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Article

P-Fluorous Phosphines as Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal Catalysts: Synthesis of Rh(I), Ir(I), Pt(II), and Au(I) Complexes Bearing P-Fluorous Phosphine Ligands

1
Center for Education and Research in Agricultural Innovation, Faculty of Agriculture, Saga University, 152-1 Shonan-cho Karatsu, Saga 847-0021, Japan
2
Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
3
Katayama Chemical Industries Co., Ltd., 26-22, 3-Chome, Higasinaniwa-cho, Amagasaki, Hyogo 660-0892, Japan
*
Authors to whom correspondence should be addressed.
Inorganics 2017, 5(1), 5; https://doi.org/10.3390/inorganics5010005
Submission received: 1 December 2016 / Revised: 1 January 2017 / Accepted: 4 January 2017 / Published: 12 January 2017
(This article belongs to the Special Issue Organophosphorus Chemistry 2016)

Abstract

:
P-Fluorous phosphine (R2PRf), in which the perfluoroalkyl group is directly bonded to the phosphorus atom, is a promising ligand because it has a hybrid functionality, i.e., electron-poor and fluorous ligands. However, examples of P-fluorous phosphine–metal complexes are still rare, most probably because the P-fluorous group is believed to decrease the coordination ability of the phosphines dramatically. In contrast, however, we have succeeded in synthesizing a series of P-fluorous phosphine–coordinated metal complexes such as rhodium, iridium, platinum, and gold. Furthermore, the electronic properties of R2PnC10F21 are investigated by X-ray analysis of PtCl2(Ph2PnC10F21)2 and the infrared CO stretching frequency of RhCl(CO)(R2PnC10F21)2. IrCl(CO)(Ph2PnC10F21)2- and AuCl(R2PnC10F21)-catalyzed reactions are also demonstrated.

Graphical Abstract

1. Introduction

P-Fluorous phosphine (R2PRf), in which the perfluoroalkyl group is directly bonded to the phosphorus atom, is a hybrid functional phosphine ligand having both “electron-poor” [1] and “fluorous” [2,3,4,5,6,7,8] characteristics. Since strongly electron-withdrawing ligands are known to promote reductive elimination steps in catalytic reactions, the former property may be exploited, not only to optimize known reactions, but also to develop new catalytic reactions [9,10,11,12]. As to the latter property, the use of a fluorous biphasic system (FBS) may make it possible to recover catalysts and ligands easily and to reuse them for catalytic reactions. We recently developed a catalytic reaction using P-fluorous phosphines as ligands, i.e., a palladium-catalyzed cross-coupling reaction between acid chlorides and terminal alkynes, and have demonstrated the recyclability of the catalyst and the ligand [13]. Namely, the poor electron density of the P-fluorous phosphine ligands induced the palladium-catalyzed cross-coupling reaction, even under copper-free conditions, and the fluorous affinity of P-fluorous phosphines enabled the reuse of their Pd-complexes by using an FBS.
Our group recently developed three types of convenient synthetic methods of P-fluorous phosphine ligands (R2PRf) (see, Scheme 1): method A, the photoinduced direct displacement of R3P with RfI under radical conditions [13]; method B, the photoinduced SH2 reaction of (Ph2P)2 with RfI [14]; method C, the reductive substitution reaction of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TMDPO, known as a representative radical initiator for polymerization) with RfI under light [15].
To synthesize a diphenyl-substituted P-fluorous phosphine ligand (Ph2PnC10F211a), method C is the best because method C can be applied to the gram-scale synthesis of 1a (Equation (1)) [15]. In the case of the synthesis of the dialkyl-substituted P-fluorous phosphine ligand (nBu2PnC10F211b), method A is the most suitable because the gram scale of 1b can be obtained by this method (Equation (2)).
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Our recent success in palladium-catalyzed cross-coupling using P-fluorous phosphines [13] and the establishment of their synthetic methods [13,14,15] strongly suggest their promising usability as functional ligands in many transition metal–catalyzed reactions. However, examples of P-fluorous phosphine–metal complexes are still rare in the literature [16,17,18,19,20], and are limited to metal-R2PRf complexes bearing a short-chain perfluoroalkyl (light fluorous) group, which cannot be separated by a FBS due to the low content of fluorine atoms. To encourage the use of P-fluorous phosphine ligands in various catalytic reactions, we investigated their reactions with representative transition metal catalysts to prepare the corresponding P-fluorous phosphine–coordinated metal catalysts. In this paper, we report the synthesis of P-fluorous phosphine–coordinated rhodium, iridium, platinum, and gold complexes, and also describe their electronic properties, structural features, and catalytic activities.

2. Results and Discussion

First, we investigated the coordination of R2PRf to Pt. When a mixture of Ph2PnC10F21 (1a) and PtCl2(CH3CN)2 was stirred in CHCl3 for two days, the P-perfluoroalkylated phosphine–platinum complex, PtCl2(Ph2PnC10F21)2 (2a), was obtained successfully (Equation (3)). The 31P NMR spectrum showed a triplet with satellites (JP–F = 55.8 Hz, JP–Pt = 3878 Hz). This indicated the successful complexation between the P-fluorous phosphine–platinum complex. When nBu2PnC10F21 (1b) was used, instead of 1a, for complexation with platinum under similar conditions, the P-perfluoroalkylated phosphine–platinum complex trans-PtCl2(nBu2PnC10F21)2 (2b) was also obtained in good yield (Equation (3)).
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We fortunately obtained a single crystal of complex 2a by recrystallization from CHCl3, which was suitable for X-ray analysis. The Oak Ridge Thermal Ellipsoid Plot (ORTEP) representation of 2a is shown in Figure 1. The P–Pt–P bond angle is 178.66°. This indicates that the platinum complex PtCl2(Ph2PnC10F21)2 has the structure of the trans form. The Pt–P bond lengths in trans-PtCl2(Ph2PnC10F21)2 are 2.3027(6) and 2.3039(6) Å. These are shorter than the corresponding bond lengths in trans-PtCl2(PPh3)2 (2.319(3) and 2.316(3) Å) [21]. The P–CF2 bond lengths in trans-PtCl2(Ph2PnC10F21)2 are 1.913(3) and 1.909(3). They are longer than the P–CF2 bond length in Ph2PC2F5 (1.891(3) Å) [18]. The four P–C(ipso) lengths in trans-PtCl2(Ph2PnC10F21)2 are 1.810(4), 1.813(3), 1.810(4), and 1.815(3) Å. These are shorter than the P–C(ipso) bond lengths in Ph2PC2F5 (1.832(3) and 1.835(3) Å) [22]. On the other hand, the average Pt–P–C(ipso) angle in trans-PtCl2(Ph2PnC10F21)2 is 115.3°. It is similar to the average Pt–P–C(ipso) angle in trans-PtCl2(PPh3)2 (113.8°). The ORTEP representation also shows two perfluoroalkyl chains aligned in a parallel direction. The nearest distance between the two F atoms of each perfluoroalkyl chain is 2.734 Å, which is slightly shorter than the sum of the van der Waals radii of two F atoms (2.94 Å). Moreover, the packing diagram of trans-PtCl2(Ph2PnC10F21)2 shows that the long perfluoroalkyl chains are assembled into a fluorous layer (Figure 2) [23,24,25]. In the case of the reported light fluorous phosphine-metal complexes, such a parallel direction of the fluorous group was not observed [18,19].
The infrared CO stretching frequency (ν(CO)) of the RhCl(CO)(PR3)2 complex provides information on the electronic properties of the phosphines [26]. Therefore, we investigated the reaction of a P-perfluoroalkylated phosphine with [RhCl(CO)2]2 for the synthesis of RhCl(CO)(R2PRf)2. When the reaction of 1a or 1b with [RhCl(CO)2]2 was examined according to a reported method [9], RhCl(CO)(Ph2PnC10F21)2 (3a) and RhCl(CO)(nBu2PnC10F21)2 (3b) were obtained in good yields, respectively (Equation (4)). Coupling in the 31P NMR spectrum was assigned to the interaction between 31P and 103Rh (JP–Rh = 143.8 Hz), confirming complexation between the P-perfluoroalkylated phosphine and rhodium. Additionally, the symmetry of the 31P NMR spectrum indicates that the steric configuration is trans.
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Using the same method, a series of RhCl(CO)(PR3)2 complexes were synthesized and their infrared CO stretching frequencies (ν(CO)) were measured to evaluate the electronic properties of R2PRf (Table 1). Large ν(CO) values indicate poor electron-donating abilities of the phosphine ligand. The ν(CO) of RhCl(CO)(Ph2PnC10F21)2 and RhCl(CO)[P(C6F5)3]2 are almost the same (2010, 2008 cm−1), and therefore the electron-donating ability of Ph2PnC10F21 is as poor as that of P(C6F5)3. The ν(CO) of RhCl(CO)(nBu2PnC10F21)2 is 1987 cm−1, which is similar to that of RhCl(CO)[P(4-CF3C6H4)3]2 (1990 cm−1). Thus, the electron-donating ability of nBu2PnC10F21 is similar to that of P(4-CF3C6H4)3.
An iridium-phosphine complex (iridium is a congener of rhodium) was also investigated. Vaska-type complexes [27], such as IrCl(CO)(PR3)2, are well-known iridium-phosphine complexes. We examined the preparation of a Vaska-type complex of P-perfluoroalkylated phosphine from IrCl3·3H2O and an excess amount of Ph2PnC10F21 via a reduction process [28,29]. As a result, IrCl(CO)(Ph2PnC10F21)2 (4a) was successfully obtained (Equation (5)). The ν(CO) of 4a was shifted to a higher frequency (1990 cm−1) compared with that of the Vaska complex IrCl(CO)(PPh3)2 (1944 cm−1) [27], as well as that of the rhodium complex. The symmetry of the 31P NMR spectrum (δP 45.0 ppm, t, JP–F = 34.6 Hz) indicates that the steric configuration of 4a is trans.
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We next investigated the application of 4a as a catalyst. Several iridium-catalyzed hydrosilylation reactions of alkynes have been reported [30,31,32,33]. We therefore attempted alkyne hydrosilylation using 4a as a catalyst. When a mixture of 1-octyne and triethylsilane was heated in the presence of 1 mol % of 4a, vinylsilane derivatives as hydrosilylation products were obtained in 81% yield (E/Z = 46/54) (Equation (6)). The result clearly indicates that the iridium complex 4a can catalyze the hydrosilylation of alkynes as well as IrCl(CO)(PPh3)2.
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Finally, we investigated a P-perfluoroalkylated phosphine–gold(I) complex. AuCl(SMe2) was selected as the starting gold complex [34]. When an equimolar amount of R2PnC10F21 (1a and 1b) and AuCl(SMe2) was stirred at room temperature, the desired complexes, AuCl(R2PnC10F21) (5a and 5b), were obtained in quantitative yields, respectively (Equation (7)). The 19F NMR and 31P NMR analyses confirmed the complexation of 1a with gold(I). The 19F NMR signal of P–CF2–CF2– appeared at −107.8 ppm (CDCl3) as a doublet of triplets (2JF–P = 64.1 Hz, 3JF–F = 14.2 Hz), which was shifted downfield to 0.9 ppm compared with the free P–CF2–CF2– of Ph2PnC10F21, due to metal complexation. The 31P NMR signal appeared at 40.1 ppm as a triplet of triplets (2JP–F = 65.0 Hz, 3JP–F = 12.9 Hz) in CH2Cl2. HRMS (FAB) analysis further confirmed the complexation: the found value 900.9848 (calculated value for C22H10F21PAu [M − Cl]+: 900.9850) indicated the presence of the Au(Ph2PnC10F21) moiety.
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A catalytic hydroalkoxylation of an alkene was demonstrated using gold complex 5, according to the literature [35]. In the presence of a catalytic amount of 5a and AgOTf, the addition reaction of 2-chloroethanol to 1-octene took place to give 2-(2′-chloroethoxy)octane in a good yield (Equation (8)). In the case of AuCl(nBu2PnC10F21), the desired adduct was also obtained in a good yield. The synthesized gold(I) complex, AuCl(Ph2PnC10F21) and AuCl(nBu2PnC10F21), was found to exhibit more excellent catalytic activity with the ethanol addition to 1-octene compared with AuClPPh3.
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It is assumed that metal-R2PRf complexes have fluorous affinities because they contain perfluoroalkyl groups. Therefore, the fluorous affinities of these metal-Ph2PnC10F21 complexes were investigated; namely, the solubility of 2a5a in a fluorous solvent (FC-72, perfluorohexane) was measured at 25 °C. The results are as follows: PtCl2(Ph2PnC10F21)2, 0.32 g/L; RhCl(CO)(Ph2PnC10F21)2, 0.40 g/L; IrCl(CO)(Ph2PnC10F21)2, 0.13 g/L; AuCl(Ph2PnC10F21), did not dissolve. Because the fluorine content of AuCl(Ph2PnC10F21) is low (42.6%), it did not dissolve in FC-72. These results show that these metal-Ph2PnC10F21 complexes, i.e., PtCl2(R2PRf)2, RhCl(CO)(R2PRf)2, and IrCl(CO)(R2PRf)2, have fluorous affinities, and therefore it is possible to extract them by using a fluorous solvent and an appropriate organic solvent.

3. Materials and Methods

3.1. General Comments

Ph2PnC10F21 (1a) [15] and nBu2PnC10F21 (1b) [13] were synthesized according to the literature. Other materials were obtained from commercial suppliers and used without purification before use.

3.2. Synthesis of P-Perfluoroalkylated Phosphine Complex with Pt(II)

Under inert atmosphere, Ph2PnC10F21 (21.1 mg, 0.03 mmol), PtCl2(CH3CN)2 (5.2 mg, 0.015 mmol), and CHCl3 (0.6 mL) were added to a sealed test tube. After standing for two days, white precipitate was formed and filtered. Then enough pure trans-PtCl2(Ph2PnC10F21)2 was obtained in 84% yield.
trans-Dichlorobis((perfluorodecyl)diphenylphosphine)palladium(II) (2a): white solid; melting point (mp) 188–190 °C; 1H NMR (396 MHz, CD2Cl2): δ 7.52–7.55 (m, 8H), 7.59–7.62 (m, 4H), 7.94 (dd, JH–H = 7.3 Hz, JH–P = 12.7 Hz, 8H); 31P NMR (160 MHz, CD2Cl2): δ 25.8 (t with satellites, JP–F = 55.8 Hz, JP–Pt = 3878 Hz); 19F NMR (373 MHz, CD2Cl2): δ −126.2 (4F), −122.8 (4F), −122.0 (8F), −121.8 (8F), −121.2 (4F), −114.3 (4F), −101.8 (d, JF–P = 57.0 Hz, 4F), −81.0 (6F); HRMS (FAB) Calcd. for C44H20Cl2F42P2Pt [M]+: 1671.9373, Found: 1671.9396.
Under inert atmosphere, nBu2PnC10F21 (132.8 mg, 0.2 mmol), PtCl2(PhCN)2 (47.2 mg, 0.1 mmol), and CHCl3 (0.6 mL) were added to a sealed test tube. After standing for two days, white precipitate was formed and then, by filtration, enough pure trans-PtCl2(nBu2PnC10F21)2 was obtained in 65% yield.
trans-Dichlorobis(dibutyl(perfluorodecyl)phosphine)palladium(II) (2b): white solid; mp 71–72 °C; 1H NMR (396 MHz, CDCl3): δ 0.97 (t, JH–H = 7.3 Hz, 12H), 1.44–1.54 (m, 12H), 1.70–1.83 (m, 4H), 2.18–2.30 (m, 4H), 2.36–2.46 (m, 4H); 31P NMR (160 MHz, CDCl3): δ 24.6 (quint with satellites, JP–F = 25.8 Hz, JP–Pt = 2720 Hz); 19F NMR (373 MHz, CDCl3): δ −126.2 (4F), −122.8 (4F), −122.0 (4F), −121.8 (12F), −121.5 (4F), −116.4 (4F), −109.1 (dt, JF–P = 57.0 Hz, J = 28.5 Hz, 4F), −80.9 (t, JF–F =11.4 Hz, 6F); HRMS (FAB) Calcd. for C36H36Cl2F42P2194Pt [M]+: 1592.0625, Found: 1592.0603. The copies of 1H NMR, 19F NMR, and 31P NMR spectra of platinum complex (2a,b) are shown in Supplementary Materials.

3.3. Synthesis of P-Perfluoroalkylated Phosphine Complex with Rh(I)

Rhodium complexes (RhCl(CO)(PR3)2) were synthesized according to the reported method [9]. Phosphine (0.044 mmol), [RhCl(CO)2]2 (4.3 mg, 0.011 mmol), and dichloromethane (1.0 mL) were added to a 20 mL two-necked round-bottomed flask under argon. The solution was stirred at room temperature for 1 h. The solution was filtrated, and concentrated under reduced pressure. The resulting solid was purified by recrystallization (solvent: CHCl3).
trans-carbonylchlorobis((perfluorodecyl)diphenylphosphine)rhodium(I) (3a): yellow solid; mp 190–192 °C (decomposition); 1H NMR (400 MHz, CDCl3): δ 7.44 (dd, JH–H = 7.3 Hz, JH–P = 8.0 Hz, 8H), 7.52 (t, J = 7.3 Hz, 4H), 7.93 (q, J = 6.3 Hz, 8H); 31P NMR (162 MHz, CDCl3): δ 52.1 (dquint, JP–Rh = 143.8 Hz, JP–F = 33.0 Hz); 19F NMR (376 MHz, CDCl3): δ −125.9 (4F), −122.5 (4F), −121.7 (4F), −121.5 (12F), −121.4 (4F), −113.7 (4F), −104.8 (m, 4F), −80.7 (6F); IR (KBr) 3067, 2010, 1481, 1439, 1373, 1339, 1246, 1207, 1153, 1099, 745, 691, 648 cm−1; HRMS (ESI) Calcd. for C45H20ClF42NaOP2Rh [M + Na]+: 1596.8960, Found: 1596.8960; Anal. Calcd. for C45H20ClF42OP2Rh: C, 34.09; H, 1.55%, Found: C, 34.32; H, 1.28%.
trans-carbonylchlorobis(dibutyl(perfluorodecyl)phosphine)rhodium(I) (3b): yellow solid; mp 49–50 °C; 1H NMR (400 MHz, CDCl3): δ 0.95 (t, JH–H = 7.7 Hz, 12H), 1.48 (sextet, JH–H = 7.3 Hz, 8H), 1.61–1.78 (m, 8H), 2.18–2.37 (m, 8H); 31P NMR (162 MHz, CDCl3): δ 46.3 (dquint, JP–Rh = 133.3 Hz, JP–F = 30.1 Hz); 19F NMR (376 MHz, CDCl3): δ −126.3 (4F), −122.9 (4F), −122.0 (4F), −121.8 (12F), −121.5 (4F), −116.5 (4F), −109.0 (m, 4F), −81.0 (t, JF–F = 11.4 Hz, 6F); IR (KBr) 2960, 1987, 1372, 1210, 1151, 1111, 973, 852 cm−1; HRMS (FAB) Calcd. for C37H36ClF42NaOP2Rh [M + Na]+: 1517.0212, Found: 1517.0245. The copies of 1H NMR, 19F NMR, and 31P NMR spectra of rhodium complex (3a,b) are shown in Supplementary Materials.
RhCl(CO)[P(C6F5)3]2 [9], RhCl(CO)[P(4-CF3C6H4)3]2 [25], and RhCl(CO)[P(C6H5)3]2 [9] were reported in the literature, respectively.

3.4. Synthesis of P-Perfluoroalkylated Phosphine Complex with Ir(I)

IrCl(CO)(Ph2PnC10F21)2 was successfully synthesized according to the reported method [28,29]. Under inert atmosphere, Ph2PnC10F21 (1.76 g, 2.5 mmol), IrCl3·3H2O (176 mg, 0.5 mmol), and DMF (7.5 mL) were added to a 30 mL two necked flask. The mixture was refluxed for 12 h and the hot solution was filtered. The filtrate was recrystallized from MeOH and trans-IrCl(CO)(Ph2PnC10F21)2 was obtained in 64% yield.
trans-carbonylchlorobis((perfluorodecyl)diphenylphosphine)iridium(I) (4a): yellow solid; mp 181–183 °C; 1H NMR (400 MHz, CDCl3): δ 7.44–7.56 (m, 12H), 7.93 (dd, JH–H = 6.4, JP–H = 6.4 Hz, 8H); 31P NMR (162 MHz, CDCl3): δ 45.0 (t, JP–F = 34.6 Hz); 19F NMR (376 MHz, CDCl3): δ −126.0 (4F), −122.6 (4F), −121.8 (8F), −121.6 (8F), −121.2 (4F), −113.9 (4F), −104.5 (d, JF–P = 34.6 Hz, 4F), −80.7 (6F); IR (KBr) 1990, 1242, 1207, 1153 cm−1; HRMS (ESI) Calcd. for C45H20ClF42OP2Ir [M]+: 1663.9636, Found: 1663.9631. The copies of 1H NMR, 19F NMR, and 31P NMR spectra of iridium complex (4a) are shown in Supplementary Materials.

3.5. Hydrosilylation Reaction Catalyzed by Iridium Complex (4a)

Under inert atmosphere, 4a (5.0 mg, 0.003 mmol), Et3SiH (34.9 mg, 0.3 mmol), and 1-octyne (66.1 mg, 0.6 mmol) were added to a sealed test tube. The solution was heated at 80 °C for 16 h. The production of hydrosilylation adducts [36] was confirmed by 1H NMR using 1,4-dioxane as internal standard.

3.6. Synthesis of P-Perfluoroalkylated Phosphine Complex with Au(I)

Under inert atmosphere, Ph2PnC10F21 (145 mg, 0.2 mmol) or nBu2PnC10F21 (132.8 mg, 0.2 mmol), AuCl(SMe2) (59 mg, 0.2 mmol), and CH2Cl2 (5 mL) were added to a sealed test tube. The solution was stirred for 1 h. After the solvent was removed in vacuo, solid was obtained as enough pure AuCl(Ph2PnC10F21) in 98% yield or AuCl(nBu2PnC10F21) in 99% yield.
Chloro((perfluorodecyl)diphenylphosphine)gold(I) (5a): white solid; mp 130–131 °C; 1H NMR (400 MHz, CDCl3): δ 7.56–7.62 (m, 4H), 7.66–7.72 (m, 2H), 7.95 (dd, JH–H = 7.8, JP–H = 13.7 Hz, 4H); 31P NMR (162 MHz, CH2Cl2): δ 40.1 (tt, 2JP–F = 65.0 Hz, 3JP–F = 12.9 Hz); 19F NMR (376 MHz, CDCl3): δ −126.0 (2F), −122.6 (2F), −121.8 (2F), −121.6 (6F), −121.2 (2F), −114.8 (2F), −104.5 (dt, JF–P = 64.1 Hz, JF–F = 14.2 Hz, 2F), −80.7 (t, JF–F =10.1 Hz, 3F); HRMS (FAB) Calcd. for C22H10F21PAu [M − Cl]+: 900.9850, Found: 900.9848.
Chloro(dibutyl(perfluorodecyl)phosphine)gold(I) (5b): reddish purple solid; mp 62–63 °C; 1H NMR (400 MHz, CDCl3): δ 1.52 (sextet, JH–H = 7.3 Hz, 4H), 1.59–1.78 (m, 4H), 1.98−2.21 (m, 4H); 31P NMR (162 MHz, CH2Cl2): δ 40.1 (t, JP–F = 65.0 Hz); 19F NMR (376 MHz, CDCl3): δ −126.0 (2F), −122.6 (2F), −121.7 (2F), −121.5 (6F), −121.1 (2F), −116.5 (2F), −110.9 (dt, JF–P = 62.6 Hz, JF–F = 17.1 Hz, 2F), −80.6 (3F); HRMS (FAB) Calcd. for C18H18AuClF21NaP [M + Na]+: 919.0063, Found: 919.0031. The copies of 1H NMR, 19F NMR, and 31P NMR spectra of gold complex (5a,b) are shown in Supplementary Materials.

3.7. Au Complex-Catalyzed Addition Reaction of 2-Chloroethanol to 1-Octene

The addition reaction was conducted according to the reported method [35]. Under inert atmosphere, 5 (0.03 mmol), AgOTf (7.7 mg, 0.03 mmol), 2-chloroethanol (8.0 mg, 1 mmol), 1-octene (561.2 mg, 5 mmol), and toluene (1 mL) were added to a three-necked flask with a condenser. The solution was heated at 85 °C for 24 h.

4. Conclusions

We demonstrated the synthesis of P-fluorous phosphine–coordinated metal complexes, PtCl2(R2PnC10F21)2, RhCl(CO)(R2PnC10F21)2, IrCl(CO)(Ph2PnC10F21)2, and AuCl(R2PnC10F21). The structure of PtCl2(Ph2PnC10F21)2 was revealed and discussed. The catalytic activities of the iridium and gold complexes for some synthetic reactions were also shown. The promising P-fluorous phosphine–transition metal complexes will be used to catalyze novel reactions in future work.

Supplementary Materials

The following are available online at www.mdpi.com/2304-6740/5/1/5/s1, copies of 1H NMR, 19F NMR, and 31P NMR spectra of complexes (2a5b). Crystal structure of the complex (2a) (CCDC No.:1445325) can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

Acknowledgments

This research was supported by a Grant-in-Aid for Exploratory Research (26620149, Akiya Ogawa, 26860168, Shin-ichi Kawaguchi), from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Author Contributions

Shin-ichi Kawaguchi and Akiya Ogawa conceived and designed the experiments; Shin-ichi Kawaguchi, Yuta Saga, Yuki Sato and Yoshiaki Minamida performed the experiments; Akihiro Nomoto analyzed the data; Shin-ichi Kawaguchi and Akiya Ogawa wrote the paper.

Conflicts of Interest

The authors declare no conflict of interest.

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Scheme 1. Synthetic methods of P-fluorous phosphines.
Scheme 1. Synthetic methods of P-fluorous phosphines.
Inorganics 05 00005 sch001
Figure 1. ORTEP representation (thermal ellipsoids at 50%) of PtCl2(Ph2PnC10F21)2. Space group: P-1 (#2), Z = 2, R1 = 0.0312, wR2 = 0.0886, selected bond lengths (Å) and angles (°): Pt(1)–Cl(1) = 2.332(10), Pt(1)–P1(1) = 2.303(6), P(1)–C(1) = 1.913(3), P(1)–C(11) = 1.810(4), Cl(1)–Pt(1)–Cl(2) = 172.79(3), Cl(1)–Pt(1)–P(1) = 89.10(3), P(1)–Pt(1)–P(2) = 178.66(4), Pt(1)–P(1)–C(1) = 117.15(8), Pt(1)–P(1)–C(11) = 116.41(9), Pt(1)–P(1)–C(17) = 116.41(9), C(1)–P(1)–C(11) = 98.16(14).
Figure 1. ORTEP representation (thermal ellipsoids at 50%) of PtCl2(Ph2PnC10F21)2. Space group: P-1 (#2), Z = 2, R1 = 0.0312, wR2 = 0.0886, selected bond lengths (Å) and angles (°): Pt(1)–Cl(1) = 2.332(10), Pt(1)–P1(1) = 2.303(6), P(1)–C(1) = 1.913(3), P(1)–C(11) = 1.810(4), Cl(1)–Pt(1)–Cl(2) = 172.79(3), Cl(1)–Pt(1)–P(1) = 89.10(3), P(1)–Pt(1)–P(2) = 178.66(4), Pt(1)–P(1)–C(1) = 117.15(8), Pt(1)–P(1)–C(11) = 116.41(9), Pt(1)–P(1)–C(17) = 116.41(9), C(1)–P(1)–C(11) = 98.16(14).
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Figure 2. Packing diagram of PtCl2(Ph2PnC10F21)2.
Figure 2. Packing diagram of PtCl2(Ph2PnC10F21)2.
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Table 1. The ν(CO) data of RhCl(CO)(PR3)2.
Table 1. The ν(CO) data of RhCl(CO)(PR3)2.
Inorganics 05 00005 i009
EntryRhCl(CO)(PR3)2ν(CO) (cm−1)
1RhCl(CO)(Ph2PnC10F21)22010
2RhCl(CO)(nBu2PnC10F21)21987
3RhCl(CO)(PPh3)21967
4RhCl(CO)(P(4-CF3C6H4)3)21990
5RhCl(CO)(P(C6F5)3)22008

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Kawaguchi, S.-i.; Saga, Y.; Sato, Y.; Minamida, Y.; Nomoto, A.; Ogawa, A. P-Fluorous Phosphines as Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal Catalysts: Synthesis of Rh(I), Ir(I), Pt(II), and Au(I) Complexes Bearing P-Fluorous Phosphine Ligands. Inorganics 2017, 5, 5. https://doi.org/10.3390/inorganics5010005

AMA Style

Kawaguchi S-i, Saga Y, Sato Y, Minamida Y, Nomoto A, Ogawa A. P-Fluorous Phosphines as Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal Catalysts: Synthesis of Rh(I), Ir(I), Pt(II), and Au(I) Complexes Bearing P-Fluorous Phosphine Ligands. Inorganics. 2017; 5(1):5. https://doi.org/10.3390/inorganics5010005

Chicago/Turabian Style

Kawaguchi, Shin-ichi, Yuta Saga, Yuki Sato, Yoshiaki Minamida, Akihiro Nomoto, and Akiya Ogawa. 2017. "P-Fluorous Phosphines as Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal Catalysts: Synthesis of Rh(I), Ir(I), Pt(II), and Au(I) Complexes Bearing P-Fluorous Phosphine Ligands" Inorganics 5, no. 1: 5. https://doi.org/10.3390/inorganics5010005

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