, 1999 3307
as both the reference and the signal lock. Respective operating
frequencies were as follows: H (200.133 and 400.135 MHz),
Sch em e 1. Liga n d System a n d Its Coor d in a tion
Mod esa
1
13C (50.323 and 100.614 MHz), 31P (81.015 and 161.977 MHz),
19F (188.313 and 376.503 MHz). External standards for 13C
and 1H were SiMe4 and for 31P, 85% H3PO4. CFCl3 was used
as solvent, internal reference, and internal lock for 19F spectra.
Positive shifts lie downfield in all cases. NMR spectra were
simulated with PANIC13 or gNMR.14 Chemical ionization (CI)
mass spectra were recorded using an AEI MS50 spectrometer
exciting with ammonia at 16 eV. Low-resolution mass spectra
(electron impact, EI) were recorded at 16 or 70 eV on an AEI
MS50 spectrometer. Infrared spectra were recorded as
CH2Cl2 casts on KBr cells using a Nicolet 7199 infrared
spectrometer. Elemental analyses were performed by the
Microanalytical Services Laboratory at the University of
Alberta. Melting points were determined on samples in sealed
melting point capillaries and are uncorrected.
The parent diazaphosphole precursor, 4-(dichlorophosphino)-
2,5-dimethyl-2H-1,2,3σ2-diazaphosphole, and the ligands, 4-(di-
fluorophosphino)-2,5-dimethyl-2H-1,2,3σ2-diazaphosphole (1),
4-(bis(dimethylamino)phosphino)-2,5-dimethyl-2H-1,2,3σ2-di-
azaphosphole (2), and 4-(bis(2,2,2-trifluoroethoxy)phosphino)-
2,5-dimethyl-2H-1,2,3σ2-diazaphosphole (3), were prepared as
described elsewhere5 Organometallic precursors TlCp,15 CpRu-
a
In the present system X ) F (1), X ) NMe2 (2), and X )
OCH2CF3 (3).
of the two P(III) centers, the three-coordinate exocyclic
phosphorus (A) or the two-coordinate ring phosphorus
(B),6,7 or the unsubstituted nitrogen (C) in the ring.
Athough possible, this ligand is unlikely to act as a bis-
(phosphine) chelate, as is sometimes occasionally ob-
served with bis(diphenylphosphino)methane(dppm),
because the single backbone carbon connecting the two
P(III) centers in the diazaphospholephosphine makes
the bite angle too large to favor a single metal incorpo-
rated in a four-membered ring. More likely is the
possibility that this ligand system would act as a bridge
in a way similar to dppm (e.g., Scheme 1, D). Both of
the modes (A5,8,9 and B6,7) have been observed. The
limited previous studies of the coordination chemistry
of this bifunctional phosphinephosphole have not yet
revealed situations in which both phosphorus centers
are simultaneously involved in coordinate interactions.
In this report we describe the application of three
selected diazaphospholephosphine ligands with Rh and
Ru sources. Both of these elements have extensive
phosphine coordination chemistry because of their
widespread use in homogeneous catalytic systems10-12
and offer opportunitues for coordination of either P(III)
center.
(PPh3)2Cl,16 [Rh(CO)2Cl]2,17 and [Cp*RhCl2]2 were prepared
18
as described in the literature.
P r ep a r a tion s. Cp Ru (P P h 3)(1)Cl (4). To a solution of
CpRu(PPh3)2Cl (0.523 g, 0.72 mmol) in 25 mL of benzene was
added the phosphole, 1 (0.1 mL, 0.72 mmol), via syringe. The
solution was heated to reflux for 24 h. The solution was cooled,
and the solvent was removed in vacuo to leave an orange oily
material. The oil was washed with hot hexanes. Recrystalli-
zation from diethyl ether/dichloromethane yielded orange
crystals. The yield of 4 was 0.357 g (76.7%), mp 112 °C. Anal.
Calcd for C27H26ClF2N2P3Ru: C, 50.20; H, 4.06; Cl 5.46; N,
4.34. Found: C, 50.15; H, 4.02; Cl 5.60; N, 4.37. MS (FAB,
m/z): 646 (M, 17.8), 611 (M - Cl, 31.5), 429 (M - C - 1, 100).
IR data (CH2Cl2 cast, cm-1): ν(P-F) 843 (s), 792 (s). NMR data
2
3
(CDCl3) 31P{1H}: P(σ2), δ 258.90 (ddd, J PP 116 Hz, J PF 19
(10) (a) Ainscough, E. W.; Brodie, A. M.; Mentzer, E. J . Chem. Soc.,
Dalton Trans. 1973, 2167-2171. (b) Chatt, J .; Venanzi, L. M. J . Chem.
Soc. 1957, 4735-4741. (c) Li, M. P.; Drago, R. S. J . Am. Chem. Soc.
1976, 98, 5129-5135. (d) Denise, B.; Pannetier, G. J . Organomet.
Chem. 1978, 148, 155-164. (e) Binger, P.; Haas, J .; Glaser, G.;
Goddard, R.; Kru¨ger, C. Chem. Ber. 1994, 127, 1927-1929.
(11) (a) Crabtree, R. H. The Organometallic Chemistry of the
Transition Metals, 2nd ed.; J ohn Wiley & Sons: New York, 1994; pp
83-86. (b) Clement, D. A.; Nixon, J . F. J . Chem. Soc., Dalton Trans.
1972, 2553-2557. (c) Bennett, M. A.; Patmore, D. J . Inorg, Chem. 1971,
10, 2387-2395. (d) Clement, D. A.; Nixon, J . F. J . Chem. Soc., Dalton
Trans. 1973, 195-200.
(12) (a) Sharp, P. R. Rhodium. In Comprehensive Organometallic
Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.;
Pergamon: Oxford, 1995; Vol. 8, Chapter 2, pp 115-302. (b) Bruce,
M. I. Rhodium. In Comprehensive Organometallic Chemistry II; Abel,
E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: Oxford, 1995;
Vol. 7; Chapter 5, pp 291-298. (c) Bennett, M. A. Rhodium. In
Comprehensive Organometallic Chemistry II; Abel, E. A., Stone, F. G.
A., Wilkinson, G., Eds.; Pergamon: Oxford, 1995; Vol. 7; Chapter 7,
pp 441-470. (d) Bennett, M. A.; Matheson, T. W. Catalysis by
Ruthenium Compounds. In Comprehensive Organometallic Chemistry
(deputy editors E. W. Abel and F. G. A. Stone); Wilkinson, G., Ed.;
Pergamon: Oxford, 1982; Vol. 4; Chapter 32.9, pp 931-965. (e)
Bennett, M. A.; Bruce, M. I.; Matheson, T. W. Mononuclear Ruthenium
Compounds. In Comprehensive Organometallic Chemistry (deputy
editors E. W. Abel and F. G. A. Stone); Wilkinson, G., Ed.; Pergamon:
Oxford, 1982; Vol. 4; Chapter 32.3, pp 691-820.
Exp er im en ta l Section
All experimental manipulations were performed under an
atmosphere of dry argon using standard Schlenk techniques.
Commercial reagents were used as received. Solvents were
dried and freshly distilled prior to use: diethyl ether was
distilled from sodium benzophenone, hexane from sodium,
acetonitrile from P2O5 (and then stored over CaH2). The
deuterated solvents, CDCl3 and CD2Cl2, were distilled over
P2O5 and stored over molecular sieves under argon before use.
NMR spectra were recorded on Bruker WH-200 and WH-
400 spectrometers using the deuterium signal of the solvent
(13) Parameter Adjustment in NMR by Iteration Calculation (PANIC);
Bru¨ker Instrument Co.: Karlsru¨he, Germany.
(6) Kraaijkamp, J . G.; Van Koten, G.; Vrieze, K.; Grove, D. M.; Klop,
E. A.; Spek, A. L.; Schmidpeter, A. J . Organomet. Chem. 1983, 256,
375-389.
(14) Spectra simulated with: Budzelaar, G. M. gNMR (4.0); Cher-
well Scientific Publishing: Oxford, 1997.
(15) Nielson, A. J .; Rickard, C. E. F.; Smith, J . M. Inorg. Synth. 1990,
28, 315.
(16) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R. C. Inorg.
Synth. 1990, 28, 270.
(17) McCleverty, J . A.; Wilkinson, G. Inorg. Synth. 1990, 28, 84.
(18) Amouri, H. E.; Gruselle, M.; J aoue´n, G. Synth. React. Inorg.
Met.-Org. Chem. 1994, 24, 395-400.
(7) Kraaijkamp, J . G.; Grove, D. M.; van Koten, G.; Schmidpeter,
A. Inorg. Chem. 1988, 27, 2612-2617.
(8) Weinmaier, J . H.; Tautz, A.; Schmidpeter, A.; Pohl, S. J .
Organomet. Chem. 1980, 185, 53-68.
(9) Mikoluk, M. D.; McDonald, R.; Cavell, R. G. Inorg. Chem., in
press.

3308 Organometallics, Vol. 18, No. 17, 1999
Mikoluk et al.
3
2
1
Hz, J PF 15 Hz); P(σ3), δ 216.59 (dddd, J PP 116 Hz, J PF 1131
solution, cm-1): ν(CO), 1978 (s). NMR data (CDCl3): 31P{1H},
1
2
2
2
4
P(σ2), δ 246.92 (second order, “t”, | J σ Pσ P + J σ Pσ P′| 51 Hz);
2
4
2
4
Hz, J PF 1057 Hz, J PPh3 74 Hz); PPh3, δ 48.16 (dd, J PPh3 74
3
2
Hz, J PF 7 Hz); 1H, C-CH3 δ 2.52 (s), P(σ2)-N-CH3 δ 3.97 (d,
P(σ3), δ 103.34 (“dt”, | J σ Pσ P + 4J σ Pσ P′| 51 Hz, 1J σ PRh 143 Hz);
2
4
2
4
3
J σ PH 8.0 Hz), Cp δ 4.70 (s), phenyl H δ 7.3-7.6 (m); 13C{1H},
1H, C-CH3 δ 2.43 (dd, J PH 0.9 Hz), P(σ2)-N-CH3 δ 4.03 (d,
3
4
2
C-CH3 δ 15.49 (s), P(σ2)-N-CH3 δ 44.88 (d, J σ PC 17 Hz),
J σ PH 12.2 Hz), P(σ3)-N-CH3 δ 2.72 (d, J σ PH 7.6 Hz); 13C-
2
2
2
3
3
2
2
3
1
P-C-P δ 138.32 (d, J σ PC 345 Hz), N-C-CH3 δ 154.36 (s);
{1H}, C-CH3 δ 14.37 (s), P(σ2)-N-CH3 δ 41.88 (d, J σ PC 18
2 3
2
19F, F1, δ -27.55 (ddd, J FF 30 Hz, J σ PF 1057 Hz, J σ PF 19
Hz), P-C-P δ 143.45 (dd, 2J σ PC 145 Hz, 2J σ PC 45 Hz), N-C-
2 2
2 3
2
1
3
3
2
2
1
3
3
2
Hz); F2, δ -42.92 (dddd, J FF 30 Hz, J σ PF 1131 Hz, J σ PF 15
CH3 δ 156.72 (dd, J σ PC 5 Hz, J σ PC 18 Hz).
3
Hz, J FPPh 7 Hz).
tr a n s-Rh (CO)Cl(3)2 (8). A solution of phosphole 3 (0.146
g, 0.42 mmol) in 10 mL of dichloromethane was added
dropwise at room temperature (22 °C) to a solution of [Rh-
(CO)2Cl]2 (0.021 g, 0.053 mmol) in 15 mL of dichloromethane
and stirred for 4 h. The solution was reduced to ∼3 mL, and
10 mL of hexanes was added. Storing the solution overnight
at room temperature gave a light orange powder, 8 (0.068 g
75.3%, mp 189 °C (dec)). Anal. Calcd for C17H20ClF12N4O5P4-
Rh: C, 24.00; H, 2.37; Cl, 4.17, N, 6.59. Found: C, 24.06; H,
2.30; Cl, 4.28, N, 6.55. MS (FAB, m/z): 850 (M, 20). NMR data
3
Cp Rh (1)2 (5). To a solution of [Rh(CO)2Cl]2 (0.11 g, 0.29
mmol) in 10 mL of hexanes was added TlCp (0.19 g, 0.73
mmol). The solution was heated to reflux overnight and then
filtered through Celite. The Celite was washed with 2.5 mL
of hexanes to give a solution of CpRh(CO)2. Phosphole 1 (0.1
mL, 0.72 mmol) was added to this solution by syringe, and
the mixture was stirred at room temperature (22 °C) for 4 h.
The solution was then reduced to half its volume and stored
at -40 °C for 24 h, yielding X-ray quality orange crystals. A
second crop was obtained by reducing the volume of hexanes
and storing the concentrated solution at -40 °C. Total yield
of 5 was 0.262 g (68.3%, mp 93-94 °C). Anal. Calcd for
2
4
(CDCl3): 31P{1H}, P(σ2), δ 251.88 (“t”, | J σ Pσ P
+
J σ Pσ P′| 52
2
4
2
4
Hz); P(σ3), δ 159.78 (d“t”, | J σ Pσ P + J σ Pσ P′| 52 Hz, J PRh 187
2
4
1
2
4
2
4
Hz); H, C-CH3 δ 2.48 (s), P(σ2)-N-CH3 δ 3.97 (d, J σ PH 8.0
1
3
2
Hz), P(σ3)-N-O-CH2 δ 4.4-4.2 (m (broad)); 13C{1H}, C-CH3
C
13H17F4N4P4Rh: C, 29.34; H, 3.22; N, 10.53. Found: C, 29.36;
δ 15.49 (s), P(σ2)-N-CH3 δ 44.93 (d, J σ2PC 19 Hz), P-C-P δ
2
H, 2.86; N, 10.13. MS (FAB, m/z): 532 (M, 100), 350 (M - 2,
85), 168 (CpRh, 66). IR data (CH2Cl2 cast, cm-1): ν(P-F), 835
(s), 786 (s). NMR data (CDCl3): 31P{1H} (second order), P(σ2),
149.36 (d, 1J σ PC 30 Hz), N-C-CH3 δ 155.03 (s); 19F, δ -74.57
2
(s).
δ 259.9 (d(broad), J PP ∼175 Hz); P(σ3), δ 188.5 (second order,
2
2
2
1
1
2
3
3
3
J σ Pσ P ∼175 Hz, J σ Pσ P 102 Hz, J PF 1114 Hz, J PRh 306 Hz);
Resu lts a n d Discu ssion
1H, C-CH3 δ 2.48 (s), P(σ2)-N-CH3 δ 3.97 (d, J σ PH 8 Hz),
3
2
Cp δ 5.32 (s); 13C{1H}, C-CH3 δ 15.49 (s), P(σ2)-N-CH3
δ
Rea ction of (1) w ith Cp Ru (P P h 3)2Cl; F or m a tion
of Cp R u (P P h 3)(1)Cl (4). The reaction of 1 with
CpRu(PPh3)2Cl in refluxing benzene produced the
monosubstituted diazaphospholephosphine complex
CpRu(PPh3)(1)Cl (4) in good yield. The 31P{1H} and the
19F NMR spectra (Figure 1) confirmed the formulation,
and in addition both the 31P and 19F NMR indicated that
the fluorine atoms on the exo-phosphorus of the phos-
phinodiazaphosphole were diastereotopic due to the
creation of a stereogenic ruthenium center through the
substitution of one phosphine with the new ligand. A
Newman projection of the complex is depicted in Figure
2. The 31P{1H} NMR spectrum showed a small down-
field shift of 4 ppm (259.34 ppm) for the resonance of
the σ2P center, indicating that this center was not likely
the donor site; however, the exo-phosphorus center also
showed only a small downfield shift of 8 ppm to 200.04
ppm. The signal for the exo-phosphorus showed two
different couplings to fluorine atoms as well as coupling
to the phosphorus atom in the diazaphosphole ring.
Coupling was also observed to the phosphorus of the
triphenylphosphine coordinated to the ruthenium. The
most dramatic spectral changes were found in the 19F
NMR spectrum because of the creation of the stereo-
genic center; one of the fluorine signals was shifted
downfield (to -27.5 ppm, a shift of 59 ppm vs the free
ligand) and showed coupling to both phosphorus centers
2
1
2
2
44.88 (d, J σ PC 17 Hz), P-C-P δ 138.35 (d, J σ PC 35 Hz),
N-C-CH3 δ 154.48 (s); 19F (second order), δ -36.13 (2J FRh 19
3
1
Hz, J σ PF 18 Hz, J σ PF 1114 Hz); 103Rh, δ -1278 ppm.
Attem p t to P r ep a r e [Rh (1)2Cl]2 fr om [Rh (CO)2Cl]2 or
[Rh (cod )Cl]2. A solution of phosphole 1 (0.1 mL, 0.72 mmol)
in 10 mL of dichloromethane was added dropwise at room
temperature (22 °C) to a solution of [Rh(CO)2Cl]2 (0.140 g, 0.36
mmol) (or of [Rh(cod)Cl]2 (0.178 g, 0.36 mmol)) in 15 mL of
dichloromethane and stirred for 4 h, during which time a red
precipitate formed. In neither case did the 31P{1H} NMR
spectrum indicate that the desired product had formed, so the
reactions were not pursued further.
2
3
Cp *Rh Cl2(1) (6). A solution of phosphole 1 (0.1 mL, 0.72
mmol) in 10 mL of dichloromethane was added dropwise at
room temperature to a solution of [Cp*RhCl2]2 (0.167 g, 0.36
mmol) in 15 mL of dichloromethane and stirred for 4 h The
solution was reduced to ∼3 mL, 10 mL of hexanes was added,
and the solution was stored overnight at room temperature
(22 °C). During this time reddish-orange crystals of 6 (0.277
g, 78.3%, mp 135-140 °C (dec)) formed. Anal. Calcd for C14H21
-
Cl2F2N2P2Rh: C, 34.24; H, 4.31; Cl, 14.44, N, 5.70. Found: C,
33.99; H, 4.20; Cl, 15.20, N, 5.82. MS (FAB, m/z): 491 (M + 1,
5). IR data (CH2Cl2 cast, cm-1): ν(P-F), 756 (s), 786 (s). NMR
data (CDCl3): 31P{1H}, P(σ2), δ 269.23 (d, J PP 103 Hz); P(σ3),
2
δ 188.78 (ddt, 2J PP 103 Hz, 1J σ PF 1171 Hz, 1J σ PRh 217 Hz); 1H,
3
3
C-CH3 δ 2.48 (s), P(σ2)-N-CH3 δ 3.97 (d, J σ PH 8 Hz), C5-
3
2
(CH3)5 δ 1.95 (s); 13C{1H}, C-CH3 δ 15.49 (s), P(σ2)-N-CH3 δ
2
1
2
2
44.88 (d, J σ PC 17 Hz), P-C-P δ 148.35 (d, J σ PC 35 Hz),
1
N-C-CH3 δ 156.70 (s), C5-(CH3)5 δ 102.42 (d, J CRh 4 Hz)
3
of the diazaphosphole ring (1J PF ) 1057, J PF ) 15 Hz)
C5-(CH3)5 δ 9.72 (s); 19F, δ -62.18 (2J FRh 12 Hz, J σ PF 13 Hz,
3
2
1
and to the other fluorine atom (2J FF ) 30 Hz). The other
fluorine resonance was shifted downfield but by a lesser
amount (to -41.0 ppm, a shift of 47 ppm vs the free
ligand). This latter fluorine signal showed coupling to
all three of the phosphorus atoms of 4 (1J PF ) 1131 Hz,
3
J σ PF 1173 Hz).
tr a n s-Rh (CO)Cl(2)2 (7). A solution of phosphole 2 (0.25
mL, 1.2 mmol) in 10 mL of dichloromethane was added
dropwise at room temperature (22 °C) to a solution of [Rh-
(CO)2Cl]2 (0.117 g, 0.30 mmol) in 15 mL of dichloromethane
and stirred for 4 h. The solution was concentrated to ∼5 mL,
and hexane was added until the solution became slightly
turbid. The solution was stored at -40 °C overnight to yield
pale red crystals of 7 (0.149 g, 78.7%, mp 178 °C (dec)). Anal.
Calcd for C17H36ClN8OP4Rh: C, 29.95; H, 5.65; Cl 11.05; N,
17.46. Found: C, 30.40; H, 5.89; Cl 11.35; N, 17.72. MS (FAB,
m/z): 631 (M + 1, 5), 602 (M - CO, 22). IR data (CH2Cl2
3
3J PF ) 19 Hz, and J (PPh3)F ) 7 Hz). Applying a Karplus-
type relationship to this vicinal coupling suggests that
the fluorine trans to the PPh3 group should show a
larger coupling to this phosphorus center than the
fluorine gauche to the PPh3, a coupling that should be
very small. The 31P{1H} exo-phosphorus spectral region

Chemistry of Diazaphosphole-Phosphines. 3
Organometallics, Vol. 18, No. 17, 1999 3309
Table 1 are also shown in Figure 1. It is interesting to
note that with an excess of 1 only the monosubstituted
product was obtained, in contrast to the behavior of
Ph2PH with the same Ru precursor, which gave both
mono- and disubstituted phosphine products.19 This
might suggest that 1 possesses dominant bulky char-
acter, but as we show below and elsewhere,5,9 multiple
substitution with 1 is possible and the ligand packs
nicely around the metal center. In this particular case,
however, it is likely that the second replacement of 1
would introduce significant interference with the Cp
ring, which inhibits further replacement by a second
mole of 1.
Rea ction s w ith Rh od iu m Com p lexes. A conve-
nient and standard route to a wide variety of mono-
nuclear and binuclear Rh(I) complexes is the simple
cleavage of the chloro-bridged dimeric complex [Rh(cod)-
Cl]2 with the selected phosphine ligand. Stoichiometric
reaction usually results in the formation of monomeric
Rh(cod)(L)Cl complexes. With excess phosphine in non-
coordinating solvents, such as pentane, displacement of
the cyclooctadiene or related olefin ligands occurs in
addition to cleavage of the dimer to yield RhCl-
(phosphine)3 complexes.10 This well-established chem-
istry along with our results5,9 in other systems which
indicates that 1 acts in a fashion similar to PF3 offering
a moderate σ donor capability coupled with good π
acceptor properties5,20,21 suggested that the difluoro-
phosphinodiazaphosphole (1) would easily form com-
plexes of the above types with a variety of rhodium(I)
precursors. It was not obvious however whether the
donor site would be the σ2 ring phosphine or the exo-
cyclic phosphine center, particularly in view of the fact
that the basicity of the σ3 center has been greatly
reduced by fluorination. Also unclear was whether the
bulk of the phosphole ring would influence the coordina-
tion abilities of the ligand. Rather surprisingly, then,
we found that reaction of 1 with a variety of dimeric
rhodium(I) precursors such as [Rh(cod)Cl]2, [Rh(coe)2Cl]2,
and [Rh(CO)2Cl]2 resulted only in the decomposition of
both the starting phosphine 1 and the rhodium com-
plexes and no identifiable complexes for reasons that
are not clear. It is possible that 1 is such a poor σ donor
that it cannot cleave the rhodium-chlorine bridge, but,
even so, phosphorus trifluoride or dimethylamino-
difluorophosphine reacts readily with a variety of rhod-
ium(I) precursors with the replacement of either the
π-alkene or carbon monoxide to give dimeric chloro-
bridged complexes of the type [RhCl(PR3)2]2.11 It is
therefore obvious that the chemistry of the difluoro-
phosphinephosphole is different from these other fluoro-
F igu r e 1. (a) Experimental 19F NMR (188.313 MHz)
spectrum of complex 4 in CDCl3. The fine structure that
appears in each of the two major doublets is illustrated in
the expansions, and the simulated pattern for each of these
multiplet units is illustrated below the expansion. (b) 31P-
{1H} NMR spectrum (81.015 MHz) of the diazaphosphole-
phosphorus centers only for complex 4 (Ru) in CDCl3. An
additional signal due to PPh3 (not illustrated) occurs at
48.16 ppm. (c) Simulated 31P spectrum of 4.
phosphines because we describe (below and elsewhere5,9
)
stable complexes of this ligand, which indicates that
normal complexes are indeed accessible and that the
difficulty encountered here in this particular Rh(I)
system lies with a subtle interplay between this ligand
and these particular precursors.
Th e Disu bstitu ted Rh (I) Com p lex 5. Reaction of
1 with the monomeric rhodium(I) complex CpRh(CO)2
(19) Lubia´n, R. T.; Paz-Sandoval, M. A. J . Organomet. Chem. 1997,
532, 17-29.
(20) Marynick, D. S. J . Am. Chem. Soc. 1984, 106, 4064-4065.
(21) Nixon, J . F. In Advances in Inorganic Chemistry and Radio-
chemistry; Emele´us, H. J ., Sharpe, A. G., Eds.; Academic Press:
Orlando, 1985; Vol. 29, pp 41-141.
F igu r e 2. Newman projection of the structure of 4.
and the 19F NMR spectra were simulated, and their
calculated spectra obtained with parameters given in

3310 Organometallics, Vol. 18, No. 17, 1999
Ta ble 1. 31P {1H} (a n d 19F NMR) Da ta for Meta l Com p lexes w ith
Mikoluk et al.
4-(Disu bstitu ted )-2,5-d im eth yl-2H-1,2,3σ2-d ia za p h osp h olesa ,b
1
3
δ σ2P (ppm)
δ σ4P (ppm)
2J PP (Hz)
1J PRh (Hz)
δ F (ppm)
4
J σ PF (Hz)
2
J σ PF (Hz)
complex
no.
CpRu(PPh3)(1)Cl
4
258.90c
216.59c
116
-27.55c
-42.92d
-36.13c
-62.32g
1057
1131
1114
1171
19
15
18
13
CpRh(1)2
Cp*Rh(1)Cl2
trans-Rh(CO)(2)2Cl
trans-Rh(CO)(3)2Cl
5
6
7
8
259.90e
269.50f
246.92h
251.88h
188.52e
188.23e
103.34h
159.78h
175h
103
51i
306
217
143
187
52i
a
b
Chemical shifts δ in ppm in CDCl3 with respect to 85% H3PO4 or CFCl3 as appropriate. In CDCl3. c Doublet of doublet of doublets.
Doublet of doublet of doublet of doublets. e Doublet of triplets. f Doublet. Doublet of doublet of triplets. Second order. | J σ Pσ P
+
d
g
h
i 2
2
4
4
2
4
J σ Pσ P′|.
provided access to a difluorophosphinediazaphosphole-
Rh(I) complex. Although in general phosphines replace
only one CO in CpRh(CO)2,22 in this case 1 replaced both
carbonyls to give 5 (eq 1), a reaction which is similar to
the behavior of this Rh precursor with phosphites.23 This
parallel reinforces our impression that 1 behaves in
ways similar to PF3 and phosphites.5,9
(1)
The 31P{1H} and the 19F NMR spectra for 5 (Figure
3) are both very complex by virtue of the number of
spins involved and because the spectra are second
order.24 The 31P{1H} NMR spectrum for the resonance
for the σ4P center consisted of a 69-line pattern centred
at 188.68 ppm, while the signal for the σ2P center
showed a broad doublet (259.81 ppm). The phosphorus
spectrum reveals a specific large separation (306 Hz),
which is the one-bond phosphorus-rhodium coupling
constant (as verified by the inverse detection Rh NMR
determination),25 and the system is further complicated
by the large triplet spacing due to 1J PF. The complexity
of the 31P NMR spectrum precluded full simulation
analysis, but (vide infra) insight was obtained from
selective decoupling experiments combined with the
1
analysis of the simplified spectra. The H NMR spec-
trum reveals that the cyclopentadienyl protons are not
coupled to the exo-phosphorus, in contrast to the
behavior of the related rhodium complex Cp*Rh-
(PF3)2.26,27 The fluorine signal was centered at -36.13
F igu r e 3. (a) 19F NMR spectrum (188.015 MHz) of CpRh-
(1)2 (5) in CDCl3 and (b) the specifically σ2 phosphorus-
decoupled 19F{31P at 260 ppm} NMR (188.313 MHz)
spectrum of 5. (c) 31P{1H} NMR spectrum (81.015 MHz) of
CpRh(1)2 (5) in CDCl3 and (d) fluorine-decoupled 31P{19F}
NMR spectrum of 5 in the same solvent.
1
ppm and is dominated by the triplet created by J PF
(which is approximately 1145 Hz). The 103Rh chemical
shift (-1280 ppm), measured by an inverse detection
31P-103Rh analysis,25 lies in a range typical of many
CpRhL2 complexes.28
Decoupling of the fluorine coupling interaction simpli-
fied the 31P{1H} NMR spectrum to an 11-line pattern.
The signal for the σ2P unit remained second order,
(22) Oliver, A. J .; Graham, W. A. G. Inorg. Chem. 1970, 9, 243-
247.
(23) Schuster-Woldan, H. G.; Basolo, F. J . Am. Chem. Soc. 1966,
88, 1657-1663.
(24) Becker, E. D. High-Resolution NMR, Theory and Chemical
Applications, 2nd ed.; Academic Press: New York, 1980; pp 88-89.
(25) Law, D. J .; Bigam, G.; Cavell, R. G. Can. J . Chem. 1995, 73,
635-642.
(26) King, R. B.; Efraty, A. J . Am. Chem. Soc. 1971, 93, 5260-5261.
(27) King, R. B.; Efraty, A. J . Am. Chem. Soc. 1972, 94, 3768-3773.
(28) Goodfellow, R. J . In Multinuclear NMR; Mason, J ., Ed.; Plenum
Press: New York, 1987; pp 521-561.

Chemistry of Diazaphosphole-Phosphines. 3
Organometallics, Vol. 18, No. 17, 1999 3311
tively) are wider than those observed for 2,5-dimethyl-
2H-1,2,3σ2-diazaphosphole itself (113.8°).31 The carbon
at the 4-position is also planar, with the P(21)-C(21)-
P(22) angle being 121.6°, showing the sp2 hybridi-
zation of the C(21). The angles about the two σ2P
centers, N(23)-P(22)-C(21) and N(13)-P(12)-C(11)
are 88.6(2)° and 88.3(2)°, respectively. These angles are
similar to that observed for the parent phosphole
(88.2°).31 Both the P(12)-N(13) and the P(21)-N(23)
bond distances (1.670(4) and 1.672(3) Å) suggest some
partial multiple-bond character when compared to the
normally accepted P-N single (1.77 Å) and PdN double
(1.57 Å) bond lengths.32 Both two-coordinate phosphorus-
carbon bond lengths show multiple bond character
(P(12)-C(11) and P(22)-C(21) ) 1.713 Å). A typical
value for a P-C single bond is 1.84 Å, while that of a
P-C double bond is 1.66 Å. The three-coordinate
phosphorus-carbon bond lengths are shortened to 1.773
Å. The F(11)-P(11)-F(12) and F(21)-P(21)-F(22) bond
angles are 95.3(2)° and 96.0(2)°, respectively, while the
average P-F bond distance is 1.569 Å, which is longer
than that previously observed33 for the oxidized imino-
(difluoro)phosphinodiazaphosphole, where the P-F bond
length was 1.537 Å. The difference in the P-F bond
lengths of these two structures shows that the fluorines
play a role in the bonding to the rhodium center by
accepting electron density into the P-F antibonding σ*
orbital formed from the phosphorus 3p orbital.
F igu r e 4. ORTEP29 plot of the molecular structure of
cyclopentadienylbis(κP-difluoro{2,5-dimethyl-1,2,3-diaza-
phosphol-4-yl}phosphine)rhodium(I), 5, showing the atom-
labeling scheme. Non-hydrogen atoms are represented by
Gaussian ellipsoids at the 20% probability level, and all
hydrogen atoms have been omitted for clarity.
which implies that both phosphorus centers in the
diazaphosphole ring are magnetically inequivalent,
and this complex should be considered as either an
AA′DD′MM′M′′M′′′X or an AA′DD′M2M′2X type spin
system.24 Decoupling of the phosphorus signal at 260
ppm led to the simplification of the fluorine NMR
spectrum to a 12-line pattern (Figure 3). From this
spectrum, the fluorine-rhodium coupling was calcu-
4
lated to be 19 Hz, but the J FF value was not resolved.
Th e Mon osu bstitu ted Rh (III) Com p lex, 6. Treat-
ing the rhodium(III) dimer, [Cp*RhCl2]2, with 1 readily
gave the reddish-orange complex Cp*RhCl2(1) (6) in
high yield (eq 2). This precursor was used to explore
both the possibility of forming a Rh(III) complex with
this ligand and because the simplest possible reaction
in this case is cleavage of the dimer, which was indeed
observed. It is therefore a little surprising that simple
dimer cleavage did not give the expected stable products
in the case of the Rh(I) dimers used above.
This spectrum also allows the calculation of the two-
bond phosphorus-phosphorus coupling to the PF2 moi-
1
ety (102 Hz), which in turn yields a J PF value of 1114
3
Hz and a J PF coupling of 11 Hz. The analogous coupling
constant values for the related Cp*Rh(PF3)2 complex27
2
1
3
were J PP ) 178 Hz, J PF ) 1135 Hz, J PF ) 6 Hz, and
3J FRh ) 30 Hz. Unfortunately the 31P data for this PF3
complex were not reported,27 as it would be of interest
to ascertain if this complex also shows a larger than
usual Rh-P coupling.
The infrared spectrum of 5 showed relatively broad
P-F stretching frequencies compared to the sharp
bands observed in the free ligand 1. These peaks were
shifted slightly to a higher frequency (835 and 786
cm-1), relative to 1 (805 and 780 cm-1), a shift that is
expected since the σ* orbitals of the P-F are accepting
electron density from the metal complex.
A solid-state structure determination of CpRh(1)2 (5)
showed a rhodium center subtended by a cyclopenta-
dienyl ring and two difluorophosphinodiazaphole ligands
as formulated (Figure 4).29 The crystal structure details
and metrical parameters are given in Tables 2-4. The
structure is quite symmetric; excluding the Cp ring, the
two phospholes are related by a C2 axis through the Rh
center. The angle between rhodium and the two exo-
phosphorus centers, P(21)-Rh-P(11), is 94.56(5)°,
smaller than that found for a similar (η5-indenyl)-
Rh(PMe3)2 complex (96.69°).30 In 5 the phosphole rings
are planar and the nitrogen at the 2-position in the ring
is also planar, the sum of the angles about the nitrogen
being 360°. The P(22)-N(23)-N(24) and the P(12)-
N(13)-N(14) angles (117.3(3)° and 117.5(3)°, respec-
(2)
The 31P{1H} NMR spectrum of 6 showed an ADMX2
spin system24 with an upfield shift for the exo-
phosphorus center resonance (ca. 189 ppm) which is also
coupled to the rhodium (216 Hz), to the σ2P center (103
Hz), and to both fluorine atoms (1171 Hz). Although the
magnitude of the rhodium-phosphorus coupling con-
stant (216 Hz) in 6 was again larger than that normally
observed for J PRh, it is smaller than that observed in 5
(cf. 306 Hz). The relatively reduced J PRh value in this
complex can be explained in terms of reduced π-bonding
between the Rh(III) metal center and the phosphine as
compared to that operative in the Rh(I) complexes.34 The
σ2P center in 6 shifted slightly downfield (by 15 ppm to
1
1
(31) Friedrich, P.; Huttner, G.; Luber, J .; Schmidpeter, A. Chem.
Ber. 1978, 111, 1558-1563.
(32) Corbridge, D. E. C. The Structural Chemistry of Phosphorus;
Elsevier Scientific Publishing Co.: New York, 1974; p 7.
(33) Mikoluk, M. D.; McDonald, R.; Cavell, R. G. Inorg. Chem. 1999,
38, 2791-2801.
(29) J ohnson, C. K. ORTEP, Report ORNL No. 5138; Oak Ridge
National Labs: Oak Ridge, TN, 1976.
(30) Marder, T. B.; Calabrese, J . C.; Roe, D. C.; Tulip, T. H.
Organometallics 1987, 6, 2012-2014.
(34) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev.
1973, 10, 335-422.

3312 Organometallics, Vol. 18, No. 17, 1999
Ta ble 2. Cr ysta llogr a p h ic Exp er im en ta l Da ta for 5 a n d 7
Mikoluk et al.
5
7
A. Crystal Data
empirical formula
fw (g/mol)
cryst dimens (mm)
cryst syst
space group
unit cell params
a (Å)
C
13H17F4N4P4Rh
C17H36ClN8OP4Rh
630.78
532.10
0.37 × 0.22 × 0.08
monoclinic
P21/c (No. 14)
a
14.653(2)
7.9711(8)
18.010(2)
0.35 × 0.18 × 0.07
triclinic
P1h (No. 2)
b
9.4866(9)
11.7338(13)
14.9972(15)
68.686(8)
73.004(8)
66.764(7)
1407.2(2)
2
b (Å)
c (Å)
R (deg)
â (deg)
105.417(10)
γ (deg)
V (Å3)
2027.9(4)
4
1.743
1.198
Z
F
calcd (g cm-3
)
1.489
0.954
µ (mm-1)
B. Data Collection and Refinement Conditions:
diffractometer
Enraf-Nonius CAD4c
Siemens P4/RAd
radiation (λ[Å])
monochromator
Mo KR (0.71073)
incident beam (graphite crystal)
Mo KR (0.71073)
incident beam (graphite crystal)
temp (°C)
scan type
-50
-60
θ-2θ
θ-2θ
50.0
data collection 2θ limit (deg)
total data collected
no. of ind reflns
no. of observations (NO)
structure solution method
refinement method
absn corr method
50.0
3687 (-17 e h e 16, 0 e k e 9, 0 e l e 21)
5245 (0 e h e 11, -12 e k e 13, -17 e l e 17)
3559
4916
2579 (Fo g 2σ(Fo2))
2918 (Fo g 2σ(Fo2))
2
2
direct methods (SHELXSI-86c)
full-matrix least-squares on F2 (SHELXSI-93f)
DIFABSg
direct methods (SHELXSI-86c)
full-matrix least-squares on F2 (SHELXSI-93f)
semiempirical (ψ scans)
range of absn corr factors
no. of data/restraints/params
goodness-of-fit (S)h
1.126-0.800
0.9965-0.8630
3558 [Fo g -3σ(Fo2)]/0/239
4916 [Fo g -3σ(Fo2)]/2e/305
2
2
1.002 [Fo g -3σ(Fo2)]
1.037 [Fo g -3σ(Fo2)]i
2
2
2
2
final R indices,i Fo > 2σ(Fo
)
R1 ) 0.0313, wR2 ) 0.0649
R1 ) 0.0688, wR2 ) 0.0747
0.363 and -0.464
R1 ) 0.0623, wR2 ) 0.0776
R1 ) 0.1345, wR2 ) 0.0964
0.521 and -0.521
all data
largest diff peak and hole (e Å-3
)
a
b
Obtained from least-squares refinement of 37 reflections with 19.2° < 2θ < 27.7°. Obtained from least-squares refinement of 32
reflections with 25.5° < 2θ < 28.0°. c Programs for diffractometer operation and data collection and reduction were those supplied by
d
Enraf-Nonius. Programs for diffractometer operation and data collection were those of the XSCANS system supplied by Siemens.
e Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467-473. f Sheldrick, G. M. SHELXL-93. Program for crystal structure determination;
University of Go¨ttingen: Germany, 1993. Refinement on Fo for all reflections (all of these having Fo < -3σ(Fo2) except in the case of 5,
2
2
where one value having Fo < -3σ(Fo2) was omitted). Weighted R-factors wR2 and all goodnesses of fit S are based on Fo2; conventional
2
R-factors R1 are based on Fo, with Fo set to zero for negative Fo2. The observed criterion of Fo > 2σ(Fo2) is used only for calculating R1
2
2
and is not relevant to the choice of reflections for refinement. R-factors based on Fo are statistically about twice as large as those based
g
h
2
on Fo, and R-factors based on ALL data will be even larger. Walker, N.; Stuart, D. Acta Crystallogr. 1983, A39, 158-166. S ) [∑w(Fo
- Fc2)2/(n - p)]1/2 (n ) number of data; p ) number of parameters varied; w ) [σ2(Fo2) + (a0P)2 + a1P]-1, where P ) [max(Fo2, 0) +
2Fc2]/3). For 5 a0 ) 0.0288, a1 ) 1.5071, for 7 a0 ) 0.0201, a1 ) 0. Distances involving the carbonyl group C(2)O(2) of the minor isomer
i
were fixed as follows: d(Rh-C(2)) ) 1.78(1) Å; d(C(2)-O(2)) ) 1.12(1) Å. R1 ) ∑||Fo| - |Fc||/∑|Fo|; wR2 ) [∑w(Fo - Fc2)2/∑w(Fo4)]1/2
.
j
2
Ta ble 3. Selected In ter a tom ic Dista n ces (Å) for
Cyclop en ta d ien ylbis(KP -d iflu or o{2,5-d im eth yl-2H-
1,2,3σ2-d ia za p h osp h ol-4-yl}p h osp h in e)r h od iu m (I)
(5)
constant of 1171 Hz. Decoupling the phosphorus signal
at 269 ppm collapsed the fluorine signal to a doublet of
doublets. Values extracted from both spectra give values
3
2
2
of 12 Hz for both J σ PF and J FRh
.
atom 1
atom 2
distance
atom 1
atom 2
distance
Rea ction s of 2 a n d 3 w ith Rh od iu m (I) P r ecu r -
sor s. F or m a tion of 7 a n d 8. In contrast to the
treatment of 1 with [Rh(CO)2Cl]2, described above,
which gave a product that could not be identified, 2
reacted smoothly with this precursor to yield exclusively
the red, crystalline complex trans-Rh(CO)Cl(2)2 (7), the
expected product by analogy with analogous phosphine
complexation reactions35 We did not observe any con-
densed intermediates, but we did not conduct an
extensive evaluation of the reaction pathway. We sug-
gest that the steric bulk of 2 influences the reaction by
directing it initially toward dimer cleavage (path B as
described by Hughes)35 as the first steps with interme-
diate formation of the monophosphine complex. The
Rh
Rh
Rh
Rh
Rh
Rh
Rh
P(11)
P(11)
P(11)
P(12)
P(12)
P(11)
P(21)
C(1)
C(2)
C(3)
2.1334(12)
2.1348(12)
2.257(5)
2.299(5)
2.231(5)
2.265(4)
2.237(4)
1.574(3)
1.562(3)
1.774(4)
1.670(4)
1.713(4)
P(21)
P(21)
P(21)
P(22)
P(22)
N(13)
N(13)
N(14)
N(23)
N(23)
N(24)
F(21)
F(22)
C(21)
N(23)
C(21)
N(14)
C(17)
C(15)
N(24)
C(27)
C(25)
1.576(3)
1.563(3)
1.771(4)
1.672(3)
1.713(4)
1.355(5)
1.464(6)
1.316(6)
1.354(5)
1.468(5)
1.322(5)
C(4)
C(5)
F(11)
F(12)
C(11)
N(13)
C(11)
269.23 ppm) and the two-bond phosphorus-phosphorus
coupling (2J PP ) 103 Hz) showed a small decrease
relative to uncoordinated 1.
The 19F NMR spectrum of 6 consisted of a resonance
of an apparent doublet of triplets centered at -62.18
ppm with a one-bond phosphorus-fluorine coupling
(35) Hughes, R. P. Rhodium. In Comprehensive Organometallic
Chemistry (deputy editors E. W. Abel and F. G. A. Stone); Wilkinson,
G., Ed.; Pergamon Press: New York, 1982; Vol. 5, Chapter 35, pp 296-
307.

Chemistry of Diazaphosphole-Phosphines. 3
Organometallics, Vol. 18, No. 17, 1999 3313
Ta ble 4. Selected In ter a tom ic An gles (d eg) for
Cyclop en ta d ien ylbis(KP -d iflu or o{2,5-d im eth yl-2H-1,2,3σ2-d ia za p h osp h ol-4-yl}p h osp h in e)r h od iu m (I) (5)
atom 1
atom 2
atom 3
angle
atom 1
atom 2
atom 3
angle
P(11)
Rh
Rh
Rh
P(21)
F(11)
F(12)
C(11)
F(12)
C(11)
C(11)
C(11)
F(21)
F(22)
C(21)
F(22)
C(21)
C(21)
C(21)
N(14)
C(17)
C(17)
94.56(5)
115.95(13)
120.59(13)
119.02(14)
95.3(2)
100.7(2)
101.0(2)
88.3(2)
114.85(13)
119.87(12)
122.60(14)
96.0(2)
99.0(2)
99.5(2)
88.6(2)
117.5(3)
126.3(4)
116.2(4)
N(13)
P(22)
P(22)
N(24)
N(23)
P(11)
P(11)
P(12)
N(14)
N(14)
C(11)
P(21)
P(21)
P(22)
N(24)
N(24)
C(21)
N(14)
N(23)
N(23)
N(23)
N(24)
C(11)
C(11)
C(11)
C(15)
C(15)
C(15)
C(21)
C(21)
C(21)
C(25)
C(25)
C(25)
C(15)
N(24)
C(27)
C(27)
C(25)
P(12)
C(15)
C(15)
C(11)
C(16)
C(16)
P(22)
C(25)
C(25)
C(21)
C(26)
C(26)
109.4(4)
117.3(3)
127.2(3)
115.5(3)
108.8(3)
119.4(2)
130.4(3)
110.2(3)
114.6(4)
118.4(4)
127.0(4)
121.6(2)
128.5(3)
109.8(3)
115.4(4)
117.5(4)
127.0(4)
P(11)
P(11)
P(11)
P(11)
P(11)
P(11)
P(12)
P(21)
P(21)
P(21)
P(21)
P(21)
P(21)
P(22)
N(13)
N(13)
N(13)
Rh
F(11)
F(11)
F(12)
N(13)
Rh
Rh
Rh
F(21)
F(21)
F(22)
N(23)
P(12)
P(12)
N(14)
Sch em e 2. Su bstitu tion a l P r ocess for th e
F or m a tion of tr a n s-[Rh (CO)Cl(2)2]
F igu r e 5. 31P {1H}NMR (161.977 MHz) spectrum of ((bis-
(bis{dimethylamino}{2,5-dimethyl-2H-1,2,3σ2-diazaphosphol-
4-yl}phosphine)rhodium(I), 7, in CDCl3. The two regions
shown in expansion are composed of deceptively simple
“triplets” with the set at 160 ppm (due to the exocyclic
process is outlined in Scheme 2. The first steps describe
the cleavage of the dimer, and in the final stage, the
second substitution, trans directed by 2 occurs. Ultimate
formation of the trans product suggests that 2 is more
trans directing than either Cl or CO in this final step.
Further study of the substitutional process with these
ligands would likely be rewarding.
1
phosphorus center) doubled by J PRh ) 143 Hz. The outer
2
2
4
lines of each “triplet” unit are separated by | J σ Pσ P
+
4
2
4
J σ Pσ P′| ) 51 Hz.
1
center was relatively unchanged. The value of J PRh is
in keeping with typical Rh-P complexes, and the
association of this coupling with the exocyclic phos-
phorus indicates the point of attachment.37
The 31P{1H} NMR spectrum of 7 (Figure 5) shows the
typical AA′XX′ pattern of a “deceptively simple triplet”
for both phosphorus centers.24 One of the P centers, the
directly bound P(III) center, has superimposed on these
The solid-state structure of 7 (major isomer shown
in Figure 629) revealed the square-planar rhodium metal
center wherein both diazaphosphole ligands lie trans
to each other, as one would anticipate with a relatively
bulky phosphine. Crystal parameters and metrical
details are given in Tables 2, 5, and 6. One interesting
feature of the structure is that the diazaphosphole rings
are oriented perpendicular to the P(1)-Rh-CO-Cl-
P(2) plane and stacked to create a mirror plane which
contains the Cl-Rh-CO axis. The diazaphosphole rings
1
“triplets” the large, essentially first-order, J PRh cou-
pling, which, at 143 Hz, is larger than the outer line
separation of the “triplet” (the value of which, 51 Hz,
represents |J AX + J AX′|) and so gives a doublet of the
“triplets”. The other portion of the spectrum arising from
2
the P(V) moiety gives only the “triplet” because J PRh is
small. In the present case there is not a sufficient
number of separated lines to allow a solution for the
spectral parameters.36 The exo-phosphorus center was
shifted downfield relative to the free ligand (by 16 ppm
to 103.34 ppm), while the chemical shift of the σ2P
(37) Pregosin, P. G. In Phosphorus-31 NMR Spectroscopy in
Stereochemical Analysis; Verkade, J . G., Quin, L. D., Eds.; VCH
Publishers, Inc.: Deerfield Beach, FL, 1987; Vol. 8, pp 465-530.
(36) Harris, R. K. Can. J . Chem. 1964, 42, 2275-2281.

3314 Organometallics, Vol. 18, No. 17, 1999
Mikoluk et al.
here. Once again, the phosphole rings are planar, and
the angles about the σ2P centers, C(11)-P(12)-N(13)
and C(21)-P(22)-N(23), are 89.1(3)8° and 88.9(4)°,
respectively. All characteristics of the phosphole rings
are comparable to those shown by 5. The phosphorus-
rhodium distance is 2.33 Å, which is comparable to that
of the Rh-P bond length (2.326 Å) in the Rh(CO)2Cl-
(PPh3) complex.39 The average P-N bond distance of
the exo-phosphorus center and the dimethylamino
groups is 1.683 Å, shorter than the normally accepted
distance of 1.77 Å, again suggesting some multiple-
bonding characteristics.32 The dimethylamino nitrogen
atoms are planar, with the sum of the angles about
these nitrogen centers being 360°.
Replacing fluorine atoms on the exo-phosphorus
center in 1 with alkoxy groups increases the basicity of
the phosphine center, but the exocyclic phosphine center
in this case is both less basic and less bulky in
comparison with the amino derivative 2. The reaction
of 3 with [Rh(CO)2Cl]2 proceeded similarly to that
demonstrated by 2 and resulted again in the formation
of trans-[Rh(CO)Cl(3)2] (8), which suggests that both
2 and 3 follow similar substitutional pathways. The
31P{1H} NMR spectrum of 8 was also second order,
showing a spectrum consisting of two deceptively simple
“triplets”, similar to the patterns displayed by the
complex formed by 2. Surprisingly, the chemical shift
of the exo-phosphorus signal in 8 was reduced only
by 8 ppm (159.78 ppm) upon complexation, whereas
the signal for the noncoordinated σ2P center suffered
a greater shift downfield of 14.5 ppm (251.88 ppm).
F igu r e 6. Perspective ORTEP29 view of the major (75%)
isomer of trans-chlorocarbonyl((bis(κP-bis{dimethylamino}-
{2,5-dimethyl-1,2,3σ2-dia za phosphol-4-yl}phosphine)-
rhodium(I), 7. Non-hydrogen atoms are represented by
Gaussian ellipsoids at the 20% probability level. The minor
(25%) isomer of 7 differs only from that illustrated in that
the Cl and CO positions relative to the “top” of the molecule
are interchanged.
Ta ble 5. Selected In ter a tom ic Dista n ces (Å) for
tr a n s-Ch lor oca r bon yl(bis(KP -bis{d im eth yla m in o}-
{2,5-d im eth yl-2H-1,2,3σ2-d ia za p h osp h ol-4-yl}-
p h osp h in e))r h od iu m (I) (7)
atom 1
atom 2
distance
atom 1
atom 2
distance
Rh
Rh
Rh
Rh
Rh
Rh
P(11)
P(11)
P(11)
P(12)
P(12)
P(21)
P(21)
P(21)
P(22)
P(22)
O(1)
O(2)
Cl(1)
Cl(2)
P(11)
P(21)
C(1)
2.395(4)a
2.46(2)b
2.333(2)
2.326(2)
1.777(13)a
1.77(1)b
1.695(5)
1.683(6)
1.784(7)
1.678(6)
1.704(7)
1.686(6)
1.668(6)
1.795(7)
1.679(7)
1.712(7)
1.13(2)a
1.12(1)b
N(11)
N(11)
N(12)
N(12)
N(13)
N(13)
N(14)
N(21)
N(21)
N(22)
N(22)
N(23)
N(23)
N(24)
C(11)
C(12)
C(21)
C(22)
C(15)
C(16)
C(17)
C(18)
N(14)
C(14)
C(12)
C(25)
C(26)
C(27)
C(28)
N(24)
C(24)
C(22)
C(12)
C(13)
C(22)
C(23)
1.455(8)
1.455(8)
1.462(8)
1.455(8)
1.350(7)
1.464(8)
1.344(8)
1.455(8)
1.480(8)
1.457(8)
1.468(9)
1.356(9)
1.473(8)
1.325(9)
1.409(9)
1.495(9)
1.413(10)
1.499(9)
2
4
2
4
2
4
The major spacing for | J σ Pσ P + J σ Pσ P′| was 52 Hz.
1
The J PRh coupling constant was 187 Hz and indicated
that despite the smaller coordination shift, the exo-
phosphorus was the coordination site.
C(2)
N(11)
N(12)
C(11)
N(13)
C(11)
N(21)
N(22)
C(21)
N(23)
C(21)
C(1)
The fluorine NMR spectrum of 8 showed a single
resonance at -74.50 ppm for the fluorines of the
trifluoroethoxy group, which were unchanged from those
of uncomplexed 3. Unlike the parent diazaphosphole
spectrum however, coupling of 19F to either the σ2P
center or the protons was not resolved. Consistently, the
proton spectrum showed only two broadened resonances
for the diastereotopic protons (4.353 and 4.585 ppm).
Even at higher magnetic fields, the coupling to other
nuclei remained unresolved.
C(2)
The 31C{1H} NMR spectrum of 8 showed an upfield
shift for the resonance for the carbon at the 4-position
of the ring which was coupled to both phosphorus
a
b
Major (75%) isomer. Minor (25%) isomer.
of 7 are parallel to the CO-Rh-Cl axis and are parallel
to each other. This symmetrical feature yields two
isomers which differ in the relative positions of the
chloride and the carbon monoxide ligands relative to the
“top” of the molecule; these two substituents are readily
interchanged to create two isomers. Both of the isomers
were identified in the crystal, one of which is more
predominant than the other (75:25). A similar result has
been reported for the dimethylphenylphosphine ana-
logue,38 wherein the phenyl rings lie on the same side
of the rhodium complex and are oriented toward the
carbonyl group. In that case it was rationalized that the
orientation of the phenyl rings arose from electronic
interaction between the oriented phenyl rings and the
carbonyl moiety, and a similar effect may be operational
1
1
2
3
centers (135.26 ppm, J σ PC ) 84 Hz, J σ PC ) 42 Hz).
The carbon at the 5-position of the ring showed only
coupling to the exo-phosphorus center (155.57 ppm,
2
4
J σ PC 10 Hz). The resonance for the trifluoromethyl
carbon showed coupling to the exo-phosphorus (122.19
3
1
4
ppm, J σ PC ) 9 Hz, J CF ) 277 Hz). Coupling to only
the fluorines was observed in the methylene carbon
signals (64.83 ppm, J CF ) 39 Hz), but the coupling to
the phosphorus was unresolved.
2
No significant change in the P-O stretching fre-
quency (1165 cm-1) of 3 was observed on coordination.
Rela tive Liga n d Ch a r a cter . The lack of systematic
substitutional patterns of the phosphinediazaphosphole
ligands investigated herein does not allow for a complete
(38) Schumann, H.; J urgis, S.; Eisen, M.; Blim, J . Inorg. Chim. Acta
1990, 172, 191-201.
(39) Chen, Y.-J .; Wang, J .-C.; Wang, Y. Acta Crystallogr. 1991, C47,
2441-2442.

Chemistry of Diazaphosphole-Phosphines. 3
Organometallics, Vol. 18, No. 17, 1999 3315
Ta ble 6. Selected In ter a tom ic An gles (d eg) for tr a n s-Ch lor oca r bon yl(bis(KP -bis{d im eth yla m in o}-
{2,5-d im eth yl-2H-1,2,3σ2-d ia za p h osp h ol-4-yl}p h osp h in e))r h od iu m (I) (7)
atom 1
atom 2
atom 3
angle
atom 1
atom 2
atom 3
angle
Cl(1)
Cl(1)
Cl(1)
Cl(2)
Cl(2)
Cl(2)
P(11)
P(11)
P(11)
P(21)
P(21)
Rh
Rh
Rh
N(11)
N(11)
N(12)
N(13)
Rh
Rh
Rh
Rh
Rh
Rh
Rh
Rh
Rh
P(11)
P(21)
C(1)
P(11)
P(21)
C(2)
P(21)
C(1)
C(2)
86.71(10)a
87.18(10)a
173.6(4)a
92.9(7)b
92.7(7)b
172.4(14)b
173.33(8)
93.6(4)a
N(22)
N(23)
P(11)
P(11)
C(15)
P(11)
P(11)
C(17)
P(12)
P(12)
N(14)
N(13)
P(21)
P(21)
C(25)
P(21)
P(21)
C(27)
P(22)
P(22)
N(24)
N(23)
Rh
P(21)
P(22)
N(11)
N(11)
N(11)
N(12)
N(12)
N(12)
N(13)
N(13)
N(13)
N(14)
N(21)
N(21)
N(21)
N(22)
N(22)
N(22)
N(23)
N(23)
N(23)
N(24)
C(1)
C(21)
C(21)
C(15)
C(16)
C(16)
C(17)
C(18)
C(18)
N(14)
C(14)
C(14)
C(12)
C(25)
C(26)
C(26)
C(27)
C(28)
C(28)
N(24)
C(24)
C(24)
C(22)
O(1)
106.2(3)
88.9(4)
124.4(5)
115.5(5)
112.6(6)
120.0(5)
120.1(5)
112.5(6)
117.3(5)
125.8(5)
116.9(6)
108.5(6)
114.8(5)
123.0(5)
111.5(6)
123.2(6)
120.6(5)
112.4(6)
117.8(5)
126.7(7)
115.5(7)
107.5(7)
175.9(13)a
127.5(7)
126.0(4)
124.5(6)
108.9(5)
116.9(7)
116.7(7)
Rh
Rh
Rh
88.1(12)b
92.1(4)a
C(1)
C(2)
85.9(12)b
117.4(2)
111.7(2)
110.7(2)
109.4(3)
103.8(3)
102.5(3)
89.1(3)
117.5(2)
112.0(2)
109.7(2)
108.9(3)
101.5(3)
177.9(44)b
122.9(4)
126.4(5)
109.9(5)
115.2(7)
117.1(6)
126.4(7)
P(11)
P(11)
P(11)
P(11)
P(11)
P(11)
P(12)
P(21)
P(21)
P(21)
P(21)
P(21)
C(2)
C(11)
C(11)
C(11)
C(12)
C(12)
C(22)
N(11)
N(12)
C(11)
N(12)
C(11)
C(11)
C(11)
N(21)
N(22)
C(21)
N(22)
C(21)
O(2)
P(12)
C(12)
C(12)
C(11)
C(13)
C(23)
Rh
Rh
N(21)
N(21)
Rh
P(11)
P(11)
P(12)
N(14)
N(14)
C(21)
C(11)
P(21)
P(21)
P(22)
N(24)
N(24)
C(12)
C(21)
C(21)
C(21)
C(22)
C(22)
C(13)
P(22)
C(22)
C(22)
C(21)
C(23)
a
b
Major (75%) isomer. Minor (25%) isomer.
classification of the ligand properties which devolve from
the substitutions on the exocyclic phosphorus center, but
some understanding can be gleaned from the IR spectra.
The carbonyl infrared stretching frequency ν(CO) for 7
is 1978 cm-1, which is comparable to values for trans-
(phosphine)Rh(CO)Cl with the ligands PPh3 (1980
did not give carbonyl products with Rh(I), although it
forms stable CpRu and CpRh complexes and a Cp*Rh
complex. This ligand, 1, readily substitutes both CO
ligands in CpRh(CO)2 to give CpRh(1)2. Elsewhere5,9 we
have shown that the difluoride is a good coordinating
and also reducing9 ligand. The replacement of one of
the PPh3 groups in the complex CpRu(PPh3)2Cl with the
difluorophosphinophosphole ligand gave the asymmetric
ruthenium complex CpRu(PPh3)(1)Cl, wherein the fluo-
rine atoms were diastereotopic. The 31P{1H} NMR
spectrum of this complex gave a complex second-order
splitting pattern for the exo-phosphorus centre. A very
large one-bond phosphorus-rhodium coupling constant
value of 306 Hz was observed. Reaction of 1 with the
dimeric complex [Cp*RhCl2]2 gave Cp*Rh(1)Cl2. In
contrast to 1, the related ligands 2 (the bis(dimethyl-
amino)) and 3 (the bis trifluoroethoxy) analogues gave
the expected trans-Rh(I) complexes, wherein the CO
stretching frequencies reflect the basicity of the ligand,
a measure that could not however be obtained for the
difluoride ligand, 1.
cm-1 40 and (C6F5)2PPh (1982 cm-1),41 thus suggesting
)
that 2 behaves with a basicity and back-donation
character similar to these aryl phosphines. The ν(CO)
stretching frequency of 8 is 2010 cm-1, which suggests
that the ligating characteristics of 3 are more similar
to those of the phosphites P(OMe)3 (2014 cm-1 42
and
)
P(OPh)3 (2018 cm-1),43 and this is reinforced by the fact
that in substitution reactions with CpRh(CO)2 both CO
ligands are replaced, a reaction characteristic of phos-
phites but not phosphines. Here and elsewhere5,9 we
observe substitutional behavior and reactivity charac-
teristics of the difluorophosphinediazaphosphole that
are very similar to those of PF3; unfortunately the
appropriate Rh(I) complex of 1 was not obtained, and
so the comparison within this series cannot be com-
pleted.
Ack n ow led gm en t. We thank the University of
Alberta and the Natural Sciences and Engineering
Research Council of Canada for support.
Su m m a r y
The diazaphoaphole phosphine set of ligands exhibits
varied chemistry which illustrates the effect of the
substituents on the exocyclic phosphine. The difluoride
Su p p or tin g In for m a tion Ava ila ble: Full structure re-
ports containing atomic coordinates, full tables of interatomic
distances and angles, torsional angles, tables of equivalent
isotropic displacement parameters, anisotropic displacement
parameters, selected least-squares planes, and derived hydro-
gen atom positions for 5 and 7. This material is available free
of charge via the Internet at http://pubs.acs.org.
(40) Vaska, L.; Peone, J ., J r. J . Chem. Soc., Chem Commun. 1971,
418-419.
(41) Kemmitt, R. D. W.; Nichols, D. I.; Peacock, R. D. J . Chem. Soc.
(A) 1968, 1898-1902.
(42) Wu, M. L.; Desmond, M. J .; Drago, R. S. Inorg. Chem. 1979,
18, 679-686.
(43) Dutta, D. K.; Singh, M. M. Transition Met. Chem. 1980, 4, 244.
OM9903590