Mixed Valence Pt(II),Pt(IV),Pt(II) Complexes from a Diplatinum(III

Apr 24, 2019 - The coordination of the S-based anions, thiophenoxide (PhS–, a), ethyl xanthogenate (EtOCS2–, b), 2-mercaptopyridinate (pyS–, c),...
0 downloads 0 Views 2MB Size
Download PDF
Article Cite This: Organometallics XXXX, XXX, XXX−XXX

pubs.acs.org/Organometallics

Mixed Valence Pt(II),Pt(IV), and Pt(II) Complexes from a Diplatinum(III) Synthon and Sulfur-Based Anions Consuelo Fortuño,*,† Antonio Martín,† Piero Mastrorilli,*,‡ Stefano Todisco,‡ and Mario Latronico‡ †

Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea-ISQCH, Universidad de Zaragoza-C.S.I.C., E-50009 Zaragoza, Spain ‡ DICATECh, Politecnico di Bari, I-70125 Bari, Italy

Organometallics Downloaded from pubs.acs.org by IDAHO STATE UNIV on 04/24/19. For personal use only.

S Supporting Information *

ABSTRACT: The coordination of the S-based anions, thiophenoxide (PhS−, a), ethyl xanthogenate (EtOCS2−, b), 2-mercaptopyridinate (pyS−, c), and 2-mercaptopyrimidinate (pymS−, d), to the central platinum atom of the trinuclear Pt(III)2,Pt(II) complex [(C6F5)2PtIII(μ-PPh2)2PtIII(μ-PPh2)2PtII(C6F5)2](Pt−Pt), 1, gives rise to three different types of complexes: (i) the Pt(II),Pt(II),Pt(II) complex [NnBu4][(C6F5)2PtII(μPPh2)2PtII{κ2-S,P-μ-(PhS)PPh2}(μ-PPh2)PtII(C6F5)2], 2a; (ii) the Pt(II),Pt(IV),Pt(II) mixed valence complexes [NnBu4 ][(C 6F5 )2 PtII(μ-PPh 2)2 PtIV (κ2-S,S′-EtOCS2 )(μPPh2)2PtII(C6F5)2], 3b, and [NnBu4][(C6F5)2PtII(μ-PPh2)2PtIV{κ2N,P-(pymS)PPh2}(μPPh2)2PtII(C6F5)2], 3d; and (iii) the Pt(II),Pt(II),Pt(II) derivatives [NnBu4][(C6F5)2PtII(μ-PPh2)2PtII{κ2N,P-μ-(pyS)PPh2}(μ-PPh2)PtII(C6F5)2], 4c, and [NnBu4][(C6F5)2PtII(μ-PPh2)2PtII{κ2N,P-μ-(pymS)PPh2}(μ-PPh2)PtII(C6F5)2], 4d. Complexes 2a, 4c, and 4d display new Ph2P(SL) ligands stemming from the reductive coupling of a PPh2 group and the S-based anions. Complex 2a exhibits a κ2-S,P bridging coordination mode while 4c and 4d exhibit a κ2-N,P mode in the solid state. In acetone solution, an equilibrium between the κ2-N,P and the κ2-S,P forms was ascertained for complexes with 2-mercaptopyrimidinate and 2mercaptopyridinate by NMR techniques. Complex 4d evolved, in acetone solution at 323 K, to the Pt(II),Pt(II),Pt(II) complex [NnBu4][(C6F5)2PtII(μ-PPh2){κ2-P,N-μ-(Pym)PPh2}PtII(κ2-S,P-μ-SPPh2)(μ-PPh2)PtII(C6F5)2], 5d. The X-ray diffraction structures of the trinuclear complexes 3′b (the complex having the same anion as 3b but Ph3PNPPh3+ as the countercation instead of NnBu4) and 4d are described.

■

the addition of nucleophiles such as I−, N3−, and OH− to the dinuclear complex [(C6F5)2PtIII(μ-PPh2)2PtIII(C6F5)2](Pt−Pt) and to the trinuclear species [(C6F5)2PtIII(μ-PPh2)2PtIII(μPPh2)2PtII(C6F5)2](Pt−Pt), 1, rendered new Pt(II) derivatives through reductive coupling involving the PPh2 group.13 The reactivity of some bidentate S-based anions, which are able to coordinate to the platinum center as chelating ligands and potentially facilitating the stabilization of six-coordinate Pt(IV) complexes of type B, toward the dinuclear complex [(C6F5)2PtIII(μ-PPh2)2PtIII(C6F5)2](Pt−Pt) has been studied.14 New Pt(II) complexes were obtained either through the reductive coupling between the PPh2 and C6F5 groups with formation of a P−C bond or through the reductive coupling between the PPh2 bridging ligand and the S-based anion with formation of a P−S bond. The alleged Pt(IV) intermediates of type B were neither isolated nor identified.14 The trinuclear Pt2(III),Pt(II) compound [(C6F5)2PtIII(μPPh2)2PtIII(μ-PPh2)2PtII(C6F5)2](Pt−Pt), 1,8 depicted in Chart 2, shows the fragment A in which the two platinum(III) metal centers are different: (a) the terminal platinum(III) is bonded to two PPh2 bridging ligands and two terminal C6F5

INTRODUCTION

The reactivity of Pt complexes in high oxidation states (III and IV) is dominated by reductive processes involving the coupling of two anionic ligands, rendering new square planar Pt(II) complexes.1−5 In the framework of diphenylphosphanido-bridged platinum complexes, the only examples of derivatives in high oxidation states, (III) and (IV), show fragments of type A or B (Chart 1):6−12 The coordination environment of the Pt(III) centers in the fragment A is square planar and the addition of two ligands to one of the Pt(III) centers could render a fragment of type B with a Pt(II) and an octahedral Pt(IV) center. Nevertheless, Chart 1. Diphenylphosphanido Complexes in Which the Formal Metal Oxidation States of Platinum Are III and IV

Received: February 13, 2019

© XXXX American Chemical Society

A

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics Chart 2. Trinuclear Compound [(C6F5)2PtIII(μPPh2)2PtIII(μ-PPh2)2PtII(C6F5)2](Pt−Pt)

formation of a P−S bond, through the reductive coupling of the coordinated diphenylphosphanide and phenylsulphide. The addition of potassium ethyl xanthogenate, KEtOCS2 (b), to a red dichloromethane or acetone solution of [(C6F5)2PtIII(μ-PPh2)2PtIII(μ-PPh2)2PtII(C6F5)2](Pt−Pt), 1, (1:1 molar ratio) at room temperature gave rise, after work up, to the Pt(II),Pt(IV),Pt(II) derivative [N n Bu 4 ][(C6F5)2PtII(μ-PPh2)2PtIV(κ2-S,S′-EtOCS2)(μPPh2)2PtII(C6F5)2], 3b, as an orange solid (Scheme 1). As to the reactivity with S^N anions, the addition of the didentate ligand tetranbutylammonium 2-mercaptopyridinate (NnBu4pyS, c, 1:1 mixture of NnBu4OH and C5H4NSH in methanol), in the same experimental conditions followed for PhS− or EtOCS2−, led to the Pt(II),Pt(II),Pt(II) derivative, [NnBu4][(C 6 F 5 ) 2 Pt II (μ-PPh 2 ) 2 Pt II {κ 2 N,P-μ-(pyS)PPh 2 }(μ-PPh 2 )PtII(C6F5)2], 4c, as a yellow solid (Scheme 1). On the other hand, the addition of tetranbutylammonium 2-mercaptopyrimidinate (NnBu4pymS, d, 1:1 mixture of NnBu4OH and C4H3N2SH in methanol) to a red dichloromethane solution of 1 rendered, at room temperature, the Pt(II),Pt(IV),Pt(II) derivative [NnBu4][(C6F5)2PtII(μ-PPh2)2PtIV{κ2N,P-(pymS)PPh2}(μ-PPh2)2PtII(C6F5)2], 3d (in mixture with inseparable residual 1) and, at reflux, the Pt(II),Pt(II),Pt(II) derivative [NnBu4][(C6F5)2PtII(μ-PPh2)2PtII{κ2N,P-μ-(pymS)PPh2}(μPPh2)PtII(C6F5)2], 4d (Scheme 1). The complexes obtained from reaction of 1 with the S-based anions a−d were characterized by elemental analysis, X-ray diffraction (XRD), HR ESI−MS, and multinuclear NMR spectroscopy. The crystal structures of the trinuclear complexes 3′b (the complex having the same anion as 3b but Ph3PNPPh3+ (PPN) as the countercation instead of NnBu4) and 4d were obtained by XRD analyses. Figure 1 shows a view of the anion of 3′b and Table 1 lists the most relevant bond distances and angles. The crystal structure of 3′b confirms the trinuclear nature of the anion and a nonlineal disposition of the three platinum metals. The terminal platinum centers are bonded to two pentafluorophenyl groups and to two P atoms of the diphenylphosphanido ligands giving rise to the well-established “cis-(C6F5)2Pt(μ-PPh2)2” fragment, with a typical square planar environment for the metals. Both of these fragments are bonded through the

groups and (b) the central platinum(III) is bonded to four PPh2 bridging groups. Thus, while the coordination of S-based anions to the terminal platinum(III) center could evolve in a similar way to the one previously observed for dinuclear [(C6F5)2PtIII(μPPh2)2PtIII(C6F5)2](Pt−Pt), the fate of the complex upon coordination of the S-based anions to the central platinum(III) atom is less predictable. However, taking into account that the central platinum atom in 1 is bonded to four P atoms, the formation of a P−C6F5 bond is unlikely and the formation of stable mixed valence complexes, Pt(II),Pt(IV), and Pt(II), by simple addition of ligands to a Pt(III)2,Pt(II) species (acting as a diplatinum(III) synthon) can be anticipated. In this paper, we report the results of the study on the addition of S-based anions, thiophenoxide (PhS−, a), ethyl xanthogenate (EtOCS2−, b), 2-mercaptopyridinate (pyS−, c), and 2-mercaptopyrimidinate (pymS−, d), to the trinuclear complex 1.

■

RESULTS The addition of tetra n butylammonium thiophenoxide (NnBu4PhS, a, 1:1 mixture of NnBu4OH and C6H5SH in methanol) to a red dichloromethane solution of the Pt(III) 2 ,Pt(II) complex [(C 6 F 5 ) 2 Pt III (μ-PPh 2 ) 2 Pt III (μPPh2)2PtII(C6F5)2](Pt−Pt), 1, (1:1 molar ratio) at room temperature resulted, after work up of the mixture, in the isolation of the platinum(II) derivative [NnBu4][(C6F5)2PtII(μPPh 2 ) 2 PtII {κ 2 -S,P-μ-(PhS)PPh 2}(μ-PPh 2 )Pt II(C 6 F5 ) 2 ], 2a (Scheme 1). The formation of 2a involves the coordination of the S-ligand to the central Pt(III) center in 1 and entails the Scheme 1. Reaction of 1 with S-Based Anions

B

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

Figure 2. Crystal structure of the anion of complex [NnBu4][(C 6 F 5 ) 2 Pt I I (μ-PPh 2 ) 2 Pt I I {κ 2 N,P-μ-(pymS)PPh 2 }(μ-PPh 2 )PtII(C6F5)2], (4d). Figure 1. Crystal structure of the anion of complex [PPN][(C6F5)2PtII(μ-PPh2)2PtIV(κ2-S,S′-EtOCS2)(μ-PPh2)2PtII(C6F5)2] (3′b).

most relevant bond distances and angles. The anion of 4d is a trinuclear complex with all of the three Pt atoms having square planar environments. The intermetallic distances (Pt(1)··· Pt(2) = 3.603(1) Å and Pt(2)···Pt(3) = 4.144(1) Å) exclude any metal−metal bond. The coordination of the 2mercaptopyrimidinate ligand occurs with the insertion in a Pt−P bond, formation of a P−S bond, and coordination of the pyrimidinic nitrogen atom to the central Pt (formation of a Pt−N bond). This insertion causes a distortion in the remaining phosphanide ligand bridging Pt(2) and Pt(3), with the Pt(2)−P(3)−Pt(3) angle broadening to 120.74(4)°. For comparison, the Pt(1)−P(1)−Pt(2) and Pt(1)−P(2)− Pt(2) angles are 103.37(4)° and 102.87(4)°, respectively. The HRMS(−) analysis of the anionic complexes 2a, 3b, 4c, 3d, and 4d showed the expected peaks with an isotope pattern superimposable to that calculated on the basis of the proposed formula. Knowing that related anionic Pt2 complexes [[NnBu4][(C6F5)2PtII(μ-PPh2)2PtII(N^O)] (N^O = 8-hydroxyquinolinate or o-picolinate)], endowed with a PtII2P2 ring oxidasable to PtIII2P2(Pt−Pt), could be oxidized electrochemically by submitting them to HRMS(+) analysis in the positive mode,12 we checked whether also the Pt(II),Pt(II),Pt(II) species 2a, 4c, and 4d could be transformed, in the ESI ionisation chamber,

four P atoms to the central Pt(2), which shows a characteristic six-coordinated platinum(IV) environment with the two S atoms of the xanthogenate ligand completing its coordination sphere. The octahedral coordination around Pt(2) is somewhat distorted because of the small bite angles of the three chelate ligands: the xanthogenate group (S(1)−Pt(2)−S(2) = 72.28(3)°) and the two “cis-(C6F5)2Pt(μ-PPh2)2” fragments (P(1)−Pt(2)−P(2) = 75.35(3)° and P(3)−Pt(2)−P(4) = 74.37(2)°). The four P−Pt(2) distances are longer than the four P−Pt(1,3) ones and the intermetallic distances between contiguous Pt atoms are of about 3.7 Å, which excludes any Pt···Pt interaction. This value can be compared with the intermetallic Pt(III)−Pt(III) distance in the precursor 1, 2.7766(10) Å,8 where a Pt−Pt bond is present. Crystals of 1, 3d, and 4d were isolated from the solid mixture of 3d and 1. The low quality of the crystals of the Pt(II),Pt(IV),Pt(II) complex 3d precluded full XRD structural characterization. Nevertheless, the collected data allowed us to establish unambiguously the connectivity shown in Scheme 1. The structure of complex 4d was also determined by XRD. Figure 2 shows a view of the anion of 4d and Table 2 lists the

Table 1. Relevant Bond Distances (Å) and Angles (deg) for the Structure of Complex [PPN][(C6F5)2PtII(μ-PPh2)2PtIV(κ2-S,S′EtOCS2)(μ-PPh2)2PtII(C6F5)2], (3′b) Pt(1)−C(7) Pt(1)−P(1) Pt(2)−S(1) Pt(2)−P(4) Pt(3)−P(4) C(7)−Pt(1)−C(1) C(1)−Pt(1)−P(2) C(1)−Pt(1)−P(1) P(1)−Pt(2)−S(2) S(2)−Pt(2)−S(1) S(2)−Pt(2)−P(3) P(1)−Pt(2)−P(2) S(1)−Pt(2)−P(2) P(1)−Pt(2)−P(4) S(1)−Pt(2)−P(4) P(2)−Pt(2)−P(4) C(19)−Pt(3)−P(4) C(19)−Pt(3)−P(3) P(4)−Pt(3)−P(3)

2.065(3) 2.3349(8) 2.4248(7) 2.4690(8) 2.3091(8)

Pt(1)−C(1) Pt(2)−P(1) Pt(2)−P(3) Pt(3)−C(19) Pt(3)−P(3) 87.27(12) 178.07(8) 100.19(8) 161.14(3) 72.28(3) 100.82(3) 75.35(3) 89.37(3) 105.79(3) 89.28(2) 178.34(3) 99.46(8) 178.28(9) 79.49(3)

2.088(3) 2.4071(8) 2.4336(8) 2.075(3) 2.3257(8) C(7)−Pt(1)−P(2) C(7)−Pt(1)−P(1) P(2)−Pt(1)−P(1) P(1)−Pt(2)−S(1) P(1)−Pt(2)−P(3) S(1)−Pt(2)−P(3) S(2)−Pt(2)−P(2) P(3)−Pt(2)−P(2) S(2)−Pt(2)−P(4) P(3)−Pt(2)−P(4) C(19)−Pt(3)−C(13) C(13)−Pt(3)−P(4) C(13)−Pt(3)−P(3)

C

Pt(1)−P(2) Pt(2)−S(2) Pt(2)−P(2) Pt(3)−C(13)

2.3032(8) 2.4148(7) 2.4625(8) 2.079(3) 92.66(9) 172.39(9) 79.84(3) 97.92(3) 92.89(3) 162.39(3) 88.23(3) 106.86(3) 90.45(3) 74.37(2) 83.98(11) 173.32(9) 96.93(8)

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics Table 2. Relevant Bond Distances (Å) and Angles (deg) for the Structure of Complex [NnBu4][(C6F5)2PtII(μPPh2)2PtII{κ2N,P-μ-(pymS)PPh2}(μ-PPh2)PtII(C6F5)2], (4d) Pt(1)−C(1) Pt(1)−P(1) Pt(2)−P(2) Pt(3)−C(19) P(4)−S C(1)−Pt(1)−C(7) C(7)−Pt(1)−P(2) C(7)−Pt(1)−P(1) N(1)−Pt(2)−P(1) P(1)−Pt(2)−P(2) P(1)−Pt(2)−P(3) C(13)−Pt(3)−C(19) C(19)−Pt(3)−P(4) C(19)−Pt(3)−P(3)

2.063(3) 2.3034(10) 2.3298(10) 2.060(4) 2.1189(14)

Pt(1)−C(7) Pt(2)−N(1) Pt(2)−P(3) Pt(3)−P(4)

2.070(4) 2.124(3) 2.3891(10) 2.2662(9)

91.13(14) 96.94(10) 169.98(10) 168.27(9) 76.35(3) 106.66(3) 83.93(15) 88.36(10) 171.78(10)

C(1)−Pt(1)−P(2) C(1)−Pt(1)−P(1) P(2)−Pt(1)−P(1) N(1)−Pt(2)−P(2) N(1)−Pt(2)−P(3) P(2)−Pt(2)−P(3) C(13)−Pt(3)−P(4) C(13)−Pt(3)−P(3) P(4)−Pt(3)−P(3)

Pt(1)−P(2) Pt(2)−P(1) Pt(3)−C(13) Pt(3)−P(3)

2.2785(9) 2.2891(9) 2.058(4) 2.3788(10) 171.37(11) 95.34(11) 77.08(3) 91.95(9) 84.78(9) 171.38(3) 162.98(10) 92.51(11) 96.95(3)

bond (P1 and P2, respectively. See Scheme 1 for P numbering).9,15−18 The signal of P3 appears at δ 14.3, in the range observed for the “Pt(μ-PPh2)(μ-X)Pt” fragments,17−19 and at lower field (δ 126.5) the signal appears due to the new thiophosphane ligand.14 The 19F NMR spectrum at 298 K (Figure S2) showed four broad signals for the ortho-F and eight sharp signals for the meta-F and para-F of the four pentafluorophenyl rings, indicating free rotation of the C6F5 groups about the Pt−C bonds. The 195Pt NMR signals were obtained at δ −3785 (Pt1), −4136 (Pt2), and −4557(Pt3) by recording a 195Pt{19F} NMR spectrum at 298 K (Figure S3). In the Pt(II),Pt(IV),Pt(II) complex 3b, the molecule generates, depending on the specific isotopologue and referring just to 31P (A, X) and 195Pt (M, N) nuclei, the following spin systems: A2X2 (isotopologue with no 195Pt, 29.1% abundance), A 2 X 2 M (isotopologue with 195 Pt2 , 14.8% abundance), A 2X 2 MM′ (isotopologue with 195 Pt1 and 195Pt3 , 7.5% abundance), AA′XX′M (isotopologue with 195Pt1 or 195Pt3, 29.6% abundance), AA′XX′MN (isotopologue with 195Pt1 and 195 2 Pt or 195Pt2 and 195Pt3, 15.1% abundance), and A2X2M2N (isotopologue with 195Pt1, 195Pt2 and 195Pt3, 3.9% abundance). The superimposition of the 31P{1H} spectra due to the six isotopologues gives rise to two multiplets centered at ca. −120 and −136 ppm flanked by several sets of 195Pt satellites. The whole spectrum was calculated (Figure 4) and the spectroscopic features reported in the Experimental Section were

into the corresponding Pt(III),Pt(III),Pt(II) cationic species. In the conditions detailed in the Experimental Section, the three monoanions were smoothly oxidized and the HRMS(+) spectrograms showed intense peaks ascribable to the corresponding monocationic trinuclear complexes deriving from the loss of two electrons. This confirms that an electrochemical oxidation of 2a, 4c, and 4d occurs, affording the Pt(III),Pt(III),Pt(II) species of formula [(C6F5)2PtIII(μPPh 2 ) 2 PtIII {μ-(L^S)PPh 2 }(μ-PPh 2 )PtII(C 6 F 5) 2 ] + (Pt1 −Pt 2) (L^S = PhS−, 2-mercaptopyridinate and 2-mercaptopyrimidinate). Figure 3 shows the HRMS(+) spectrogram of 2a stemming from the cation [(C6F5)2PtIII(μ-PPh2)2PtIII(μPhSPPh2)(μ-PPh2)PtII(C6F5)2]+(Pt1−Pt2).

Figure 3. HRMS(+) spectrogram of 2a in MeCN showing the peaks corresponding to the oxidized cation [(C6F5)2PtIII(μ-PPh2)2PtIII(μPhSPPh2)(μ-PPh2)PtII(C6F5)2]+(Pt1−Pt2).

The behavior of the complexes 2a, 3b, 4c, 3d, and 4d was studied in solution by 31P, 1H, 19F, and 195Pt NMR spectroscopy. The 31P{1H} NMR spectrum of 2a in deuteroacetone at room temperature (Figure S1) showed four signals flanked by 195 Pt satellites. The pattern and chemical shifts of the signals are in agreement with the structure depicted in Scheme 1. This spectrum shows two high-field signals, δ −117.2 and δ −136.1, due to the P atoms of the two diphenylphosphanide groups bridging two Pt(II) centers not joined by the metal−metal

Figure 4. Experimental (top) and calculated (bottom) 31P{1H} NMR spectra of 3b. D

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics obtained. The chemical shift of the P atoms trans to S (PA) was −119.6 ppm while that of the P atoms trans each other (PX) was −136.4 ppm. The geminal coupling constants between PX and PX′ and between PX and PA are 280 and 121 Hz, respectively, consistent with the PX−Pt2−PX′ and PX−Pt2−PA angles of 178° and 75°, respectively. The coupling constants of PA/X atoms with the terminal Pt(II) atoms are all about 2000 Hz while the P−Pt coupling constants with the central Pt(IV) atom are quite different, passing from PA (1JPA,Pt2 = 1691 Hz) to PX (1JPX,Pt2 = 842 Hz), as a result of markedly different transinfluences of P and S. Moreover, these two 1JP,Pt values are smaller than couplings measured in analogous trans-P−Pt(II)− S and trans-P−Pt(II)−P systems, as is expected because of the presence of an octahedral platinum(IV) center in 3b. The 195Pt NMR signals were obtained by combining informations coming from 1H−195Pt HMQC and 19F−195Pt HMQC experiments. The chemical shift of the square planar 195Pt(II) atoms fell at δPt −3657 while that of the octahedral 195Pt(IV) atom fell at δPt −2923. The latter value is comparable to that (δPt −2917) found for the related octahedral 195Pt(IV) nucleus of the mixed valence phosphanido complex [(C6F5)2PtII(μPPh2)2PtIV(κ2,N,C-C13H8N)I2].11 The 31P{1H} NMR spectra obtained by dissolving solid 4c in deuteroacetone at 298 K showed four very broad signals (δ 122, δ 8, δ −134, and δ −149), with a pattern analogous to that observed for complex 2a, which are ascribed to 2c (Scheme 2), the isomer of 4c in which the (pyS)PPh2 ligand

Figure 5. VT 31P{1H} spectrum of the solution obtained by dissolving solid 4c in deuteroacetone.

S8). 195Pt NMR signals for 4c and 2c are comparable to those found for 2a and are reported in the Experimental Section. It is interesting to note that an equilibrium in solution between the “κ2N,P-μ-(L^S)PPh2” and the “κ2S,P-μ-(L^S)PPh2” forms has been detected also for the related diplatinum complexes [(C6F5)2PtII{κ2N,P-μ-(L^S)PPh2}(μ-PPh2)PtII(C6F5)2]− (L^S = 2-mercaptopyridinate or 2-mercaptopyrimidinate). In this case, however, the predominant form at room temperature was the “κ2S,P-μ-(L^S)PPh2” one.14 The 31P{1H} NMR spectrum at 298 K of complex 3d (obtained from reaction of 1 with pymS− at 298 K and impure for residual 1) showed only very broad signals in the −90 to −120 ppm region, indicating a very fluxional system. The lowtemperature 31P{1H} NMR spectrum (223 K, Figure S9) showed several broad signals that were attributed to the Pt(II),Pt(IV),Pt(II) complex 3d along with the solvento species 3d_Solv (plus the signals at δ −127 and δ +262 due to residual 1) (Scheme 3) in a 3d/3d_Solv molar ratio of ca.

Scheme 2. Equilibrium between “κ2N,P-μ-(L^S)PPh2” (4c− d) and “κ2S,P-μ-(L^S)PPh2” (2c−d) Forms for Complexes with L^S = 2-Mercaptopyridinate or 2Mercaptopyrimidinate in Acetone

Scheme 3. Proposed Dissociation Equilibrium for 3d in Acetone Solution bridges Pt2 and Pt3 by S and P (instead of N and P) atoms. Lowering the temperature caused a sharpening of these four signals with contemporary appearance of further four broad 31P signals (δ 31.2, δ −22.3, δ −158.5, and δ −163.5) which became sharp at 223 K and that are attributed to 4c (Figure 5). This outcome can be explained admitting that dissolving solid 4c in deuteroacetone causes the setting of an equilibrium between the 4c and 2c forms, the latter being predominant at room temperature and with the former being predominant at low temperature (the 4c/2c molar ratio at 223 K is ca. 60/40). The observed behavior can be rationalized in terms of positive ΔH° and positive ΔS° of reaction. A positive entropy change on passing from 4 to 2 is in line with the increased freedom degrees associated with structures 2c, where the pyridine ring can freely rotate. The signals of 4c at δ 31.2, δ −22.3, δ −158.5, and δ −163.5 are attributed to P4, P3, P2, and P1, respectively (see Scheme 2 for numbering). The existence of the 4c−2c equilibrium was ascertained by recording the 31P{1H} EXSY spectrum at 263 K of the solution obtained by dissolving solid 4c in deuteroacetone, which showed exchange cross-peaks between 31 P signals of 4c with the corresponding signals of 2c (Figure

60/40. The solvento species 3d_Solv is formed by detachment of the nitrogen from platinum. The attribution of the NMR peaks to the appropriate P atoms was made by means of 31 1 P{ H} COSY (Figure S10) and 31P{1H} EXSY experiments at low temperature and is reported in the Experimental Section. The 31P{1H} EXSY spectrum at low T (Figure S11) indicated that the two Pt(II),Pt(IV),Pt(II) species 3d and 3d_Solv are in equilibrium and that the residual 1 present in solution does not participate in such an equilibrium. Complex 3d undergoes an irreversible transformation into the Pt(II),Pt(II),Pt(II) complex 4d when left in acetone solution for one week at room temperature. Moreover, stirring E

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

104.9 and δ 75.9 are attributed to μ-(Pym)PPh2 and μ-(S) PPh2, respectively, while the doublets at δ 11.2 and δ −7.1 are attributed to the mutually trans-μ-PPh2 groups. The 195Pt{1H} NMR signals were found at δ −4492 (Pt1), δ −3901 (Pt2), and δ −4428 (Pt3). IR spectroscopy is not very informative about the nature of these complexes except in the absorption bands of the pentafluorophenyl groups in the 950 cm−1 region, related with the formal oxidation state of the platinum center.21 The starting material 1 shows C6F5 groups bonded to Pt(III) and Pt(II) centers and it shows two absorptions at 963 and 955 cm−1 in this region. All new products isolated here show only one absorption at ca. 950 cm−1, according to the presence of pentafluophenyl groups bonded only to Pt(II) centers.

an acetone solution of 4d at 323 K for 2 h triggered C−S bond breaking and P−S bond forming reactions leading to the Pt(II),Pt(II),Pt(II) complex 5d depicted in Scheme 4. Scheme 4. Irreversible Transformations of 3d in Acetone Solution

■

DISCUSSION The oxidative addition to a d8 center and the reductive elimination from a d6 center are the prominent processes involved in the formation and evolution of the M(II)/M(IV)/ M(II) transformations.1−4 The direct reductive coupling processes from 18-electron octahedral M(IV) derivatives are rare, and the dissociation of one of the ligands, affording 16electron unsaturated derivatives with subsequent reductive coupling forming the M(II) complex, is usually the proposed path.22−30 Thus, the synthesis of the trinuclear platinum(II) 2a conceivebly starts with the coordination of the S center of PhS− to the central platinum(III) forming a Pt(II),Pt(IV),Pt(II) intermediate with an unsaturated Pt(IV) center.31,32 The reductive coupling between the two formally anionic groups PhS− and PPh2− bonded to the platinum(IV) center affords the new bridging ligand PhS−PPh2, which remains coordinated to Pt. An analogous process could explain the formation of the platinum(II) complexes 4c and 4d. In the Pt(II),Pt(IV),Pt(II) intermediates, the Pt(IV) center is bonded to four anionic P ligands and one anionic S ligand and the reductive coupling between the incoming S-based group and a diphenylphosphanido group, with the formation of a P−S bond, is preferred over the reductive coupling between two diphenylphosphanido groups, with the formation of a P−P bond.33 The synthesis of complexes 3b and 3d proves our initial hypothesis: the coordination of bidentate S-based anions to the central platinum atom in the Pt(III),Pt(III),Pt(II) complex 1 leads to the formation of the Pt(II),Pt(IV),Pt(II) derivatives. The xanthogenate derivative 3b does not evolve to structures 2 or 4 while the 2-mercaptopyrimidinate derivative 3d slowly transforms into 4d, which, on turn, renders quantitatively 5d upon heating. The hexacoordination of the Pt(IV) in 3b and 3d is achieved through the bonding of three didentate fragments coordinated in a chelating way: two “(RF)2PtII(μ-PPh2)2” fragments and one ethyl xanthogenate (3b) or 2-mercaptopyrimidinate (3d) ligand. The small bite angle of these two latter S-based anions could favor the formation of the six-coordinated octahedral platinum(IV) with the participation of the two very bulky metalloligands. The differences in the reactivity of complex 1 depending on the reacting S-based anions can be rationalized invoking different behaviors of the mixed valence Pt(II),Pt(IV),Pt(II) intermediate with respect to dissociation on the Pt(IV) center, a preliminary step for the occurrence of the P−S reductive coupling. In the case of the Pt(II),Pt(IV),Pt(II) complex 3b, the Pt(IV) atom is bonded to the xanthogenate group through two equivalent Pt−S bonds, with low tendency to dissociate.

The behavior of complex 4d in solution parallels that observed for 4c (Scheme 2). In fact, the existence of an equilibrium between the “κ2N,P-μ-(pymS)PPh2” (4d) and the “κ2S,P-μ-(pymS)PPh2” (2d) forms was ascertained (31P{1H} EXSY), also in the case of the 2-mercaptopyrimidinate system. The “κ2N,P-μ-(pymS)PPh2” form (4d) of the 2-mercaptopyrimidinate system gave 31P signals at T = 193 K centered at δ: 33.8 (P4), δ −20.4 (P3), δ −163.1 (P1), and δ −165.2 (P2) while the 31P signals of the “κ2S,P-μ-(pymS)PPh2” form (2d) were found, at T = 298 K, at δ 88 (P4), δ 3.4 (P3), δ −151 (P1), and δ −163.7 (P2) (Figure 6). The 4d/2d molar ratio at 193 K was ca. 2/1.

Figure 6. VT 31P{1H} spectrum of the solution obtained by dissolving solid 4d in deuteroacetone.

The 31P{1H} NMR in acetone-d6 of the Pt(II),Pt(II),Pt(II) complex 5d (Figure S12) showed two broad singlets at δ 104.9 and δ 75.9 and two mutually coupled doublets at δ 11.2 and δ −7.1 (1JP,P3 = 269 Hz), all flanked by one (signals at δ 104.9 and δ 75.9) or two (signals at δ 11.2 and δ −7.1) sets of 195Pt satellites stemming from direct Pt−P coupling. The ensemble of ESI−MS, elemental analyses, and polynuclear NMR data for complex 5d indicates the structure depicted in Scheme 4, a linear trinuclear Pt(II) complex in which a central Pt atom, coordinated to two P, one N, and one S, is bonded on one side to a cis-Pt(C6F5) fragment through a μ-PPh2 group and a μ(Pym)PPh2 group (through the N atom) and on the other side to another cis-Pt(C6F5) fragment through another μ-PPh2 group and a μ-(S)PPh2 group (through the S atom). Thus, the HRMS(−) analysis of CH3CN solution of 5d gave a peak at m/z 2105.0791, indicating that the molecular formula is identical to that of 3d or 4d.20 The 31P NMR singlets at δ F

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

Figure 7. HRMS in positive and negative ion modes of pyrimidine derivatives 4d and 5d. solutions by continuous infusion with the aid of a syringe pump at a flow rate of 180 μL/h. The instrument was operated at end plate offset −500 V and capillary −4500 V. Nebulizer pressure was 0.3 bar (N2) and the drying gas (N2) flow was 4 L/min. Drying gas temperature was set at 453 K. The software used for the simulations is Bruker Daltonics Data Analysis (version 4.0). The methanolic solutions of NnBu4RS were prepared by adding methanol to equimolar amounts of the RSH ligand and NnBu4OH. The literature method was used to prepare the starting material 1 [(C6F5)2PtIII(μPPh2)2PtIII(μ-PPh2)2PtII(C6F5)2](Pt−Pt).8 All described complexes are air-stable. [N n Bu 4 ][(C 6 F 5 ) 2 Pt II (μ-PPh 2 ) 2 Pt II {κ 2 -S,P-μ-(PhS)PPh 2 }(μ-PPh 2 )PtII(C6F5)2] (2a). To a dark red solution of 1 (0.100 g, 0.050 mmol) in CH2Cl2 (20 mL), NnBu4C6H5S (0.1 mmol, 4.2 mL of a methanol solution 0.024 M) was added and the mixture was stirred for 20 h at room temperature. The yellow solution was evaporated to 1 mL, i PrOH (8 mL) was added, and the mixture was stirred for 0.5 h. 2a crystallized as a yellow solid that was filtered, washed with iPrOH (2 × 0.5 mL), and dried. 2a, 0.078 g, 67% yield. Anal. Found (calcd for C94H81F20NP4Pt3S): C, 47.97 (48.13); H, 3.41 (3.48); N, 0.49 (0.60); S, 1.66 (1.37). HRMS(−), exact mass for the anion [C78H45F20P4Pt3S]− ([M]−): 2103.0839 Da; measured: m/z: 2103.0820 (M)− (error 0.3 ppm). IR (cm−1): 950.21 1H NMR (acetone-d6, 298 K, 400 MHz): δ 7.65 (m, 3H, overlapped ortho SPh + para SPh), from 7.49 to 7.34 (m, 12H, overlapped ortho Ph2−P3 + ortho Ph2−P2 + meta SPh), from 7.13 to 6.95 (m, 20H, overlapped para Ph2−P2 + ortho Ph2−P3 + ortho Ph2−P1 + para Ph2−P3 + meta Ph2−P2 + meta Ph2−P4 + para Ph2−P4) 6.87 (t, 2H, 3JH,H = 7 Hz, para Ph2−P1), 6.80 (t, 4H, 3JH,H = 7 Hz, meta Ph2−P3), 6.64 (t, 4H, 3 JH,H = 7 Hz, meta Ph2−P1), 3.45 (m, 8H, NnBu4+), 1.83 (pseudo quintet, 3JH,H = 7 Hz, 8H, NnBu4+), 1.43 (pseudo sextet, 3JH,H = 7 Hz, 8H, NnBu4+), 0.97 (t, 3JH,H = 7 Hz, 12H, NnBu4+). 19F NMR (acetoned6, 298 K, 376.5 MHz): δ −114.0 (br m, 3JPt,F = 339 Hz, 2 ortho-F of a C6F5 bonded to Pt1), −114.5 (br m, 3JPt,F = 361 Hz, 2 ortho-F of a C6F5 bonded to Pt1), −115.0 (br m, 3JPt,F = 294 Hz, 2 ortho-F of a C6F5 bonded to Pt3), −116.0 (br m, 3JPt,F = 331 Hz, 2 ortho-F of a C6F5 bonded to Pt3), −165.4 (t, 3JF,F = 20 Hz, 1 para-F), −165.8 (pseudo t of d, 3JF,F = 20 Hz, 5JF,P = 10 Hz, 2 meta-F of a C6F5 bonded to Pt3), −166.0 (ddd, 3JF,F = 22 Hz, 3JF,F = 20 Hz, 5JF,P = 7 Hz, 2 metaF of a C6F5 bonded to Pt3), −166.8 (t, 3JF,F = 20 Hz, 1 para-F), −167.3 (ddd, 3JF,F = 23 Hz, 3JF,F = 20 Hz, 5JF,P = 10 Hz, 2 meta-F of a C6F5 bonded to Pt1), −167.5 (ddd, 3JF,F = 23 Hz, 3JF,F = 20 Hz, 5JF,P = 10 Hz, 2 meta-F of a C6F5 bonded to Pt1), −168.1 (t, 3JF,F = 20 Hz, 1 para-F), −168.3 (t, 3JF,F = 20 Hz, 1 para-F). 31P{1H} NMR (acetoned6, 298 K, 162.0 MHz): δ 126.5 (s, 1JP4,Pt3 = 2922 Hz, P4), 14.3 (d, 1 3 2 JP ,Pt = 1830 Hz, 1JP3,Pt3 = 1736 Hz, 1JP2,P3 = 241 Hz, P3), −117.2 (d, 1 1 1 JP ,Pt = 1830 Hz, 1JP1,Pt2 = 2513 Hz, 1JP1,P2 = 143 Hz, P1), −136.1 (dd, 1 2 2 JP ,Pt = 1437 Hz, 1JP2,Pt1 = 1792 Hz, P2) ppm. 195Pt{19F} NMR (acetone-d6, 298 K, 86 MHz): δ 3785 (pseudo t, 1JPt1,P1 = 1830 Hz,

On the contrary, in complexes 3c (not isolated) or 3d (isolated), the Pt(IV) atom is bonded to the relevant S-based anion (mercaptopyridinate or mercaptopyrimidinate) through a Pt−N(sp2) and a Pt−S(sp3) in a Pt−S−C−N ring. This asymmetrical bonding presumably favors the dissociation on the Pt(IV) center and the subsequent reductive coupling. If this hypothesis is correct, the tendency to dissociate the mercaptopyridinate intermediate 3c should be higher than that of the mercaptopyrimidinate intermediate 3d so that 3c could not be isolated, whereas 3d could be isolated but is not stable in solution where it evolves irreversibly toward 4d/2d. It is worth mentioning that, in these Pt(II),Pt(II),Pt(II) anionic complexes, the presence of a PtII2P2 ring can be confirmed also by the detection of HRMS(+) peaks because of the PtII2P2 → PtIII2P2 (Pt−Pt) oxidation (Figure 7).

■

CONCLUDING REMARKS The isolation of the complexes 3b and 3d demonstrates that phosphanido-bridged platinum(IV) complexes can be prepared by coordination of didentate ligands (S-based anions) to a suitable platinum(III) center. This procedure joins that already reported by us, consisting in the oxidative addition of I2 to platinum(II) derivatives. Moreover, this work represents another example of P−Pt bond activation in phosphanido-bridged complexes with transformation of the diphenylphosphanido group into other ligands, according to the following sequence:

■

EXPERIMENTAL SECTION

General Procedures and Materials. C, H, N, and S analyses were performed with a PerkinElmer 2400 CHNS analyzer. IR spectra were recorded on a PerkinElmer Spectrum 100 FT-IR spectrometer (ATR in the range 250−4000 cm−1). NMR spectra in solution were recorded on a Bruker AV-400 spectrometer with SiMe4, CFCl3, H2PtCl6, and 85% H3PO4 as external references for 1H, 19F, 195Pt, and 31 P, respectively. The signal attributions and coupling constant assessment were made on the basis of a multinuclear NMR analysis including 1H−31P HMQC, 1H−195Pt HMQC, 19F−195Pt HMQC, COSY, and NOESY experiments. High-resolution mass spectrometry (HRMS) analyses were performed using a time-of-flight mass spectrometer equipped with an electro-spray ion source (Bruker micrOTOF-Q II). The analyses were carried out in positive and negative ion modes. The samples were introduced as acetonitrile G

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics JPt1,P2 = 1792 Hz, Pt1), −4136 (m, 1JP1,Pt2 = 2513 Hz, 1JP3,Pt2 = 1830 Hz, 1JP2,Pt1 = 1792 Hz, Pt2), −4557 (dd, 1JP4,Pt3 = 2922 Hz, 1JP3,Pt3 = 1736 Hz, Pt3).

1

mixture was stirred for 20 h at room temperature. The orange-yellow solution was evaporated to 1 mL, methanol (15 mL) was added, and a solid crystallized that was filtered, washed with methanol (3 × 2 mL), and dried. The solid (0.013 g) was identified (IR spectroscopy) as the starting material 1. The yellow solution was evaporated to ca. 2 mL and [NnBu4][(C6F5)2PtII(μ-PPh2)2PtII{κ2N,P-μ-(pyS)PPh2}(μ-PPh2)PtII(C6F5)2], (4c) crystallized as a yellow solid that was filtered, washed with methanol (2 × 0.5 mL), and dried. 4c, 0.046 g, 39% yield. Anal. Found (calcd for C93H80F20N2P4Pt3S): C, 47.68 (47.60); H, 3.26 (3.44); N, 1.30 (1.19); S, 1.58 (1.37). HRMS(−), exact mass for the anion [C77H44F20NP4Pt3S]− ([M]−): 2104.0777 Da; measured: m/z: 2104.0803 (M)− (error 1.4 ppm). IR (cm−1): 949.21 1H NMR (acetone-d6, 298 K, 400 MHz): δ of 2c 8.09 (br s, 1H, H1), 7.77 (d, 3JH4,H3 = 7.7 Hz, 1H, H4), 7.69 (pseudo t of d, 3JH3,H4 = 3JH3,H2 = 7.7 Hz, 2JH3,H1 = 1.8 Hz, H3, 1H), 7.49 (overlapped m, ortho Ph2−P2, 3JH,H = 7.7 Hz, 4H), 7.47 (overlapped m, 3JH,H = 7.7 Hz, para Ph2−P4, 2H), 7.42 (overlapped m, H2, 1H), 7.30 (m, ortho Ph2−P4, 4H), 7.23 (m, ortho Ph2−P3, 4H), 7.19 (overlapped, para-Ph2−P1, 2H), 7.14 (t, 7.0 Hz, para Ph2− P2, 2H), 7.02 (m, overlapped ortho Ph2−P1 + para-Ph2−P3 + meta Ph2−P2 + meta Ph2−P4, 14H), 6.76 (t, 3JH,H = 7.5 Hz, overlapped meta Ph2−P1 + meta Ph2−P3, 8H), 3.46 (m, 8H, NnBu4+), 1.83 (m, 8H, NnBu4+), 1.43 (pseudo sextet, 3JH,H = 7.5 Hz, 8H, NnBu4+), 0.98 (t, 3JH,H = 7.3 Hz, 12H, NnBu4+). Low T 1H NMR (acetone-d6, 223 K, 376.5 MHz): δ of 4c + 2c 8.52 (br, overlapped H1 of 2c) 8.48 (br, overlapped H1 of 4c), 8.14 (br, H4 of 2c), 8.07 (br, H4 of 4c), 7.94 (br, overlapped H3 of 4c + 2c), from 7.87 to 6.0 (m, H2 + Ph of 4c and 2c). 19 F NMR (acetone-d6, 298 K, 376.5 MHz): δ of 2c −114.1 (br, 3 JPt,F = 332 Hz, 2 ortho-F of a C6F5 bonded to Pt1), −114.6 (br, 3JPt,F = 342 Hz, 2 ortho-F of a C6F5 bonded to Pt1), −115.1 (br, 3JPt,F = 320 Hz, 4 ortho-F of the C6F5 bonded to Pt3), −165.0 (t, 3JF,F = 20 Hz, 1 para-F), −165.5 (t, 3JF,F = 24 Hz, 2 meta-F), −165.7 (br, 2 meta-F), −166.3 (t, 3JF,F = 20 Hz, 1 para-F), −167.0 (m, overlapped 4 meta-F), −167.7 (t, 3JF,F = 20 Hz, 1 para-F), −168.0 (t, 3JF,F = 19.8 Hz, 1 paraF). Low T 19F NMR (acetone-d6, 223 K, 376.5 MHz): δ of 4c + 2c −112.1 (very br, ortho-F), −114.1 (br, ortho-F), −114.7 (br, orthoF), −114.9 (br, ortho-F), −115.5 (br, ortho-F), −116.1 (br, ortho-F), −116.6 (br, ortho-F), −118.6 (br, ortho-F), −164.3 (t, 3JF,F = 21 Hz, 1 para-F), −164.7 (br, 1 para-F), −165.0 (t, 3JF,F = 21 Hz, 1 para-F), −165.2 (br, 2 meta-F), −165.4 (t, 3JF,F = 21 Hz, 1 para-F), −165.7 (br, 4 meta-F), −165.9 (t, 3JF,F = 21 Hz, 1 para-F), −165.6 (br, overlapped 4 meta-F + 1 para-F), −167.2 (m, overlapped 6 meta-F + 1 para-F), −167.8 (t, 3JF,F = 20 Hz, 1 para-F). 31P{1H} NMR (acetone-d6, 298 K, 162.0 MHz): δ of 2c ca. 122 (very br, P4), ca. 8 (very br, P3), −134.0 (m, P1), −149.1 (dd, 2JP1,P2 = 152 Hz, 2JP2,P3 = 247 Hz, 1JP2,Pt1 = 1743 Hz, 1JP2,Pt2 = 1636 Hz, P2), ppm. Low T 31 1 P{ H} NMR (acetone-d6, 223 K, 162.0 MHz). 4c: 31.2 (s, 2JP4,Pt3 = 2694 Hz, P4), −22.3 (d, 2JP3,P2 = 245 Hz, 1JP3,Pt2 = 1818 Hz, 1JP3,Pt3 = 1755 Hz, P3), −158.5 (dd, 2JP2,P3 = 245 Hz, 2JP2,P1 = 160 Hz, P2), −163.5 (d, 2JP1,P2 = 160 Hz, P1). 2c: δ: ca. 119.8 (very br, P4), 13.9 (br d, 2JP3,P2 = 247 Hz, 1JP3,Pt2 = 1832 Hz, 1JP3,Pt3 = 1764 Hz, P3), −134 (very br, P1), −153 (very br, P2) ppm; 195 Pt NMR (acetone-d6, 298 K, 86 MHz): δ of 2c −3772 (Pt1), −4132 (Pt2), −4543 (Pt3). Low T 195Pt NMR (acetone-d6, 223 K, 86 MHz): δ of 4c −3829 (Pt1), −4123 (Pt2), −4425 (Pt3).

[NnBu4][(C6F5)2PtII(μ-PPh2)2PtIV(κ2-S,S′-EtOCS2)(μ-PPh2)2PtII(C6F5)2] (3b). To a dark red solution of 1 (0.200 g, 0.100 mmol) in CH2Cl2 (50 mL), EtOCS2K (0.018 g, 0.112 mmol) in methanol (6 mL) was added and the mixture was stirred for 20 h at room temperature. NnBu4ClO4 (0.035 g, 0.100 mmol) in iPrOH (10 mL) was added and the solvent was evaporated to ca. 10 mL while stirring. An orange solid crystallized that was filtered, washed with iPrOH (2 × 1 mL), and dried. The orange solid was solved in CH2Cl2 (10 mL) and filtered. The solution was evaporated to ca. 1 mL and iPrOH (15 mL) was added. 3b crystallized as an orange solid that was filtered, washed with iPrOH (2 × 0.5 mL), and dried. 3b, 0.158 g, 70% yield. Anal. Found (calcd for C91F20H81NOP4Pt3S2): C, 46.29 (46.35); H, 3.42 (3.46); N, 0.72 (0.59); S, 2.87 (2.72). HRMS(−), exact mass for the anion [C75H45F20P4Pt3S]− ([M]−): 2115.0494 Da; measured: m/z: 2115.0561 (M)− (error 1.6 ppm). IR (cm−1): 952.21 1H NMR (acetone-d6, 298 K, 400 MHz): δ 8.28 (br pseudo t, 3JH,H ≈ 3JH,P ≈ 7.3 Hz, 4H, ortho-PX(Ph1)(Ph2)), 7.95 (br, 4H, ortho-PA(Ph1)(Ph2)), from 7.40 to 7.17 (m, 22H, overlapped ortho-PA(Ph1)(Ph2) + metaPA(Ph1)(Ph2) + meta-PX(Ph1)(Ph2) + meta-PA(Ph1)(Ph2) + paraPX(Ph1)(Ph2) + para-PA(Ph1)(Ph2) + para-PA(Ph1)(Ph2)), 6.94 (m, 6H, overlapped ortho-PX(Ph1)(Ph2) + para-PX(Ph1)(Ph2)), 6.49 (pseudo t, 3JH,H = 7.48 Hz, 4H, meta-PX(Ph1)(Ph2)), 4.16 (dq, 2 JH,H = 9.6 Hz, 3JH,H = 7.0 Hz, 1H, CH3C(H)HOCS2), 3.63 (dq, 2JH,H = 9.6 Hz, 3JH,H = 7.0 Hz, 1H, CH3C(H)HOCS2), 3.46 (m, 8H, NnBu4+), 1.84 (m, 8H, NnBu4+), 1.44 (pseudo sextet, 3JH,H = 7.6 Hz, 8H, NnBu4+), 1.31 (t, 3JH,H = 7.0 Hz, 3H, CH3CH2CS2), 0.98 (t, 3JH,H = 7.2 Hz, 12H, NnBu4+). 19F NMR (acetone-d6, 298 K, 376.5 MHz): δ −114.5 (br, 3JPt,F = 273 Hz, 2 ortho-F), −115.9 (br, platinum satellites appear overlapped and 3JPt,F was not measured, 2 ortho-F), −116.1 (br, platinum satellites appear overlapped and 3JPt,F was not measured, 2 ortho-F), −118.3 (br, 3JPt,F = 290 Hz, 2 ortho-F), −167.6 (br m, 2 meta-F), −167.8 (t, 3JF,F = 18.4 Hz, 2 para-F), −167.9 (br m, 2 meta-F), −168.1 (t, 3JF,F = 19.9 Hz, 2 para-F), −168.2 (br m, 2 meta-F), −168.6 (br m, 2 meta-F). 31P{1H} NMR (acetone-d6, 298 K, 162.0 MHz): δ −119.6 (m, 2JPA,PX = 121 Hz, 1JPA,Pt1 = 2045 Hz, 1JPA,Pt2 = 1691 Hz, PA), −136.4 (m, 2JPX,PX′ = 280 Hz, 2JPX,PA = 121 Hz, 1JPX,Pt1 = 1956 Hz, 1JPX,Pt2 = 842 Hz, PX). 195Pt NMR (acetone-d6, 298 K, 86 MHz): δ −3657 (Pt1/3), −2923 (Pt2).

[PPN][(C6F5)2PtII(μ-PPh2)2PtIV(κ2-S,S′-EtOCS2)(μ-PPh2)2PtII(C6F5)2] (3′b). To a dark red solution of 1 (0.110 g, 0.055 mmol) in acetone (20 mL), EtOCS2K (0.009 g, 0.056 mmol) in methanol (2 mL) was added and the mixture was stirred for 1 h at room temperature. [PPN]ClO4 (0.035 g, 0.055 mmol) was added. The solvent was evaporated to ca. 2 mL and MeOH (10 mL) was added while stirring. An orange solid crystallized that was separated by filtration and washed with MeOH (3 × 5 mL). The filtrate was stirred and 3′b crystallized as an orange solid that was filtered, washed with MeOH (2 × 0.5 mL), and dried. 3′b, 0.068 g, 46% yield. Anal. Found (calcd for C111F20H75NOP6Pt3S2): C, 50.09 (50.23); H, 2.69 (2.85); N, 0.44 (0.53); and S, 2.63 (2.42). Reaction of 1 with 2-Mercaptopyridinate. To a dark red solution of 1 (0.100 g, 0.050 mmol) in CH2Cl2 (20 mL), NnBu4C5H4NS (0.05 mmol, 2.5 mL of a methanol solution 0.020 M) was added and the

Reaction of 1 with 2-Mercaptopyrimidinate. To a dark red solution of 1 (0.150 g, 0.075 mmol) in CH2Cl2 (25 mL), NnBu4C4H3N2S (0.088 mmol, 2.2 mL of a methanol solution 0.040 M) was added and the mixture was stirred for 1.5 h. The orange H

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

MHz). 2d: δ: 97.3 (s, 1JP4,Pt3 = 2913 Hz, P4), 10.0 (br d, 2JP3,P2 = 250 Hz, 1JP3,Pt2 = 1832 Hz, 1JP3,Pt3 = 1764 Hz, P3), −158.6 (br, P1), −174.6 (br, P2); 4d: 33.8 (s, 2JP4,Pt3 = 2627 Hz, P4), −20.4 (d, 2JP3,P2 = 232 Hz, 1 3 2 JP ,Pt = 1850 Hz, 1JP3,Pt3 = 1730 Hz, P3), −163.1 (br, P1), −165.2 (br, 2 2 3 JP ,P = 232 Hz, 2JP2,P1 = 167 Hz, P2). 195 Pt NMR (acetone-d6, 298 K, 86 MHz): δ of 2d −3762 (Pt1), −4095 (Pt2), −4497 (Pt3).

solution was evaporated to 2 mL and an orange solid crystallized. i PrOH (10 mL) was added while stirring and the solid was filtered, washed with iPrOH (3 × 1 mL), and dried. The orange solid (0.143 mg) revealed to be a mixture of the starting material [(C6F5)2PtIII(μPPh2)2PtIII(μ-PPh2)2PtII(C6F5)2] 1, and [NnBu4][(C6F5)2PtII(μPPh2)2PtIV(κ-C4H3NNS)(μ-PPh2)2PtII(C6F5)2], 3d. The HRMS analysis of the mixture showed only the peak ascribable to 3d in the negative ion mode: exact mass for the anion C76H43F20N2 P4 Pt3 S ([M]−): 2105.0729 Da; measured: m/z: 2105.0628 (M)− (error 5.1 ppm). When run in the positive ion mode, the HRMS analysis showed only the peak due to 1 in the mixture: exact mass for the cation [C72H40F20NaP4Pt3]+ ([1 + Na]+): 2017.0599 Da; measured: m/z: 2017.0651. Low T 31P{1H} NMR (acetone-d6, 203 K, 162.0 MHz). δ of 3d: −104.9 (d, 2JP3,P4 = 121 Hz, 1JP3,Pt3 ≈ 2040 Hz, 1JP3,Pt2 ≈ 1780 Hz, P3), −130.4 (d, 2JP1,P2 = 116 Hz, 1JP1,Pt1 = 2042 Hz, 1JP1,Pt2 = 1580 Hz, P1), −134.7 (m, 2JP4,P2 ≈ 300 Hz, 2JP4,P3 = 121 Hz, 1JP4,Pt3 ≈ 1900 Hz, 1JP4,Pt2 ≈ 840 Hz, P4), −136.0 (m, 2JP2,P4 = ca. 300 Hz, 2JP2,P1 = 116 Hz, 1JP2,Pt1 ≈ 1900 Hz, 1JP2,Pt2 ≈ 900 Hz, P2). δ of 3d_Solv: −84.8 (br, P4), −92.2 (br m, P2), −97.8 (d, 2JP1,P2 = 115 Hz), 1JP1,Pt1 ≈ 1980 Hz, 1JP1,Pt2 ≈ 1680 Hz, P1, −102.4 (dd, 2JP3,P2 = 300 Hz, 2JP3,P4 = 115 Hz, P3). 195 Pt{1H} NMR (acetone-d6, 298 K, 162.0 MHz). δ of 3d: −3636 1 (Pt ), −2804 (Pt2), −3823 (Pt3).

[N n Bu 4 ][(C 6 F 5 ) 2 Pt II (μ-PPh 2 ){κ 2 -P,N-μ-(Pym)PPh 2 }Pt II (κ 2 -S,P-μSPPh2)(μ-PPh2)PtII(C6F5)2] (5d). A solution of 4d (0.100 g, 0.043 mmol) in acetone (5 mL) was stirred for 2 h at 323 K. The orange solution was evaporated to dryness and the recovered 5d was dried under vacuum. 5d, 0.097 g, 97% yield. Found (calcd for C92F20H79N3P4Pt3S): C, 47.15 (47.06); H, 3.32 (3.39); N, 1.89 (1.79); S, 1.63 (1.37). HRMS(−), exact mass for the anion [C76H43F20N2P4Pt3S]− ([M]−): 2105.0729 Da; measured: m/z: 2105.0791 (M)− (error 2.6 ppm). IR (cm−1): 952.21 1H NMR (acetone-d6, 298 K, 400 MHz): δ 9.13 (pseudo t, 2H, 3JH,H = 8.6 Hz, ortho PhA−P3), 8.99 (pseudo t, 2H, 3JH,H = 9.2 Hz, ortho PhA−P1), 8.54 (m, 1H, 3JH,H = 6.7 Hz, 4JH,H = 4.2 Hz, 4JH,P = 2.1 Hz, H1), 8.37 (pseudo t, 2H, 3JH,H = 8.6 Hz, ortho PhA−P2), 8.04 (m, 2H, 3JH,P = 10.9 Hz, 3JH,H = 7.2 Hz, ortho PhA−P4), 7.85 (m, 2H, 3JH,P = 10.7 Hz, 3JH,H = 7.6 Hz, ortho PhB− P4), from 7.75 to 7.08 (m, 25H, partially overlapped para PhA−P1, meta PhA−P4 + H3 + meta PhA−P1 + para PhA−P4 + ortho PhB−P1 + para PhA−P3 + para PhB−P1, + ortho PhB−P2, meta PhA−P2, meta PhA−P3 + para PhA−P2 + meta PhB−P1 + meta PhB−P4 + para PhB− P4 + ortho PhB−P3), 6.72 (m, 3H, overlapped meta PhB−P2 + para PhB−P2) 6.35 (dd, 1H, 3JH,H = 6.8 Hz, 4JH,H = 4.2 Hz, H2), 6.32 (partially overlapped t, 1H, 3JH,H = 6.9 Hz, para PhB−P3), 6.18 (br, 2H, meta PhB−P3), 3.45 (m, 8H, NnBu4+), 1.83 (pseudo quintet, 3JH,H = 7 Hz, 8H, NnBu4+), 1.43 (pseudo sextet, 3JH,H = 7 Hz, 8H, NnBu4+), 0.98 (t, 3JH,H = 7 Hz, 12H, NnBu4+). 19 F NMR (acetone-d6, 298 K, 376.5 MHz): δ −110.2 (br, 3JPt,F = 317 Hz, 1 ortho-F), −113.3 (br, 3JPt,F = 300 Hz, 1 ortho-F), −113.4 (br, 3JF,F = 27 Hz, partially overlapped 1 ortho-F), −114.2 (br, 3JPt,F = 265 Hz, 1 ortho-F), −114.8 (br, 3JPt,F = 336 Hz, 1 ortho-F), −115.0 (m, overlapped 2 ortho-F), −116.0 (dd, 3JF,P = 43 Hz, 3JF,F = 21 Hz, 1 ortho-F), −165.0 (m, overlapped 1 para-F + 1 meta-F), −165.5 (m, 1 meta-F), −166.2 (m, 1 meta-F), −166.9 (m, overlapped 2 para-F), −167.2 (m, 1 meta-F), −167.7 (m, overlapped 2 meta-F), −168.3 (m, 1 meta-F), −168.7 (t, 3JF,F = 20 Hz, 1 para-F). 31P{1H} NMR (acetone-d6, 298 K, 162.0 MHz): δ 104.9 (s, 1JP1,Pt1 = 2852 Hz, P1), 75.9 (s, 1JP4,Pt3 = 2592 Hz, 2JP4,Pt2 = 170 Hz, P4), 11.2 (d, 1JP3,P2 = 269 Hz, 1JP3,Pt2 = 2044 Hz, 1JP3,Pt3 = 1830 Hz, P3), −7.1 (dd, 1JP2,P3 = 269 Hz, 1JP2,Pt2 = 2097 Hz, 1JP2,Pt1 = 1836 Hz, P2) ppm. 195Pt{1H} NMR (acetone-d6, 298 K, 86 MHz): δ −4492 (dd, 1JPt1,P1 = 2852 Hz, 1JPt1,P2 = 1836 Hz, Pt1), −3901 (pseudo t, 1JPt2,P2 = 2097 Hz, 1JPt2,P3 = 2044 Hz, Pt2), −4428 (dd, 1JPt3,P4 = 2592 Hz, 1JPt3,P3 = 1830 Hz, Pt3).

[Nn Bu 4][(C 6 F 5) 2Pt II (μ-PPh2 ) 2PtII {κ 2N,P-μ-(pymS)PPh 2}(μ-PPh 2)PtII(C6F5)2], (4d). To a dark red solution of 1 (0.150 g, 0.075 mmol) in acetone (30 mL), NnBu4C4H3N2S (0.080 mmol, 2 mL of a methanol solution 0.040 M) was added and the mixture was stirred for 30 min at reflux temperature. The yellow solution was evaporated to ca. 1 mL and methanol (10 mL) was added. The mixture was stirred for 30 min and [NnBu4][(RF)2PtII(μ-PPh2)2PtII{κ2N,P-μ-(pymS)PPh2}(μ-PPh2)PtII(RF)2], and (4d) crystallized as a yellow solid which was filtered, washed with methanol (3 × 1 mL), and dried. 4d, 0.073 g, 41% yield. Anal. Found (calcd for C92F20H79N3P4Pt3S): C, 47.15 (47.06); H, 3.32 (3.39); N, 1.89 (1.79); S, 1.63 (1.37). HRMS(−), exact mass for the anion [C76H43F20N2P4Pt3S]− ([M]−): 2105.0729 Da; measured: m/z: 2105.0724 (M)− (error 2.0 ppm). IR (cm−1): 949.21 1H NMR (acetone-d6, 298 K, 400 MHz): δ of 2d 8.23 (br, 2H, H1), 7.59 (m, overlapped ortho Ph2−P2 + ortho Ph2−P4 + para Ph2−P4, 10H), 7.36 (m, overlapped meta Ph2−P4 + H2, 5H), 7.22 (t, 3JH,H = 7.2 Hz, para Ph2−P2, 2H), 7.13 (m, overlapped para-Ph2−P1 + meta-Ph2−P2, 6H), 7.00 (t, 3JH,H = 7.2 Hz, para Ph2−P3, 2H), 6.88 (m, overlapped ortho Ph2−P1 + meta Ph2−P1, 8H), 6.78 (t, 3JH,H = 8.6 Hz, ortho Ph2−P3, 4H), 6.67 (t, 3JH,H = 7.2 Hz, meta Ph2−P3, 4H), 3.45 (m, 8H, NnBu4+), 1.83 (m, 8H, NnBu4+), 1.44 (pseudo sextet, 3JH,H = 7.5 Hz, 8H, NnBu4+), 0.98 (t, 3JH,H = 7.3 Hz, 12H, NnBu4+). Low T 1H NMR (acetone-d6, 223 K, 376.5 MHz): δ of 4d + 2d 9.31 (br, H3 of 4d), 8.30 (br, H1 of 2d), 8.13 (br, H1 of 4d), from 8.00 to 5.4 (m, H2 + Ph of 4c and 2c). 19 F NMR (acetone-d6, 298 K, 376.5 MHz): δ of 2d −114.0 (br, 3 JPt,F = 301 Hz, 2 ortho-F of a C6F5 bonded to Pt1), −114.8 (br, 3JPt,F = 309 Hz, 2 ortho-F of a C6F5 bonded to Pt1), −115.2 (br, 3JPt,F = 294 Hz, 2 ortho-F of a C6F5 bonded to Pt3), −116.2 (br, 3JPt,F = 286 Hz, 2 ortho-F of a C6F5 bonded to Pt3), −165.0 (t, 3JF,F = 21 Hz, 1 para-F), −165.6 (m, 2 meta-F), −166.2 (m, 1 para-F + 2 meta-F), −167.0 (m, overlapped 4 meta-F), −167.5 (t, 3JF,F = 19 Hz, 1 para-F), −168.0 (t, 3 JF,F = 21 Hz, 1 para-F). 31 1 P{ H} NMR (acetone-d6, 298 K, 162.0 MHz): δ of 2d ca. 88 (very br, P4), 3.4 (very br, P3), −151 (br d, 2JP1,P2 = 177 Hz, P1), −163.7 (dd, 2JP2,P1 = 177 Hz, 2JP2,P3 = 250 Hz, 1JP2,Pt1 = 1788 Hz, 1JP2,Pt2 = 1507 Hz, P2) ppm. Low T 31P{1H} NMR (acetone-d6, 223 K, 162.0

X-ray Structure Determinations. Crystal data and other details of the structure analyses are presented in Table S1. Suitable crystals for XRD studies were obtained by slow diffusion of n-hexane into concentrated solutions of the complexes in 3 mL of Me2CO. Crystals I

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics were mounted at the end of quartz fibers. The radiation used in all cases was graphite-monochromated Mo Kα (λ = 0.71073 Å). X-ray intensity data were collected on an Oxford Diffraction Xcalibur diffractometer. The diffraction frames were integrated and corrected from absorption by using the CrysAlis RED program.34 The structures were solved by Patterson and Fourier methods and refined by fullmatrix least squares on F2 with SHELXL-97.35 All nonhydrogen atoms were assigned anisotropic displacement parameters and refined without positional constraints, except as noted below. All hydrogen atoms were constrained to idealized geometries and assigned isotropic displacement parameters equal to 1.2 times the Uiso values of their attached parent atoms (1.5 times for the methyl hydrogen atoms). In the structure of 3′b·1.3Me2CO·0.35n-C6H14, the space near the inversion center is occupied with an acetone and half n-hexane molecules, which were refined with partial occupancies 0.3 and 0.7, respectively. Weak restrains were used for the geometry of this acetone moiety and it was refined isotropically. Full-matrix leastsquares refinement of these models against F2 converged to final residual indices given in Table S1.

■

(2) Canty, A. J. Organopalladium and platinum chemistry in oxidising milieu as models for organic synthesis involving the higher oxidation states of palladium. Dalton Trans. 2009, 47, 10409−10417. (3) Labinger, J. A.; Bercaw, J. E. The Role of Higher Oxidation State Species in Platinum-Mediated C-H Bond Activation and Functionalization. In Higher Oxidation State Organopalladium and Platinum Chemistry; Canty, A. J., Ed.; Springer, 2011; Vol. 35, pp 29−59. (4) Canty, A. J.; Sharma, M. eta(1)-Alkynyl Chemistry for the Higher Oxidation States of Palladium and Platinum. In Higher Oxidation State Organopalladium and Platinum Chemistry; Canty, A. J., Ed.; Springer, 2011; Vol. 35, pp 111−127. (5) Holleman, A.; Wiberg, N.; Krieger-Hauwede, M.; et al. Band 1+2 [Set Anorganische Chemie Band 1+2], 103rd ed., De Gruyter: 2016; Vol. 1, p 2047. (6) Alonso, E.; Casas, José M.; Cotton, F. Albert; Feng, X.; Forniés, J.; Fortuño, C.; Tomas, M. Synthesis and crystal and electronic structures of the dinuclear platinum compounds (PEtPh3)2[Pt2(μPPh2)2(C6F5)4] and [Pt2(μ-PPh2)2(C6F5)4]: A computational study by density functional theory. Inorg. Chem. 1999, 38, 5034−5040. (7) Ara, I.; Chaouche, N.; Forniés, J.; Fortuño, C.; Kribii, A.; Tsipis, A. C. Formation of PPh2C6F5 through phosphido platinum and/or palladium(III) intermediates. Organometallics 2006, 25, 1084−1091. (8) Alonso, E.; Casas, J. M.; Forniés, J.; Fortuño, C.; Martín, A.; Orpen, A. G.; Tsipis, C. A.; Tsipis, A. C. Synthesis of homo- or hetero-trinuclear palladium(II)/platinum(II) compounds with bridging phosphido ligands. Crystal and electronic structures (DFT) of [N(PPh3)2][Pt3(μ-PPh2)4(C6F5)4] and of its oxidation product [Pt3(μ-PPh2)4(C6F5)4]. Organometallics 2001, 20, 5571−5582. (9) Ara, I.; Forniés, J.; Fortuño, C.; Ibáñez, S.; Martín, A.; Mastrorilli, P.; Gallo, V. Unsymmetrical Platinum(II) Phosphido Derivatives: Oxidation and Reductive Coupling Processes Involving Platinum(III) Complexes as Intermediates†. Inorg. Chem. 2008, 47, 9069−9080. (10) Forniés, J.; Fortuño, C.; Ibáñez, S.; Martín, A.; Mastrorilli, P.; Gallo, V. Behavior of Neutral Phosphido Derivatives of Platinum and Palladium toward Silver Centers. Inorg. Chem. 2011, 50, 10798− 10809. (11) Arias, A.; Forniés, J.; Fortuño, C.; Martín, A.; Latronico, M.; Mastrorilli, P.; Todisco, S.; Gallo, V. Formation of P-C Bond through Reductive Coupling between Bridging Phosphido and Benzoquinolinate Groups. Isolation of Complexes of the Pt(II)/Pt(IV)/Pt(II) Sequence. Inorg. Chem. 2012, 51, 12682−12696. (12) Arias, A.; Forniés, J.; Fortuño, C.; Martín, A.; Mastrorilli, P.; Todisco, S.; Latronico, M.; Gallo, V. Oxidatively Induced P-O Bond Formation through Reductive Coupling between Phosphido and Acetylacetonate, 8-Hydroxyquinolinate, and Picolinate Groups. Inorg. Chem. 2013, 52, 5493−5506. (13) Arias, A.; Forniés, J.; Fortuño, C.; Ibáñez, S.; Martín, A.; Mastrorilli, P.; Gallo, V.; Todisco, S. Addition of Nucleophiles to Phosphanido Derivatives of Pt(III): Formation of P-C, P-N, and P-O Bonds. Inorg. Chem. 2013, 52, 11398−11408. (14) Fortuño, C.; Martín, A.; Mastrorilli, P.; Gallo, V.; Todisco, S. Solvent-Driven P-S vs P-C Bond Formation from a Diplatinum(III) Complex and Sulfur-Based Anions. Organometallics 2017, 36, 4325− 4337. (15) Alonso, E.; Forniés, J.; Fortuño, C.; Martín, A.; Orpen, A. G. Reactivity of [NBu4][(C6F5)2M(μ-PPh2)2M ’(acac-O,O ’)] (M, M ’ = Pt, Pd) toward silver centers. Synthesis of polynuclear complexes containing M-Ag bonds (M = PdPt). Organometallics 2003, 22, 5011−5019. (16) Ara, I.; Chaouche, N.; Forniés, J.; Fortuño, C.; Kribii, A.; Martín, A. A dinuclear phosphidoplatinum(II) fragment as a building block for tri-, tetra-, hexa-, and octanuclear complexes. Eur. J. Inorg. Chem. 2005, 2005, 3894−3901. (17) Forniés, J.; Fortuño, C.; Gil, R.; Martín, A. Tetranuclear Platinum Phosphido Complexes with Different Structures†. Inorg. Chem. 2005, 44, 9534−9541. (18) Mastrorilli, P. Bridging and Terminal (Phosphanido)platinum Complexes. Eur. J. Inorg. Chem. 2008, 2008, 4835−4850.

ASSOCIATED CONTENT

* Supporting Information S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.9b00096. NMR spectra of complexes 2a, 3b, 2c, 4c, 3d, and 5d. Crystal data and structure refinement for complexes [PPN][(C6F5)2PtII(μ-PPh2)2PtIV(κ2-S,S′-EtOCS2)(μPPh 2 ) 2 Pt II (C 6 F 5 ) 2 ] ·1.3Me 2 CO·0.35n-C 6 H 14 (3′b· 1.3Me2CO·0.35n-C6H14) and [NnBu4][(C6F5)2PtII(μPPh2)2PtII{κ2-N,P-μ-(pymS)PPh2}(μ-PPh2)PtII(C6F5)2] 3Me2CO (4d·3Me2CO) (PDF) Accession Codes

CCDC 1896970−1896971 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 [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

■

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (C.F.). *E-mail: [email protected] (P.M.). ORCID

Antonio Martín: 0000-0002-4808-574X Piero Mastrorilli: 0000-0001-8841-458X Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS Dedicated to Prof. Pablo Espinet on the occasion of his 70th birthday. This work was supported by the Spanish MINECO/ FEDER (Proyect CTQ2015-67461-P) and the Gobierno de Aragón and Fondo Social Europeo (Grupo de Referencia ́ E17_17R: Quimica Inorgánica y de los Compuestos Organometálicos).

■

REFERENCES

(1) Vigalok, A. Electrophilic Halogenation-Reductive Elimination Chemistry of Organopalladium and -Platinum Complexes. Acc. Chem. Res. 2015, 48, 238−247. J

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics (19) Latronico, M.; Sánchez, S.; Rizzuti, A.; Gallo, V.; Polini, F.; Lalinde, E.; Mastrorilli, P. Reactivity of the phosphinito bridged Pt(I) complex (PHCy2) Pt(mu-PCy2){kappa P-2,O-mu-P(O)Cy-2}Pt(PHCy2) (Pt-Pt) towards Au(I) and Ag(I) electrophiles. Dalton Trans. 2013, 42, 2502−2511. (20) In the case of 5d, the HRMS(+) analysis did not reveal any peak due to oxidation of the complex, as expected due to lack, in the molecule, of any Pt2II P2 ring. (21) Usóan, R.; Forniéas, J. Organopalladium and Platinum Compounds with Pentahalophenyl Ligands. Adv. Organomet. Chem. 1988, 28, 219−297. (22) Shaw, P. A.; Rourke, J. P. Selective C-C coupling at a Pt(IV) center: 100% preference for sp(2)-sp(3) over sp(3)-sp(3). Dalton Trans. 2017, 46, 4768−4776. (23) Crosby, S. H.; Thomas, H. R.; Clarkson, G. J.; Rourke, J. P. Concerted reductive coupling of an alkyl chloride at Pt(IV). Chem. Commun. 2012, 48, 5775−5777. (24) Crosby, S. H.; Clarkson, G. J.; Rourke, J. P. Relieving Steric Strain at Octahedral Platinum(IV): Isomerization and Reductive Coupling of Alkyl and Aryl Chlorides. Organometallics 2012, 31, 7256−7263. (25) Bowes, E. G.; Pal, S.; Love, J. A. Exclusive Csp3-Csp3 vs Csp2Csp3 Reductive Elimination from Pt-IV Governed by Ligand Constraints. J. Am. Chem. Soc. 2015, 137, 16004−16007. (26) Lanci, M. P.; Remy, M. S.; Lao, D. B.; Sanford, M. S.; Mayer, J. M. Modulating Sterics in Trimethylplatinum(IV) Diimine Complexes To Achieve C-C Bond-Forming Reductive Elimination. Organometallics 2011, 30, 3704−3707. (27) Rivada-Wheelaghan, O.; Roselló-Merino, M.; Díez, J.; Maya, C.; López-Serrano, J.; Conejero, S. Formation of C-X Bonds through Stable Low-Electron-Count Cationic Platinum(IV) Alkyl Complexes Stabilized by N-Heterocyclic Carbenes. Organometallics 2014, 33, 5944−5947. (28) Crespo, M.; Anderson, Craig M.; Kfoury, N.; Font-Bardia, M.; Calvet, T. Reductive Elimination from Cyclometalated Platinum(IV) Complexes To Form Csp2-Csp3 Bonds and Subsequent Competition between Csp2-H and Csp3-H Bond Activation. Organometallics 2012, 31, 4401−4404. (29) Dubinsky-Davidchik, I.; Goldberg, I.; Vigalok, A.; Vedernikov, Andrei N. Selective Aryl-Fluoride Reductive Elimination from a Platinum(IV) Complex. Angew. Chem., Int. Ed. 2015, 54, 12447− 12451. (30) Yahav-Levi, A.; Goldberg, I.; Vigalok, A.; Vedernikov, A. N. Aryl-bromide reductive elimination from an isolated Pt(IV) complex. Chem. Commun. 2010, 46, 3324−3326. (31) Canty, A. J.; Gardiner, M. G.; Jones, R. C.; Rodemann, T.; Sharma, M. Binuclear Intermediates in Oxidation Reactions: (Me3SiC≡C)Me2(bipy)Pt-PtMe2(bipy) (+) in the Oxidation of (PtMe2)-Me-II(bipy) (bipy=2,2 ’-Bipyridine) by IPh(C≡CSiMe3)(OTf) (OTf = Triflate). J. Am. Chem. Soc. 2009, 131, 7236−7237. (32) Grice, K. A.; Scheuermann, M. L.; Goldberg, K. I. FiveCoordinate Platinum(IV) Complexes. In Higher Oxidation State Organopalladium and Platinum Chemistry; Canty, A. J., Ed.; Springer, 2011; Vol. 35, pp 1−27. (33) Forniés, J.; Fortuño, C.; Ibáñez, S.; Martín, A.; Tsipis, A. C.; Tsipis, C. A. Reversible transformation of two diphenylphosphanido ligands into the neutral tetraphenyldiphosphane ligand. Angew. Chem., Int. Ed. 2005, 44, 2407−2410. (34) CrysAlisRED Program for X-Ray CCD Camera Data Reduction, Program for X-Ray CCD Camera Data Reduction, Version 1.171.32.19; Oxford Diffraction Ltd.: Oxford, U.K., 2008. (35) Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta Cryst. 2015, C71, 3−8.

K

DOI: 10.1021/acs.organomet.9b00096 Organometallics XXXX, XXX, XXX−XXX