Reactions of Lithiated Diphosphanes R2P–P (SiMe3) Li (R= tBu, iPr

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Reactions of Lithiated Diphosphanes R2P−P(SiMe3)Li (R = tBu, iPr, i Pr2N, Et2N) with [Cp2WCl2]. Syntheses and Structures of the First Terminal Phosphanylphosphido Complexes of Tungsten(IV) Rafał Grubba,† Katarzyna Baranowska,† Dietrich Gudat,‡ and Jerzy Pikies*,† †

Chemical Faculty, Department of Inorganic Chemistry, Gdansk University of Technology, G. Narutowicza Street 11/12, Pl-80-233 Gdansk, Poland ‡ Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany S Supporting Information *

ABSTRACT: Reactions of R2P−P(SiMe3)Li (R = tBu, iPr, i Pr2N, Et2N) with [Cp2WCl2] yield terminal phosphanylphosphido complexes [Cp(C5H4P-PR2)WH] or [Cp{C5H4P-PR2}W(SiMe3)] by way of a hydrogen or SiMe3 migration to tungsten. The solid-state structures of [Cp(C5H4P−PtBu2)WH] and [Cp(C5H4P-PNEt2)WH] were established by singlecrystal X-ray diffraction. Two stereoisomers of [Cp(C 5H4P− PtBu2)WH] were identified by solution NMR spectroscopy. Reaction of iPr2P−P(SiMe3)Li with [Cp2WCl2] yields red crystals of dimeric phosphinidene complex [Cp(C5H4P)W]2 as side product.

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phinidene moiety.9c Terminal phosphanylphosphido complexes [L2MCl(P−PR2)] (M = Zr, Hf; L = Cp, indenyl) were also obtained from R2P−P(SiMe3)Li and [L2MrCl2] in toluene or pentane.9c−e Here we present results of our studies on the reactivity of R 2 P−P(SiMe 3)Li (R = tBu, iPr, Et 2 N, i Pr 2N) toward [Cp2WCl2].10

INTRODUCTION Phosphido (R2P) and phosphinidene (RP) groups are important and versatile ligands in transition metal chemistry. The synthesis and properties of stable mononuclear phosphido and phosphinidene complexes are currently intensively studied; for reviews see ref 1. Moreover, phosphinidene and phosphido complexes have also proven useful in the synthesis of organophosphorus compounds.2 Tungsten forms several types of complexes with terminal phosphinidene ligands: (a) electrophilic (Fischer-type) complexes with bent phosphinidene units that exist as transient species ([RPW(CO) 5]1d,3) or as isolable compounds ([Cp*(CO) 3 WP−N iPr 2 )][AlCl4]4); (b) nucleophilic (Schrock-type) complexes with bent ([Cp2WPMes*]5) and linear phosphinidene moieties ([(OC)(MePh 2P)2Cl2 WPMes*]6); and (c) a side-on bonded cationic phosphanyl phosphinidene complex, [(η2Ph2PP)W{NiPr(3,5-Me2C6H3)}3]+.7 An attempt to synthesize nucleophilic complexes [(η5-C5H4Me)2WPMes*] via metathesis of [(η5-C5H4Me)2WCl2] with Mes*(Me3Si)PLi gave isomeric phosphido complexes via insertion of P atoms into C− H bonds of Cp rings.8 R2P−P(SiMe3)Li can act as a precursor of phosphanylphosphido ligands, R2P−P(SiMe3), or phosphanylphosphinidene ligands, R2P−P, which may adopt different coordination modes. Thus, R2P−P(SiMe3)Li and [L2PtCl2] (L = tertiary phosphane) give Pt(0) complexes with a side-on bonded R2P−P moiety [(η2-R2PP)PtL2],9a reaction of tBu2P−P(SiMe3)Li with [Cp2ZrCl2] in THF in the presence of a small tertiary phosphane affords the terminal phosphanylphosphinidene complex [{Zr(PPhMe2)Cp2}(η1-P−PtBu2)],9b and (Et2N)2P− P(SiMe3)Li yields under similar conditions a dimeric [Cp2Zr{μ2-PP(NEt2)2}2ZrCp2] with a μ2-bridging phosphanylphos© 2011 American Chemical Society

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RESULTS AND DISCUSSION

Synthetic and Spectroscopic Studies. Treatment of [Cp2WCl2] with 1 equiv of tBu2P−P(SiMe3)Li·2THF in toluene results in formation of two spectroscopically detectable tungsten complexes, which were later identified as cis- and trans-[Cp(C5H4P−PtBu2)WH], 1a and 1b (molar ratio ≈ 8:1, Scheme 1). Reactions in THF or DME give similar results, Scheme 1

indicating that in contrast to the reactions of [Cp 2ZrCl2] with R2P−P(SiMe3)Li9b the influence of donor solvents is not significant. Received: September 8, 2011 Published: November 23, 2011 6655

dx.doi.org/10.1021/om2008452 | Organometallics 2011, 30, 6655−6660

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The major product (1a) was isolated in 14% yield and identified by spectroscopic and crystallographic studies (see below). A 31P CP-MAS NMR spectrum of the isolated solid showed a set of two signals with chemical shifts of 47.9 and 39.7 ppm connected by a large homonuclear coupling (1JPP = 228 Hz), which we attribute to 1a; signals of the second product, 1b, were not visible. After dissolving a sample of the isolated solid in C6D6, again both 1a and 1b were detectable in a molar ratio of ∼16:1, which changed after one year to approximately 11:1. These findings suggest that the two products are isomers that can be separated by crystallization but are very slowly interconvertible in solution. Further identification of the stereochemistry of 1a and elucidation of the constitution of 1b were feasible from characterization of the obtained isomer mixture by homo- and heteronuclear 2D NMR experiments. Crucial information allowing localizing the position of the metal-bound hydrogen atom (W−H) was obtained from a 1H,1H NOESY spectrum, which shows strong correlation peaks connecting the hydride resonance of 1a with the signals of the protons in the Cp ring, the more deshielded of the two terminal protons (δ = 5.71, H1) belonging to the (CH)4 unit in the monosubstituted C5H4 ring, and one of the two diastereotopic tBu groups; additional crosspeaks of lower intensity are also observed between the hydride and the second tBu group and one of the inner protons in the C5H4 ring (δ 5.03, H2). The observation of NOESY crosspeaks connecting the signals of both tBu groups with that of H1 indicates that H1 and the PtBu2 fragment are situated on the same side of the three-membered W−P1−C1 ring (see Figure

Figure 2. Molecular structure of 1a showing the atom-numbering scheme (50% probability displacement ellipsoids). H atoms have been omitted. Important bond lengths (pm) and bond angles (deg): P1−P2 222.8(1), P1−W1 255.3(1), P1−C1 181.0(4), P2−P1−W1 108.35(5).

more shielded terminal proton in the (CH)4 unit of the C5H4 ring, but any NOEs to the tBu groups are absent. The observed patterns are consistently explained by assuming that the W−H and P−PtBu2 bonds are on the same side of the threemembered W−P1−C1 ring in 1a and on opposite sides in 1b. The stereochemical assignment is corroborated by the analysis of long-range couplings that are visible in the 1H,1H COSY and 1H,31P HMQC spectra. The 1H,1H COSY shows weak cross-peaks connecting the W−H resonance with both t Bu signals in 1a, which are absent in the second isomer, 1b (see Figure 1); homodecoupling experiments revealed that the splitting associated with this coupling is too small to be observable. We interpret the described correlations as resulting from through-space interaction between the metal hydride and the tBu protons and conclude that 1a must then exhibit a much closer W−H···tBuP contact than 1b, in accord with the proposed stereochemistry. The 1H,31P HMQC spectrum allows assigning the large doublet splitting of 7.7 Hz to the 2JPH coupling connecting the hydride with the metal-bound phosphorus atom; similar couplings in 1a are not resolved, but the 2D spectrum shows that the hydride exhibits small couplings of similar magnitude (as judged by the cross-peak intensity) to both phosphorus atoms. Considering the known relation between the size of 2JPH and the dihedral angle between the XH bond and the phosphorus lone pair in PXH fragments of organophosphorus compounds,11 the observed coupling pattern in 1a,b suggests that the W−H bond and the phosphorus lone pair should be cis-oriented with respect to the WPC ring in 1b and trans-oriented in 1a, which agrees once more with the proposed stereochemistry. The observation of resolved 183W satellites for the hydride resonance allowed also determining the 183W NMR data of 1a,b of a 1H,183W HMQC spectrum; the close similarity of the chemical shifts of both species (δ183W = −3985 (1a), −3890 (1b)) is also in accord with the presence of isomers that differ only in the spatial arrangement of the metal-bound ligands. Reaction of iPr2P−P(SiMe3)Li with [Cp2WCl2] yielded according to 31P and 1H NMR studies a complex reaction mixture. Signal assignment by 2D NMR allowed identifying as main products complexes 3a (which displays 1H NMR data that are closely similar to those of 1a and is thus attributed an analogous structure), 3c (Scheme 2) together with large amounts of iPr2PH and iPr2PSiMe3, and small quantities of P(SiMe3)3, iPr2PP(SiMe3)2, and a second stereoisomer, 3b (with an analogous structure to 1b). In addition, the signals of a

Figure 1. Expansion of the 400 MHz 1H gsCOSY spectrum (magnitude mode) of a mixture of 1a,b showing the correlations between the W−H protons (in F2) with the signals of the cyclopentadienyl and tBu groups (in F1). The spectrum was recorded with a spectral width of 10 000 Hz in both dimensions with 4k data points in t2 and 1024 t1 increments.

2). This assignment is in accord with the absence of a NOE between the tBu signals and the other terminal C5H4− proton. The second isomer, 1b, is characterized by NOE cross-peaks connecting the hydride with the protons in the Cp ring and the 6656


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Scheme 2

further species containing a metal-hydride moiety were also detected. Although the observed resonance pattern seems compatible with a tentative assignment as an anionic complex [Cp2W(H)PPiPr2]− (3x, data given in the Experimental Section), unambiguous structural assignment was yet unfeasible. Attempts to isolate any of the products by crystallization afforded a few crystals of dimeric phosphinidene complex [Cp(C5H4P)W]2 (3d), which was identified by single-crystal Xray diffraction, but we were unable to isolate any of the other products. As neither of the observable signals in the solution can be assigned to 3d, we presume that 3a−c are slightly unstable, and 3d forms slowly by condensation of two molecules of either species with elimination of iPr2PH or i Pr2PSiMe3 (in principle, it is also conceivable that the reaction proceeds via intramolecular elimination to yield a transient phosphinidene complex, which then dimerizes) and precipitates out of the solution. Reaction of (Et2N)2P−P(SiMe3)Li with [Cp2WCl2] produced a red solution (Scheme 3). The 31P spectrum showed

NMR spectroscopy was not feasible, as the product decomposed rapidly even at −30 °C. In the reaction of (iPr2N)2P−P(SiMe3)Li with [Cp2WCl2] we observed, besides relatively large amounts of (iPr2N)2P− P(SiMe3)H and (iPr2N)2PH, the formation of [Cp{C5H4P− P(NiPr2)2}W(SiMe3)] (4), which could be isolated in moderate yield by crystallization (Scheme 4). Solutions of 4 in C6D6 are Scheme 4

Chart 1 unstable at ambient temperature and decompose slowly under formation of iPr2NH and further unknown products. The fact that both 2 and 4 appear to be thermally significantly more labile than 1a,b and 3a−c suggests that the stability is presumably not connected with the size but rather the electronic properties of the NR2 substituents. X-ray Crystallographic Studies of 1a, 2, and 3d. The crystal data and details of the data collection and refinement for 1a, 2, and 3d are collected in Table 1 of the Supporting Information, together with details of the structure solution and refinement. The molecular structures of 1a, 2, and 3d are shown in Figures 2−4. Complexes 1a and 2 exhibit very similar geometry. The influence of the different substituents at phosphorus on the bond lengths and bond angles is not visible. The geometries around W atoms are strongly distorted pseudotetrahedral, and the centers of the Cp centroids and the P1 atoms in both compounds exhibit an almost planar alignment around the W1 atoms. The geometries around P1 are pyramidal, with a sum of bond angles of 264.7° for 1a and 261.5° for 2. The coordination sphere of the P2 atoms is less pyramidalized, with the sum of bond angles amounting to 310.2° for 1a and 310.1° for 2. The W1−P1 distances of 255.3 pm (1a) and 255.3 pm (2) are in the range of W−P single bonds. The P2−P1 distances of

Scheme 3

only a very weak singlet attributable to (Et2N)3P. Workup of the reaction mixture at low temperature produced a small amount of red crystals together with a large amount of an orange amorphous material, which was insoluble in organic solvents. A single-crystal X-ray diffraction study of the crystalline fraction allowed the identification of the isolated product as [Cp(C 5H4P-PNEt2)WH] (2) with a similar molecular structure to 1a. Further characterization by solution 6657


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222.8 pm (1a) and 221.8 pm (2) are likewise very similar and show typical values of P−P single bonds. Centrosymmetric complex 3d can be viewed as a dimer of a transient phosphinidene complex. The W1 and W1A atoms adopt a strongly distorted pseudotetrahedral geometry in which the angle between the centroids of the Cp rings (Cp1centroid− W1−Cp2centroid 146.28°) is much wider and the P1−W1−P1A angle (73.24°) much smaller than the ideal tetrahedral angle. The W1−P1 and W1−P1A distances of 257.2 and 256.7 pm are similar to those in 1a and 2 and suggest W−P single bonds. Mechanistic Considerations. Complexes 1a,b, 2, and 3a,b (formula C in Scheme 5) arise formally from insertion of the phosphinidene ligand of a hypothetical transient phosphinidene complex B into a CH bond in the Cp ring (Scheme 5). Generation of B can in turn be explained by dehalosilylation of a precursor complex A, which represents the initial product of the metathesis reaction of the starting materials. Formation of species with similar structures to A and products C is precedented in a report on the metathesis reactions of [Cp2WCl2] with Mes*(Me3Si)PLi by Cowley et al.8 The insertion of a phosphinidene into the C−H bond of coordinated Cp rings has previously been suggested by Cowley8 (for nucleophilic phosphinidene complexes), Mathey12 (for electrophilic phosphinidene complexes of Cr, Mo, W), and Ruiz13 (for a nucleophilic dinuclear phosphinidene complex of Mo). These reactions are formally electrophilic substitutions at the Cp ring. However, Lappert et al.5 have synthesized and isolated the stable, terminal phosphinidene complex [Cp2W(PMes*)] from [(Cp2WHLi)4] and Mes*PCl2, proving that a complex of type B is at least metastable. It is worth emphasizing that the synthetic route of Lappert5 avoids the formation of a phosphido complex of A type. In the light of these previous investigations, a mechanism assuming a conversion of the starting materials A to C in a sequence avoiding a phosphinidene intermediate of type B cannot be totally excluded. The mechanism of formation of metal silyls 3c and 4 is not entirely clear. It can be however explained by Li/H exchange between the metal hydride and (iPr2N)2P−P(SiMe3)Li and subsequent metathesis with ClSiMe3. Formation of similar metal silyls is even more pronounced in the analogous reactions

Figure 3. Molecular structure of 2 showing the atom-numbering scheme (50% probability displacement ellipsoids). H atoms have been omitted. Important bond lengths (pm) and bond angles (deg): P1−P2 221.8(2), P1−W1 255.3(2), P1−C10 181.1(6), P2−P1−W1 104.30(7).

Figure 4. Molecular structure of 3d showing the atom-numbering scheme (50% probability displacement ellipsoids). H atoms have been omitted. Important bond lengths (pm) and bond angles (deg): P1− W1 257.2(3), P1A−W1 256.7(3), P1−C1 184.5(11), P1−W1−P1A 73.2(1), W1−P1−W1A 106.8(1).

Scheme 5

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by pentane. A few red crystals of 3d were formed after a few days at room temperature. NMR examination (1H NMR 500 MHz, 31P 202.5 MHz) of the reaction solution allowed identifying the following products (2D spectra did not allow unequivocal assignment of all expected resonances; listed data include only sure assignments):

of [Cp2MoCl2] with R2P−P(SiMe3)Li and is in this case promoted by the presence of R2P−P(SiMe3)Li in excess.14

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EXPERIMENTAL SECTION

Toluene and THF were dried over Na/benzophenone and distilled under argon. Pentane was dried over Na/benzophenone/diglyme and distilled under argon. All manipulations were performed in flame-dried Schlenk-type glassware on a vacuum line. Solution 31P, 13C, and 1H spectra were recorded on Bruker AV300 MHz, Bruker AV400 MHz, or Varian 500 MHz spectrometers (external standard TMS for 1H, 13C; 85% H3PO4 for 31P; aq WO42− (Ξ = 4.166388 MHz for 183W)) at ambient temperature. Two-dimensional gradient-selected 1H COSY, 1 H NOESY, and 1H,31P and 1H,183W HMQC spectra were measured using standard pulse sequences. Solid-state 31P CP-MAS NMR spectra of 1a were recorded on a Bruker AV400 MHz spectrometer equipped with a 4 mm MAS probe using a spinning speed of 9 kHz and crosspolarization with a ramp-shaped contact pulse and mixing times of 5 ms for signal enhancement. Literature methods were used to prepare R2P−P(SiMe3)Li·nL (R = tBu, iPr, iPr2N, L = THF, DME;15 R = NEt216) and [Cp2WCl2].17 Synthesis of 1a. A solution of 0.323 g (0.808 mmol) of tBu2P− P(SiMe3)Li·2THF in 2 mL of toluene was added dropwise to a suspension of 0.243 g (0.631 mmol) of [Cp2WCl2] in 2 mL of toluene at −30 to −40 °C. Then the solution was held at ambient temperature for 1 h. The solution was reduced to a half under reduced pressure and investigated by 31P{1H}, 31P, and 1H NMR. The solvent was evaporated under reduced pressure, and the residue was extracted with pentane. The extract was filtrated and stored at −30 °C. Red crystals were formed after a few days (65 mg, yield 14%). From a similar reaction in DME (molar ratio 2:1) crystals of 1a have been also isolated. 1a. 31P{1H} (162.9 MHz, C6D6, ambient temp): δ 46.8 (m, 1JPP = 244.4 Hz, 1JPW = 10.2 Hz tBu2P); 46.2 (m, 1JPP = 244.4 Hz, 1JPW = 7.2 Hz WP). 1H (500 MHz, C6D6 ambient temp): δ 5.72 (m, 1 H,C5H4); 5.03 (m, 1 H, C5H4); 4.40 (s, 5 H, C5H5); 4.08 (m, 1 H, C5H4); 3.44 (m, 1 H, C5H4); 1.47 (dd, 9 H, 1.3 + 9.9 Hz, CCH3); 1.31 (dd, 9 H, 2.1 + 8.7 Hz, CCH3); −12.32 (m-unresolved t, 1 H, 1JWH = 75.1 Hz, WH). 13C{1H} (100.6 MHz, C6D6, ambient temp): δ 103.93 (dd, 4.2 + 12.2 Hz, C5H4P) 77.81 (s, C5H5); 77.9 (dd, 10.2 + 24.4 Hz, C5H4P); 75.54 (dd, 2.8 + 7.0 Hz, C5H4P); 72.99 (d, 1.6 Hz, C5H4P); 33.32 (dd, 7.5 + 10.4 Hz CCH3); 33.00 (d, 20.7 Hz, CCH3); 32.53 (d, 13.0 Hz, CCH3); 32.13 (dd 6.4 + 12.2 Hz, CCH3). Anal. Found: C = 44.48, H = 5.85. Calcd for C18H28P2W: C = 44.10, H = 5.76. 1b. 31P{1H}(162.9 MHz, C6D6 ambient temp): δ 36.1 (d, 1JPP = 236.1 Hz, 1JPW = 6.5 Hz, tBu2P); 26.1 (d, 1JPP = 236.1 Hz, 1JPW = 25.3 Hz, WP). 1H (500 MHz, C6D6, ambient temp): δ 5.19 (m, 1 H, C5H4); 4.77 (m, 2 H,C5H4); 4.47 (s, 5 H, C5H5); 3.46 (m, 1 H, C5H4); 1.49 (dd, 9 H, 0.2 + 10.44 Hz, CCH3); 1.29 (dd, 9 H, 0.6 + 10.25 Hz, CCH3); −13.20 (m-unresolved d, 7.7 Hz, 1 H, 1JWH = 68.3 Hz, WH). 13 C{1H}(100.6 MHz, C6D6, ambient temp): δ 78.31(s; C5H5). Synthesis of 2. A solution of 0.270 g (0.947 mmol) of (Et2N)2P− P(SiMe3)Li in 2 mL of DME was added dropwise to a solution of 0.178 g (0.462 mmol) of [Cp2WCl2] in 2 mL of DME at −30 to −40 °C. Then the solution was held at ambient temperature for 1 h. The solution was reduced to a half under reduced pressure and investigated by 31P{1H}, 31P, and 1H NMR. The solvent was evaporated under reduced pressure, and the residue was extracted by pentane. The dark red extract was filtrated and stored at −30 °C. After 24 h, the extract turned yellow, and a few red crystals of 2 together with a relatively large amount of orange, amorphous powder were formed. This powder was insoluble in organic solvents. Synthesis of 3d. A solution of 0.481 g (1.098 mmol) of iPr2P− P(SiMe3)Li·1.25THF·1.33 toluene in 2 mL of toluene was added dropwise to a solution of 0.218 g (0.566 mmol) of [Cp 2WCl2] in 2 mL of toluene at −30 to −40 °C. Then the solution was held at ambient temperature for 1 h. The solution was reduced to half under reduced pressure and investigated by 31P{1H}, 31P, and 1H NMR. The solvent was evaporated under reduced pressure, and the residue was extracted

i

Pr2P(SiMe3): 31P{1H} δ −44.3 (s); 1H: δ 0.18 (d, JPH = 4 Hz), 1.96 (dd), 1.13 (dd). i Pr2PH: 31P{1H} δ −16.0 (s); 1H: 2.85 (d, 1JPH = 190 Hz), 1.79 (m, CH), 1.00 (dd, CH3). i Pr2PP(SiMe3)2.15 3c: 31P{1H} δ 30.9 (d,1JPP = 221 Hz, WP); 10.0 (d, 1JPP = 221 Hz, iPr2P); 1H: δ 4.85 (C5H4), 4.70 (C5H4), 4.50(C5H4), 4.38 (Cp), 3.50 (C5H4), 1.90 (CH3), 1.76 (CH3), 1.21 (CH3), 0.29 (d, JPH = 2 Hz, SiMe3). 3a: 31P{1H} δ 48.2 (d, 1JPP = 206 Hz, 1JPW = 22 Hz, WP); 19.1 (d, 1JPP = 206 Hz, iPr2P); 1H δ 5.55 (C5H4), 5.09 (C5H4), 4.44 (Cp), 4.08 (C5H4), 3.58 (C5H4), 1.95 (CH), 1.87 (CH), 1.33 (CH3), 1.18 (CH3), −12.6 (munresolved t, 1JWH = 73 Hz, WH). 3b: 31P{1H} δ 25.8 (d, 1JPP = 216 Hz, 1JPW = 20 Hz, WP); 10.7 (d, 1JPP = 216 Hz, iPr2P); 1H −13.3 (munresolved d, 7.1 Hz, 1JWH = 69.4 Hz, WH).

In addition, the signals of a further component of yet unidentified constitution were observed. 3x: 31P{1H} δ −97.0 (d, 1JPP = 340 Hz, 1JPW = 219 Hz, iPr2P), −160.9 (d, 1JPP = 340 Hz, WP); 1H: δ 4.17 (s), 1.77 (CH), 1.42 (CH), 1.32 (CH 3), 1.15 (CH3), 0.99 (CH3), 0.73 (CH3), −11.5 (m-unresolved d, 22.1 Hz, 1JWH = 65 Hz, WH). Synthesis of 4. A solution of 0.457 g (0.828 mmol) of (iPr2N)2P−P(SiMe3)Li·2.92THF in 2 mL of toluene was added dropwise to a suspension of 0.165 g (0.428 mmol) of [Cp 2WCl2] in 2 mL of toluene at −30 to −40 °C. Then the solution was held at ambient temperature for 1 h. The volume of the solution was reduced to half under reduced pressure and investigated by 31P{1H}, 31P, and 1 H NMR. The solvent was evaporated under reduced pressure, and the residue was extracted by pentane. The extract was filtrated and stored at 4 °C. After 6 days, red crystals of 4 deposited (120 mg, yield 43%). 4. 31P{1H} NMR (161.97 MHz, C6D6 ambient temp): δ 72.9 (d, 1 JPP = 222.4 Hz, 1JPW = 10.2 Hz (iPr2N)2P); 41.4 (d, 1JPP = 222.4 Hz, 1 JPW = 15.5 Hz WP). 1H (400 MHz, C6D6, ambient temp): δ 5.12 (m, 1 H, C5H4); 4.83 (m, 1 H, C5H4); 4.49 (m, 1 H, C5H4), 4.42 (s, 5 H, C5H5); 3.88−3.76 (m, 4 H, NCH); 3.41 (m, 1 H, C5H4); 1.41 (d, 3JHH = 6.6 Hz, 8 H, NCHCH3); 1.24 (d, 3JHH = 6.7 Hz, 8 H, NCHCH3); 1.18 (d, 3JHH = 6.6 Hz, 8 H, NCHCH3); 1.11 (d, 3JHH = 6.7 Hz, 8 H, NCHCH3); 0.44 (s, 9 H, SiCH3). In addition, small signals of (iPr2N)2P−P(SiMe3)H, arising presumably from hydrolytic decomposition, were visible. Crystallographic data for the structures of 1a, 2, and 3d reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication No. CCDC 832578, CCDC 832579, and CCDC 832580. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: (+44) 1223-336-033; e-mail: [email protected]).

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ASSOCIATED CONTENT

S Supporting Information *

This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author *E-mail: [email protected]. Tel: + 48 58 3472874. 6659


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ACKNOWLEDGMENTS

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REFERENCES

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J.P. and R.G. thank the Polish Ministry of Science and Higher Education (Grant No. N N204 271535) for financial support and J.P., R.G., D.G. thank the COST action CM0802 “PhoSciNet” for additional support. (1) (a) Cowley, A. H. Acc. Chem. Res. 1997, 30, 445. (b) Stephan, D. W. Angew. Chem., Int. Ed. 2000, 39, 314. (c) Lammertsma, K. Top. Curr. Chem. 2003, 229, 95. (d) Mathey, F. Dalton Trans. 2007, 1861. (e) Aktaş, H.; Slootweg, J. C.; Lammertsma, K. Angew. Chem., Int. Ed. 2010, 49, 2902. (2) (a) Waterman, R. Dalton Trans. 2009, 18. (b) Slootweg, J. C.; Lammertsma, K. In Science of Synthesis: Organophosphorus Compounds v.42; Thieme Chemistry, 2008. (3) Reviews: (a) Mathey, F. Angew. Chem. 1987, 99, 285. (b) Mathey, F.; Tran Huy, N. H.; Marinetti, A. Helv. Chim. Acta 2001, 84, 2938. (c) Lammertsma, K.; Vlaar, M. J. M. Eur. J. Org. Chem. 2002, 1127. (4) (a) Sterenberg, B. T.; Udachin, K. A.; Carty, A. J. Organometallics 2001, 20, 2657. (b) Sterenberg, B. T.; Sanli Senturk, O.; Udachin, K. A.; Carty, A. J. Organometallics 2007, 26, 925. (5) Hitchcock, P. B.; Lappert, M. F.; Wing-Por, L. J. Chem. Soc., Chem. Commun. 1987, 1282. (6) Cowley, A. H.; Pellerin, B.; Atwood, J. L.; Bott, S. G. J. Am. Chem. Soc. 1990, 112, 6734. (7) Fox, A. R.; Clough, C. R.; Piro, N. A.; Cummins, C. C. Angew. Chem., Int. Ed. 2007, 46, 973. (8) Arif, A. M.; Cowley, A. H.; Nunn, C. M; Pakulski, M. J. Chem. Soc., Chem. Commun. 1987, 994. (9) (a) Domańska-Babul, W.; Chojnacki, J.; Matern, E.; Pikies, J. Dalton Trans. 2009, 146. (b) Pikies, J.; Baum, E.; Matern, E.; Chojnacki, J.; Grubba, R.; Robaszkiewicz, A. J. Chem. Soc., Chem. Commun. 2004, 2478. (c) Grubba, R.; Wisń iewska, A.; Baranowska, K.; Matern, E.; Pikies, J. Dalton Trans. 2011, 40, 2017. (d) Grubba, R.; Wiśniewska, A.; Baranowska, K.; Matern, E.; Pikies, J. Polyhedron 2011, 30, 1238. (e) Łapczuk-Krygier.. Dissertation, Gdańsk University of Technology, 2011. (10) This work was presented in a preliminary form at the 18th International Conference on Phosphorus Chemistry; Pikies, J.; Grubba, R.; Ponikiewski, Ł.; Wiśniewska, A.; Łapczuk-Krygier, A.; Kruczyński, T. International Conference on Phosphorus Chemistry, July 11−15, 2010, Wroclaw, Poland, Book of Abstracts, p 69. (11) Bentrude, W. G.; Setzer, W. N. In Phosphorus-31 NMR Spectroscopy in Stereochemical Analysis; Verkade, J. G.; Quin, L. D., Eds.; Wiley-VCH: Deerfield Beach, FL, 1987; 331ff. (12) Mathey, F.; Svara, J. Organometallics 1986, 5, 1159. (13) Amor, I.; Garcia, M. E.; Ruiz, M.; Sáez, D.; Hamidov, H.; Jeffery, J. Organometallics 2006, 25, 4857. (14) Kruczyński, T.; Grubba, R.; Pikies, J. 8th European Workshop on Phosphorus Chemistry, March 28−29, 2011, Münster, Book of Abstracts, p 45. (15) Domańska-Babul, W.; Baranowska, K.; Grubba, R.; Matern, E.; Pikies., J. Polyhedron 2007, 26, 2491. (16) Kovacs, I.; Matern, E.; Fritz, G. Z. Anorg. Allg. Chem. 1996, 622, 935. (17) Persson, C.; Andersson, C. Organometallics 1993, 12, 2370.

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