Article pubs.acs.org/Organometallics
Ring Expansion of Cyclic Triplatinum(0) Silylene Complexes Induced by Insertion of Alkyne into a Si−Pt Bond Kimiya Tanaka, Megumi Kamono, Makoto Tanabe, and Kohtaro Osakada* †
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259-R1-3 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan S Supporting Information *
ABSTRACT: Triangular triplatinum(0) complexes with bridging diarylsilylene ligands, [{Pt(PMe3)}3(μ-SiAr2)3] (1: Ar = Ph, 2: Ar = C6H4F-4), reacted with dimethyl acetylenedicarboxylate to afford new Pt3 complexes. The equimolar reaction of complex 1 produced a linear triplatinum complex with μ2diphenylsilylene and μ3-phenyl(vinylene)silylene ligands. The latter ligand was formed via migration of a Ph group of the bis(diphenylsilyl)ethylene ligand. The reaction of 2 with the alkyne in a 1:3 molar ratio yielded the product having a disilaplatinacyclic moiety and a Pt center with the donorstabilized silylene ligand, and they were separated by the coordinated alkyne molecule. A common intermediate having a disilaplatinacyclopentene group was converted into the respective triplatinum complexes, depending on the substituents of the silylene ligand.
■
INTRODUCTION Multinuclear complexes of low-valent late transition metals are mostly stabilized by bridging inert and electron-withdrawing ligands, such as μ-CO and μ-CNR.1 The bridging silylene ligands (μ-SiR2), having electron-donating nature, bind two transition metals and form stable dinuclear complexes.2 The multinuclear late transition metal complexes with the bridging Si ligands were uncommon until recently.3 Our group4 and Braddock-Wilking’s group5 reported triangular triplatinum(0) complexes with bridging silylene ligands, formulated as [{Pt(PR′3)}3(μ-SiR2)3]. These complexes are stable up to 100 °C despite mismatched coordination of the d10 transition metal centers to the electrondonating ligands. An analogous complex with bridging germylene ligands contains a stable triangular Pt3 framework, which is kept after protonation and insertion of alkyne into a Pt−Ge bond.6 A triplatinum complex with bridging carbonyl ligand, [{Pt(PR3)}3(μ-CO)3], reacts with alkyne to afford a diplatinum−alkyne complex, accompanied by elimination of the Pt(PR3)(CO) fragment.7 Recently, tetranuclear Pd complexes, with more flexibility than the cyclic Pt3 complexes, were reported to undergo their skeletal rearrangement. Linear tetrapalladium complexes in a sandwich framework underwent reversible change in alignment of the Pd metals upon chemical oxidation and reduction.8 We found structural change of the planar Pd4Ge3 complex [Pd{Pd(dmpe)}3(μ-GePh2 )3] (dmpe = 1,2-bis(dimethylphosphino)ethane) caused by addition of thiol, giving a linear hexapalladium complex, although the reaction occurred irreversibly.9 Thus, the cyclic triplatinum(0) complexes tend not to change the Pt3 core in most reactions reported so far. In this paper, we report rearrangement reactions of the silylene-bridged triplatinum(0) complexes induced by insertion of alkyne into a © 2015 American Chemical Society
Si−Pt bond and its pathway involving isomerization of the initial product.
■
RESULTS AND DISCUSSION The triplatinum(0) complexes with bridging diarylsilylene ligands, [{Pt(PMe3)}3(μ-SiAr2)3] (1: Ar = Ph, 2: Ar = C6H4F-4), were prepared by an equimolar reaction of H2SiAr2 with [Pt(PMe3)4] at 100 °C (eq 1).6 Yield of complex 1 (75%) was
much higher than that obtained by thermal treatment of [Pt(SiHPh2)2(PMe3)2] (28%).4A new complex 2 was obtained in 54% and was fully characterized by X-ray crystallography and NMR spectroscopy (Supporting Information). Although the Pt3Si3 core of 1 is almost planar, the plane composed of three Si atoms of 2 is deviated from the Pt3 plane by 0.53 Å, probably due to flexible coordination of the d10 metal centers. The Pt−Si bonds of 1 (2.337(5)−2.364(5) Å) and 2 (2.342(3)−2.373(2) Å) are in a similar range, but the Pt−Pt bonds of 2 (2.7259(7)−2.7514(7) Å) are significantly longer than those of 1 (2.697(1)−2.716(1) Å). The 195Pt{1H} NMR signals of 1 (δ −3980) and 2 (δ −4004) are Received: April 10, 2015 Published: May 28, 2015 2985
DOI: 10.1021/acs.organomet.5b00291 Organometallics 2015, 34, 2985−2990
Article
Organometallics
palladium,13 and gold.14 Ratios of the bond lengths, 0.935 (d(Pt2−Si1)/d(Pt3−Si1)) and 0.987 (d(Pt2−Si1)/d(Pt1−Si1)), are larger than corresponding metal−Si bond ratios in [Pd{Pd(dmpe)}3(μ-SiPh2)3] (0.885−0.905)11 and [Pd{Pd(dmpe)}3{μ3SiH(C6H4-1,2)SiMe2}2(μ3-SiH2)] (0.879−0.926).13a Three 31P NMR signals are observed at δ −5.6, −6.4, and −10.3 for 3. The singlet at δ −10.3 is assigned to P1, and its small JPtP value (1452 Hz) is attributed to the large trans influence of the Si2 atom. Two doublets at δ −5.6 and −6.4 (3JPP = 75 Hz), assigned to P3 and P2, displayed JPtP values (4074 and 3851 Hz) similar to those of diplatinum(I) complexes with μ-silyl ligands, [{Pt(PCy3)}2(μ-SiHR2)2] (R2 = Me2, Et2, Hex2, Ph2, MePh: JPtP = 3957−3982 Hz).15 The phenyl group attached to Pt1 shows a 13C NMR signal of the ipso-carbon at δ 180.6. The JPtC value (770 Hz) is comparable with that of cis-[PtPh2(PEt3)2] (879 Hz).16 The 195Pt NMR spectrum of 3 displays one signal at δ −4635 (JPPt = 1452 Hz), assigned as Pt1, and two upfield signals of Pt2 and Pt3 (δ −5041, JPPt = 3851 Hz; δ −5195, JPPt = 4074 Hz). Thus, the NMR results and the elongated Pt2−Pt3 bonds of 3,17 compared to the Pt−Pt bonds of Pt(I) complexes or Pt(0) complex, suggest the triplatinum core with Pt(II)Pt(0)2 configuration. A reaction of DMAD with 2 in a 3:1 ratio at room tempera-
split with a typical spinning pattern of the triangular triplatinum complexes. The coupling constant of 2 (2500 Hz) is smaller in comparison to the JPtPt value of 1 (2950 Hz).10 Thus, the fluoro substituents of complex 2 render the Pt−Pt bonds longer and the Pt−Pt coupling constants smaller. Addition of equimolar dimethyl acetylenedicarboxylate (DMAD) to the toluene solution of 1 at 0 °C yielded a linear triplatinum complex with triply and doubly bridging silylene ligands, [{(Me3P)(Ph)Pt}(μ3-SiPhCZCZSiPh2){Pt(PMe3)}2(μ-SiPh2)] (3, Z = CO2Me) in 71% yield, as shown in eq 2.The
molecular structure of 3, determined by X-ray crystallography, shows a bending alignment of the Pt3 core with the bridging Si ligands (Figure 1). The Pt1 atom is accommodated in a distorted
ture afforded a triplatinum complex [{Pt(SiAr2CZCZSiAr2){Pt(PMe3)2}}{(Me3P)PtSiAr2}(μ3-η1:η1:η2-(E)-CZCZ)] (4: 26%, Ar = C6H4F-4, Z = CO2Me), as shown in eq 3. The
disilaplatinacyclopentene group was formed during the reaction, and the second alkyne inserted into the Pt−Pt bond to give the product, which contained the (E)-vinylene group bonded to the two Pt centers via Pt−C σ bonds. Complex 4 is stable under air and moisture. It shows a green color in the solid state, similar to the neutral platinum silylene complex [(Cy 3 P) 2 PtSi(C6H2Me3-2,4,6)2].18 Addition of a smaller amount of alkyne to complex 2 formed intermediate Pt3 complexes, but they were not characterized. Crystallographic study of 4 revealed a disilaplatinacyclopentene structure around Pt2 (Figure 2). The two Pt−C σ bonds exist between the sp2 carbon atoms of the DMAD ligand and the two Pt centers (Pt1 and Pt3). The CC double bond forms a πcoordination with Pt2 atom. The Pt2−C2 bond (2.171(5) Å) is bridged by Pt3 and becomes shorter than Pt2−C1 bond (2.277(5) Å). A diarylsilylene ligand (Si1) and the DMAD ligand are linked with the O−Si dative bond and form a tridentate ligand of Pt1. The sum of the three bond angles around Si1 in 4, C13−Si1−C19 106.0(3), C13−Si1−Pt1 128.0(2), C19−Si1− Pt1 112.6(2), is 346.6(2)°, which is between the ideal sp2 (360°) and sp3 (328.5°) Si center. The Pt1Si1 bond (2.237(2) Å) is slightly longer than the reported PtSi bond distances of neutral platinum−silylene complexes (2.208(2)−2.212(1) Å).18,19 The Fe complex with the O-donor-stabilized silylene complex has an FeSi (2.214(1)−2.294(1) Å)20 bond longer than that in the base-free complexes (2.154(1) Å).21 The ligand contains
Figure 1. Thermal ellipsoidal plot of 3 (50% probability level). All hydrogen atoms were omitted for clarity. Selected bond distances (Å) and angles (deg): Pt1−Pt2 2.8495(4), Pt2−Pt3 2.7350(5), Pt1−Si1 2.335(2), Pt1−Si2 2.358(2), Pt2−Si1 2.305(2), Pt2−Si3 2.279(2), Pt3−Si1 2.464(2), Pt3−Si3 2.281(2), Pt1−C7 2.099(6), Si1−C1, 1.902(8), Si2−C4 1.912(8), C1−C4 1.332(9), Si1−Pt1−Si2 80.24(6), P1−Pt1−Si2 170.93(6), Pt1−Pt2−Pt3 105.06(2), P2−Pt2−Pt3 157.99(5), P3−Pt3−Pt2 158.90(5), Pt1−Si1−Pt3 134.94(8).
trigonal bipyramidal coordination with P1 and Si2 atoms at the apical positions. Both Pt2 and Pt3 are bridged by two Si atoms and are bonded with a PMe3 ligand. The Pt1−Pt2 and Pt2−Pt3 bond distances of 3 (2.8495(4) and 2.7350(5) Å) are much longer than those of triangular Pt3 complex 1 (2.697(1)− 2.716(1) Å). The chelating ligand is bonded to Pt1 via a silyl group and to Pt2 via a μ3-phenyl(vinylene)silylene group. The Pt2−Si1 bond (2.305(2) Å) is shorter than the other Pt−Si1 bonds (2.335(2) and 2.464(2) Å). The silylene-bridged tetrapalladium complex included significantly shorter Pdcent−Si bonds (av. 2.26 Å) than Pdout−Si bonds (av. 2.53 Å) in the planar hexagonal Pd4Si3 core.11 Thus, the Si1 atom is bonded to three Pt centers, and similar μ3-coordination of the silylene ligand was reported also in the multinuclear complexes of nickel,12 2986
DOI: 10.1021/acs.organomet.5b00291 Organometallics 2015, 34, 2985−2990
Article
Organometallics Scheme 2
Figure 2. Thermal ellipsoidal plot of 4 (50% probability level) viewed from (a) the upper side and (b) the edge of the fused-ring plane. All hydrogen atoms and CH3 carbon atoms of the PMe3 ligands were omitted for clarity. Selected bond distances (Å) and angles (deg): Pt1− Si1 2.237(2), Pt1−C1 2.037(5), Pt1−O3 2.202(4), Pt2−Pt3 2.6931(4), Pt2−Si2 2.322(2), Pt2−Si3 2.292(2), Pt2−C1 2.277(5), Pt2−C2 2.171(5), Pt3−C2 2.015(6), Si1−O1 1.743(4), Si2−C7 1.920(6), Si3− C8 1.908(6), O1−C3 1.320(7), O3−C5 1.253(7), C1−C2 1.474(8), C1−C3 1.381(8), C2−C5 1.444(8), C7−C8 1.347(8), C1−Pt1−O3 79.5(2), C1−Pt1−Si1 81.6(2), O3−Pt1−Si1 157.6(1), P1−Pt1−C1 177.2(1), Si3−Pt2−Si2 83.17(5), P2−Pt3−P3 99.56(6), Pt2−Pt3−P2 148.38(4), Pt2−Pt3−P3 110.28(4), C13−Si1−C19 106.0(3), C13− Si1−Pt1 128.0(2), C19−Si1−Pt1 112.6(2), C3−C1−C2 127.3(5), Pt2−C2−Pt3 80.0(2), C5−C2−C1 110.0(5), O1−C3−C1 122.1(5), O3−C5−C2 125.5(5).
elongated bonds such as Si1−O1 (1.743(4) Å) and O1−C3 (1.320(7) Å) bonds compared to the typical Si−O (1.66 Å) and OC (1.20 Å) bonds.22 The C1−C2 bond distance (1.474(8) Å) is longer than typical CC bonds (1.35 Å) and longer than that of (E)-MeO2CCHCHCO2Me (1.318(2) Å).23 π-Coordination of Pt2 also serves to elongate the bond. The C1−C3 and C2−C5 bonds (1.381(8) and 1.444(8) Å) are longer than usual CC bonds (1.35 Å). These results are consistent with a structure having some contribution of canonical form 4′ with a zwitterionic character, shown in Scheme 1.
molecule. Scheme 2 summarizes pathways for formation of two complexes, 3 and 4, via a common intermediate. Insertion of the alkyne into a Pt−Si bond forms a five-membered siladiplatinacyclopentene (A). Mononuclear disilaplatinacyclopentenes were reported to be formed via double oxidative addition of two Si−H bonds of the disilanyl compounds to Pt(0) complexes24−26 and via insertion of alkynes into the Pt−Si bonds of [{Pt(PMe3)2}2(μ-SiPh2)2].27 The second Si−C bond formation from the μ-SiPh2 and μ-CZCZSiPh2 ligands and subsequent ring contraction by the silyl migration afford a disilaplatinacyclopentene intermediate (B) with a silylene-bridged diplatinum moiety. It is contrasted with the reaction of [{Pt(PMe3)}3(μ-GePh2)3], which also undergoes insertion of the alkyne into the Pt−Ge bond but produces the triangular Pt3 complexes.6b In the reaction of 1, a Ph group bonded with the Si1 atom migrates to the Pt1 atom. The intramolecular transfer of the Ph group from Si to Pt leads to the triply bridging silylene ligand, giving 3 as the isolable product. Similar migration of the aromatic group from the Si atom to a transition metal takes place in the redistribution of organosilanes catalyzed by the Rh, Ir, or Pt complexes.28 Migration of a C6H4F-4 group does not take place in the reaction of 2 or is preceded by ligation of the second alkyne to the Pt−Pt bond, giving C. Insertion of the alkyne into the Pt−Pt bonds affords complex 4 with E conformation of the CC bond, which is σ- or π-bonded with three Pt atoms. Rearrangement of the bridging silylene ligand to the PtSi
Scheme 1
The 31P{1H} NMR signals at δ −16.6 and −38.8 are coupled with each other (2JPP = 13 Hz). The latter is flanked with two 195Pt satellite signals (JPtP = 4407 Hz, 2JPtP = 615 Hz) and assigned to the P2 atom with a large Pt2−Pt3−P2 angle (148.38(4)°). The former due to P3 shows a smaller JPtP value (2519 Hz), and the Pt2−Pt3−P3 angle is smaller (110.28(4)°). The signal of P1 shows smaller P−P couplings with P2 and P3 (4 and 8 Hz). Formation of complex 3 is accompanied by activation of a Si−C bond, while the reaction leading to complex 4 does not involve the bond cleavage and requires additional alkyne 2987
DOI: 10.1021/acs.organomet.5b00291 Organometallics 2015, 34, 2985−2990
Article
Organometallics
Si{1H} NMR (99 MHz, C6D6, room temperature): δ 279 (JPtSi = 948 Hz). 195Pt{1H} NMR (107 MHz, C6D6, room temperature): δ −4004 (JPPt = 2962 Hz, 2JPPt = 411 Hz, JPtPt = 2500 Hz). Preparation of [{(Me 3 P)(Ph)Pt}(μ 3 -SiPhCZCZSiPh 2 ){Pt(PMe3)}2(μ-SiPh2)] (3, Z = CO2Me). To a toluene (4 mL) solution of 1 (80 mg, 0.059 mmol) was added dropwise a toluene solution of DMAD (7.2 μL, 0.059 mmol) at 0 °C. The reaction temperature was gradually increased to room temperature upon stirring for 1 h, and the solvent was removed under reduced pressure. The resulting red material was washed with hexane (1 mL × 2) and Et2O (1 mL × 2) and dried in vacuo to afford 3 (63 mg, 71%). Red crystals of 3 suited for X-ray crystallography were obtained by slow diffusion of hexane into the toluene solution. Anal. Calcd for C51H63O4P3Pt3Si3: C, 40.77; H, 4.23. Found: C, 40.53; H, 4.17. HRMS (ESI): calcd for C51H63O4P3Pt3Si3 [M]+ 1501.2190, found m/z 1501.2189. 1H NMR (500 MHz, C6D6, room temperature): δ 8.26 (2H, C6H5 ortho, J = 6.5 Hz), 8.14 (2H, C6H5 ortho, J = 6.5 Hz), 7.96 (2H, C6H5 ortho, J = 6.5 Hz), 7.90 (2H, C6H5 ortho, J = 6.5 Hz), 7.81 (4H, C6H5 ortho, J = 7.0 Hz), 7.35−6.86 (18H, C6H5 meta and para), 3.32 (s, 3H, OCH3), 3.11 (s, 3H, OCH3), 1.01 (d, 9H, PCH3, JPH = 8.5 Hz, JPtH = 40 Hz), 0.90 (d, 9H, PCH3, JPH = 9.5 Hz), 0.77 (d, 9H, PCH3, JPH = 8.0 Hz). 13C{1H} NMR (126 MHz, THF-d8, room temperature): δ 180.6 (d, PtC, JPC = 13 Hz, JPtC = 770 Hz), 174.1, 170.7 (CO), 157.4, 156.5, 143.8, 142.9, 142.6, 141.9 (C6H5 ipso), 137.7, 137.5, 137.2, 137.0, 136.3 (C6H5 ortho), 128.8, 128.0, 127.8, 127.5, 126.9, 126.3 (C6H5 meta), 129.9, 129.3, 129.2, 129.0, 127.3 (C6H5 para), 121.1 (SiC=), 52.0, 50.2 (OCH3), 19.2 (d, PCH3, JPC = 32 Hz, 2 JPtC = 46 Hz), 17.0 (d, PCH3, JPC = 32 Hz, 2JPtC = 47 Hz), 16.1 (d, PCH3, JPC = 25 Hz). A few signals were not observed clearly due to decomposition during the measurement. 31P{1H} NMR (202 MHz, C6D6, room temperature): δ −5.6 (d, P3, JPtP = 4074 Hz, 2JPtP = ca. 370 Hz, 3JPP = 75 Hz), −6.4 (d, P2, JPtP = 3851 Hz, 2JPtP = ca. 500 Hz, 3JPP = 75 Hz), −10.3 (s, P1, JPtP = 1452 Hz, 2JPtP = 72 Hz). 195Pt{1H} NMR (107 MHz, THF-d8, room temperature): δ −4635 (d, Pt1, JPPt = 1452 Hz, JPtPt = ca. 890 Hz), −5041 (dd, Pt2, JPPt = 3851 Hz, 2JPPt = ca. 370, 72 Hz, JPtPt = ca. 890, 810 Hz), −5195 (d, Pt3, JPPt = 4074 Hz, 2JPPt = ca. 500 Hz, JPtPt = ca. 810 Hz). The 2JPPt and JPtPt values in 31P{1H} and 195Pt{1H} NMR spectra were not estimated clearly. IR (KBr): 1710 (s, νCO). Preparation of [{Pt(SiAr2CZCZSiAr2){Pt(PMe3)2}}{(PMe3)PtSiAr2}(μ3-η1:η 1:η2-(E)-CZCZ)] (4: Ar = C6H4F-4, Z = CO2Me). To a toluene (4 mL) solution of 2 (202 mg, 0.14 mmol) was added a 3-fold amount of DMAD (51 μL, 0.42 mmol) at room temperature. The reaction mixture was stirred for 4 days at the same temperature, giving a dark orange solution. The solvent was removed under reduced pressure. The resulting material was washed with hexane (3 mL × 3) and Et2O (3 mL × 3) and dried in vacuo to afford 4 (67 mg, 26%). Green crystals of 4 suited for X-ray crystallography were obtained by recrystallization from toluene/hexane (1:10). Anal. Calcd for C57H63F6O8P3Pt3Si3: C, 39.06; H, 3.62; F, 6.50. Found: C, 38.83; H, 3.39; F, 6.68. HRMS (ESI): calcd for C57H63F6O8P3Pt3Si3 [M]+ 1751.1891, found m/z 1751.1906. 1H NMR (500 MHz, C6D6, room temperature): δ 8.54 (dd, 2H, C6H4F ortho, J = 6.5, 9.0 Hz), 7.74 (dd, 2H, C6H4F ortho, J = 6.5, 9.0 Hz), 7.65 (m, 4H, C6H4F ortho), 7.41 (dd, 2H, C6H4F ortho, J = 6.5, 9.0 Hz), 7.23 (dd, 2H, C6H4F ortho, J = 6.0, 8.5 Hz), 6.944 (apparent triplet, 2H, C6H4F meta, J = 9.0 Hz), 6.936 (apparent triplet, 2H, C6H4F meta, J = 9.0 Hz), 6.88 (apparent triplet, 2H, C6H4F meta, J = 9.0 Hz), 6.78−6.74 (6H, C6H4F meta), 3.45 (3H, OCH3), 3.35 (3H, OCH3), 3.20 (3H, OCH3), 2.79 (3H, OCH3), 1.03 (d, 18H, PCH3, JPH = 9.0 Hz), 0.93 (d, 9H, PCH3, JPH = 8.5 Hz). 13 C{1H} NMR (126 MHz, C6D6, room temperature): δ 190.4 (apparent triplet, PtC=, JPC = 7.3 Hz), 178.0 (PtC=), 172.1, 170.9, 164.9, 164.0 (CO), 164.2, 163.7, 163.62, 163.57, 163.1 (C6H4F para, JFC = 245− 249 Hz; 2:1:1:1:1), 140.7, 140.0, 138.3, 137.9, 137.1 (C6H4F ortho, JFC = 6.4−7.4 Hz; 1:1:2:1:1), 140.3, 140.2, 138.9, 138.7, 132.7 (C6H4F ipso, JFC = 3.5−4.0 Hz; 1:1:1:1:1), 114.7, 114.6, 114.1, 113.9, 113.5, 113.2 (C6H4F meta, 3JFC = 18.6−19.5 Hz), 98.9, 98.2 (SiC=), 55.4, 51.9, 50.9, 50.8 (OCH3), 19.5 (dd, PCH3, JPC = 41, 3.3 Hz), 18.7, 17.0 (d, PCH3, JPC = 30 Hz). One of the C6H4F ipso carbon signals was presumably overlapped. 19F{1H} NMR (376 MHz, C6D6, room temperature): δ −111.7, −112.7, −115.2, −115.5, −115.6, −116.0. 31P{1H} NMR 29
bond is enhanced by coordination of the CO2Me groups to the Si and Pt atoms and formation of two planar five-membered chelating rings.
■
CONCLUSION In summary, the cyclic triplatinum(0) complexes with electronreleasing μ-silylene ligands undergo insertion of a DMAD molecule into a Si−Pt bond and the Si−C bond formation, accompanied by rearrangement of the Pt3 core, to form a disilaplatinacyclopentene intermediate. The subsequent reaction is dependent on the μ-SiAr2 groups. The Ph group easily undergoes the intramolecular transfer from the Si to Pt atoms, while the Si(C6H4F-4)2-coordinated complex undergoes coordination of the second alkynes and results in conversion of a bridging silylene ligand to the unbridged one with dative bonds from CO2Me groups. Insertion of the alkyne into a Pt−Si bond resulted in formation of two complexes with new structures. The reactions are realized by versatile reactivity of the bridging silylene ligand.
■
EXPERIMENTAL SECTION
General Procedures. All manipulations were carried out using standard Schlenk line techniques under an atmosphere of argon or nitrogen or in a nitrogen-filled glovebox (Miwa MFG). Hexane, toluene, and tetrahydrofuran (THF) were purified by using a Grubbs-type solvent purification system (Glass Contour).29 Diethyl ether (Et2O) was distilled from sodium/benzophenone and stored under nitrogen. Acetonitrile and dichloromethane (CH2Cl2) were used as received (super-dehydrated grade). The 1H, 13C{1H}, 19F{1H}, 29Si{1H}, 31 1 P{ H}, and 195Pt{1H} NMR spectra were recorded on a Bruker Biospin Avance III 400 MHz and Avance III HD 500 MHz NMR spectrometers. Chemical shifts in 1H and 13C{1H} NMR spectra were referenced to the residual peaks of the solvents used.30 The peak positions of the 19F{1H}, 29Si{1H}, 31P{1H}, and 195Pt{1H} NMR spectra were referenced to external CF3CO2H (δ −77.7), SiMe4 (δ 0), and 85% H3PO4 (δ 0) in deuterated solvents and external K2PtCl4 in D2O (δ −1624), respectively. The signals of 3 and 4 in the 1H and 13C{1H} NMR spectra were assigned by 2D HMQC NMR experiments. The IR spectrum was recorded on a JASCO FTIR-4100 spectrometer. Elemental analyses were performed using a J-science JM10 or Yanaco HSU-20 autorecorders. Compounds [Pt(PMe3)4]31 and H2Si(C6H4F-4)232 were prepared according to the literature. H2SiPh2 (Wako) and dimethyl acetylenedicarboxylate (ZCCZ, Z = CO2Me, SigmaAldrich) were used as received. Preparation of [{Pt(PMe3)}3(μ-SiPh2)3] (1). To a toluene (5 mL) solution of [Pt(PMe3)4] (751 mg, 1.50 mmol) was added an equimolar amount of H2SiPh2 (280 mg, 1.53 mmol). The reaction mixture was stirred for 17 h at 100 °C, giving a dark red solution. The solvent was removed under reduced pressure. The resulting material was washed with hexane (1 mL × 3) and acetonitrile (1 mL × 3) and dried in vacuo to afford 1 (509 mg, 75%) as a red solid. The NMR spectroscopic data were consistent with the literature.4 Preparation of [{Pt(PMe3)}3{μ-Si(C6H4F-4)2}3] (2). The procedure to obtain 2 was similar to the preparation of 1. The reaction of [Pt(PMe3)4] (403 mg, 0.81 mmol) with an equimolar amount of H2Si(C6H4F-4)2 (194 mg, 0.88 mmol) gave complex 2 (213 mg, 54%) as a red solid. Red crystals of 2 suited for X-ray crystallography were obtained from recrystallization with CH2Cl2/hexane (1:10). Anal. Calcd for C45H51F6P3Pt3Si3: C, 36.81; H, 3.50; F, 7.76. Found: C, 36.62; H, 3.23; F, 7.98. 1H NMR (400 MHz, C6D6, room temperature): δ 7.93 (apparent triplet, 12H, C6H4F ortho, J = 8.0 Hz), 6.93 (apparent triplet, 12H, C6H4F meta, J = 8.8 Hz), 1.01 (m, 27H, PCH3). 13C{1H} NMR (126 MHz, C6D6, room temperature): δ 163.7 (d, C6H4F para, JFC = 262 Hz), 148.3 (C6H4F ipso), 138.1 (d, C6H4F ortho, 3JFC = 6 Hz), 115.3 (d, C6H4F meta, 2JFC = 19 Hz), 21.7 (PCH3). 19F{1H} NMR (471 MHz, C6D6, room temperature): δ −111.5. 31P{1H} NMR (202 MHz, C6D6, room temperature): δ 26.9 (JPtP = 2962 Hz, 2JPtP = 411 Hz, 3JPP = 85 Hz). 2988
DOI: 10.1021/acs.organomet.5b00291 Organometallics 2015, 34, 2985−2990
Article
Organometallics (162 MHz, THF-d8, room temperature): δ −9.2 (dd, P1, JPtP = 2530 Hz, JPP = 4, 8 Hz), −16.6 (dd, P3, JPtP = 2519 Hz, JPP = 8, 13 Hz), −38.8 (br dd, P2, JPtP = 4407 Hz, 2JPtP = 615 Hz, JPP = 4, 13 Hz). IR (KBr): 1714 (s, νCO). X-ray Crystal Structure Analysis. Single crystals of 2−4 suitable for X-ray diffraction study were mounted on MicroMounts (MiTeGen). The crystallographic data of 2−4 were collected on a Rigaku Saturn CCD area detector or Bruker SMART APEXII ULTRA/CCD diffractometer equipped with monochromated Mo Kα radiation (λ = 0.71073 Å) at 153 or 90 K. Calculations were carried out using the program package Crystal Structure or APEXII for Windows. The positional and thermal parameters of non-hydrogen atoms were refined anisotropically on F2 by full-matrix least-squares methods using SHELXL-2013. Hydrogen atoms were placed at calculated positions and refined with a riding mode on their corresponding carbon atoms. Crystallographic data of 2−4 are listed in Supporting Information.
■
(5) (a) Braddock-Wilking, J.; Corey, J. Y.; Dill, K.; Rath, N. P. Organometallics 2002, 21, 5467−5469. (b) Braddock-Wilking, J.; Corey, J. Y.; French, L. M.; Choi, E.; Speedie, V. J.; Rutherford, M. F.; Yao, S.; Xu, H.; Rath, N. P. Organometallics 2006, 25, 3974−3988. (c) Whtie, C. P.; Braddock-Wilking, J.; Corey, J. Y.; Xu, H.; Redekop, E.; Sedinkin, S.; Rath, N. P. Organometallics 2007, 26, 1996−2004. (6) (a) Tanaka, K.; Tanabe, M.; Ide, T.; Osakada, K. Organometallics 2014, 33, 2608−2612. (b) Tanabe, M.; Tanaka, K.; Omine, S.; Osakada, K. Chem. Commun. 2014, 50, 6839−6842. (7) (a) Spivak, G. J.; Puddephatt, R. J. J. Organomet. Chem. 1998, 551, 383−386. (b) Ros, R.; Tassan, A.; Roulet, R.; Duprez, V.; Detti, S.; Laurenczy, G.; Schenk, K. J. Chem. Soc., Dalton Trans. 2001, 2858−2863. (8) Murahashi, T.; Shirato, K.; Fukushima, A.; Takase, K.; Suenobu, T.; Fukuzumi, S.; Ogoshi, S.; Kurosawa, H. Nat. Chem. 2012, 4, 52−58. (9) Tanabe, M.; Ishikawa, N.; Chiba, M.; Ide, T.; Osakada, K.; Tanase, T. J. Am. Chem. Soc. 2011, 133, 18598−18601. (10) The coupling patterns of the Pt3 complexes were simulated by using the gNMR program (version 4.1.2, Adept Scientific Inc.). (11) Yamada, T.; Mawatari, A.; Tanabe, M.; Osakada, K.; Tanase, T. Angew. Chem., Int. Ed. 2009, 48, 568−571. (12) Beck, R.; Johnson, S. A. Organometallics 2012, 31, 3599−3609. (13) (a) Shimada, S.; Li, Y.-H.; Choe, Y.-K.; Tanaka, M.; Bao, M.; Uchimaru, T. Proc. Natl. Acad. Sci. U.S.A. 2007, 104, 7758−7763. (b) Sunada, Y.; Haige, R.; Otsuka, K.; Kyushin, S.; Nagashima, H. Nat. Commun. 2013, 4, 3014. (14) Wilfling, M.; Klinkhammer, K. W. Angew. Chem., Int. Ed. 2010, 49, 3219−3223. (15) (a) Auburn, M.; Ciriano, M.; Howard, J. A. K.; Murray, M.; Pugh, N. J.; Spencer, J. L.; Stone, F. G. A.; Woodward, P. J. Chem. Soc., Dalton Trans. 1980, 659−666. (b) Tanabe, M.; Ito, D.; Osakada, K. Organometallics 2008, 27, 2258−2267. (16) Gudat, D.; Jain, V. K.; Klein, A.; Schurr, T.; Záliš, S. Eur. J. Inorg. Chem. 2005, 4056−4063. (17) Sculfort, S.; Braunstein, P. Chem. Soc. Rev. 2011, 40, 2741−2760. (18) (a) Feldman, J. D.; Mitchell, G. P.; Nolte, J.-O.; Tilley, T. D. J. Am. Chem. Soc. 1998, 120, 11184−11185. (b) Feldman, J. D.; Mitchell, G. P.; Nolte, J.-O.; Tilley, T. D. Can. J. Chem. 2003, 81, 1127−1136. (19) (a) Watanabe, C.; Inagawa, Y.; Iwamoto, T.; Kira, M. Dalton Trans. 2010, 39, 9414−9420. (b) Agou, T.; Sasamori, T.; Tokitoh, N. Organometallics 2012, 31, 1150−1154. (20) (a) Zybill, C.; Müller, G. Angew. Chem., Int. Ed. Engl. 1987, 26, 669−670. (b) Zybill, C.; Müller, G. Organometallics 1988, 7, 1368− 1372. (c) Zybill, C.; Wilkinson, D. L.; Leis, C.; Müller, G. Angew. Chem., Int. Ed. Engl. 1989, 28, 203−205. (d) Leis, C.; Wilkinson, D. L.; Handwerker, H.; Zybill, C. Organometallics 1992, 11, 514−529. (e) Lang, H.; Weinmann, M.; Frosch, W.; Büchner, M.; Schiemenz, B. Chem. Commun. 1996, 1299−1300. (f) Kobayashi, H.; Ueno, K.; Ogino, H. Chem. Lett. 1999, 239−240. (21) Tobita, H.; Matsuda, A.; Hashimoto, H.; Ueno, K.; Ogino, H. Angew. Chem., Int. Ed. 2004, 43, 221−224. (22) Emsley, J. The Elements, 3rd ed; Oxford University Press: Oxford, UK, 1998. (23) Kooijman, H.; Sprengers, J. W.; Agerbeek, M. J.; Elsevier, C. J.; Spek, A. L. Acta Crystallogr., Sect. E: Struct. Rep. Online 2004, E60, o917− o918. (24) Eaborn, C.; Metham, T. N.; Pidcock, A. J. Organomet. Chem. 1973, 63, 107−117. (25) (a) Tanaka, M.; Uchimaru, Y.; Lautenschlager, H.-J. Organometallics 1991, 10, 16−18. (b) Tanaka, M.; Uchimaru, Y.; Lautenschlager, H.-J. J. Organomet. Chem. 1992, 428, 1−12. (c) Tanaka, M.; Uchimaru, Y. Bull. Soc. Chim. Fr. 1992, 129, 667−675. (d) Shimada, S.; Tanaka, M.; Honda, K. J. Am. Chem. Soc. 1995, 117, 8289−8290. (e) Shimada, S.; Rao, M. L. N.; Li, Y.-H.; Tanaka, M. Organometallics 2005, 24, 6029−6036. (f) Shimada, S.; Li, Y.-H.; Rao, M. L. N.; Tanaka, M. Organometallics 2006, 25, 3796−3798. (26) (a) Hanada, S.; Tsutsumi, E.; Motoyama, Y.; Nagashima, H. J. Am. Chem. Soc. 2009, 131, 15032−15040. (b) Tsutsumi, H.; Sunada, Y.; Nagashima, H. Organometallics 2011, 30, 68−76.
ASSOCIATED CONTENT
S Supporting Information *
A CIF file and table giving crystallographic data for 2−4, NMR spectroscopic data for 2−4. The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.5b00291.
■
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS This work was financially supported by Grants-in-Aid for Scientific Research (B) (No. 24350027) and (C) (No. 25410061) from the Ministry of Education, Culture, Sport, Science, and Technology of Japan. We thank our colleagues in the Center for Advanced Materials Analysis, Technical Department, Tokyo Institute of Technology, for elemental analysis and HRMS (ESI) measurements.
■
REFERENCES
(1) Reviews on triplatinum complexes: (a) Puddephatt, R. J.; Manojlović-Muir, L.; Muir, K. W. Polyhedron 1990, 9, 2767−2802. (b) Imhof, D.; Venanzi, L. M. Chem. Soc. Rev. 1994, 23, 185−193. (c) King, R. B. J. Cluster Sci. 1995, 6, 5−20. (d) Burrows, A. D.; Mingos, D. M. P. Coord. Chem. Rev. 1996, 154, 19−69. (2) Reviews on transition metal complexes with bridging Si and Ge ligands: (a) Ogino, H.; Tobita, H. Adv. Organomet. Chem. 1998, 42, 223−290. (b) Corey, J. Y.; Braddock-Wilking, J. Chem. Rev. 1999, 99, 175−292. (c) Braunstein, P.; Boag, N. M. Angew. Chem., Int. Ed. 2001, 40, 2427−2433. (d) Osakada, K.; Tanabe, M. Bull. Chem. Soc. Jpn. 2005, 78, 1887−1898. (e) Shimada, S.; Tanaka, M. Coord. Chem. Rev. 2006, 250, 991−1011. (f) Corey, J. Y. Chem. Rev. 2011, 111, 863−1071. (3) (a) Brookes, A.; Knox, S. A. R.; Stone, F. G. A. J. Chem. Soc. (A) 1971, 3469−3471. (b) Anema, S. G.; Lee, S. K.; Mackay, K. M.; Nicholson, B. K. J. Organomet. Chem. 1993, 444, 211−218. (c) Chen, W.; Shimada, S.; Tanaka, M. Science 2002, 295, 308−310. (d) Evans, C.; Harfoot, G. J.; McIndoe, J. S.; McAdam, C. J.; Mackay, K. M.; Nicholson, B. K.; Robinson, B. H.; van Tiel, M. L. J. Chem. Soc., Dalton Trans. 2002, 4678−4683. (e) Hirotsu, M.; Nishida, T.; Sasaki, H.; Muraoka, T.; Yoshimura, T.; Ueno, K. Organometallics 2007, 26, 2495−2498. (f) Arii, H.; Takahashi, M.; Nanjo, M.; Mochida, K. Organometallics 2009, 28, 4629−4631. (g) Braunschweig, H.; Brenner, P.; Gross, M.; Radacki, K. J. Am. Chem. Soc. 2010, 132, 11343−11349. (h) Arii, H.; Takahashi, M.; Nanjo, M.; Mochida, K. Organometallics 2011, 30, 917−920. (4) Osakada, K.; Tanabe, M.; Tanase, T. Angew. Chem., Int. Ed. 2000, 39, 4053−4055. 2989
DOI: 10.1021/acs.organomet.5b00291 Organometallics 2015, 34, 2985−2990
Article
Organometallics (27) Tanabe, M.; Jiang, J.; Yamazawa, H.; Osakada, K.; Ohmura, T.; Suginome, M. Organometallics 2011, 30, 3981−3991. (28) (a) Curtis, M. D.; Epstein, P. S. Adv. Organomet. Chem. 1981, 19, 213−255. (b) Kobayashi, T.; Hayashi, T.; Yamashita, H.; Tanaka, M. Chem. Lett. 1988, 1411−1414. (c) Hashimoto, H.; Tobita, H.; Ogino, H. J. Organomet. Chem. 1995, 499, 205−211. (d) Tamao, K.; Sun, G.-R.; Kawachi, A. J. Am. Chem. Soc. 1995, 117, 8043−8044. (e) Radu, N. S.; Hollander, F. J.; Tilley, T. D.; Rheingold, A. L. Chem. Commun. 1996, 2459−2460. (f) Park, S.; Kim, B. G.; Gö ttker-Schnetmann, I.; Brookhart, M. ACS Catal. 2012, 2, 307−316. (29) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.; Timmers, F. J. Organometallics 1996, 15, 1518−1520. (30) Fulmer, G. R.; Miller, A. J. M.; Sherden, N. H.; Gottlieb, H. E.; Nudelman, A.; Stoltz, B. M.; Bercaw, J. E.; Goldberg, K. I. Organometallics 2010, 29, 2176−2179. (31) Lin, W.; Wilson, S. R.; Girolami, G. S. Inorg. Chem. 1997, 36, 2662−2669. (32) Osakada, K.; Sarai, S.; Koizumi, T.; Yamamoto, T. Organometallics 1997, 16, 3973−3980.
2990
DOI: 10.1021/acs.organomet.5b00291 Organometallics 2015, 34, 2985−2990
