Novel Bidentate [N,S] Palladacycle Metalloligands. 1Hâ15N HMBC as

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Novel Bidentate [N,S] Palladacycle Metalloligands. 1H−15N HMBC as a Decisive NMR Technique for the Structural Characterization of Palladium−Rhodium and Palladium−Palladium Bimetallic Complexes M. Teresa Pereira,† José M. Antelo,† Luis A. Adrio,† Javier Martínez,† Juan M. Ortigueira,† Margarita López-Torres,‡ and José M. Vila*,† †

Departamento de Química Inorgánica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain Departamento de Química Fundamental, Universidade da Coruña, E-15071 La Coruña, Spain

‡

S Supporting Information *

ABSTRACT: Treatment of tetranuclear palladacycles with 2-(diphenylphosphino)pyridine, Ph2Ppy, in acetone at room temperature for 10 h, gave the new bidentate [N,S] palladacycle metalloligands 1−7. Treatment of [Rh2Cl2(CO)4] with AgClO4 in acetone at room temperature for 10 min, followed by addition of 1−7 and stirring at room temperature for 10 h, gave the novel heterobimetallic palladium−rhodium compounds 1a−7a as 1:1 electrolytes, where the new bidentate [N,S] palladacycle metalloligands are bonded to the second metal through the pyridine nitrogen atom, and the sulfur atom of the thiosemicarbazone moiety; they exhibit a six-membered bimetallic central ring of differing atoms. In a similar manner, reaction of [PdBr2(Ph2PR4PPh2)] (R4 = CH2, CCH2, (CH2)2, cis-CHCH) with AgClO4 in acetone at room temperature, followed by addition of 1−7, gave the homobimetallic palladium−palladium compounds, 2b, 3b, 5b−7b, and 5c−7c, as 1:2 electrolytes, also with [N,S] coordination of the corresponding metalloligand. 1H−15N HMBC experiments were a most valuable tool in helping to unequivocally ascertain rhodium−nitrogen and palladium−nitrogen coordination in the bimetallic species. The crystal and molecular structures of 3, 6, 2b, and 3b have been determined by X-ray crystallography; for compounds 3 and 3b, inter- and intramolecular interactions in the solid state result in crystal selforganization, leading to chains and/or layers in the molecular array.

1. INTRODUCTION The chemistry of cyclometalated compounds1 has attracted much research interest in past years because of their varied structural features, as well as for their broad applications in numerous fields, such as in organic synthesis,2 photochemistry,3 optical resolution processes,4,5 catalysis,6 as potential biologically active materials,7 and liquid crystals.8 Particularly, palladacycles have become one of the most noteworthy fields of modern organometallic chemistry and they are known for an extensive range of organic moieties;9 their chemistry may be modulated upon appropriate choice of the ligand. For instance, C-bonded pincer-type ligands that will strongly bind to the metal in a terdentate fashion are most adequate for firmly occupying all but one coordination site in the square-planar palladacycle, hindering chelation of bidentate ligands; depending on their flexibility, the latter may behave as monodentate rendering an uncoordinated donor to the final compound or as bridging ligands or simply display no bonding at all to the metal in the case of the more rigid planar π delocalized systems. We have previously shown that C-bonded thiosemicarbazones in the thiolate form bind tightly to the metal as terdentate [C,N,S], enabling the [P,S] palladacycle metalloligands bearing © XXXX American Chemical Society

a monocoordinated diphosphine, which produce a rather large array of homo- and heterobimetallics with simultaneous chelating [C,N,S], bridging [P,P], and chelating [P,P] or [P,N] donors. We reasoned that new palladacycle metalloligands should be possible depending on the nature of the donor atoms and on the length and flexibility of the carbon chain spanning between them. Therefore, we sought out to prepare thiosemicarbazone palladacycles containing the ligand Ph2Ppy-P, which, in light of our previous results, may be described as [N,S]-metalloligands: a series of new cyclometalated palladium compounds, for which we herein describe their syntheses and characterization. Also, the ensuing palladium/rhodium and palladium/palladium bimetallic complexes with Ph2Ppy-P,N spanning between the two metal atoms are described accordingly. In the new bimetallic complexes, coordination of the nitrogen atom to the second metal center was unambiguously confirmed by 1H−15N HMBC experiments and by crystal structure analysis. Received: November 4, 2013

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dx.doi.org/10.1021/om401069a | Organometallics XXXX, XXX, XXX−XXX

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Scheme 1

2. RESULTS AND DISCUSSION For the convenience of the reader, the compounds and reactions are shown in Scheme 1. The compounds described in this paper were characterized by elemental analysis (C, H, N) and by IR spectroscopy and by 1H, 31P−{1H} spectroscopy, and 1H−15N HMBC correlation experiments and, in part, crystal structure analysis (see the Experimental Section). The results, as depicted in Scheme 1, showed not only that short-bite diphosphines, such as Ph2P(CH2)PPh2 or (PPh2)2CCH2, yielded the metalloligands reported previously10 but also that other bidentate donors could also produce analogous species, provided the carbon chain between donor atoms was sufficiently short to hinder the bridging mode of the said ligand, and that, also, ligand flexibility allowed monocoordination until the second metal binds to the free donor atom and to the thiolate sulfur of the thiosemicarbazone. Therefore, strong chelating ligands were useful should their flexibility permit the η1-mode, whereas the more rigid delocalized π systems failed to give the η1-mode; in fact, they showed no reaction with the metallacycle due to the strong bonds to palladium of the pincer-type thiosemicarbazone. Consequently, the attempts to prepare [N,N] or [O,O] metalloligands with 2,2′-bipyridine, ophenanthroline, or with acetylacetonato failed. Therefore, in our quest to make bidentate metalloligands with hard/hard or with hard/soft donor atoms, as opposed to the soft/soft donor atom metalloligands previously prepared by us, we reacted the corresponding palladacycles with 2-(diphenylphosphino)pyridine, Ph2Ppy, as shown in Scheme 1. Thus, treatment of the tetranuclear complexes I with Ph2Ppy in acetone gave the new bidentate [N,S] palladacycle metalloligands 1−7, bearing hard/soft donors, namely, nitrogen and sulfur. The compounds were conveniently purified by recrystallization from dichloromethane/n-hexane to give pure solids that were adequately characterized (see the Experimental Section). Compounds 1−7 were stable under ambient conditions and could be stored for long periods without change. Their solubility was found to be

good in common organic solvents, viz., chloroform, dichloromethane, acetone, and DMSO. The position of the υ(N− H)amide stretch in the complexes showed that this group was uncoordinated to the metal atom. The υ(CN) stretch was somewhat shifted to lower wavenumbers ca. 30 cm−1, in agreement with coordination of the metal through the nitrogen lone pair.11−13 The 31P−{1H} NMR spectra for 1−7 showed a singlet ca. 36−39 ppm downfield shifted from the free phosphine δ value of −3.5 ppm, indicating bonding to the metal through the phosphorus donor atom, as opposed to the pyridine nitrogen donor, in accordance with the soft acid/soft base character of palladium and phosphorus, respectively. Moreover, the H5 resonance showed coupling to the 31P nucleus with 4J(PH) ca. 4.5 Hz. The 15N chemical shift is a valuable tool that not only helps to characterize the corresponding [N,S]-metalloligand but also allows one to make sure that the latter coordinates to a second metal center through the pyridine nitrogen. In order to determine δ15N, an alternative route to running the 15N NMR spectra is the 1H−15N HMBC correlation experiment. This technique is sensitive to the coupling constant between the correlated nuclei, making it necessary to set the coupling constant to a known value, or at least to a reasonable approximation. The 2J(NH) for pyridine is 10.8 Hz.14 1H−15N HMBC spectra for 3 and 3b were run several times using the same sample and selecting the parameters for a 1H−15N coupling constant of 4.5, 10.7, and 14 Hz. The best results were obtained with J(NH) 14.0 Hz, in the case of the uncoordinated metalloligand 3, and with J(NH) 10.7 Hz, in the bimetallic compound 3b. Accordingly, these values were used in the remaining experiments for the metalloligands and for the bimetallic compounds, respectively. Thus, 1H−15N HMBC experiments, performed in natural abundance avoiding the synthesis of 15N enriched compounds, were run for 1−7 in order to determine the 15N shift of the uncoordinated nitrogen atom, to give N4[Hd] ca. δ −57 (Figure 1a). Likewise, where B


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possible, chemical shifts for the N1, N2, and N3 nuclei are given in the Experimental Section.

Figure 2. 1H−15N HMBC for 4a showing the correlation for the four nitrogen nuclei.

Figure 3. Bimetallic ring of six different atoms in 1a−7a.

characterized (see the Experimental Section). The 31P−{1H} NMR data were consistent with coordination of the three phosphorus atoms to the metal centers. Thus, a singlet ca. 36.5 ppm was assigned to the PA nucleus; the PB and PC resonances of the chelated diphosphine were influenced by ring size15 and showed negative (four-membered) and positive (five-membered) chemical shifts, appearing as doublets ca. −44.5 and −34 ppm (2b, 3b, 5b−7b) and 33.1−21.7 ppm (5c), and as singlets 70.3 ppm (6c) and 65.9, 63.5 ppm (7c), respectively. In all cases, the higher field value was assigned to PB (trans to sulfur), in agreement with the greater trans influence of the sulfur atom. As with the Pd−Rh bimetallics, the 1H−15N HMBC spectra showed the shift of N4[Hd, He, Hg] ca. δ−135; cross-peaks with Hd, He, and Hg were assigned where possible. 2.1. Molecular Structures of 3 and 6. The molecular structures of the new metalloligands 3 and 6 were determined by single-crystal X-ray crystallography and are shown in Figures 4 and 5; crystallographic data and selected bond lengths and angles are listed in Tables 1 and 2. The asymmetric unit of each crystal structure comprises a mononuclear square-planar palladium(II) complex, bonded to four different atoms from the terdentate [C,N,S] thiosemicarbazone, and from the η1pyridil phosphine-P ligand, bonded trans to the imine nitrogen atom. All bond distances are within the expected values, with the Pd−N bond displaying marked lengthening due to the trans influence of the phosphine ligand. The angles in the environment of the metal atom show moderate deviations from the ideal 90° consequent upon chelation. The S(1)−C(8) bond length, 1.759(3) Å 3, 1.748(3) Å 6, and the N(2)−C(8) length, 1.311(4) Å 3, 1.322(4) Å 6, are consistent with increased single and double bond character, respectively, as a result of deprotonation. 2.2. Molecular Structures of 2b and 3b. The molecular structures of 2b and 3b were determined by single-crystal X-ray crystallography and are shown in Figures 6 and 7; crystallographic data and selected bond lengths and angles are listed in Tables 1 and 2. The crystal structures comprise dinuclear palladium(II) complexes, which present two slightly distorted

Figure 1. 1H−15N HMBC for (a) 7 and (b) 7b showing the differing N4 chemical shifts arising from nitrogen coordination in 7b.

Reaction of [RhCl(CO)2]2 with AgClO4 in acetone and elimination of the silver chloride precipitate, followed by treatment with compounds 1−7, gave the new heterobimetallic palladium−rhodium complexes 1a−7a, as air-stable 1:1 electrolytes, which were fully characterized (see the Experimental Section). The IR spectra showed two υ(CO) stretches ca. 2085 and 2025 cm−1, and a band ca. 1070 cm−1 for the perchlorate counterion. N-coordination to rhodium was unequivocally proven by the shift of the N4 resonance in the 1H−15N HMBC experiments. Accordingly, the 1H−15N HMBC spectra for 1a− 7a for J(NH) 10.7 Hz showed cross-peaks with Hd, He, and Hg with the shift of N4[Hd, He, Hg] ca. δ−140 (Figure 2), a shift of ca. −85 ppm toward lower frequency consequent upon coordination of the ligand to the rhodium atom, putting forward the goodness of the technique in confirming Rh−N bond formation. A further novelty to these compounds is that they contain a bimetallic six-membered ring of all-different atoms (Figure 3); unfortunately, attempts to produce a crystal structure have not been successful so far. Treatment of the metalloligands with [PdBr2(Ph2R4PPh2)]/ AgClO4 gave the homobimetallic palladacycles 2b, 3b, 5b−7b, and 5c−7c as dicationic complexes (1:2 electrolytes) with bridging [P,N] and chelating [P,P] ligands, which were fully C


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P3) are essentially planar, and nearly perpendicular at an angle of 88.70(6)° 2b and 88.95(7)° 3b. The Cremer and Pople puckering parameters17 for the sixmembered ring Pd1−P1−C25−N4−Pd2−S1 for the bimetallic compounds are in accordance with a twist-boat/half chair conformation [Q = 1.474(4) Å; θ = 113.8(2)°; ϕ = 268.8(2)° for 2b and Q = 1.524(4) Å; θ = 66.97(2)°; ϕ = 90.9(2) for 3b]. The distance between the palladium atoms (3.237(1) Å for 2b and 3.218(1) Å for 3b) are shorter than the sum of the van der Waals radii,18,19 which suggests a certain degree of metal−metal interaction. 2.3. Crystal Packing and Intermolecular Interactions. A view of the crystal packing shows that the dinuclear compounds 3 and 3b display interesting structural features. The analysis of weak interactions20−23 shows the presence of hydrogen bonds, π−π and C−H···π interactions. In the crystal structure of complex 3, the hydrogen bonds N(3)−H(3A)··· O(1)#1 (#1: x + 1, y − 1, z) produce chains along the (2, 2, 1) plane (Figure 8). In the structure of 3b (Figure 9, and Table 3 for intermolecular π−π and C−H···π stacking parameters), there are three features to be considered regarding the intermolecular interactions: (a) hydrogen bonding between the molecules and the perchlorate counterions produce chains along the a axis; (b) intermolecular π−π and C−H···π interactions involving the chelating and bridging phosphine phenyl rings, as well as the thiosemicarbazone metalated ring, generate chains along the b− c direction; and (c) multiple weak interactions between the perchlorate ions and solvent molecules furnish the resulting assembly of the supramolecular architecture contributing to the building of the crystal network. When observed on the b/c plane, the solvent molecules can be seen as occupying channels along the a axis. This justifies the instability of the crystal at room temperature, making it necessary to gather the crystal data at low temperature.

Figure 4. Molecular structure of 3. Ellipsoids are shown at the 30% probability level. Hydrogen atoms have been omitted for clarity.

3. CONCLUSIONS We have shown that, along with the previously reported bidentate [P,S] metalloligands, the related new [N,S] metalloligands are possible provided care is taken in choosing the appropriate incoming phosphine, especially in what relates to the length of the carbon chain between the donor atoms. Thus, the analogue to the P−C−P set, P−C−N in 2-(diphenylphosphino)pyridine, deems Ph2Ppy to play an equivalent role in the ensuing metalloligands, providing them with the second donor that completes the bidentate coordination mode. The metal−nitrogen bond was fully established by means of 1 H−15N HMBC experiments based on the variation of the 15 N chemical shift upon coordination.

Figure 5. Molecular structure of 6·C3H6O. Ellipsoids are shown at the 30% probability level. Dashed lines show the hydrogen bonds.

4. EXPERIMENTAL SECTION

square-planar (II) centers with different sets of donors. The Pd(1) atom is bonded to four different atoms, whereas Pd(2) is bonded the sulfur and nitrogen atoms of the metalloligand, and to two phosphorus atoms from the chelated diphohsphine. The metal atoms show distorted square-planar environments, with the distortion most noticeable in the Pd(2) atom, due to the tension generated in the case of the four-membered chelate rings. The bond lengths are within the expected range, with allowance for the strong trans influence of the phosphorus donor ligand. The Pd−P bond lengths are in agreement with previous findings and suggest a slight degree of partial double bond between the palladium atom and phosphorus atom.16 The metal coordination planes (C6, N1, S1, P1) and (S1, N4, P2,

4.1. General Remarks. Solvents were purified by standard methods.24 [Rh2Cl2(CO)4] and the phosphines PPh2py, Ph2PCH2PPh2 (dppm), Ph2PCCH2PPh2 (vdpp), cis-Ph2PCHCHPPh2, and Ph2P(CH2)2PPh2 (dppe), were purchased from Sigma-Aldrich. The complexes [PdBr2(Ph2PR4PPh2)-P,P] [R4: CH2, CCH2, cis-CH CH, (CH2)2] were prepared from [PdBr2(NCPh)2] and the corresponding diphosphine in acetone. The synthesis of the tetranuclear cyclometalated precursors was performed as reported previously in papers from this laboratory.25−27 All preparations were carried out under dry dinitrogen. Elemental analyses were performed with a Fisons elemental analyzer, Model 1108. IR spectra were recorded as Nujol mulls or polythene discs on PerkingElmer 1330, Mattson Model Cygnus-100, D


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Table 1. Crystal Data and Structure Refinement Data for 3, 6·C3H6O, 2b, and 3b·4CHCl3 empirical formula M crystal system space group a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z temperature (K) crystal size (mm3) μ (mm−1) ind. reflections (Rint) data/restrains/paramenters goodness-of-fit R [F, I > 2σ(I)] wR [F2, all data]

3

6·C3H6O

2b

3b·4CHCl3

C29H29N4O2PPdS 634.99 triclinic P1̅ 8.894(5) 9.756(5) 16.809(5) 80.959(5) 84.527(5) 74.360(5) 1384.9(11) 2 293(2) 0.40 × 0.19 × 0.10 0.837 4340 (0.0376) 4340/0/351 0.848 0.0338 0.0759

C31H33N4OPPdS 647.04 triclinic P1̅ 9.6553(9) 11.9234(11) 13.5784(13) 103.1340(10) 99.9930(10) 92.0640(10) 1494.6(2) 2 293(2) 0.51 × 0.27 × 0.23 0.775 6077 (0.0353) 6077/0/361 1.046 0.0269 0.0706

C54H51Cl2N4O9P3Pd2S 1308.66 triclinic P1̅ 12.6747(12) 12.9371(13) 17.4291(17) 79.370(5) 68.872(5) 81.035(5) 2607.6(4) 2 293(2) 0.30 × 0.17 × 0.06 0.986 9720 (0.0585) 9720/0/679 1.229 0.068 0.1856

C58H55Cl14N4O10P3Pd2S 1802.13 triclinic P1̅ 11.2069(9) 17.0855(15) 19.6442(15) 71.881(3) 84.511(4) 79.138(3) 3508(2) 2 100(2) 0.15 × 0.11 × 0.04 1.202 13 232 (0.0879) 13 232/0/837 1.051 0.0661 0.1808

Table 2. Selected Bond Lengths (Å) and Angles (deg) for Complexes C(6)−Pd(1) N(1)−Pd(1) S(1)−Pd(1) P(1)−Pd(1) S(1)−Pd(2) N(4)−Pd(2) Pd(2)−P(2) Pd(2)−P(3) C(7)−N(1) N(1)−N(2) N(2)−C(8) C(8)−S(1) Pd(1)−Pd(2) P(2)−P(3) C(6)−Pd(1)−N(1) N(1)−Pd(1)−S(1) S(1)−Pd(1)−P(1) C(6)−Pd(1)−P(1) S(1)−Pd(2)−P(3) P(2)−Pd(2)−P(3) P(2)−Pd(2)−N(4) N(4)−Pd(2)−S(1)

3

6·C3H6O

2b

3b·4CHCl3

2.043(3) 2.010(3) 2.339(1) 2.262(1)

2.040(2) 2.0331(18) 2.3435(6) 2.2520(6)

1.296(4) 1.384(4) 1.311(4) 1.759(3)

1.296(2) 1.374(3) 1.308(3) 1.756(2)

2.036(9) 2.039(7) 2.340(2) 2.240(3) 2.358(3) 2.156(7) 2.304(3) 2.273(2) 1.29(1) 1.39(1) 1.30(1) 1.794(9) 3.236(1) 2.657(3) 80.6(3) 83.4(2) 98.35(8) 97.5(3) 105.40(9) 70.97(9) 101.9(2) 81.9(2)

2.057(8) 2.027(7) 2.347(2) 2.264(2) 2.376(2) 2.137(7) 2.285(2) 2.266(2) 1.29(1) 1.39(1) 1.29(1) 1.800(9) 3.218(1) 2.680(3) 80.5(3) 83.0(2) 98.05(8) 98.4(3) 107.36(8) 72.17(8) 101.3(2) 80.0(2)

80.8(1) 83.06(8) 97.64(4) 98.5(1)

81.12(8) 82.30(5) 99.09(2) 97.52(7)

and Bruker Model IFS-66 V spectrophotometers. 1H NMR spectra in solution were recorded in CDCl3 at room temperature on a Varian Mercury 300 spectrometer operating at 300.14 MHz using 5 mm o.d. tubes; chemical shifts, in parts per million (ppm), are reported downfield relative to TMS using the solvent signal (CDCl3, δ1H = 7.26 ppm) as reference. 31P NMR spectra were recorded at 202.46 MHz on a Bruker AMX 500 spectrometer using 5 mm o.d. tubes and are reported in ppm relative to external H3PO4 (85%). 15N HMBC chemical shifts are reported relative to MeNO2. Coupling constants are reported in Hz. All chemical shifts are reported downfield from standards. Conductivity measurements were made on a CRISON GLP 32 conductivimeter using 10−3 mol dm−3 solutions in dry acetonitrile The physical measurements were carried out by the RIAIDT services of the Universidad de Santiago de Compostela.

4.2. Synthesis of the Pyridil Phosphine Complexes. A corresponding amount of diphosphine Ph2Ppy (4 equiv) was added to a solution of the corresponding tetranuclear cyclometalated complex (1 equiv) in acetone (15 cm3). The mixture was stirred for 10 h. Then, the solvent was removed under reduced pressure and the residue was recrystallized from dichloromethane/n-hexane. [Pd{4-(MeOC6H3C(Me)NNC(S)NHMe}(Ph2Ppy-P)] (1). Yield: 116.3 mg, 82%. Anal. Found: C: 55.8, H: 4.4, N: 9.4, S: 5.2; C28H27N4OPSPd (605.00 g/mol) requires C: 55.6, H: 4.5, N: 9.3, S: 5.3%. IR(cm−1): ν(N−H) 3374; ν(CN) 1580. 1H NMR (CDCl3, δ/ ppm, J/Hz): 7.9−7.3 (m, 11H, 2 × Ph, Hg), 8.77 (m, 1H, Hd), 8.29 (m, 1H, Hf), 7.77 (m, 1H, He), 7.04(d, 1H, H2, 3J(H2H3) = 8.2), 6.37 (dd, 1H, H3, 3J(H2H3) = 8.2, 4J(H3H5) = 2.3), 5.92 (dd, 1H, H5, 4 J(H5P) = 4.7, 4J(H3H5) = 2.3), 4.59 (br, 1H, NHMe), 3.08 (s, 3H, pOMe), 2.90 (d, 3H, NHMe, 3JNHMe= 4.8), 2.37 (s, 3H, MeCN). E


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P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 39.5 s. HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −57 N4 [Hd], −95 N1 [MeC N], −305 N3 [NHEt, NHCH2CH3]. [Pd[{3-MeOC6H3C(Me)NNC(S)NHEt}(Ph2Ppy-P)] (2). Yield: 132.9 mg, 95%. Anal. Found: C: 56.7, H: 4.5, N: 9.0, S: 5.1; C29H29N4OPSPd (619.03 g/mol) requires C: 56.3, H: 4.7, N: 9.1, S: 5.2%. IR(cm−1): ν(N−H) 3411; ν(CN) 1571. 1H NMR (CDCl3, δ/ ppm, J/Hz): 7.8−7.3 (m, 10H, 2 × Ph), 8.77 (m, 1H, Hd), 8.35 (m, 1H, Hf), 7.67 (m, 1H, He), 7.37 (m, 1H, Hg), 6.71 (d, 1H, H2, 4 J(H2H4) = 2.9), 6.19 (dd, 1H, H5, 3J(H4H5) = 8.2, 4J(H5P) = 4.1), 6.06 (dd, 1H, H4, 3J(H4H5) = 8.2, 4J(H2H4) = 2.9), 4.70 (br, 1H, NHEt), 3.66 (s, 3H, m-OMe), 3.35 (m, 2H, NHCH2CH3), 2.38 (s, 3H, MeCN), 1.13 (t, 3H, NHCH2CH3, 3JEt = 7.0). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 39.8 s. HMBC-{15N−1H} NMR (CDCl3, δ/ ppm) [correlation]: −58 N4 [Hd]. [Pd{2,4-(MeO) 2 C 6 H 2 C(Me)NNC(S)NHMe](Ph 2 Ppy-P)] (3). Yield: 126.4 mg, 93%. Anal. Found: C: 55.1, H: 4.5, N: 8.8, S: 5.0; C29H29N4O2PSPd (635.02 g/mol) requires C: 54.96, H: 4.6, N: 8.8, S: 5.1%. IR(cm−1): ν(N−H) 3383; ν(CN) 1582. 1H NMR (CDCl3, δ/ ppm, J/Hz): 7.8−7.3 (m, 10H, 2 × Ph), 8.76 (m, 1H, Hd), 8.33 (m, 1H, Hf), 7.68 (m, 1H, He), 7.37 (m, 1H, Hg), 5.95 (d, 1H, H3, 4 J(H3H5) = 2.3), 5.62 (dd, 1H, H5, 4J(H5P) = 5.3, 4J(H3H5) = 2.3), 4.47 (q, 1H, NHMe, 3JNHMe = 4.7), 3.72 (s, 3H, o-OMe), 2.92 (s, 3H, p-OMe), 2.88 (d, 3H, NHMe, 3JNHMe = 4.7), 2.60 (s, 3H, MeCN). 31 P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 39.3 s. HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −58 N4 [Hd], −102 N1 [MeCN], −293 N3 [NHEt, NHCH2CH3]. Single crystals of 3 were grown by slow evaporation from a chloroform/ethanol (3:1) solution. [Pd{3,4-(MeO)2C6H2C(Me)NNC(S)NHEt}(Ph2Ppy-P)] (4). Yield: 120.4 mg, 89%. Anal. Found: C: 55.2, H: 5.0, N: 8.5, S: 4.7; C30H31N4O2PSPd (649.05 g/mol) requires C: 55.5, H: 4.8, N: 8.6, S: 4.9%. IR(cm−1): ν(N−H) 3407; ν(CN) 1582. 1H NMR (CDCl3, δ/ ppm, J/Hz): 7.9−7.3 (m, 10H, 2 × Ph), 8.75 (m, 1H, Hd), 8.28 (m, 1H, Hf), 7.69 (m, 1H, He), 7.31 (m, 1H, Hg), 6.68 (s, 1H, H2), 5.89 (d, 1H, H5, 4J(H5P) = 4.5), 4.61 (br 1H, NHEt), 3.79 (s, 3H, mOMe), 3.35 (m, 2H, NHCH2CH3), 2.87 (s, 3H, p-OMe), 2.36 (s, 3H, MeCN), 1.12 (t, 3H, NHCH2CH3, 3JEt = 7.1). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 37.2 s. HMBC-{15N−1H} NMR (CDCl3, δ/ ppm) [correlation]: −56 N4 [Hd], −276 N3 [NHEt, NHCH2CH3]. [Pd{C6H4C(Et)NNC(S)NHEt}(Ph2Ppy-P)] (5). Yield: 123.7 mg, 87%. Anal. Found: C: 58.1, H: 5.0, N: 9.1, S: 5.2; C29H29N4PSPd (603.03 g/mol) requires C: 57.8, H: 4.9, N: 9.3, S: 5.3%. IR(cm−1): ν(N−H) 3417, ν(CN) 1571. 1H NMR (CDCl3, δ/ppm, J/Hz): 7.9−7.4 (m, 10H, 2 × Ph), 8.78 (m, 1H, Hd), 8.37 (m, 1H, Hf), 7.67 (m, 1H, He), 7.38 (m, 1H, Hg), 7.09 (dd, 1H, H2, 3J(H2H3) = 7.6, 4 J(H2H4) = 1.2), 6.86 (td, 1H, H3, 3J(HH) = 7.6, 4J(H3H5) = 1.2), 6.47 (td, 1H, H4, 3J(HH) = 7.6, 4J(H2H4) = 1.2), 6.33 (ddd, 1H, H5, 3 J(H4H5) = 7.6, 4J(H5P) = 4.1, 4J(H3H5) = 1.2), 4.65 (t, 1H, NHEt, 3 JNHEt = 5.3), 3.33 (m, 2H, NHCH2CH3), 2.85 (q, 2H,CH3CH2CN, 3 JEt = 7.6), 1.25 (t, 3H,CH3CH2CN, 3JEt = 7.6), 1.12 (t, 3H, NHCH2CH3, 3JEt = 7.0). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 39.3 s. HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −57 N4 [Hd]. [Pd{4-MeC6H 3C(Me)NNC(S)NHMe}(Ph2Ppy-P] (6). Yield: 126.5 mg, 87%. Anal. Found: C: 57.4, H: 4.4, N: 9.2, S: 5.1; C28H27N4PSPd (589.67 g/mol) requires C: 57.1, H: 4.6, N: 9.5, S: 5.4%. IR(cm−1): ν(N−H) 3432, ν(CN) 1573. 1H NMR (CDCl3, δ/ ppm, J/Hz): 7.9−7.3 (m, 10H, 2 × Ph), 8.78 (m, 1H, Hd), 8.28 (m, 1H, Hf), 7.68 (m, 1H, He), 7.30 (m, 1H, Hg), 6.98 (d, 1H, H2, 3 J(H2H3) = 8.0), 6.67 (d, 1H, H3, 3J(H2H3) = 8.0), 6.08 (d, 1H, H5, 4 J(H5P) = 4.4), 4.63 (br, 1H, NHMe), 2.92 (d, 3H, NHMe, 3JNHMe = 4.8), 2.38 (s, 3H, MeCN), 1.72 (s, 3H, p-Me). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 36.7 s. HMBC-{15N−1H} NMR (CDCl3, δ/ ppm) [correlation]: −58 N4 [Hd]. Single crystals of 6 were obtained by slow evaporation from the mother liquor. [Pd{4-AcOC6H3C(Me)NNC(S)NHMe}(Ph2Ppy-P)] (7). Yield: 131.3 mg, 96%. Anal. Found: C: 56.2, H: 4.7, N: 8.8, S: 4.9; C29H27N4OPSPd (617.01 g/mol) requires C: 56.5, H: 4.4, N: 9.1, S: 5.2%. IR(cm−1): ν(N−H) 3358; ν(CO) 1672; ν(CN) 1571. 1H 31

Figure 6. Molecular structure of 2b. Ellipsoids are shown at the 30% probability level. Hydrogen atoms have been omitted for clarity.

Figure 7. Molecular structure of 3b. Ellipsoids are shown at the 30% probability level. Hydrogen atoms, perchlorate counterions, and solvent molecules have been omitted for clarity.

Figure 8. c axis perspective view of compound 3 showing the hydrogen bond interactions along the (2, 2, 1) plane. F


Organometallics

Article

Figure 9. (a) ORTEP representation of hydrogen bonds along b axis of compound 3b. Dashed lines show the interactions. (b) ORTEP representation of π−π and C−H···π interactions in 3b. Dashed lines show the interactions. (c) Crystal packing of 3b viewed from a axis: (1) including solvent molecules (chloroform); (2) solvent molecules have been omitted. 3

J(H2H3) = 8.0, 4J(H3H5) = 1.6), 7.32 (m, 1H, Hg), 7.13 (d, 1H, H2, J(H2H3) = 8.0), 6.86 (dd, 1H, H5, 4J(H5P) = 4.4, 4J(H3H5) = 1.6), 4.83 (br, 1H, NHMe), 2.95 (d, 3H, NHMe, 3JNHMe = 5.2), 2.41 (s, 3H, MeCN), 1.70 (s, 3H, p-Ac). 31P−{1H} NMR (CDCl3, δ/ppm, J/ Hz): 36.6 s. HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −57 N4 [Hd], −83 N1 [MeCN]. 4.3. Synthesis of the Palladium−Rhodium Complexes. [Rh2Cl2(CO)4] (80 mg, 0.20 mmol), AgClO4 (85.3 mg, 0.40 mmol) and acetone (20 cm3) were added in a centrifuge tube, and the mixture was stirred at room temperature for 10 min. Then, the resulting suspension was centrifuged. A white solid of AgCl was deposited on the bottom of the tube. The pale yellow-brown solution was added to a 100 cm3 volumetric flask, and a 4 mM solution was prepared. Then, 12.5 cm3 of the solution was added to the corresponding amount (0.05 mmol) of 1 (30.3 mg), 2 (31.0 mg), 3 (31.8 mg), 4 (32.5 mg), 5 (30.2 mg), 6 (29.5 mg), and 7 (30.9 mg), respectively. The resulting

Table 3. Selected Intermolecular Bond Lengths (Å) and Angles (°) for 3b π···π interactions

Cg···Cg

Cg(1)···Cg(2) 3.674 Cg(3)···Cg(4) 3.836 C−H···π interactionsa

α

β

3

γ

18.10 9.15 9.00 20.01 33.08 13.36 H···Cg C···Cg C−H···Cg

2.89 3.628 134 C(12)−H(12C)···Cg(1)#5 C(40)−H(40)···Cg(5)#1 2.47 3.383 165 Cg rings (1): Pd(1), N(1), C(7), C(1), C(6); (2): C(49)−C(54); (3): C(19)−C(24); (4): C(36)−C(41); (5): C(30)−C(35). a

Symmetry code: #1: 1 − x, 1 − y, 1 − z; #5: 1 − x, 2 − y, −z.

NMR (CDCl3, δ/ppm, J/Hz): 7.9−7.3 (m, 10H, 2 × Ph), 8.80 (m, 1H, Hd), 8.17 (m, 1H, Hf), 7.69 (m, 1H, He), 7.48 (dd, 1H, H3, G


Organometallics

Article

3H,CH3CH2CN, 3JEt = 7.2), 1.14 (t, 3H, NHCH2CH3, 3JEt = 7.6). 31 P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 33.2 s. HMBC-{15N−1H} NMR (CDCl 3 , δ/ppm) [correlation]: −277 N3 [NHEt, NHCH2CH3], −143 N4 [Hd, He, Hg], −100 N1 [CH3CH2CN]. Specific molar conductivity ΛM = 98.6 Ω−1 cm2 mol−1. [Rh(CO)2{Pd[4-MeC6H3C(Me)NNC(S)NHMe](Ph2Ppy-P)}-N,S][ClO4] (6a). Yellow solid, yield: 39.0 mg, 89%. Anal. Found: C: 42.7, H: 3.2, N: 6.8, S: 4.0; C30H29ClN4O6PPdRhS (849.39 g/mol) requires C: 42.4, H: 3.4, N: 6.6, S: 3.9%. IR(cm−1): ν(N−H) 3329; ν(CO) 2083, 2026; ν(CN) 1582. 1H NMR (CDCl3, δ/ppm, J/Hz): 7.9− 7.5 (m, 11H, 2 × Ph, He), 9.21 (m, 1H, Hd), 7.97 (m, 1H, Hf), 7.14 (d, 1H, H2, 3J(H2H3) = 7.8), 7.11 (m, 1H, Hg), 6.84 (d, 1H, H3, 4 J(H2H3) = 7.8), 6.42 (br, 1H, NHMe), 6.13 (d, 1H, H5, 4J(H5P) = 5.2), 3.05 (br, 3H, NHMe), 2.50 (s, 3H, MeCN), 1.80 (s, 3H, pMe). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 33.5 s. HMBC{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −143 N4 [Hd]. Specific molar conductivity ΛM = 103.8 Ω−1 cm2 mol−1. [Rh(CO) 2 {Pd[4-AcOC 6 H 3 C(Me)NNC(S)NHMe](Ph2 Ppy-P)}N,S][ClO4] (7a). Yellow solid, yield: 41.4 mg, 94%. Anal. Found: C: 43.8, H: 2.9, N: 6.1, S: 3.4; C31H29ClN4O7PPdRhS (877.40 g/mol) requires C: 43.6, H: 3.1, N: 6.2, S: 3.6%. IR(cm−1): ν(N−H) 3329; ν(CO) 1678; ν(CO) 2085, 2024 ν(CN) 1585. 1H NMR (CDCl3, δ/ppm, J/Hz): 7.9−7.4 (m, 10H, 2 × Ph), 9.25 (m, 1H, Hd), 7.96 (m, 1H, Hf), 7.63 (dd, 1H, H3, 3J(H2H3) = 8.4, 4J(H3H5) = 1.3), 7.53 (m, 1H, He), 7.34 (d, 1H, H2, 3J(H2H3) = 8.4), 7.12 (m, 1H, Hg), 6.97 (dd, 1H, H5, 4J(H5P) = 5.8, 4J(H3H5) = 1.3), 6.88 (br, 1H, NHMe), 3.07 (d, 3H, NHMe, 3JNHMe = 5.2), 2.55 (s, 3H, MeC N), 1.92 (s, 3H, p-Ac). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 33.3 s. HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −144 N4 [Hd, He, Hg], −90 N1 [MeCN]. Specific molar conductivity ΛM = 100.6 Ω−1 cm2 mol−1. 4.4. Preparation of 2b, 3b, 5b, 6b, and 7b. [PdBr2(Ph2PCH2PPh2-P,P)] (150 mg, 0.23 mmol), AgClO4 (95.5 mg, 0.46 mmol), and 60 cm3 of acetone were added into a centrifuge tube, and the mixture was stirred at room temperature for 2 h. Then, the resulting suspension was centrifuged. A white solid of AgBr was deposited on the bottom of the tube. The brown solution was added to a 100 cm3 volumetric flask, and a 2.3 mM solution was prepared. Then, 20 cm3 of the solution was added to the corresponding amount (0.046 mmol) of 2a (28.5 mg), 3a (29.3 mg), 5a (27.8 mg), 6a (27.2 mg), and 7a (28.5 mg), respectively. The mixtures were stirred for 10 h at room temperature. Then, the solvent was removed under reduced pressure and the residues were recrystallized from dichloromethane/n-hexane. [Pd(Ph2PCH2PPh2-P,P){Pd[3-MeOC6H3C(Me)NNC(S)NHEt](Ph2Ppy-P)}-N,S][ClO4]2 (2b). Orange solid, yield: 54.2 mg, 90%. Anal. Found: C: 49.8, H: 4.0, N: 4.1, S: 2.4; C54H51Cl2N4O9P3SPd2 (1308.74 g/mol) requires C: 49.6, H: 3.9, N: 4.3, S: 2.5%. IR(cm−1): ν(N−H) 3429, ν(CN) 1584. 1H NMR (CDCl3, δ/ppm, J/Hz): 8.3−6.8 (m, 32H, 6 × Ph, He, Hg), 9.43 (m, 1H, Hd), 7.97 (m, 1H, Hf), 6.98 (br, 1H, NHEt), 6.60 (d, 1H, H2, 4J(H2H4) = 2.3), 6.13 (dd, 1H, H4, 3 J(H3H4) = 8.2, 4J(H2H4) = 2.3), 6.06 (dd, 1H, H5, 3J(H3H5) = 8.2, 4 J(H5P) = 4.7), 4.89 (m, 1H, PBCHPC), 4.10 (m, 1H, PBCHPC), 3.69 (s, 3H, m-OMe), 3.11 (m, 2H, NHCH2CH3), 2.08 (s, 3H, MeCN), 1.07 (t, 3H, NHCH2CH3, 3JEt = 7.0). 31P−{1H} NMR (CDCl3, δ/ ppm, J/Hz): 37.0 (s, PA), −32.8 (d, 2JBC = 77.0), −44.6 (d, 2JBC = 77.0). HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −142 N4 [Hd]. Specific molar conductivity ΛM = 226 Ω−1 cm2 mol−1. Suitable crystals were obtained from a chloroform:ethanol (3:1) solution. [Pd(Ph 2 PCH 2 PPh 2 -P,P){Pd[2,4-(MeO) 2 C 6 H 2 C(Me)NNC(S)NHMe](Ph2Ppy-P)}-N,S][ClO4]2 (3b). Brown solid, yield: 56.7 mg, 93%. Anal. Found: C: 49.1, H: 4.1, N: 4.2, S: 2.4; C54H51Cl2N4O10P3SPd2 (1324.74 g/mol) requires C: 49.0, H: 3.9, N: 4.2, S: 2.4%. IR(cm−1): ν(N−H) 3356, ν(CN) 1570. 1H NMR (CDCl3, δ/ppm, J/Hz): 8.2−6.8 (m, 31H, 6 × Ph, He), 9.33 (m, 1H, Hd), 7.97 (m, 1H, Hf), 7.21 (m, 1H, Hg), 6.65 (q, 1H, NHMe, 3JNHMe = 4.7), 6.01 (d, 1H, H3, 4 J(H3H5) = 1.8), 5.44 (dd, 1H, H5, 4J(H5P) = 5.9, 4J(H3H5) = 1.8), 4.80 (m, 1H, PBCHPC), 4.08 (m, 1H, PBCHPC), 3.77 (s, 3H, o-OMe), 3.06 (s, 3H, p-OMe), 2.65 (d, 3H, NHMe, 3JNHMe = 4.7), 2.30 (s, 3H, MeCN). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 35.5 (s, PA),

mixtures were stirred for 10 h at room temperature, after which the solvent was removed under reduced pressure and the residues were recrystallized from dichloromethane/n-hexane, to give the desired compound in each case. [Rh(CO)2 {Pd[4-MeOC6 H 3C(Me)NNC(S)NHMe](Ph 2Ppy-P)}N,S][ClO4] (1a). Yellow solid, yield: 39.8 mg, 90%. Anal. Found: C: 41.5, H: 3.6, N: 6.4, S: 3.7; C30H29ClN4O7PPdRhS (865.39 g/mol) requires C: 41.6, H: 3.4, N: 6.5, S: 3.7%. IR(cm−1): ν(N−H) 3405, ν(CO) 2084, 2026, ν(CN) 1576. 1H NMR (CDCl3, δ/ppm, J/ Hz): 7.9−7.3 (m, 10H, 2 × Ph), 9.29 (m, 1H, Hd), 7.93 (m, 1H, Hf), 7.55 (m, 1H, He), 7.22 (d, 1H, H2, 3J(H2H3) = 8.4), 7.07 (m, 1H, Hg), 6.54 (dd, 1H, H3, 4J(H2H3) = 8.4, 4J(H3H5) = 2.6), 6.35 (q, 1H, NHMe, 3JNHMe= 5.2), 5.96 (dd, 1H, H5, 4J(H5P) = 5.8, 4J(H3H5) = 2.6), 3.18 (s, 3H, p-OMe), 3.05 (d, 3H, NHMe, 3JNHMe = 5.2), 2.50 (s, 3H, MeCN). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 33.1 s. HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −144 N4 [Hd, He, Hg], −100 N1 [MeCN]. Specific molar conductivity ΛM = 109 Ω−1 cm2 mol−1. [Rh(CO)2{Pd[3-MeOC6H3C(Me)NNC(S)NHEt](Ph2Ppy-P)}-N,S][ClO4] (2a). Yellow solid, yield: 42.0 mg, 94%. Anal. Found: C: 42.5, H: 3.7, N: 6.3, S: 3.8; C31H31ClN4O7PPdRhS (879.42 g/mol) requires C: 42.3, H: 3.6, N: 6.4, S: 3.7%. IR(cm−1): ν(N−H) 3319, ν(CO) 2083, 2026, ν(CN) 1585. 1H NMR (CDCl3, δ/ppm, J/Hz): 7.9− 7.4 (m, 11H, 2 × Ph, He), 9.23 (m, 1H, Hd), 7.93 (m, 1H, Hf), 7.06 (m, 1H, Hg), 6.86 (d, 1H, H2, 4J(H2H4) = 2.6), 6.48 (br, 1H, NHEt), 6.25 (dd, 1H, H5, 3J(H4H5) = 8.4, 4J(H5P) = 4.6), 6.22 (dd, 1H, H4, 3 J(H4H5) = 8.4, 4J(H2H4) = 2.6), 3.71 (s, 3H, m-OMe), 3.47 (m 2H, NHCH2CH3), 2.50 (s, 3H, MeCN), 1.28 (t, 3H, NH CH2CH3, 3JEt = 7.1). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 33.5 s. HMBC{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −142 N4 [Hd]. Specific molar conductivity ΛM = 107.6 Ω−1 cm2 mol−1. [Rh(CO)2{Pd[2,4-(MeO)2C6H2C(Me)NNC(S)NHMe](Ph2PpyP)}-N,S][ClO4] (3a). Yellow solid, yield: 42.0 mg, 92%. Anal. Found: C: 41.7, H: 3.6, N: 6.2, S: 3.5; C31H31ClN4O8PPdRhS (895.42 g/mol) requires C: 41.6, H: 3.5, N: 6.3, S: 3.6%. IR(cm−1): ν(N−H) 3424, ν(CO) 2085, 2027, ν(CN) 1572. 1H NMR (CDCl3, δ/ppm, J/ Hz): 7.9−7.6 (m, 10H, 2 × Ph), 9.18 (m, 1H, Hd), 7.95 (m, 1H, Hf), 7.64 (m, 1H, He), 7.05 (m, 1H, Hg), 6.10 (d, 1H, H3, 4J(H3H5) = 2.0), 6.01 (q, 1H, NHMe, 3JNHMe = 4.6), 5.68 (dd, 1H, H5, 4J(H5P) = 6.5, 4J(H3H5) = 2.0), 3.79 (s, 3H, o-OMe), 3.04 (s, 3H, p-OMe), 3.02 (d, 3H, NHMe, 3JNHMe = 4.6), 2.70 (s, 3H, MeCN). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 32.3 s. HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −299 N3 [NHEt, NHCH2CH3], −144 N4 [Hd, He, Hg], −107 N1 [MeCN]. Specific molar conductivity ΛM = 99.1 Ω−1 cm2 mol−1. [Rh(CO)2{Pd[3,4-(MeO)2C6H2C(Me)NNC(S)NHEt](Ph2Ppy-P)}N,S][ClO4] (4a). Brown solid, yield: 40.3 mg, 93%. Anal. Found: C: 42.7, H: 3.8, N: 6.4, S: 3.5; C32H33ClN4O8PPdRhS (909.44 g/mol) requires C: 42.3, H: 3.7, N: 6.2, S: 3.5%. IR(cm−1): ν(N−H) 3321, ν(CO) 2083, 2026, ν(CN) 1584. 1H NMR (CDCl3, δ/ppm, J/ Hz): 7.9−7.5 (m, 11H, 2 × Ph, He), 9.23 (m, 1H, Hd), 7.97 (m, 1H, Hf), 7.09 (m, 1H, Hg), 6.83 (s, 1H, H2), 6.27 (br, 1H, NHEt), 5.95 (d, 1H, H5, 4J(H5P) = 5.8), 3.84 (s, 3H, m-OMe), 3.47 (m 2H, NHCH2CH3), 2.97 (s, 3H, p-OMe), 2.50 (s, 3H, MeCN), 1.27 (t, 3H, NH CH2CH3, 3JEt = 7.8). 31P−{1H} NMR (CDCl3, δ/ppm, J/ Hz): 33.2 s. HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −280 N3 [NHEt, NHCH2CH3], −144 N4 [Hd, He, Hg], −108 N2 [NHEt], −100 N1 [MeCN]. Specific molar conductivity ΛM = 101.4 Ω−1 cm2 mol−1. [Rh(CO)2{Pd[C6H4C(Et)NNC(S)NHEt](Ph2Ppy-P)}-N,S][ClO4] (5a). Brown solid, yield: 38.1 mg, 90%. Anal. Found: C: 43.0, H: 3.7, N: 6.4, S: 3.7; C31H31ClN4O6PPdRhS (863.42 g/mol) requires C: 43.1, H: 3.6, N: 6.5, S: 3.7%. IR(cm−1): ν(N−H) 3332, ν(CO) 2085, 2023, ν(CN) 1578. 1H NMR (CDCl3, δ/ppm, J/Hz): 7.9− 7.4 (m, 11H, 2 × Ph, He), 9.21 (m, 1H, Hd), 8.01 (m, 1H, Hf), 7.11 (m, 1H, Hg), 7.06 (dd, 1H, H2, 3J(H2H3) = 7.4, 4J(H2H4) = 1.6), 6.89 (td, 1H, H3, 3J(HH) = 7.6, 4J(H3H5) = 1.6), 6.44 (td, 1H, H4, 3 J(HH) = 7.4, 4J(H2H4) = 1.6), 6.35 (ddd, 1H, H5, 3J(H4H5) = 7.4, 4 J(H5P) = 4.1, 4J(H3H5) = 1.6), 6.22 (br, 1H, NHEt), 3.38 (m 2H, NHCH2CH3), 2.79 (q, 2H,CH3CH2CN, 3JEt = 7.2), 1.20 (t, H


Organometallics

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−33.7 (d, 2JBC = 80.0), −44.7 (d, 2JBC = 80.0). HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −299 N3 [NHMe], −138 N4 [Hd, He, Hg], −107 N1 [MeCN]. Specific molar conductivity ΛM = 224 Ω−1 cm2 mol−1. Suitable crystals were obtained from a chloroform:ethanol (3:1) solution. [Pd(Ph2PCH2PPh2-P,P){Pd[C6H4C(Et)NNC(S)NHEt](Ph2PpyP)}-N,S][ClO4]2 (5b). Orange solid, yield: 52.8 mg, 89%. Anal. Found: C: 49.9, H: 4.1, N: 4.4, S: 2.4; C54H51Cl2N4O8P3SPd2 (1292.74 g/mol) requires C: 50.2, H: 4.0, N: 4.3, S: 2.5%. IR(cm−1): ν(N−H) 3336, ν(CN) 1579. 1H NMR (CDCl3, δ/ppm, J/Hz): 8.2−6.7 (m, 32H, 6 × Ph, He, Hg), 9.34 (m, 1H, Hd), 7.98 (m, 1H, Hf), 6.94 (br, 2H, NHEt, H3), 7.01 (m, 1H, H2), 6.55 (m, 1H, H4), 6.21 (m, 1H, H5), 4.83 (m, 1H, PBCHPC), 4.13 (m, 1H, PBCHPC), 3.05 (m 2H, NHCH 2 CH 3 ), 2.65 (m, 1H,CH 3 CHCN), 2.33 (m, 1H, CH3CHCN), 1.05 (m, 6H, CH3CH2CN, NHCH2CH3). 31P− {1H} NMR (CDCl3, δ/ppm, J/Hz): 36.4 (s, PA), −33.3 (d, 2JBC = 77.0), −44.3 (d, 2JBC = 77.0). HMBC-{15N−1H} NMR (CDCl3, δ/ ppm) [correlation]: −143 N4 [Hd]. Specific molar conductivity ΛM = 237 Ω−1 cm2 mol−1. [Pd(Ph 2PCH 2 PPh2-P,P){Pd[4-MeC 6 H 3C(Me)NNC(S)NHMe](Ph2Ppy-P)}-N,S][ClO4]2 (6b). Dark brown solid, yield: 53.7 mg, 91%. Anal. Found: C: 49.5, H: 4.0, N: 4.3, S: 2.6; C53H49Cl2N4O8P3SPd2 (1278.71 g/mol) requires C: 49.8, H: 3.9, N: 4.4, S: 2.5%. IR(cm−1): ν(N−H) 3334, ν(CN) 1581. 1H NMR (CDCl3, δ/ppm, J/Hz): 8.2−6.7 (m, 31H, 6 × Ph, He), 9.35 (m, 1H, Hd), 8.00 (m, 1H, Hf), 7.10 (m, 1H, Hg), 6.90 (d, 1H, H2, 3J(H2H3) = 8.2), 6.73 (d, 1H, H3, 3 J(H2H3) = 8.2), 5.97 (d, 1H, H5, 4J(H5P) = 5.3), 4.83 (m, 1H, PBCHPC), 4.12 (m, 1H, PBCHPC), 2.69 (d, 3H, NHMe, 3JNHMe = 4.7), 2.09 (s, 3H, MeCN), 1.75 (s, 3H, p-Me). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 36.92 (s, PA), −33.65 (d, 2JBC = 77.0), −44.91 (d, 2JBC = 77.0). HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −136 N4 [Hd]. Specific molar conductivity ΛM = 217 Ω−1 cm2 mol−1. [Pd(Ph2PCH2PPh2-P,P){Pd[4-(Ac)C6H3C(Me)NNC(S)NHMe](Ph2Ppy-P)}-N,S][ClO4]2 (7b). Orange solid, yield: 49.4 mg, 88%. Anal. Found: C: 49.2, H: 3.5, N: 4.2, S: 2.3; C54H49Cl2N4O9P3SPd2 (1306.72 g/mol) requires C: 49.6, H: 3.8, N: 4.3, S: 2.5%. IR(cm−1): ν(N−H) 3324, ν(CO) 1677, ν(CN) 1584. 1H NMR (CDCl3, δ/ppm, J/ Hz): 8.2−6.8 (m, 30H, 6 × Ph), 9.35 (m, 1H, Hd), 8.00 (m, 1H, Hf), 7.61 (m, 1H, He), 7.55 (dd, 1H, H3, 3J(H2H3) = 7.8, 4J(H3H5) = 1.3), 7.31 (m, 1H, Hg), 7.23 (br, 1H, NHMe), 7.08 (d, 1H, H2, 3 J(H2H3) = 7.8), 6.79 (dd, 1H, H5, 4J(H5P) = 5.2, 4J(H3H5) = 1.3), 4.97 (m, 1H, PBCHPC), 4.10 (m, 1H, PBCHPC), 2.72 (d, 3H, NHMe, 3 JNHMe = 4.9), 2.16 (s, 3H, MeCN), 1.96 (s, 3H, p-Ac). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 36.5 (s, PA), −35.4 (d, 2JBC = 77.9), −45.5 (d, 2JBC = 77.9). HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −137 N4 [Hd, He, Hg], −89 N1 [MeCN]. Specific molar conductivity ΛM = 231 Ω−1 cm2 mol−1. Compounds 5c, 6c, and 7c were prepared similarly from Ph2PC CH2PPh2, cis-Ph2PCHCHPPh2, Ph2P(CH2)2PPh2 ,and 5, 6, and 7, as appropriate. [Pd(Ph 2 PCCH 2 PPh 2 -P,P){Pd[C 6 H 4 C(Et)NNC(S)NHEt](Ph2Ppy-P)}-N,S][ClO4]2 (5c). Yield: 49.2 mg, 83%. Anal. Found: C: 50.9, H: 4.0, N: 4.1, S: 2.5; C55H51Cl2N4O8P3SPd2 (1304.75 g/mol) requires C: 50.6, H: 3.9, N: 4.3, S: 2.5%. IR(cm−1): ν(N−H) 3340, ν(CN) 1582. 1H NMR (CDCl3, δ/ppm, J/Hz): 8.6−6.8 (m, 38H, 6 × Ph, He, H2, H3, NHEt, PCCH2), 9.35 (m, 1H, Hd), 7.97 (m, 1H, Hf), 7.18 (m, 1H, Hg), 6.47 (m, 1H, H4), 6.11 (m, 1H, H5), 3.14 (m, 1H, NHCHCH3), 2.87 (m, 2H, CH3CHCN, NHCHCH3), 2.25 (m, 1H, CH3CHCN), 1.02 (m, 6H, CH3CH2CN, NHCH2CH3). 31 P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 36.2 (s, PA), −21.7 (d, 2JBC = 71.1), −33.1 (d, 2JBC = 71.1). HMBC-{15N−1H} NMR (CDCl3, δ/ ppm) [correlation]: −278 N3 [NHEt, NHCH2CH3], −135 N4 [Hd, He, Hg], −104 N2 [NHEt]. Specific molar conductivity ΛM = 229 Ω−1 cm2 mol−1. [Pd(cis-Ph2PCHCHPPh2-P,P){Pd[4-(Me)C6H3C(Me)NNC(S)NHMe](Ph2Ppy-P)}-N,S][ClO4]2 (6c). Yield: 50.5 mg, 86%. Anal. Found: C: 49.9, H: 3.9, N: 4.5, S: 2.3; C54H49Cl2N4O8P3SPd2 (1290.72 g/mol) requires C: 50.3, H: 3.8, N: 4.4, S: 2.5%. IR(cm−1): ν(N−H) 3435, ν(CN) 1586. 1H NMR (CDCl3, δ/ppm, J/Hz): 8.4−6.4 (m, 34H, 6 × Ph, CHCH, He, Hg), 9.11 (m, 1H, Hd), 7.97

(m, 1H, Hf), 6.84 (d, 1H, H2, 3J(H2H3) = 7.6), 6.62 (d, 1H, H3, J(H2H3) = 7.6), 5.67 (d, 1H, H5, 4J(H5P) = 5.3), 2.47 (d, 3H, NHMe, 3JNHMe= 4.7), 2.29 (s, 3H, MeCN), 1.65 (s, 3H, p-Me). 31P− {1H} NMR (CDCl3, δ/ppm, J/Hz): 70.3 (s, PB, PC), 36.9 (s, PA). HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −136 N4 [Hd, He, Hg], −94 N1 [MeCN]. Specific molar conductivity ΛM = 215 Ω cm2 mol−1. [Pd(Ph2P(CH2)2P152-P,P){Pd[4-(Ac)C6H3C(Me)NNC(S)NHMe](Ph2Ppy-P)}-N,S][ClO4]2 (7c). Yield: 46.1 mg, 83%. Anal. Found: C: 49.6, H: 3.6, N: 4.2, S: 2.1; C55H51Cl2N4O9P3SPd2 (1320.75 g/mol) requires C: 50.0, H: 3.9, N: 4.3, S: 2.4%. IR(cm−1): ν(N−H) 3338, ν(CO) 1675, ν(CN) 1583. 1H NMR (CDCl3, δ/ppm, J/Hz): 8.2−6.5 (m, 30H, 6 × Ph), 9.40 (m, 1H, Hd), 7.82 (m, 1H, Hf), 7.56 (m, 1H, He), 7.49 (dd, 1H, H3, 3J(H2H3) = 8.2, 4J(H3H5) = 1.2), 7.21 (m, 1H, Hg), 7.06 (d, 1H, H2, 3J(H2H3) = 8.2), 6.91 (br, 1H, NHMe), 6.65 (dd, 1H, H5, 4J(H5P) = 5.3, 4J(H3H5) = 1.2),3.4−1.8 (m, 4H PBCH2CH2PC), 2.54 (d, 3H, NHMe, 3JNHMe = 4.7), 2.28 (s, 3H, MeCN), 1.96 (s, 3H, p-Ac). 31P−{1H} NMR (CDCl3, δ/ppm, J/Hz): 65.9 s, 63.5 s, 36.7 (s, PA). HMBC-{15N−1H} NMR (CDCl3, δ/ppm) [correlation]: −137 N4 [Hd]. Specific molar conductivity ΛM = 217 Ω−1 cm2 mol−1. 4.5. X-ray Structure Determination. The molecular structures of 3, 6, 2b, and 3b have been solved. Crystallographic data were collected at 293(2) K (except 3b) using a Siemens Smart-CCD-100028 Bruker diffractometer (Mo Kα radiation, λ = 0.71073 Å) equipped with a graphite monochromator. Intensity data were collected as a series of frames, each of ω width 0.3°, integrated29 and corrected for absorption30 and solved and refined using routine techniques.31 All non-hydrogen atoms, were refined anisotropically. The crystallographic data of 3b were collected at 100(1) K, because, at room temperature, the monocrystal broke down. The asymmetric units comprise a molecule of the compound together with a molecule of acetone in 6, and four molecules of chloroform in 3b. Crystallographic data and selected interatomic distances and angles are listed in Tables 1 and 2, and intermolecular stacking parameters are listed in Table 3 for 3b. ORTEP32 and Mercury33 drawings are shown in Figures 4−9. 3

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ASSOCIATED CONTENT

S Supporting Information *

X-ray crystallographic data and tables giving atomic coordinates, displacement parameters, and bond distances and angles for 3, 6, 2b, and 3b [CCDC no. 969069 (3), 969070 (6), 969071 (2b), 969072 (3b)]. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We thank the Xunta de Galicia (projects 10DPI209017PR and 10PXIB209226PR) for financial support. J.M. acknowledges an Isidro Parga Pondal contract from the Xunta de Galicia.

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REFERENCES

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