Kinetics of the SN1 Dissociation of Ligands L (Nitriles, Phosphines) in

22 Jun 2017 - Kinetics of the SN1 Dissociation of Ligands L (Nitriles, Phosphines) in the Complexes [CpFe(P-P)L]PF6 with Variable Chelate Ring Size...
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Kinetics of the SN1 Dissociation of Ligands L (Nitriles, Phosphines) in the Complexes [CpFe(P-P)L]PF6 with Variable Chelate Ring Size. A Surprising Bimolecular Substitution in the Nonchelate Complex [CpFe(PPh2Me)2L]PF6 Henri Brunner,*,† Hikaru Kitamura,‡ and Takashi Tsuno*,‡ †

Institut für Anorganische Chemie, Universität Regensburg, 93040 Regensburg, Germany Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Chiba 275-8575, Japan

‡

S Supporting Information *

ABSTRACT: The complexes [CpFe{Ph2P(CH2)nPPh2}NCMe]PF6, [CpFe(PPh2Me)2NCMe]PF6, and [CpFe{Ph2P(CH2)nPPh2}PPh2(OR)]PF6, R = Me, Et, and iPr, with chelate ring sizes between 4 and 7 were synthesized and characterized by spectroscopy and Xray analysis. In these complexes, the monodentate ligands acetonitrile and PPh2(OR) tend to dissociate. The kinetics of the ligand exchanges MeCN/P(OMe)3 and PPh2(OR)/P(OMe)3 was measured. In the acetonitrile series, the first-order reaction of the five-membered chelate complex [CpFe(dppe)NCMe]PF6 had a half-life of 549 min in CDCl3 at 293 K. The other chelate complexes [CpFe(P-P)NCMe]PF6 and the nonchelate analogue [CpFe(PPh2Me)2NCMe]PF6 reacted faster by factors of 20−50. The PPh2(OR) series revealed a dramatic difference between the complexes [CpFe(P-P)PPh2(OR)]PF6 with five- and six-membered chelate rings. The PPh2(OR)/P(OMe)3 exchange in the dppp complex (six-membered chelate ring) was 500 times faster than in the dppe complex (five-membered chelate ring). This is due to the increase of the P−Fe−P angle in the dppp chelate ring, which diminishes the binding pocket of the PPh2(OR) ligand. In the nonchelate complex [CpFe(PPh2Me)2NCMe]PF6, a novel and unexpected bimolecular PPh2Me/PPh2(OMe) substitution was observed.

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INTRODUCTION In the 1930s, the classical SN1- and SN2-mechanisms of the nucleophilic substitution at the saturated carbon atom were established by Hughes and Ingold. The SN1 mechanism remains an integral part of organic chemistry.1 SN1-type ligand dissociation (dissociative substitution D) is also an important elementary step in transition metal chemistry. It is the basis of mechanistic studies, and it generates unsaturated species in homogeneous catalysis. In a series of papers, we investigated the ligand dissociation in chiral-at-metal complexes to learn about chiral 16-electron intermediates in epimerization (change of the metal configuration) and ligand exchange reactions.2−5 In particular, we dealt with the complexes [CpFe(Prophos)NCMe]PF6 and [CpFe(Prophos)PPh2(OR)]PF6, R = Me, Et, and iPr.6,7 In both types of compounds, the monodentate ligands acetonitrile and PPh2(OR) tend to dissociate, leaving an unsaturated 16-electron intermediate [CpFe(Prophos)]+. For the 16-electron intermediate [CpRu(Prophos)]+, a pyramidal structure, chiral at the Ru atom, is firmly established.5 In the present paper, we report a systematic study of the ligand exchange in the compounds [CpFe(P-P)NCMe]PF6 and [CpFe(P-P)PPh2(OR)]PF6, varying the ring size of the chelate ligand P-P. We include a comparison of the complex © XXXX American Chemical Society

[CpFe(dppe)NCMe]PF6, containing the chelate ligand dppe = Ph2P(CH2)2PPh2, with its nonchelate analogue [CpFe(PPh2Me)2NCMe]PF6.

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RESULTS AND DISCUSSION Syntheses of the Complexes [CpFe(P-P)L]PF6. The acetonitrile complexes [CpFe{Ph2P(CH2)nPPh2}NCMe]PF6, containing the easily dissociating acetonitrile ligand, were prepared by irradiation of [CpFe(CO)2I] with the chelate ligands P-P and NH4PF6 in acetonitrile (Scheme 1). The yields were between 60% and 80%. The complex with n = 5 could not be obtained. We also synthesized the complex [CpFe(PPh2Me)2NCMe]PF6 (Scheme 1, bottom), which is analogous to the complex [CpFe(dppe)NCMe]PF6 by the relation Ph2PCH2-CH2PPh2 ≡ PPh2CH2-H + H-CH2PPh2 (PPh2CH2H = PPh2Me). Replacement of the C−C bond in the chelate of [CpFe(dppe)NCMe]PF6 by two C−H bonds in [CpFe(PPh2Me)2NCMe]PF6 removes the chelate effect. The red nitrile complexes are air-stable in the solid state. They dissolve in CHCl3 or CH2Cl2, but not in diethyl ether or hexane. Received: April 22, 2017

A

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics Scheme 1. Synthesis of the Complexes [CpFe(P-P)NCMe]PF6

Table 1. Synthesis of the Complexes [CpFe(P-P)L]PF6 and [CpFe(PPh2Me)2L]PF6

product Ph2P(CH2)nPPh2 dppm dppe

dppp

dppb 2 × PPh2Me

L

yield/%

P(OMe)3 P(OMe)3 PPh(OMe)2 PPh2(OMe) PPh2(OEt) PPh2(OiPr) P(OMe)3 PPh(OMe)2 PPh2(OMe) PPh2(OEt) P(OMe)3 P(OMe)3 PPh(OMe)2

49 85 54 51 54 55 58 63 33 39 73 37 73

Figure 1. First line: Cations of the complexes [CpFe{Ph2P(CH2)nPPh2}NCMe]PF6 with n = 1−4. Second line: Cations of the complexes [CpFe(Prophos)NCMe]PF6 and [CpFe(PPh2Me)2NCMe]PF6. Hydrogen atoms and PF6 anion are omitted for clarity.

B

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

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Figure 2. Cations of the complexes [CpFe{Ph2P(CH2)nPPh2}PPh2(OR)]PF6, R = Me, Et, iPr, with n = 2−3. Hydrogen atoms and PF6 anion are omitted for clarity.

PF6. The structures of the complexes are shown in the Supporting Information. Substitution of the Leaving Group Acetonitrile in the Complexes [CpFe(P-P)NCMe]PF6. The ligand acetonitrile dissociated from the complex [CpFe(dppe)NCMe]PF6 in CDCl3 solutions at 293 K. In the presence of a 10-fold excess, the ligand P(OMe)3 occupied the empty coordination position, forming the substitution product [CpFe(dppe)P(OMe)3]PF6. Figure 3 shows the decrease of the intensity of the 31P{1H}

We used the acetonitrile complexes [CpFe(P-P)NCMe]PF6 and [CpFe(PPh2Me)2NCMe]PF6 as starting materials for the synthesis of the complexes [CpFe(P-P)L]PF6 and [CpFe(PPh2Me)2L]PF6 which contain dissociating and nondissociating phosphorus ligands L (Table 1). The complexes [CpFe(PP)L]PF6 and [CpFe(PPh2Me)2L]PF6 were obtained as airstable crystals of orange-yellow color in moderate yields. They are soluble in CHCl3 and CH2Cl2 and insoluble in diethyl ether or hexane. X-ray Crystallography. Five acetonitrile complexes were characterized by X-ray crystallography. Table S1 (Supporting Information) contains the crystallographic data. The first line of Figure 1 shows the structures of the complexes [CpFe{Ph2P(CH2)nPPh2}NCMe]PF6 with n = 1−4. The structures with the ligands dppm and dppb are in the literature.8,9 The PPh2 groups on the right sides of the dppm and dppe complexes resemble each other. The second line of Figure 1 repeats the structure of [CpFe(Prophos)NCMe]PF6,6 a close relative of [CpFe(dppe)NCMe]PF6, and shows the structure of its nonchelate relative [CpFe(PPh2Me)2NCMe]PF6. The structures of the dppe and Prophos complexes are almost identical, including the conformations of the PPh2 groups. Interestingly, the structures of [CpFe(dppe)NCMe]PF6 and [CpFe(Prophos)NCMe]PF 6 on the one side and [CpFe(PPh2Me)2NCMe]PF6 on the other side are completely different with respect to their PP ligands. In our study, the phosphorus ligands PPh2(OR), R = Me, Et, iPr, had turned out to dissociate in solutions of the complexes [CpFe(Prophos)PPh2(OR)]PF6.7 We characterized five chelate complexes [CpFe{Ph2P(CH2)nPPh2}PPh2(OR)]PF6 with n = 2 and 3 by X-ray crystallography (Figure 2 and Table S1 in the Supporting Information). The structural similarity of the PPh2(OMe) and PPh2(OEt) complexes in the dppe as well as in the dppp series is striking. We also characterized eight configurationally stable complexes [CpFe{Ph2P(CH2)nPPh2}L]PF6, n = 1−4, and [CpFe(PPh2Me)2L]PF6, L = P(OMe)3 and PPh(OMe)2, by X-ray crystallography to compare bond lengths and geometries with the labile complexes. In addition, we included the structures of [CpFe(PPh 2 Me) 2 I], [CpFe(PPh 2 Me){PPh 2 (OMe)} 2 ]PF 6 , [CpFe{PPh2(OMe)}2NCMe]PF6, and [CpFe{PPh2(OMe)}3]-

Figure 3. Time-resolved 31P{1H} NMR spectra of the ligand exchange of [CpFe(dppe)NCMe]PF6 with P(OMe)3 (10 equiv) at 293 K in CDCl3.

NMR signal of dppe in [CpFe(dppe)NCMe]PF6 and the simultaneous increase of the signals of [CpFe(dppe)P(OMe)3]PF6. The clean first-order reaction had a half-life of τ1/2 = 549 min (Table 2). Parallel experiments demonstrated that the limits of error are below 10%. In ref 6, we had reported the kinetics of the MeCN/ P(OMe)3 ligand exchange in the diastereomers of [CpFe(Prophos)NCMe]PF6. For the (SFe,RC) diastereomer, the halflife τ1/2 had been 572 min in CDCl3 at 293 K. Thus, the rates of the MeCN/P(OMe)3 exchange in the related complexes [CpFe(dppe)NCMe]PF6 and [CpFe(Prophos)NCMe]PF6 are comparable. This is not surprising, as due to almost identical C

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

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Table 2. Kinetics of the MeCN/P(OMe)3 Ligand Exchange Reaction in [CpFe(P-P)NCMe]PF6 [P-P = Ph2P(CH2)nPPh2 (n = 1−4), PPh2Me × 2]

P-P activation parameters for 293 K a,b

dppm dppec ΔH⧧ = 118 ± 2 kJ mol−1 ΔS⧧ = 70 ± 5 J mol−1 K−1 ΔG⧧ = 98 ± 3 kJ mol−1 dpppc ΔH⧧ = 84 ± 4 kJ mol−1 ΔS⧧ = −21 ± 14 J mol−1 K−1 ΔG⧧ = 90 ± 7 kJ mol−1 dppbc ΔH⧧ = 88 ± 1 kJ mol−1 ΔS⧧ = −10 ± 4 J mol−1 K−1 ΔG⧧ = 91 ± 3 kJ mol−1 PPh2Me × 2c ΔH⧧ = 91 ± 2 kJ mol−1 ΔS⧧ = 10 ± 6 J mol−1 K−1 ΔG⧧ = 88 ± 3 kJ mol−1 a

k/min−1

temp/K 293 293 300 307 313 293 296 300 303 293 296 300 303 278 283 288 293

4.5 1.3 4.3 1.3 3.0 3.1 4.3 6.8 1.0 2.2 3.2 5.3 7.3 9.4 1.7 3.6 7.3

× × × × × × × × × × × × × × × × ×

10−4 10−3 10−3 10−3 10−2 10−2 10−2 10−2 10−1 10−2 10−2 10−2 10−2 10−3 10−2 10−2 10−2

± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

0.2 0.1 0.2 0.1 0.3 0.1 0.5 0.2 0.1 0.1 0.3 0.5 0.2 0.7 0.1 0.3 0.7

τ1/2/min × × × × × × × × × × × × × × × × ×

10−4 10−3 10−3 10−3 10−2 10−2 10−2 10−2 10−1 10−2 10−2 10−2 10−2 10−3 10−2 10−2 10−2

1540 549 163 53 23 22 16 10 7 32 22 13 10 74 40 19 10

In CD2Cl2. bFor side-reactions, see text. cIn CDCl3.

times faster than in its chelate analogue [CpFe(dppe)NCMe]PF6. The rate of acetonitrile substitution in the complexes [CpFe(L-L)NCMe]PF 6 follows the order [CpFe(PPh2Me)2NCMe]PF6 > [CpFe(dppb)NCMe]PF6 = [CpFe(dppp)NCMe]PF6 > [CpFe(dppe)NCMe]PF6 > [CpFe(dppm)NCMe]PF6. For explanation, trends in the Fe− NCMe bond lengths have already been given above. In addition, there are trends in the bond lengths Cp(Cent)−Fe [1.698 (dppm) < 1.705 (dppe) < 1.709 (dppp) < 1.714 (dppb) < 1.717 Å (PPh2Me × 2)] and Fe−P [2.207, 2.196 (dppm) < 2.211, 2.207 (dppe) ∼ 2.211, 2.208 (dppp) < 2.235, 2.228 (dppb) ∼ 2.227, 2.225 Å (PPh2Me × 2)]. However, the most important difference between the slowly reacting fivemembered chelate complex [CpFe(dppe)NCMe]PF6 and the faster reacting complexes is in the entropy of activation (Table 2). The dppe complex had a high positive activation entropy, while the ring-enlarged complexes had small negative activation entropies and the nonchelate complex [CpFe(PPh2Me)2NCMe]PF6 had a small positive activation entropy. The high positive activation entropy indicates a somewhat advanced acetonitrile dissociation in the transition state of the reaction of [CpFe(dppe)NCMe]PF6 compared to the other complexes. Substitutions in the Nonchelate Complex [CpFe(PPh 2 Me) 2 NCMe]PF 6 . In the reaction of [CpFe(PPh2Me)2NCMe]PF6 with 10 equiv of P(OMe)3, only the product [CpFe(PPh2Me)2P(OMe)3]PF6 was formed. Definitely, there is no formation of side-products (Figure 4). The same is true, when PPh(OMe)2 is used instead of P(OMe)3 (Figure S1 in the Supporting Information).

structures, there are no steric differences between the two complexes. Furthermore, the additional methyl group in the saturated backbone of the Prophos ligand does not change the electron density at the Fe atom, which is a crucial factor for the cleavage of the Fe−NCMe bond in the rate-determining step.6 The temperature dependence of the MeCN/P(OMe)3 exchange in [CpFe(dppe)NCMe]PF6 was as expected (Table 2). At 313 K, the half-life τ1/2 was down to 23 min. Table 2 contains the corresponding data of the dppp and dppb complexes. The enlargement of the chelate ring size to six and seven members increased the rate of the MeCN/P(OMe)3 exchange by factors of about 20. The faster cleavage of the Fe− NCMe bond in the rate-determining step of the dppp and dppb complexes with respect to the dppe complex with its fivemembered chelate ring is reflected by the increase of the Fe−N bond lengths [1.895 (dppe) < 1.903 (dppp) < 1.917 Å (dppb)]. The MeCN/P(OMe)3 exchange in [CpFe(dppm)NCMe]PF6 was not a clean reaction (Table 2, first line). Besides the expected accumulation of [CpFe(dppm)P(OMe)3]PF6, the slow formation of [CpFe{P(OMe)3}3]PF6 was observed. This is the only example in the present study in which substitution of a chelate ligand, due to the strain in the four-membered ring, is observed at ambient temperatures. The half-life of the acetonitrile substitution in [CpFe(dppm)NCMe]PF6 was τ1/2 = 1540 min at 293 K. Thus, the substitution of acetonitrile in [CpFe(dppm)NCMe]PF6 was even slower than that in [CpFe(dppe)NCMe]PF6. The MeCN/P(OMe)3 exchange in the nonchelate complex [CpFe(PPh2Me)2NCMe]PF6 was the fastest substitution reaction of the whole series (Table 2, last part). With a half-life of τ1/2 = 10 min at 293 K, it was about 55 D

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

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Otherwise, in the reaction of [CpFe(PPh2Me)2NCMe]PF6 with P(OMe)3, the ligand PPh2Me should dissociate, leaving the unsaturated intermediate [CpFe(PPh2Me)NCMe]+. This high-energy intermediate should react with P(OMe)3 to give the product [CpFe(PPh2Me){P(OMe)3}NCMe]PF6 which should be a stable compound. Steric reasons cannot be responsible for the fact that the reactive unsaturated intermediate [CpFe(PPh2Me)NCMe]+ did not react with P(OMe)3 (and PPh(OMe)2). Keeping the reaction partner [CpFe(PPh2Me)2NCMe]PF6 constant, fundamental differences must be attributed to the other reaction partner P(OMe)3, PPh(OMe)2, and PPh2(OMe). It is the increasing nucleophilicity in the series P(OMe)3 < PPh(OMe)2 < PPh2(OMe) that explains the differences in the reaction of [CpFe(PPh2Me)2NCMe]PF6 with P(OMe)3/PPh(OMe)2/ PPh2(OMe). Due to the low nucleophilicities of P(OMe)3 and PPh(OMe)2, their bimolecular reactions with [CpFe(PPh2Me)2NCMe]PF6 were too slow. The higher nucleophilicity of PPh2(OMe) speeded up its bimolecular reaction with [CpFe(PPh2Me)2NCMe]PF6 such that it competed with the SN1 dissociation of acetonitrile. Support for the bimolecularity of the reaction of [CpFe(PPh2Me)2NCMe]PF6 with PPh2(OMe) came from the side of the starting material and the products in Figures 6 and 7. In the

Figure 4. Time-resolved 31P{1H} NMR spectra of the ligand exchange of [CpFe(PPh2Me)NCMe]PF6 with P(OMe)3 (10 equiv) at 293 K in CDCl3.

We present these results in such detail, because the use of the reactant PPh2(OMe), which is a better nucleophile than P(OMe)3 and PPh(OMe)2, changes the picture completely and forces us to assume bimolecularity for the reaction of [CpFe(PPh2Me)2NCMe]PF6 with PPh2(OMe). Up to now, ligand substitution in half-sandwich complexes of the threelegged piano-stool type has always been preceded by the dissociation of a leaving ligand. Clear examples of associative reactions are unknown. The reaction of [CpFe(PPh2Me)2NCMe]PF6 with PPh2(OMe) is an example of a dissociative reaction (Figure 5).

Figure 6. Time dependence of the concentrations of reactants and products in the reaction of [CpFe(PPh2Me)2NCMe]PF6 with 10 equiv of PPh2(OMe) in CDCl3 at 293 K: [CpFe(PPh2Me)2NCMe]PF6 (blue square), [CpFe(PPh2Me)2PPh2(OMe)]PF6 (burgundy diamond), [CpFe(PPh2Me){PPh2(OMe)}2]PF6 (green triangle), [CpFe(PPh 2 Me){PPh 2 (OMe)}NCMe]PF 6 (purple circle), [CpFe{PPh 2 (OMe)} 2 NCMe] (blue open triangle), and [CpFe{PPh2(OMe)}3] (orange open diamond).

reaction with 10 equiv of PPh2(OMe) (Figure 6), the concentration of the starting material [CpFe(PPh2Me)2NCMe]PF6 decreases faster than with 1 equiv of PPh2(OMe) (Figure 7). Similarly, the first-order formation of [CpFe(PPh2Me)2P(OMe)3]PF6 is relatively faster than the bimolecular formation of [CpFe(PPh2Me){P(OMe)3}NCMe]PF6 for the reaction with 1 equiv of PPh2(OMe) compared to 10 equiv of PPh2(OMe). The situation with 5 equiv of PPh2(OMe) is intermediate (Figure S2 in the Supporting Information). Compound [CpFe(PPh2Me){PPh2(OMe)}2]PF6 was the product of subsequent substitution reactions in the primary products [CpFe(PPh2 Me) 2 PPh 2(OMe)]PF6 and [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6. Its concentration rose steadily with time (Figures 5−7). Because of the complexity of the systems, the mechanism of its formation will not be commented.

Figure 5. Time-resolved 31P{1H} NMR spectra of the ligand exchange of [CpFe(PPh2Me)2NCMe]PF6 with PPh2(OMe) (10 equiv) at 293 K in CDCl3.

Besides the expected accumulation of [CpFe(PPh2Me)2PPh2(OMe)]PF6, the formation of [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6 was observed (Figure 5). In addition, the double substitution product [CpFe(PPh2Me){PPh2(OMe)}2]PF6 built up and the compounds [CpFe{PPh2(OMe)}3]PF6 and [CpFe{(PPh2(OMe)}2NCMe]PF6, albeit in low concentrations. The formation of [CpFe(PPh2Me)2PPh2(OMe)]PF6 occurs by dissociation of acetonitrile from [CpFe(PPh2Me)2NCMe]PF6 via the unsaturated 16-electron intermediate [CpFe(PPh2Me)2]+. The formation of [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6, however, cannot follow a similar pathway. E

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

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In principle, the bimolecular reactions of [CpFe(PPh2Me)2NCMe]PF6 with PPh2(OMe) and PPh2(OiPr) can occur by backside or frontside attack. Whether it occurs by an SN2-type mechanism (associative substitution A) as in organic chemistry or not remains open. Contrary, all the other substitution reactions are dissociative in nature, monomolecular, and independent of the nucleophile concentration. Substitution of the Leaving Group PPh2(OR) in the Complexes [CpFe(P-P)PPh2(OR)]PF6. The most configurationally stable complex in the series [CpFe(P-P)PPh2(OR)]PF6, R = Me, Et, iPr, is the five-membered chelate complex [CpFe(dppe)PPh2(OMe)]PF6 with the small PPh2(OMe) ligand. The half-life of the PPh2(OMe)/P(OMe)3 exchange in CDCl3 at 323 K was 2083 h (Table 3). At 338 K, the half-life dropped to 222 h. Due to changes in the steric/electronic effects, the half-lives of the PPh2(OEt) complex were 1698 h at 323 K and 109 h at 338 K and of the PPh2(OiPr) complex 204 h at 323 K and 14 h at 338 K (Table 4). These values are in agreement with those of the PPh2(OR)/P(OMe)3 exchange in [CpFe(Prophos)PPh2(OR)]PF6.7 The increase of the rate in the series PPh2(OMe) < PPh2(OEt) < PPh2(OiPr) of the complexes [CpFe(dppe)PPh2(OR)]PF6 is supported by the increasing Fe−P bond lengths 2.199 < 2.210 < 2.224 Å. Surprisingly, the dissociation of the ligands PPh2(OMe) and PPh2(OEt) in the six-membered chelate complexes [CpFe(dppp)PPh2(OR)]PF6 was in a completely different category than that of the five-membered chelate complexes [CpFe(dppe)PPh2(OR)]PF6. The half-lives in CDCl3 at 323 K were 5 h for the ligand PPh2(OMe) and 3 h for the ligand PPh2(OEt) (Table 4). The dramatic difference must be ascribed to steric effects. A dramatic structural difference between dppe and dppp complexes was observed in the Cp*Fe(P-P) series. Whereas [Cp*Fe(dppe)OTf] is a neutral 18-electron complex,10,11 [Cp*Fe(dppp)]+OTf− is a salt-like complex with a 16-electron cation.12 In the dissociation of the acetonitrile ligand in the complexes [CpFe(P-P)NCMe]PF6, there were no steric effects, because the Fe−N bond breaks in the linear system Fe-N-CMe. The huge differences between the complexes [CpFe(dppe)PPh2(OR)]PF6 and [CpFe(dppp)PPh2(OR)]PF6 can only be explained by strongly increased steric hindrance. A comparison of the structures of [CpFe(dppe)PPh2(OMe)]PF6 and [CpFe(dppp)PPh2(OMe)]PF6 shows that the Fe−P[PPh2(OR)] bond lengths increase from 2.199 to 2.218 Å and, more importantly, that the angles P−Fe−P within the chelate rings increase from 84.5° to 92.3°. The increase of the P−Fe−P angles diminishes the size of the binding pocket for the ligand PPh2(OR) in the dppp complex with respect to the dppe complex and explains the large rate differences. The small rate increase from the PPh2(OMe) to the PPh2(OEt) complexes by factors of 1.5 and 1.8 is due to the slight increase of the electron density at the Fe atom and the slight

Figure 7. Time dependence of the concentration of reactants and products in the reaction of [CpFe(PPh2Me)2NCMe]PF6 with 1 equiv of PPh2(OMe) in CDCl3 at 293 K: [CpFe(PPh2Me)2NCMe]PF6 (blue square), [CpFe(PPh2Me)2PPh2(OMe)]PF6 (burgundy diamond), [CpFe(PPh2Me){PPh2(OMe)}2]PF6 (green triangle), [CpFe(PPh 2 Me){PPh 2 (OMe)}NCMe]PF 6 (purple circle), [CpFe{PPh 2 (OMe)} 2 NCMe] (blue open triangle), and [CpFe{PPh2(OMe)}3] (orange diamond).

Table 3 shows the kinetics of the ligand exchange in [CpFe(PPh2Me)2NCMe]PF6 in the presence of 1, 5, and 10 equiv of PPh2(OMe) in CDCl3 at 293 K. From the data in Figures 6, 7, and S2 (the Supporting Information), we extracted the rates of disappearance of [CpFe(PPh2Me)2NCMe]PF6 and the rates of formation of [CpFe(PPh2Me)2{PPh2(OMe)}]PF6 and [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6, not taking into account the formation of the byproducts, [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6, [CpFe{PPh2(OMe)}2NCMe], and [CpFe{PPh2(OMe)}3]. In accord with a dissociative substitution, the rates k D of the formation of [CpFe(PPh2Me)2{PPh2(OMe)}]PF6 are independent of the concentration of PPh2(OMe), whereas the rates kA of the formation of [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6 increase with increasing concentration of PPh2(OMe), in accord with an associative substitution. Assuming a dissociative mechanism, the rates of dissociation of the Fe−NCMe bond in the ligand exchange of the systems [CpFe(PPh2Me)2NCMe]PF6/10 equiv P(OMe)3 and [CpFe(PPh2Me)2NCMe]PF6/10 equiv PPh2(OMe) should be the same. We ascribe the differences between 7.3 × 10−2 min−1 (Table 2) and 1.8 × 10−2 min−1 (Table 3) to the complexity of the system [CpFe(PPh2Me)2NCMe]PF6/10 equiv PPh2(OMe). Instead of PPh2(OMe), we also used PPh2(OiPr) (1 equiv) in the reaction with [CpFe(PPh 2Me) 2NCMe]PF 6 . We observed fast formation of [CpFe(PPh2Me){PPh2(OiPr)}NCMe]PF6 and slow formation of [CpFe(PPh2Me)2PPh2(OiPr)]PF6, in accord with the similar nucleophilicities of the ligands PPh2(OMe)/PPh2(OiPr) (Figure S3 in the Supporting Information). In addition, there was a small amount of [CpFe{PPh2(OiPr)}3]PF6.

Table 3. Ligand Exchange of [CpFe(PPh2Me)2NCMe]PF6 (ca. 35 mmol mol−1) with PPh2(OMe) in CDCl3 at 293 K PPh2(OMe)

kobsa/min−1

ratio [CpFe(PPh2Me)2{PPh2(OMe)}]PF6: [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6 (disappear. of [CpFe(PPh2Me)2NCMe]PF6)

kDb/min−1

kAc/min−1

1 equiv 5 equiv 10 equiv

5.8 × 10−3 1.3 × 10−2 1.9 × 10−2

71:29 (27%) 84:16 (39%) 91:9 (48%)

4.1 × 10−3 1.1 × 10−2 1.8 × 10−2

1.7 × 10−3 2.0 × 10−3 1.8 × 10−3

a

Rate of disappearance of [CpFe(PPh2Me)2NCMe]PF6. bRate of formation of [CpFe(PPh2Me)2{PPh2(OMe)}]PF6. cRate of formation of [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6. F

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

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Organometallics

Table 4. Kinetics of the PPh2(OR)/P(OMe)3 Ligand Exchange Reaction in [CpFe(P-P)PPh2(OR)]PF6 [P-P = Ph2P(CH2)nPPh2 (n = 2, 3)] in CDCl3

P-P, R activation parameters for 323 K dppe, Me ΔH⧧ = 136 ± 1 kJ mol−1 ΔS⧧ = 39 ± 2 J mol−1 K−1 ΔG⧧ = 122 ± 1 kJ mol−1 dppe, Et ΔH⧧ = 160 ± 1 kJ mol−1 ΔS⧧ = 118 ± 1 J mol−1 K−1 ΔG⧧ = 121 ± 1 kJ mol−1 dppe, iPr ΔH⧧ = 164 ± 3 kJ mol−1 ΔS⧧ = 147 ± 10 J mol−1 K−1 ΔG⧧ = 117 ± 6 kJ mol-1 dppp, Me ΔH⧧ = 133 ± 4 kJ mol−1 ΔS⧧ = 79 ± 12 J mol−1 K−1 ΔG⧧ = 107 ± 7 kJ mol−1 dppp, Et ΔH⧧ = 142 ± 1 kJ mol−1 ΔS⧧ = 115 ± 1 J mol−1 K−1 ΔG⧧ = 105 ± 1 kJ mol−1

k/min−1

temp/K 323 328 333 338 323 328 333 338 323 328 333 338 313 318 323 328 313 318 323 328

5.5 1.1 2.7 5.2 6.8 2.2 4.6 1.1 5.7 1.1 3.7 8.2 4.0 7.6 2.4 3.9 7.4 1.9 4.3 9.5

× × × × × × × × × × × × × × × × × × × ×

−6

10 10−5 10−5 10−5 10−6 10−5 10−5 10−4 10−5 10−4 10−4 10−4 10−4 10−4 10−3 10−3 10−4 10−3 10−3 10−3

± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

1.0 0.3 0.2 0.5 0.1 0.2 0.3 0.3 0.2 0.2 0.3 0.5 0.2 0.2 0.2 0.4 0.4 0.3 0.2 0.5

τ1/2/h × × × × × × × × × × × × × × × × × × × ×

−7

10 10−5 10−5 10−5 10−6 10−5 10−5 10−5 10−5 10−4 10−4 10−4 10−4 10−4 10−3 10−4 10−4 10−4 10−3 10−3

2083 1035 422 222 1698 519 251 109 204 102 31 14 29 15 5 3 16 6 3 1

Figure 8. Energy profile for the MeCN/P(OMe)3 and PPh2R/P(OMe)3 ligand exchange in the complexes [CpFe(P-P)L]PF6. G

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

five- to the six-membered chelate complex [CpFe(P-P)PPh2(OR)]PF6, ascribed to a diminution of the binding pocket of the PPh2(OR) ligand, which favored its dissociation. In the nonchelate complex [CpFe(PPh2Me)2NCMe]PF6, a novel and unexpected bimolecular substitution PPh2Me/PPh2(OR), R = Me, iPr, was observed.

enlargement of the ligand cone angle from 132° to 133° (Table 4).13 Is the 16-Electron Intermediate [CpFe(P-P)]+ Pyramidal or Planar? The rate-determining cleavage of the Fe−L bond in solutions of [CpFe(P-P)L]PF6 leaves the unsaturated intermediate [CpFe(P-P)]+.5−7 Calculations predict pyramidal structures for 16-electron intermediates [CpFeL2)]+, when L is a π-accepting ligand, while [CpFe(NH3)2]+ is assigned a planar structure.14 The energy profile of Figure 8 shows a smaller activation energy for the dissociation of acetonitrile in the complexes [CpFe(P-P)NCMe]PF6 than for the dissociation of PPh2(OR) ligands in the complexes [CpFe(P-P)PPh2(OR)]PF6. However, both types of complexes, labile toward ligand dissociation, are still above the borderline of configurational stability, whereas all the products [CpFe(P-P)P(OMe)3]PF6 and [CpFe(P-P)PPh(OMe)2]PF6 are configurationally stable and below this line. Their ligands P(OMe)3 and PPh(OMe)2 do not dissociate at ambient temperatures. In a stereochemical study with the diastereomers (RFe,RC)and (SFe,RC)-[CpFe(Prophos)NCMe]PF6, we had shown that the epimerization (change of the Fe configuration) is faster than the MeCN/P(OMe)3 ligand exchange.6 This was explained by a much higher barrier for the bimolecular reaction intermediate/P(OMe)3 compared to the bimolecular reaction intermediate/MeCN (Figure 8).6 The results of the present paper show that the rates of the MeCN/P(OMe)3 exchange in [CpFe(dppe)NCMe]PF6 and [CpFe(Prophos)NCMe]PF6 are of the same magnitude. The MeCN/P(OMe)3 ligand exchange in the diastereomers (RFe,RC)- and (SFe,RC)-[CpFe(Prophos)NCMe]PF6 had given constant ratios of the product diastereomers.6 With respect to the structure of the 16-electron intermediate [CpFe(Prophos)]+, two explanations had been suggested: (a) the intermediate [CpFe(Prophos)]+ is planar or (b) there is fast equilibration between the pyramidal intermediates. Assuming planar intermediates [CpFe(P-P)]+, the understanding of the rate trend, observed in the acetonitrile substitutions, would be straightforward. The 16-electron intermediate [CpFe(PPh2Me)2]+ with two separate PPh2Me ligands could easily adopt a planar structure with a P−Fe−P angle of about 100°. For comparison, the P−M−P angles of the planar 18-electron complexes [CpCo(PPh3)2] and [CpNi(PPh3)2]+ are 99.7° and 102.9°.15,16 Thus, the acetonitrile dissociation in [CpFe(PPh2Me)2NCMe]PF6 is fastest. For intermediates with decreasing chelate ring sizes, the planarization becomes increasingly difficult, which would explain the decreasing rates from the seven-membered to the four-membered chelate complexes. On the other hand, strain would build up in planar intermediates with decreasing chelate ring size. In particular, a planar intermediate [CpFe(dppm)]+ would be a highly strained species, as the four-membered chelate rings of the dppm ligand have P−M−P angles of about 70°. The P−Fe−P angle in the complex [CpFe(dppm)NCMe]PF6 is 74.67°, which seems too small for a planar structure.8

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EXPERIMENTAL SECTION

General. We characterized the 26 compounds in this experimental section by IR, 1H, 13C, 31P{1H} NMR, mass spectroscopy, including high resolution mass spectroscopy, and elemental analysis. IR: JASCO FT/IR4100ST. 1H, 13C and 31P{1H} NMR: Bruker Avance 400S (400/100/162 MHz) or Bruker Avance III 500 (500/125/202 MHz) (1H: TMS as internal standard, 31P: H3PO4 as external standard). The multiplicity in 13C NMR spectra is shown as 13C−31P couplings. MS: Agilent Q-TOF 6540 UHD, JEOL AccuTOF GCX, Finnigan MAT 95, or ThermoQuest Finnigan TSQ 7000. All manipulations were carried out in purified nitrogen. All solvents were dried and distilled before use according to standard procedures. PPh(OMe)2 and dppe were purchased from Wako Pure Chem. Ind. Ltd. PPh2Me, PPh2(OMe), PPh2(OEt), and dppm were purchased from TCI Chem. Ind. Co. Ltd. dppp and dppb were purchased from Kanto Chem. Co. Inc. PPh2(OiPr) was prepared according to the literature.7 X-ray Analysis. Crystal and refinement data are given in Table S1 (Supporting Information). X-ray data were collected on a Rigaku RAXIS-RAPID imaging plate diffractometer using Mo-Kα (graphite monochromated, λ = 0.71073 Å, fine focus tube, ω-scan) radiation at 173 K. The structures were solved by SIR 201117 or SIR 9718 and refined by full-matrix least-squares on F2 by SHELX 97.19 All H atoms were included at calculated positions. Synthesis of the Complexes [CpFe{Ph2P(CH2)nPPh2}NCMe]PF6, n = 1−4. A solution of [CpFe(CO)2I], the chelate ligand P-P, and NH4PF6 in 100 mL of MeCN was irradiated using a 100 W highpressure Hg lamp with a Pyrex jacket under a nitrogen atmosphere at 0 °C for 8 h. After evaporation of the solvent, the residue was dissolved in CH2Cl2. The insoluble material was removed by filtration through Celite. The solution was concentrated and chromatographed on silica gel using CH2Cl2 as an eluent. The red-orange color fraction was collected and evaporated to give the products [CpFe(P-P)NCMe]PF6. (Acetonitrile-κN)(η 5 -cyclopentadienyl)[1,1′-methylenebis(diphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(dppm)NCMe]PF6:8,20,21 [CpFe(CO)2I] (316 mg, 1.04 mmol), 1,1′-methylenebis[1,1diphenylphosphine], dppm, (400 mg, 1.04 mmol), and NH4PF6. Chromatography with CH2Cl2. Yield: 57% (414 mg) of [CpFe(dppm)NCMe]PF6. IR (KBr): ν 2270 (NC), 837 cm−1 (PF). 1H NMR (400 MHz, acetone-d6, 293 K): δ = 7.90−7.80 (m, 4H, Ar-H), 7.70−7.63 (m, 4H, Ar-H), 7.59−7.46 (m, 12H, Ar-H), 5.23 (dt, 1H, 2JH‑H = 15.9 Hz, 2JP‑H = 10.9 Hz, CH), 4.63 (s, 5H, Cp-H), 4.19 (dt, 1H, 2JH‑H = 15.9 Hz, 2 JP‑H = 11.2 Hz, CH), 1.82 (t, 3H, 5JP‑H = 1.4 Hz, Me) ppm. 13C NMR (100 MHz, acetone-d6, 293 K): δ = 135.64 (t, 2C, 1JP‑C = 19.6 Hz, ipsoC), 136.33 (s, 1C, CN), 133.19 (t, 2C, 1JP‑C = 18.9 Hz, ipso-C), 133.09 (t, 4C, 2 or 3JP‑C = 5.5 Hz, o- or m-C), 132.38 (t, 4C, 2 or 3JP‑C = 5.1 Hz, o- or m-C), 131.61 (s, 2C, p-C), 131.55 (s, 2C, p-C), 129.99 (t, 4C, 2 or 3 JP‑C = 5.1 Hz, o- or m-C), 129.78 (t, 4C, 2 or 3JP‑C = 4.9 Hz, o- or mC), 77.99 (s, 5C, Cp), 43.40 (t, 1C, 1JP‑C = 20.2 Hz, CH2), 4.28 (s, 1C, Me) ppm. 31P{1H} NMR (162 MHz, acetone-d6, 293 K): δ = 35.94 (s, 2P, dppm), −144.22 (septet, 1P, 1JP‑F = 712.1 Hz, PF6) ppm. Anal. Calcd for C32H30F6FeNP3 (691.34): C, 55.59; H, 4.37; N, 2.03. Found: C, 55.56; H, 4.21; N, 1.78 (Acetonitrile-κN) (η 5 -cyclopentadienyl)[1,2-ethanediylbis(diphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(dppe)NCMe]PF6:9,20−24 [CpFe(CO)2I] (318 mg, 1.05 mmol), 1,1′-(1,2-ethanediyl)bis[1,1diphenylphosphine], dppe, (425 mg, 1.07 mmol), and NH4PF6 (1.22 g, 7.48 mmol). Chromatography with CH2Cl2/THF (50:1, v/v). Yield: 76% (559 mg) of [CpFe(dppe)NCMe]PF6. Crystallization from CHCl3/diethyl ether gave crystals suitable for X-ray analysis.

■

CONCLUSION The ligand exchange MeCN/P(OMe)3 in the complexes [CpFe{Ph2P(CH2)nPPh2}NCMe]PF6, n = 1−4, occurred according to first-order kinetics, indicating a dissociative substitution of the acetonitrile ligand. The same was found for the PPh2(OR)/P(OMe)3 exchange in the compounds [CpFe{Ph2P(CH2)nPPh2}PPh2(OR)]PF6, R = Me, Et, and iPr. The PPh2(OR) series revealed a dramatic rate increase from the H

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics IR (KBr): ν 2268 (NC), 840 cm−1 (PF). 1H NMR (400 MHz, CDCl3, 293 K): δ = 7.79−7.75 (m, 4H, Ar-H), 7.58−7.54 (m, 4H, ArH), 7.51−7.44 (m, 8H, Ar-H), 7.32−7.29 (m, 4H, Ar-H), 4.32 (s, 5H, Cp-H), 2.64−2.34 (m, 4H, CH2CH2), 1.50 (s, 3H, MeCN) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 137.14 (t, 2C, 1JP‑C = 18.7 Hz, ipso-C), 136.73(t, 2C, 1JP‑C = 18.7 Hz, ipso-C), 134.27 (s, 1C, CN), 132.56 (t, 4C, 2 or 3JP‑C = 4.7 Hz, o- or m-C), 131.26 (t, 4C, 2 or 3JP‑C = 4.6 Hz, o- or m-C), 130.84 (s, 2C, p-C), 130.48 (s, 2C, p-C), 129.20 (t, 4C, 2 or 3JP‑C = 4.9 Hz, o- or m-C), 129.09 (t, 4C, 2 or 3JP‑C = 4.7 Hz, oor m-C), 78.88 (s, 5C, Cp), 27.95 (t, 2C, 1JP‑C = 21.1 Hz, CH2), 3.88 (s, 1C, Me) ppm. 31P{1H} NMR (400 MHz, CDCl3, 293 K): δ = 97.72 (s, 2P, dppe), −144.16 (septet, 1P, 1JP‑F = 712.0 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C33H32FeNP2+ 560.1367, found m/ z 560.1354. Anal. Calcd for C33H32F6FeNP3 (705.37): C, 56.19; H, 4.57; N, 1.99. Found: C, 56.33; H, 4.70; N, 1.83. (Acetonitrile-κN)(η 5 -cyclopentadienyl)[1,3-propanediylbis(diphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(dppp)NCMe]PF6: [CpFe(CO)2I] (350 mg, 1.15 mmol), 1,1′-(1,3-propanediyl)bis[1,1-diphenylphosphine], dppp, and NH4PF6 (1.06 g, 6.50 mmol). Chromatography with THF/CH2Cl2 (1:50, v/v). Yield: 59% (485 mg) of [CpFe(dppp)NCMe]PF6. Crystallization from CHCl3 gave crystals of [CpFe(dppp)NCMe]PF6 suitable for X-ray analysis. IR (KBr): ν 2259 (NC), 839 cm−1 (PF). 1H NMR (400 MHz, CDCl3, 293 K): δ = 7.63−7.60 (m, 4H, Ar-H), 7.53−7.44 (m, 8H, ArH), 7.30 (m, 4H, Ar-H), 7.22−7.18 (m, 4H, Ar-H), 4.15 (s, 5H, CpH), 2.55−2.26 (m, 3H, CH2 and CH), 2.40 (s, 3H, Me), 1.87 (t, 2H, J = 13.8 Hz, CH2), 1.59−1.48 (m, 1H, CH) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 137.95 (t, 2C, 1JP‑C = 20.7 Hz, ipso-C), 136.57 (t, 2C, 1JP‑C = 21.3 Hz, ipso-C), 135.73 (s, 1C, CN), 132.81 (t, 4C, 2 or 3 JP‑C = 4.9 Hz, o- or m-C), 131.52 (t, 4C, 2 or 3JP‑C = 4.6 Hz, o- or mC), 130.48 (s, 2C, p-C), 130.31 (s, 2C, p-C), 129.01 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 128.48 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 79.79 (s, 5C, Cp), 26.68 (t, 2C, 1JP‑C = 13.1 Hz, CH2), 20.23 (s, 1C, CH2), 5.07 (s, 1C, Me) ppm. 31P{1H} NMR (400 MHz, CDCl3, 293 K): δ = 56.22 (s, 2P, dppp), −144.31 (septet, 1P, 1JP‑F = 712.8 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C34H34FeNP2+ 574.1516, found m/ z 574.1510. Anal. Calcd for C34H34F6FeNP3 (719.40): C, 56.76; H, 4.76; N, 1.95. Found: C, 56.74; H, 4.52; N, 1.96. (Acetonitrile-κN)(η 5 -cyclopentadienyl)[1,4-butanediylbis(diphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(dppb)NCMe]PF6:9 [CpFe(CO)2I] (234 mg, 0.77 mmol), 1,1′-(1,4-butanediyl)bis[1,1diphenylphosphine], dppb (345 mg, 0.81 mmol), and NH4PF6 (1.04 g, 6.39 mmol). Chromatography with THF/CH2Cl2 (1:50, v/v). Yield: 79% (447 mg) of [CpFe(dppb)NCMe]PF6. 1 H NMR (400 MHz, CDCl3, 293 K): δ = 7.57−7.49 (m, 16H, ArH), 7.37−7.21 (m, 4H, Ar-H), 3.94 (s, 5H, Cp-H), 2.65−2.59 (m, 2H, CH2), 2.30−1.33 (m, 6H, CH2), 2.24 (s, 3H, MeCN) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 137.07 (t, 2C, 1JP‑C = 19.5 Hz, ipso-C), 135.56 (s, 1C, CN), 135.98 (t, 2C, 1JP‑C = 18.7 Hz, ipso-C), 132.29 (t, 4C, 2 or 3JP‑C = 4.5 Hz, o- or m-C), 131.59 (t, 4C, 2 or 3JP‑C = 4.2 Hz, oor m-C), 130.69 (s, 2C, p-C), 130.28 (s, 2C, p-C), 129.09 (t, 4C, 2 or 3 JP‑C = 4.6 Hz, o- or m-C), 128.90 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or mC), 79.92 (s, 5C, Cp), 29.60 (t, 2C, 1JP‑C = 10.7 Hz, CH2), 23.82 (s, 2C, CH2), 5.04 (s, 1C, Me) ppm. 31P{1H} NMR (400 MHz, CDCl3, 293 K): δ = 62.37 (s, 2P, dppb), −144.24 (septet, 1P, 1JP‑F = 712.5 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C35H36FeNP2+ 588.1671, found m/ z 588.1667. Anal. Calcd for C35H36F6FeNP3 (733.42): C, 57.32; H, 4.95; N, 1.91. Found: C, 57.31; H, 5.09; N, 1.83. Synthesis of the Complexes [CpFe(PPh2Me)2I] and [CpFe(PPh2Me)2NCMe]PF6. (η5-Cyclopentadienyl)[bis(methyldiphenylphosphine-κP)]iodo iron, [CpFe(PPh2Me)2I]: A solution of [CpFe(CO)2I] (269 mg, 0.73 mmol) and PPh2Me (0.5 mL, 2.69 mmol) in toluene (80 mL) was irradiated by a 100 W high-pressure mercury lamp with a Pyrex jacket under a nitrogen

atmosphere for 8 h. After evaporation of the solvent, the black reside was chromatographed on silica gel using CH2Cl2 as an eluent. The purple-black fraction gave [CpFe(PPh2Me)2I] in 6% (46 mg) yield. Crystallization from CH2Cl2/hexane gave pure crystals of [CpFe(PPh2Me)2I]·CH2Cl2 suitable for X-ray analysis. 1 H NMR (400 MHz, benzene-d6, Cp2Co, 293 K): δ = 8.00−7.02 (m, 20H, Ar-H), 4.10 (s, 5H, Cp-H), 1.70 (s, 6H, Me) ppm. 13C NMR (100 MHz, benzene-d6, Cp2Co, 293 K): δ = 142.48 (t, 2C, 1JP‑C = 18.7 Hz, ipso-C), 140.19 (t, 2C, 1JP‑C = 17.8 Hz, ipso-C), 133.30 (t, 4C, 2 or 3 JP‑C = 3.3 Hz, o- or m-C), 132.77 (t, 4C, 2 or 3JP‑C = 3.7 Hz, o- or mC), 129.33−128.02 (m, 12C, Ar-C), 76.64 (s, 5C, Cp), 19.74 (t, 2C, JP‑C = 12.4 Hz, Me) ppm.31P{1H} NMR (162 MHz, benzene-d6, Cp2Co, 293 K): δ = 57.20(s, 2P, PPh2Me) ppm. FD-HRMS: Calcd for the cation C31H31FeIP2+ 648.0290, found m/z 648.0285. (Acetonitrile-κN)(η5-cyclopentadienyl)[bis(methyldiphenylphosphineκP)]iron hexafluorophosphate, [CpFe(PPh2Me)2NCMe]PF6: Method a: A solution of [CpFe(PPh2Me)2I] (46.4 mg, 0.72 mmol) and NH4PF6 (120 mg, 0.74 mmol) in MeCN (20 mL) was stirred for 14 h at room temperature. After evaporation of the solvent, the residue was filtrated on Celite with CHCl3 to give [CpFe(PPh2Me)2NCMe]PF6 in quantitative yield. Method b: A solution of [CpFe(CO)2I] (311 mg, 1.02 mmol), PPh2Me (0.5 mL, 2.69 mmol), and NH4PF6 (1.34 g, 8.22 mmol) in MeCN (100 mL) was irradiated and worked up as described in the synthesis of the complexes [CpFe{Ph2P(CH2)nPPh2}NCMe]PF6, n = 1−4. Yield: 45% (325 mg) of [CpFe(PPh 2 Me)2 NCMe]PF6 . Crystallization from CH2Cl2/EtOAc/hexane gave crystals suitable for X-ray analysis. IR (KBr): ν 2180 (NC), 843 cm−1 (PF). 1H NMR (400 MHz, CDCl3, 293 K): δ = 7.64−6.91 (m, 20H, Ar-H), 4.25 (s, 5H, Cp-H), 2.48 (s, 3H, MeCN), 1.28 (s, 6H, PMe) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 139.51 (t, 2C, 1JP‑C = 19.8 Hz, ipso-C), 136.04 (s, 1C, CN), 135.25 (t, 2C, 1JP‑C = 19.8 Hz, ipso-C), 132.49 (t, 4C, 2 or 3 JP‑C = 4.5 Hz, o- or m-C), 130.82 (s, 2C, p-C), 130.66 (t, 4C, 2 or 3 JP‑C = 4.4 Hz, o- or m-C), 129.78 (s, 2C, p-C), 128.89 (t, 4C, 2 or 3 JP‑C = 4.2 Hz, o- or m-C), 128.72 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or mC), 79.27 (s, 5C, Cp), 14.40 (t, 2C, JP‑C = 12.3 Hz, Me), 5.13 (s, 1C, Me) ppm. 31P{1H} NMR (400 MHz, CDCl3, 293 K): δ = 47.07 (s, 2P, PPh2), −144.04 (septet, 1P, 1JP‑F = 712.5 Hz, PF6) ppm. ES-MS (CH2Cl2/MeCN): m/z 562 ([CpFe(PPh2Me)2NCMe]+, 26), 521 ([CpFe(PPh2Me)2]+, 100). Anal. Calcd for C33H34F6FeNP3 (707.39): C, 56.03; H, 4.84; N, 1.98. Found: C, 55.84; H, 4.72; N, 1.88. Synthesis of the Complexes [CpFe{Ph2P(CH2) nPPh 2}P(OMe)3]PF6, n = 1−4. A solution of [CpFe(P-P)NCMe]PF6, the chelate ligand P-P, and P(OMe)3 in CHCl3 (40 mL) was stirred for 20 h at room temperature. After evaporation of the solvent, the residue was chromatographed on silica gel using CH2Cl2 as an eluent. The yellow fraction was collected to give the yellow products [CpFe(PP)P(OMe)3]PF6. (η 5 -Cyclopentadienyl)[1,1-methylenebis(diphenylphosphine-κP)](trimethyl phosphite-κP)iron hexafluorophosphate, [CpFe(dppm)P(OMe)3]PF6: [CpFe(dppm)NCMe]PF6 (150 mg, 0.22 mmol) and P(OMe)3 (0.20 mL, 0.15 mmol). Orange crystals of [CpFe(dppm)P(OMe)3]PF6, suitable for X-ray analysis, were deposited in the reaction mixture and washed with diethyl ether. Yield: 49% (83 mg). 1 H NMR (400 MHz, acetone-d6, 293 K): δ = 7.69−7.63 (m, 4H, Ar-H), 7.48−7.31 (m, 16H, Ar-H), 4.86 (ddt, 1H, 4JP‑H = 2.5 Hz, 2JH‑H = 15.2 Hz, 2JP‑H = 10.5 Hz, CH), 4.71 (t, 5H, 3JP‑H = 1.5 Hz, Cp-H), 4.51 (dt, 1H, 2JP‑H = 15.2 Hz, 2JP‑H = 12.6 Hz, CH), 3.25 (d, 9H, 3JP‑H = 10.7 Hz, OCH3) ppm. 13C NMR (100 MHz, acetone-d6, 293 K): δ = 137.83 (dt, 2C, 3JP‑C = 2.7 Hz, 1JP‑C = 18.4 Hz, ipso-C), 136.73 (dt, 2C, 3 JP‑C = 2.8 Hz, 1JP‑C = 23.7 Hz, ipso-C), 132.18 (t, 4C, 2 or 3JP‑C = 4.9 Hz, o- or m-C), 132.01 (t, 4C, 2 or 3JP‑C = 4.9 Hz, o- or m-C), 131.28 (s, 2C, p-C), 131.09 (s, 2C, p-C), 129.85 (t, 4C, 2 or 3JP‑C = 5.1 Hz, o- or m-C), 129.19 (t, 4C, 2 or 3JP‑C = 5.1 Hz, o- or m-C), 79.19 (s, 5C, Cp), 54.19 (d, 3C, JP‑C = 9.5 Hz, OCH3), 42.25 (dt, 1C, 1JP‑C = 24.4 Hz, I

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

2.38 (m, 2H, CH2), 1.96−1.48 (m, 4H, CH2) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 139.16 (t, 2C, 1JP‑C = 23.5 Hz, ipso-C), 138.13 (ddd, 2C, 1JP‑C = 17.3 Hz, 2JP‑C = 15.5 Hz, 2JP‑C = 2.2 Hz, ipsoC), 132.16 (t, 4C, 2 or 3JP‑C = 4.0 Hz, o- or m-C), 131.33 (t, 4C, 2 or 3 JP‑C = 4.2 Hz, o- or m-C), 130.40 (s, 2C, p-C), 129.70 (s, 2C, p-C), 128.82 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 128.22 (t, 4C, 2 or 3JP‑C = 4.6 Hz, o- or m-C), 80.74 (s, 5C, Cp), 54.01 (d, 3C, JP‑C = 10.5 Hz, OCH3), 32.01 (t, 2C, 1JP‑C = 11.8 Hz, CH2), 23.08 (s, 2C, CH2) ppm. 31 1 P{ H} NMR (162 MHz, CDCl3, 293 K): δ = 170.74 (t, 1P, 2JP‑P = 91.0 Hz, P(OMe)3), 56.61 (d, 2P, 2JP‑P = 91.0 Hz, dppb), −144.33 (septet, 1P, 1JP‑F = 712.8 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C36H42FeO3P3+ 671.1696, found m/z 671.1691. Anal. Calcd for C36H42F6FeO3P4 (816.45): C, 52.96; H, 5.19. Found: C, 52.98; H, 4.86. Synthesis of the Complexes [CpFe(PPh2Me)2L]PF6, L = P(OMe) 3 and PPh(OMe) 2 , and [CpFe(P(OMe) 3 ]PF 6 . (η 5 Cyclopentadienyl)[bis(methyldiphenylphosphine-κP)](trimethyl phosphite-κP)iron hexafluorophosphate, [CpFe(PPh2Me)2P(OMe)3]PF6: A solution of [CpFe(PPh2Me)2NCMe]PF6 (222 mg, 0.31 mmol) and P(OMe)3 (1.0 mL, 8.48 mmol) in CHCl3 (30 mL) was stirred for 30 min at room temperature. After evaporation of the solvent, the residue was washed with diethyl ether/hexane to give [CpFe(PPh2Me)2P(OMe)3]PF6 as orange crystals in 37% (91 mg) yield. Crystallization from CH2Cl2/hexane gave crystals of [CpFe(PPh2Me)2P(OMe)3]PF6·CH2Cl2 suitable for X-ray analysis. IR (KBr): ν 1044 (PO), 842 cm−1 (PF). 1H NMR (400 MHz, CDCl3, 293 K): δ = 7.50−7.03 (m, 20H, Ar-H), 4.36 (s, 5H, Cp-H), 3.69 (d, 9H, 3JP‑H = 9.6 Hz, OCH3), 1.72 (s, 6H, PCH3) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 139.06−138.48 (m, 4C, ipso-C), 131.69 (t, 4C, 2 or 3JP‑C = 4.5 Hz, o- or m-C), 131.31 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 130.09 (s, 4C, p-C), 128.81 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 128.46 (t, 4C, 2 or 3JP‑C = 4.6 Hz, o- or m-C), 80.49 (s, 5C, Cp), 54.56 (d, 3C, 1JP‑C = 11.1 Hz, OCH3), 18.21 (t, 2C, 2JP‑C = 14.0 Hz, CH3) ppm. 31P{1H} NMR (162 MHz, CDCl3, 293 K): δ = 171.52 (t, 1P, 2JP‑P = 99.7 Hz, P(OMe)3), 46.35 (d, 2P, 2JP‑P = 99.7 Hz, dppb), −144.31 (septet, 1P, 1JP‑F = 712.8 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C34H40FeO3P3+ 645.1548, found m/z 645.1534. Anal. Calcd for C34H40F6FeO3P4 (790.41): C, 51.66; H, 5.10. Found: C, 51.60; H, 4.81. (η 5 -Cyclopentadienyl)(dimethyl P-phenylphosphonite-κP)[bis(methyldiphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(PPh2Me)2PPh(OMe)2]PF6: A solution of [CpFe(PPh2Me)2NCMe]PF6 (106 mg, 0.15 mmol) and PPh(OMe)2 (0.5 mL, 3.15 mmol) in CHCl3 (20 mL) was stirred at room temperature for 1 h. After evaporation of the solvent, the residue was chromatographed on silica gel. The orange fraction was collected and evaporated. The residue was crystallized by CHCl3/ EtOAc/hexane to afford [CpFe(PPh2Me)2PPh(OMe)2]PF6 in 73% (134 mg) yield. Crystallization from CH2Cl2/diethyl ether gave crystals of [CpFe(PPh2Me)2PPh(OMe)2]PF6·CH2Cl2 suitable for Xray analysis. 1 H NMR (400 MHz, CDCl3, 293 K): δ = 7.52−7.25 (m, 20H, ArH), 6.97−6.77 (m, 5H, Ar-H), 4.11 (s, 5H, Cp-H), 3.65 (d, 6H, 3JP‑H = 10.4 Hz, POMe), 1.87 (t, 6H, 3JP‑H = 10.4 Hz, PMe) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 140.76−140.35 (m, 2C, ipso-C), 138.96−138.50 (m, 2C, ipso-C), 135.37 (d, 1C, 1JP‑C = 41.8 Hz, ipsoC), 132.36 (t, 4C, 2 or 3JP‑C = 4.8 Hz, o- or m-C), 131.28 (s, 1C, p-C), 131.76 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 130.16 (s, 2C, p-C), 129.81 (d, 2C, 2JP‑C = 10.9 Hz, o-C), 129.76 (s, 2C, p-C), 129.37 (d, 2C, 3JP‑C = 8.7 Hz, m-C), 128.86 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 128.79 (t, 4C, 2 or 3JP‑C = 4.6 Hz, o- or m-C), 81.57 (s, 5C, Cp), 57.51 (d, 2C, 2JP‑C = 16.4 Hz, OCH3), 18.79 (dd, 2C, 1JP‑C = 2JP‑C = 12.9 Hz, CH3) ppm. 31P{1H} NMR (CDCl3, 293 K): δ = 198.49 (t, 1P, 2JP‑P = 93.2 Hz, P(OMe)2, 46.83 (d, 2P, 2JP‑P = 93.2 Hz, PCH3), −144.24 (septet, 1P, 1JP‑F = 712.8 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C39H42FeO2P3+ 691.1747, found m/z 691.1742.

2

JP‑C = 6.0 Hz, CH2) ppm. 31P{1H} NMR (162 MHz, CDCl3, 293 K): δ = 172.15 (t, 1P, 2JP‑P = 93.2 Hz, P(OMe)3), 31.94 (d, 2P, 2JP‑P = 93.2 Hz, dppm), −144.24 (septet, 1P, 1JP‑F = 712.4 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C33H36FeO3P3+ 629.1227, found m/z 629.1221. Anal. Calcd for C33H36F6FeO3P4 (774.37): C, 51.18; H, 4.69. Found: C, 51.18; H, 4.83. (η 5 -Cyclopentadienyl)[1,2-ethanediylbis(diphenylphosphine-κP)](trimethyl phosphite-κP)iron hexafluorophosphate, [CpFe(dppe)P(OMe)3]PF6:22 [CpFe(dppe)NCMe]PF6 (245 mg, 0.35 mmol) and P(OMe)3 (1.0 mL, 8.48 mmol). Yield: 85% (233 mg) of [CpFe(dppe)P(OMe)3]PF6. Crystallization from CHCl3/EtOAc/diethyl ether gave yellow crystals suitable for X-ray analysis. IR (KBr): ν 1060 (PO), 1018 (PO), 836 cm−1(PF). 1H NMR (400 MHz, CDCl3, 293 K): δ = 7.65−7.61 (m, 4H, Ar-H), 7.52−7.32 (m, 12H, Ar-H), 7.19−7.15 (m, 4H, Ar-H), 4.53 (s, 5H, Cp-H), 3.12 (d, 9H, 3JP‑H = 10.5 Hz, OCH3), 2.95−2.77 (m, 2H CH2), 2.61−2.45 (m, 2H, CH2) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 139.61 (dt, 1C, 3JP‑C = 3.6 Hz, 1JP‑C = 12.4 Hz, ipso-C), 139.22 (dt, 1C, 3JP‑C = 3.6 Hz, 1JP‑C = 12.7 Hz, ipso-C),135.65 (dt, 1C, 3JP‑C = 2.8 Hz, 1JP‑C = 8.0 Hz, ipso-C), 135.40 (dt, 1C, 3JP‑C = 2.7 Hz, 1JP‑C = 7.5 Hz, ipso-C), 131.90 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 131.12 (t, 4C, 2 or 3JP‑C = 4.6 Hz, o- or m-C), 130.36 (s, 2C, p-C), 130.03 (s, 2C, p-C), 128.75 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 128.50 (t, 4C, 2 or 3JP‑C = 4.9 Hz, oor m-C), 79.94 (s, 5C, Cp), 53.79 (d, 3C, JP‑C = 10.9 Hz, OCH3), 27.34 (ddd, 2C, 1JP‑C = 22.9 Hz, 1JP‑C = 20.2 Hz, 2JP‑C = 2.7 Hz, CH2) ppm. 31P{1H} NMR (162 MHz, CDCl3, 293 K): δ = 168.30 (t, 1P, 2 JP‑P = 93.7 Hz, P(OMe)3), 96.49 (d, 2P, 2JP‑P = 93.7 Hz, dppe), −144.29 (septet, 1P, 1JP‑F = 712.5 Hz, PF6) ppm. ES-MS (CH2Cl2/MeOH): m/z 643 ([CpFe(dppe)P(OMe)3]+, 100), 519 ([CpFe(dppe)]+, 15). Anal. Calcd for C34H38F6FeO3P4 (788.39): C, 51.80; H, 4.86. Found: C, 51.67; H, 4.77. (η 5-Cyclopentadienyl)[1,3-propanediylbis(diphenylphosphineκP)](trimethyl phosphite-κP)iron hexafluorophosphate, [CpFe(dppp)P(OMe)3]PF6: [CpFe(dppp)NCMe]PF6 (195 mg, 0.27 mmol) and P(OMe)3 (1.0 mL, 8.48 mmol). Yield: 58% (127 mg) of [CpFe(dppp)P(OMe)3]PF6 (yellow powder). Crystallization from CHCl3/diethyl ether gave crystals suitable for X-ray analysis. IR (KBr): ν 1053 (PO), 1032 (PO), 842 cm−1 (PF). 1H NMR (400 MHz, CDCl3, 293 K): δ = 7.62−7.16 (m, 20H, Ar-H), 4.52 (s, 5H, Cp-H), 3.34 (d, 9H, 3JP‑H = 10.4 Hz, OCH3), 2.64−2.48 (m, 3H, CH2 and CH), 2.22−2.10 (m, 2H, CH2), 1.71−1.55 (m, 1H, CH) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 140.57 (dt, 2C, 3JP‑C = 2.9 Hz, 1 JP‑C = 19.5 Hz, ipso-C), 136.70 (t, 2C, 1JP‑C = 23.3 Hz, ipso-C), 132.43 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 132.00 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 130.23 (s, 2C, p-C), 130.20 (s, 2C, p-C), 128.43 (t, 4C, 2 or 3 JP‑C = 4.4 Hz, o- or m-C), 128.32 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or mC), 80.85 (s, 5C, Cp), 53.68 (d, 3C, JP‑C = 9.9 Hz, OCH3), 26.75 (t, 2C, 1JP‑C = 15.1 Hz, CH2), 20.39 (s, 1C, CH2) ppm. 31P{1H} NMR (162 MHz, CDCl3, 293 K): δ = 170.14 (t, 1P, 2JP‑P = 89.9 Hz, P(OMe)3), 51.48 (d, 2P, 2JP‑P = 89.4 Hz, dppp), −144.36 (septet, 1P, 1 JP‑F = 712.8 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C35H40FeO3P3+ 657.1540, found m/z 657.1534. Anal. Calcd for C35H40F6FeO3P4 (802.42): C, 52.39; H, 5.02. Found: C, 52.28; H, 4.79. (η5-Cyclopentadienyl)[1,3-propanediylbis(diphenylphosphine-κP)](trimethyl phosphite-κP)iron hexafluorophosphate, [CpFe(dppb)P(OMe)3]PF6: [CpFe(dppb)NCMe]PF6 (166 mg, 0.23 mmol) and P(OMe)3 (1.0 mL, 8.48 mmol). Yield: 73% (134 mg) of [CpFe(dppb)P(OMe)3]PF6 (yellow powder). Crystallization from CHCl3/diethyl ether gave crystals suitable for X-ray analysis. IR (KBr): ν 1051, 1028 (PO), 841 cm−1 (PF). 1H NMR (400 MHz, CDCl3, 293 K): δ = 7.55−7.40 (m, 20H, Ar-H), 4.20 (s, 5H, Cp-H), 3.45 (d, 9H, 3JP‑H = 10.4 Hz, OCH3), 2.80−2.68 (m, 2H, CH2), 2.49− J

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics 2 or 3

JP‑C = 4.9 Hz, o- or m-C), 128.13 (d, 4C, 2 or 3JP‑C = 9.5 Hz, o- or m-C), 80.31 (s, 5C, Cp), 56.23 (d, 1C, 2JP‑C = 7.7 Hz, OCH3), 27.63 (t, 2C, 2JP‑C = 22.0 Hz, CH2) ppm. 31P{1H} NMR (CDCl3, 293 K): δ = 171.97 (t, 1P, 2JP‑P = 65.4 Hz, POMe), 87.68 (d, 2P, 2JP‑P = 65.4 Hz, dppe), −144.16 (septet, 1P, 1JP‑F = 712.9 Hz, PF6) ppm. ES-MS (CH2Cl2/MeOH): m/z 735 ([CpFe(dppe)PPh2(OMe)]+, 100), 519 ([CpFe(dppe)]+, 68). Anal. Calcd for C44H42F6FeOP4 (880.53): C, 60.02; H, 4.81. Found: C, 59.99; H, 4.73. (η 5 -Cyclopentadienyl)(ethyl P,P-diphenylphosphinite-κP)[1,2ethanediylbis(diphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(dppe)PPh2(OEt)]PF6: [CpFe(dppe)NCMe]PF6 (203 mg, 0.29 mmol) and PPh2OEt (1 mL, 4.63 mmol). Yield: 54% (139 mg) of [CpFe(dppe)PPh2(OEt)]PF6 after crystallization from EtOAc/hexane. Crystallization from CHCl3/diethyl ether gave crystals suitable for X-ray analysis. IR (KBr): ν 1024 (PO), 838 (PF) cm−1. 1H NMR (CDCl3, 293 K): δ = 7.44−7.22 (m, 22H, Ar-H), 7.07 (t, 4H, 3JH‑H = 7.1 Hz, Ar-H), 6.72 (t, 4H, 3JH‑H = 8.4 Hz, Ar-H), 4.40 (s, 5H, Cp-H), 3.31−3.24 (m, 2H, POCH2), 2.92−2.47 (m, 4H, CH2), 1.40 (t, 3H, 3JH‑H = 7.2 Hz, CH3) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 138.67−138.00 (m, 2C, ipso-C), 136.50−135.97 (m, 2C, ipso-C), 135.24 (d, 2C, 1JP‑C = 38.6 Hz, ipso-C), 131.86 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 131.42 (d, 4C, 3JP‑C = 10.2 Hz, m-C), 131.40 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 133.51 (d, 2C, 4JP‑C = 1.8 Hz p-C), 130.33 (s, 2C, p-C), 130.14 (s, 2C, p-C), 129.04 (t, 4C, 2 or 3JP‑C = 4.7 Hz, o- or m-C), 128.86 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 128.10 (d, 4C, 2JP‑C = 14.5 Hz, o-C), 80.51 (s, 5C, Cp), 65.69 (t, 1C, 1JP‑C = 14.9 Hz, OCH2), 21.62 (t, 2C, 2 JP‑C = 21.3 Hz, CH2), 16.27 (d, 1C, 2JP‑C = 6.5 Hz, CH3) ppm. 31 1 P{ H} NMR (CDCl3, 293 K): δ = 169.29 (t, 1P, 2JP‑P = 66.5 Hz, P(OEt)), 86.30 (d, 2P, 2JP‑P = 66.5 Hz, dppe), −144.18 (septet, 1P, 1 JP‑F = 712.8 Hz, PF6) ppm. ES-MS (CH2Cl2/MeOH): m/z 749 ([CpFe(dppe)PPh2(OEt)]+, 100), 519 ([CpFe(dppe)]+, 85). Anal. Calcd for C45H44F6FeOP4 (894.56): C, 60.42; H, 4.96. Found: C, 60.44; H, 5.03. (η 5 -Cyclopentadienyl)[1,2-ethanediylbis(diphenylphosphine-κP)](isopropyl P,P-diphenylphosphinite-κP)iron hexafluorophosphate, [CpFe(dppe)PPh2(OiPr)]PF6: [CpFe(dppe)NCMe]PF6 (214 mg, 0.30 mmol) and PPh2(OiPr) (1 mL) in PhCl (20 mL) were warmed at 50 °C for 14 h. The reaction mixture was evaporated, and the residue was chromatographed on silica gel with CH2Cl2. The orange fraction was collected and evaporated. The orange powder was crystallized from EtOAc to give [CpFe(dppe)PPh2(OiPr)]PF6 in 55% (151 mg) yield. Crystallization from CHCl3/diethyl ether gave crystals of [CpFe(dppe)PPh2(OiPr)]PF6·CHCl3 suitable for X-ray analysis. IR (KBr): ν 1093 (PO), 841 (PF) cm−1. 1H NMR (CDCl3, 293 K): δ = 7.53−7.18 (m, 22H, Ar-H), 7.11−7.024 (m, 4H, Ar-H), 6.90−6.81 (m, 4H, Ar-H), 4.36 (s, 5H, Cp-H), 4.20−4.07 (m, 1H, POCH), 2.91−2.5 (m, 4H, CH2), 0.94 (d, 6H, 3JH‑H = 6.5 Hz, CH3) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 138.81−138.15 (m, 2C, ipso-C), 135.45 (d, 2C, 1JP‑C = 37.3 Hz, ipso-C), 136.53−135.89 (m, 2C, ipsoC), 132.09 (d, 4C, 3JP‑C = 10.4 Hz, m-C), 131.80 (t, 4C, 2 or 3JP‑C = 4.0 Hz, o- or m-C), 131.68 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 130.62 (d, 2C, 4JP‑C = 1.8 Hz p-C), 130.23 (s, 4C, p-C), 129.15 (t, 4C, 2 or 3JP‑C = 4.7 Hz, o- or m-C), 128.81 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 127.85 (d, 4C, 2JP‑C = 8.9 Hz, o-C), 80.54 (s, 5C, Cp), 74.40 (d, 1C, 2 JP‑C = 16.2 Hz, OCH), 26.95 (t, 2C, 2JP‑C = 20.6 Hz, CH2), 24.41 (d, 2C, 3JP‑C = 2.9 Hz, CH3) ppm. 31P{1H} NMR (CDCl3, 293 K): δ = 165.99 (t, 1P, 2JP‑P = 65.3 Hz, P(OiPr)), 84.92 (d, 2P, 2JP‑P = 65.1 Hz, dppe), −144.18 (sept, 1P, 1JP‑F = 712.8 Hz, PF6) ppm. ES-MS (CH2Cl2/MeOH): m/z 763 ([CpFe(dppe)PPh2(OiPr)]+, 76), 519 ([CpFe(dppe)]+, 100). Anal. Calcd for C46H46F6FeOP4·CHCl3 (1027.96): C, 54.91; H, 4.61. Found: C, 54.91; H, 4.66. Synthesis of the Complexes [CpFe(dppp)L]PF 6 , L = PPh2(OMe), PPh2(OEt), and PPh(OMe)2. A solution of [CpFe(dppp)NCMe]PF6 and the ligand L was warmed at 50 °C for 6 h.

Anal. Calcd for C39H42F6FeO2P4 (836.48): C, 56.00 H, 5.06. Found: C, 56.21; H, 5.17. (η5-Cyclopentadienyl)[tris(trimethyl phosphite-κP)]iron hexafluorophosphate, [CpFe{P(OMe)3}3]PF6:20,25 A solution of [CpFe(CO)2I] (256 mg, 0.84 mmol), P(OMe)3 (0.5 mL, 4.24 mmol), and NH4PF6 (700 mg, 0.43 mmol) in THF (30 mL) was irradiated for 5 h using a 100 W high-pressure mercury lamp with a Pyrex jacket. After evaporation of the solvent, the residue was chromatographed on silica gel using CHCl3 as an eluent. The yellow fraction was collected to give [CpFe{P(OMe)3}3]PF6 as a yellow powder in 47% (254 mg) yield. Crystallization from CHCl3/diethyl ether gave crystals of [CpFe{P(OMe)3}3]PF6·CH2Cl2 suitable for Xray analysis. 1 H NMR (400 MHz, CDCl3, 293 K): δ = 4.67 (s, 5H, Cp-H), 3.71 (s, 27H, OCH3) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 80.90 (s, 5C, Cp), 53.59 (s, 9C, OMe) ppm. 31P{1H} NMR (CDCl3, 293 K): δ = 176.31 (s, 3P, P(OMe)3), −144.40 (sept, 1P, 1JP‑F = 710.7 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C14H32FeO9P3+ 493.0609, found m/z 493.0629. Synthesis of the Complexes [CpFe(dppe)L]PF6, L = PPh(OMe)2, PPh2(OMe), PPh2(OEt), and PPh2(OiPr). A solution of [CpFe(dppe)NCMe]PF6 and the ligand L in THF (40 mL) was refluxed for 18 h. After evaporation of the solvent, the residue was chromatographed on silica gel with CH2Cl2. The orange fraction was collected to give the products [CpFe(dppe)L]PF6 as orange powders. (η 5 -Cyclopentadienyl)[1,2-ethanediylbis(diphenylphosphine-κP)](dimethyl P-phenylphosphonite-κP)iron hexafluorophosphate, [CpFe(dppe)PPh(OMe)2]PF6: [CpFe(dppe)NCMe]PF6 (206 mg, 0.29 mmol) and PPh(OMe)2 (1.0 mL, 6.30 mmol). Yield: 54% (127 mg) of [CpFe(dppe)PPh(OMe)2]PF6. Crystallization from CHCl3/diethyl ether gave orange crystals suitable for X-ray analysis. 1 H NMR (400 MHz, CDCl3, 293 K): δ = 7.62−7.26 (m, 20H, ArH), 7.15−7.08 (m, 3H, Ar-H), 6.47 (t, 2H, 3JH‑H = 7.9 Hz), 4.40 (d, 5H, 3JP‑H = 1.1 Hz, Cp-H), 3.12 (d, 6H, J = 9.8 Hz, OCH3), 3.02−2.56 (m, 4H, CH2) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 140.28−139.73 (m, 2C, ipso-C), 135.64−135.02 (m, 2C, ipso-C), 134.58 (d, 1C, 1JP‑C = 43.6 Hz, ipso-C), 132.06 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 131.10 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 130.69 (d, 1C, 4JP‑C = 1.4 Hz, p-C), 130.23 (s, 2C, p-C), 129.87 (s, 2C, p-C), 129.38 (d, 2C, 2 or 3JP‑C = 10.2 Hz, o- or m-C), 128.92 (d, 2C, 2 or 3JP‑C = 9.3 Hz, o- or m-C), 128.73 (t, 4C, 2 or 3JP‑C = 5.1 Hz, o- or m-C), 128.67 (t, 4C, 2 or 3JP‑C = 4.9 Hz, o- or m-C), 80.60 (s, 5C, Cp), 56.90 (d, 2C, 1JP‑C = 15.6 Hz, OCH3), 27.66 (t, 2C, 2JP‑C = 21.1 Hz, CH2) ppm. 31P{1H} NMR (CDCl3, 293 K): δ = 195.14 (t, 1P, 2JP‑P = 80.7 Hz, POMe), 96.53 (d, 2P, 2JP‑P = 80.7 Hz, dppe), −144.24 (sept, 1P, 1 JP‑F = 712.8 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C39H40FeO2P3+ 689.1590, found m/z 689.1590. Anal. Calcd for C39H40F6FeO2P4 (834.46): C, 56.13; H, 4.83. Found: C, 56.13; H, 4.80. (η 5 -Cyclopentadienyl)[1,2-ethanediylbis(diphenylphosphine-κP)](methyl P,P-diphenylphosphinite-κP)iron hexafluorophosphate, [CpFe(dppe)PPh2(OMe)]PF6: [CpFe(dppe)NCMe]PF6 (197 mg, 0.28 mmol) and PPh2(OMe) (1.0 mL, 4.99 mmol). Yield: 51% (125 mg) of [CpFe(dppe)PPh2(OMe)]PF6 after crystallization from EtOAc/hexane. Crystallization from CHCl3/diethyl ether gave crystals suitable for X-ray analysis. IR (KBr): ν 1092 (PO), 840 cm−1 (PF). 1H NMR (CDCl3, 293 K): δ = 7.44−7.17 (m, 22H, Ar-H), 7.06 (dt, 4H, 3JH‑H = 7.9 Hz, 3JP‑H = 1.8 Hz, o-CH), 6.73 (t, 4H, 3JH‑H = 8.2 Hz, m-CH), 4.42 (s, 5H, CpH), 3.19 (d, 3H, 3JP‑H = 11.1 Hz, POCH3), 2.96−2.45 (m, 4H, CH2) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 139.08−138.49 (m, 2C, ipso-C), 136.26 (d, 2C, 1JP‑C = 21.5 Hz, ipso-C), 135.34 (d, 2C, 1 JP‑C = 38.6 Hz, ipso-C), 131.85 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 131.49 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 131.33 (d, 4C, 2 or 3JP‑C = 6.7 Hz, o- or m-C), 130.47 (s, 2C, p-C), 130.15 (s, 2C, p-C), 129.97 (s, 2C, p-C), 129.02 (t, 4C, 2 or 3JP‑C = 4.5 Hz, o- or m-C), 128.72 (t, 4C, K

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

ipso-C), 132.27 (t, 4C, 2 or 3JP‑C = 4.0 Hz, o- or m-C), 131.12 (t, 4C, JP‑C = 4.2 Hz, o- or m-C), 131.11 (d, 2C, 2 or 3JP‑C = 10.2 Hz, o- or m-C), 130.99 (s, 1C, p-C), 129.94 (s, 2C, p-C), 129.73 (s, 2C, p-C), 129.02 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 128.46 (t, 4C, 2 or 3JP‑C = 4.3 Hz, o- or m-C), 128.29 (d, 2C, 2JP‑C = 9.1 Hz, o-C), 80.50 (s, 5C, Cp), 56.44 (d, 2C, 1JP‑C = 16.7 Hz, OCH3), 27.55 (t, 2C, 2JP‑C = 14.0 Hz, CH2), 18.84 (s, 1C, CH2) ppm. 31P{1H} NMR (CDCl3, 293 K): δ = 169.74 (t, 1P, 2JP‑P = 62.7 Hz, POMe), 37.84 (d, 2P, 2JP‑P = 62.7 Hz, dppp, −144.21 (sept, 1P, 1JP‑F = 712.9 Hz, PF6) ppm. ES-HRMS: calcd for the cation C40H42FeO2P3+ 703.1744, found m/ z 703.1744. Anal. Calcd for C40H42F6FeO2P4 (848.49): C, 56.62; H, 4.99. Found: C, 56.68; H, 5.10. Ligand Exchange of [CpFe(PPh 2 Me) 2 NCMe]PF 6 with PPh2(OMe). A solution of [CpFe(PPh2Me)2NCMe]PF6 (5 mg) and PPh2(OMe) (10, 5, or 1 equiv) in CDCl3 (0.4 mL) was monitored by time-resolved 31P{1H} NMR. The spectral data for the resulting complexes are as follows: (η5-Cyclopentadienyl)(methyldiphenylphosphine-κP)[bis(methyl P,Pdiphenylphosphinite-κP)]iron hexafluorophosphate, [CpFe(PPh2Me){PPh2(OMe)}2]PF6: This complex was also prepared by the ligand exchange of [CpFe{PPh2(OMe)}2NCMe]PF6 (116 mg, 1.64 × 10−1 mmol) with PPh2Me (0.3 mL, 1.50 mmol) in CHCl3 (20 mL): Yield: 82% (128 mg). Crystallization from CH2Cl2/hexane gave crystals suitable for Xray analysis. 1 H NMR (400 MHz, CDCl3, 293 K): δ = 7.50−6.95 (m, 30H, ArH), 4.12 (s, 5H, Cp-H), 3.26 (br s, 6H, OCH3), 1.95−1.89 (m, 3H, Me) ppm. 31P{1H} NMR (CDCl3, 293 K): δ = 167.63 (d, 2P, 2JP‑P = 68.1 Hz, POMe), 41.78 (t, 1P, 2JP‑P = 68.1 Hz, PPh2Me), −143.84 (sept, 1P, 1JP‑F = 712.4 Hz, PF6) ppm. ES-HRMS: calcd for the cation C44H44FeO2P3+ 753.1904, found m/ z 753.1889. (Acetonitrile-κN)(η5-cyclopentadienyl)(methyldiphenylphosphine-κP)(methyl P,P-diphenylphosphinite-κP)iron hexafluorophosphate, [CpFe(PPh2Me){PPh2(OMe)}NCMe]PF6: 31 1 P{ H} NMR (CDCl3, 293 K): δ = 175.61 (d, 1P, 2JP‑P = 74.7 Hz, POMe), 51.02 (d, 1P, 2JP‑P = 74.7 Hz, PPh2Me), −144.08 (sept, 1P, 1 JP‑F = 712.4 Hz, PF6) ppm. (η5-Cyclopentadienyl)[bis(methyldiphenylphosphine-κP)](methyl P,Pdiphenylphosphinite-κP)]iron hexafluorophosphate, [CpFe(PPh2Me)2{PPh2(OMe)}]PF6: 31 1 P{ H} NMR (CDCl3, 293 K): δ = 169.97 (t, 1P, 2JP‑P = 67.0 Hz, POMe), 35.61 (d, 2P, 2JP‑P = 67.0 Hz, PPh2Me), −144.08 (sept, 1P, 1 JP‑F = 712.4 Hz, PF6) ppm. (Acetonitrile-κN)(η5-cyclopentadienyl)[bis(methyl P,P-diphenylphosphinite-κP)]iron hexafluorophosphate, [CpFe{PPh2(OMe)}2NCMe]PF6: This complex was also prepared by the photolysis of [CpFe(CO)2I] (227 mg, 7.47 × 10−1 mmol), PPh2(OMe) (0.5 mL, 2.49 mmol), and NH4PF6 (971 mg, 5.98 mmol) in MeCM (100 mL): Yield: 58% (325 mg). Crystallization from CH2Cl2/diethyl ether gave crystals suitable for X-ray analysis. 1 H NMR (400 MHz, CDCl3, 293 K): δ = 7.60−7.29 (m, 20H, ArH), 4.21 (s, 5H, Cp-H), 3.22 (t, 6H, 3JP‑H = 5.6 Hz, OCH3), 1.98 (s, 3H, CH3) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 136.14 (t, 2C, 1JP‑C = 19.6 Hz, ipso-C), 135.89 (t, 2C, 1JP‑C = 18.7 Hz, ipso-C), 134.83 (s, 1C, CN), 131.41 (t, 4C, 2 or 3JP‑C = 4.9 Hz, o- or m-C), 131.02 (t, 4C, 2 or 3JP‑C = 4.7 Hz, o- or m-C), 130.92 (s, 2C, p-C), 130.73 (s, 2C, p-C), 128.61 (t, 4C, 2 or 3JP‑C = 4.0 Hz, o- or m-C), 128.49 (t, 4C, 2 or 3JP‑C = 4.3 Hz, o- or m-C), 80.61(s, 5C, Cp), 54.91 (t, 2C, 2JP‑C = 6.4 Hz, OCH3), 4.38 (s, 1C, CH3) ppm.31P{1H} NMR (CDCl3, 293 K): δ = 174.57 (s, 2P, POMe), −144.24 (sept, 1P, 1JP‑F = 712.9 Hz, PF6) ppm. (η5-Cyclopentadienyl)[tris(methyl P,P-diphenylphosphinite-κP)]iron hexafluorophosphate, [CpFe{PPh2(OMe)}3]PF6: This complex was also prepared by the ligand exchange of [CpFe{PPh2(OMe)}2NCMe]PF6 (116 mg, 1.57 × 10−1 mmol), PPh2(OMe) (1.0 mL, 4.96 mmol) in a mixture of CHCl3 (20 mL) and methanol (20 mL): Yield 63% (90 mg). Crystallization from CH2Cl2/ diethyl ether gave crystals suitable for X-ray analysis.

After evaporation of the solvent, the residue was chromatographed on silica gel using CH2Cl2 as an eluent. The orange fraction was collected and evaporated. Crystallization from EtOAc/diethyl ether gave the products [CpFe(dppp)L]PF6 as orange powders. (η5-Cyclopentadienyl)[1,3-propanediylbis(diphenylphosphine-κP)](methyl P,P-diphenylphosphinite-κP)iron hexafluorophosphate, [CpFe(dppp)PPh2(OMe)]PF6: [CpFe(dppp)NCMe]PF6 (255 mg, 0.35 mmol) and PPh2(OMe) (1.0 mL, 4.99 mmol). Yield: 63% (200 mg) of [CpFe(dppp)PPh2(OMe)]PF6 after crystallization from EtOAc/diethyl ether. Crystallization from CHCl3/diethyl ether gave crystals suitable for X-ray analysis. IR (KBr): ν 1092 (PO), 840 cm−1 (PF). 1H NMR (CDCl3, 293 K): δ = 7.44−7.20 (m, 22H, Ar-H), 7.06 (t, 4H, 3JH‑H = 4.4 Hz, o-CH), 6.78 (t, 4H, 3JH‑H = 8.2 Hz, m-CH), 4.40 (s, 5H, Cp-H), 3.25 (d, 3H, 3 JP‑H = 11.8 Hz, POCH3), 2.70−2.42 (m, 5H, CH2 and CH), 1.77− 1.60 (m, 1H, CH) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 140.09−139.39 (m, 2C, ipso-C), 137.75−137.33 (m, 2C, ipso-C), 135.25 (d, 2C, 1JP‑C = 36.9 Hz, ipso-C), 132.27 (t, 4C, 2 or 3JP‑C = 4.0 Hz, o- or m-C), 131.12 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 131.11 (d, 4C, 2 or 3JP‑C = 9.8 Hz, o- or m-C), 130.60 (s, 2C, p-C), 129.94 (s, 2C, p-C), 129.73 (s, 2C, p-C), 129.02 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 128.46 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 128.29 (d, 4C, 2 or 3JP‑C = 9.1 Hz, o- or m-C), 80.50 (s, 5C, Cp), 56.44 (d, 1C, 2JP‑C = 16.6 Hz, OCH3, 26.55 (t, 2C, 2JP‑C = 14.0 Hz, CH2), 18.84 (s, 1C, CH2) ppm. 31 1 P{ H} NMR (CDCl3, 293 K): δ = 169.74 (t, 1P, 2JP‑P = 62.7 Hz, POMe), 38.84 (d, 2P, 2JP‑P = 62.7 Hz, dppp), −144.21 (septet, 1P, 1 JP‑F = 712.9 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C45H44FeOP3+ 749.1954, found m/ z 749.1949. (η5-Cyclopentadienyl)(ethyl P,P-diphenylphosphinite-κP)[1,3-propanediylbis(diphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(dppp)PPh2(OEt)]PF6: [CpFe(dppp)NCMe]PF6 (220 mg, 0.31 mmol) and PPh2OEt (1 mL, 4.63 mmol). Yield: 33% (92 mg) of [CpFe(dppp)PPh2(OEt)]PF6 after crystallization from EtOAc/hexane. Crystallization from CH2Cl2/ diethyl ether gave crystals suitable for X-ray analysis. IR (KBr): ν 1024 (PO), 838 cm−1 (PF). 1H NMR (CDCl3, 293 K): δ = 7.50−7.20 (m, 22H, Ar-H), 7.04 (t, 4H, 3JH‑H = 7.0 Hz, Ar-H), 6.71 (t, 4H, 3JH‑H = 8.2 Hz, Ar-H), 4.47 (s, 5H, Cp-H), 3.56 (dq, 2H, 3 JP‑H = 12.6 Hz, 3JH‑H = 6.9 Hz, POCH2), 2.74−2.42 (m, 5H, CH2 and CH), 1.83−1.66 (m, 1H, CH), (t, 3H, 3JH‑H = 6.9 Hz, CH3) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 139.48 (t, 2C, 1JP‑C = 18.7 Hz, 2 JP‑C = 3.6 Hz, Hz, ipso-C), 137.45 (t, 2C, 1JP‑C = 20.9 Hz, ipso-C), 135.42 (d, 2C, 1JP‑C = 37.1 Hz, ipso-C), 132.28 (t, 4C, 2 or 3JP‑C = 4.2 Hz, o- or m-C), 131.21 (d, 4C, 3JP‑C = 9.8 Hz, m-C), 130.98 (t, 4C, 2 or 3 JP‑C = 3.4 Hz, o- or m-C), 130.62 (s, 2C, p-C), 130.02 (s, 2C, p-C), 129.84 (s, 2C, p-C), 129.13 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o or m-C), 128.55 (t, 4C, 2 or 3JP‑C = 4.4 Hz, o- or m-C), 128.17 (d, 4C, 2JP‑C = 14.1 Hz, o-C), 80.60 (s, 5C, Cp), 65.83 (t, 1C, 2JP‑C = 14.7 Hz, OCH2), 26.46 (t, 2C, 2JP‑C = 13.8 Hz, CH2), 18.83 (s, 1C, CH2), 16.44 (d, 1C, 2JP‑C = 6.6 Hz, CH3) ppm. 31P{1H} NMR (CDCl3, 293 K): δ = 167.79 (t, 1P, 2JP‑P = 63.2 Hz, P(OEt)), 38.30 (d, 2P, 2JP‑P = 63.2 Hz, dppe), −144.23 (septet, 1P, 1JP‑F = 712.9 Hz, PF6) ppm. ES-HRMS: Calcd for the cation C46H46FeOP3+ 763.2111, found m/ z 763.2115. (η 5 -Cyclopentadienyl)(dimethyl P-phenylphosphonite-κP)[1,2propanediylbis(diphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(dppp)PPh(OMe)2]PF6: [CpFe(dppp)NCMe]PF6 (241 mg, 0.34 mmol) and PPh(OMe)2 (1.0 mL, 6.30 mmol). Yield: 39% (111 mg) of [CpFe(dppp)PPh(OMe)2]PF6. Crystallization from CHCl3/diethyl ether gave crystals suitable for X-ray analysis. 1 H NMR (400 MHz, CDCl3, 293 K): δ = 7.44−7.20 (m, 17H, ArH), 7.06 (t, 4H, 3JH‑H = 7.0 Hz, Ar-H), 6.78 (t, 4H, 3JH‑H = 8.2 Hz, ArH), 4.44 (s, 5H, Cp-H), 3.25 (d, 6H, J = 11.1 Hz, OCH3), 2.71−2.40 (m, 5H, CH2 x 2 and CH), 1.78−1.60 (m, 1H, CH) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 139.98−139.61 (m, 2C, ipso-C), 137.54 (t, 2C, 1JP‑C = 20.7 Hz, ipso-C), 135.25 (d, 1C, 1JP‑C = 36.9 Hz,

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DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics H NMR (400 MHz, CDCl3, 293 K): δ = 7.53−7.14 (m, 30H, ArH), 3.93 (s, 5H, Cp-H), 3.17 (s, 9H, OCH3) ppm. 13C NMR (100 MHz, CDCl3, 293 K): δ = 136.36 (br t, 3C, 1JP‑C = 15.1 Hz, ipso-C), 131.86 (br s, 12C, o- or m-C), 130.82 (s, 6C, p-C), 128.36 (br s, 12C, o- or m-C), 62.67 (s, 5C, Cp), 55.54 (br s, 3C, OCH3) ppm.31P{1H} NMR (CDCl3, 293 K): δ = 166.16 (s, 3P, POMe), −144.21 (sept, 1P, 1 JP‑F = 711.8 Hz, PF6) ppm. ES-HRMS: calcd for the cation C44H44FeO3P3+ 769.1853, found m/ z 769.1854. Ligand Exchange of [CpFe(PPh 2 Me) 2 NCMe]PF 6 with PPh2(OiPr). A solution of [CpFe(PPh2Me)2NCMe]PF6 (5 mg) and PPh2(OiPr) (1 equiv) in CDCl3 (0.4 mL) was monitored by timeresolved 31P{1H} NMR. The spectral data for the resulting complexes are as follows: (Acetonitrile-κN)(η5-cyclopentadienyl)(isopropyl P,P-diphenylphosphinite-κP)(methyldiphenylphosphine-κP)iron hexafluorophosphate, [CpFe(PPh2Me){PPh2(OiPr)}NCMe]PF6: 31 1 P{ H} NMR (CDCl3, 293 K): δ = 169.68 (d, 1P, 2JP‑P = 74.1 Hz, POMe), 39.62 (d, 1P, 2JP‑P = 74.1 Hz, PPh2Me), −144.19 (sept, 1P, 1 JP‑F = 711.6 Hz, PF6) ppm. (η5-Cyclopentadienyl)(isopropyl P,P-diphenylphosphinite-κP)[bis(methyldiphenylphosphine-κP)]iron hexafluorophosphate, [CpFe(PPh2Me)2{PPh2(OiPr)}]PF6: 31 1 P{ H} NMR (CDCl3, 293 K): δ = 163.23 (t, 1P, 2JP‑P = 65.0 Hz, POiPr), 33.34 (d, 2P, 2JP‑P = 65.0 Hz, PPh2Me), −144.19 (sept, 1P, 1 JP‑F = 711.6 Hz, PF6) ppm. (η5-Cyclopentadienyl)[tris(isopropyl P,P-diphenylphosphinite-κP)]iron hexafluorophosphate, [CpFe{PPh2(OiPr)}3]PF6: 31 1 P{ H} NMR (CDCl3, 293 K): δ = 167.65 (s, 3P, POiPr), −144.19 (sept, 1P, 1JP‑F = 711.6 Hz, PF6) ppm. Kinetics for the Ligand Exchange of the Complexes. To a solution of [CpFe(P-P)NCMe]PF6 or [CpFe(P-P)PPh2(OR)]PF6 (ca. 5 mg) in a deuterated solvent (0.4 mL) was added a ligand (10 equiv) using a microsyringe at 273 K under a nitrogen atmosphere. The solution was immediately measured in the 31P{1H} NMR spectrometer adjusted to the respective temperature. During this time, ligand exchange had already started. Therefore, the diastereomer ratios of the first measurement under controlled conditions were used as “starting ratios” in tables, figures, and calculations. 1

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ORCID

Takashi Tsuno: 0000-0003-0034-0710 Notes

The authors declare no competing financial interest.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.7b00311. Crystallographic data of 20 complexes [CpFe(PP)L]PF6. Time-resolved 31P{1H} NMR spectra as well as 1H NMR spectra, 13C NMR spectra, 31P{1H} NMR spectra, and ORTEP drawings of the complexes [CpFe(P-P)L]PF6 (PDF) Accession Codes

CCDC 1535363−1535379, 1549806, 1549807, and 1550539 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_request@ccdc. cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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*Fax: +49-941-9434439. E-mail: [email protected] (H.B.). *Fax: +81-47-474-2579. E-mail: [email protected] (T.T.). M

DOI: 10.1021/acs.organomet.7b00311 Organometallics XXXX, XXX, XXX−XXX