Platinum-Conjugated Homo- and Heterobichromophoric Complexes

Oct 31, 2012 - The dark red product was collected from column chromatography (silica gel, 20 cm × 4 cm column, hexane/dichloromethane 4/1). Yield: 14...
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Platinum-Conjugated Homo- and Heterobichromophoric Complexes of Tetracene and Pentacene Minh-Hai Nguyen and John H. K. Yip* Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 S Supporting Information *

ABSTRACT: Homobichromophoric platinum(II) complexes containing tetracenyl rings (T-Pt-T) and pentacenyl rings (PPt-P) were synthesized by Sonogashira coupling between trans[Pt(PEt3)2I2] and 5-ethynyl-12-[(triisopropylsilyl)ethynyl]tetracene (T-SiH) and 6-ethynyl-13-[(triisopropylsilyl)ethynyl]pentacene (P-SiH), respectively. A heterobichromophoric complex consisting of tetracenyl and pentacenyl rings (T-PtP) was generated by coupling P-SiH and platinated T-SiH. The homobichromophoric complexes were characterized by singlecrystal X-ray diffraction. The electronic absorption and emission spectra of the complexes were investigated. All the complexes displayed acene-based fluorescence. The emission spectrum of T-Pt-P showed dual emissions of the tetracenyl and pentacenyl rings. Monitoring the pentacenyl emission gave an excitation spectrum which resembled the absorption spectrum, suggesting the presence of intramolecular energy transfer from the singlet excited state of the tetracenyl ring to the singlet excited state of the pentacenyl ring.

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INTRODUCTION Multichromophoric molecules have been attracting a great deal of attention because of their applications in topical areas such as light-limiting and nonlinear optical materials,1 photovoltaics,2 and molecular electronics.3 On a fundamental level, the molecules can serve as model systems for studies of important processes such as intramolecular energy or electron transfer, exciton migration, light harvesting, two-photon absorption, and singlet fission.4 While conventionally the scene is dominated by organic molecules, we have witnessed a growth in recent years of organometallic multichromophoric complexes in which organic chromophores, which usually have two trans-oriented ethynyl groups, coordinate to metal ions, mainly Pt(II) ions, forming metallopolyynes.5 The metal ions can not only act as connectors in controlling the geometry of the oligomers but also affect the photophysical properties of the chromophores. The heavy-atom effect of platinum could increase the rate of intersystem crossing and hence the quantum yield of the triplet excited state of the organic chromophores. In addition, an electronic structure such as the HOMO−LUMO gap of the chromophore can be altered through orbital interactions with the metals. These properties arising from metal−ligand interactions are shown to be advantageous for photovoltaics, as demonstrated by Wong,6 and triplet exciton formation, as shown by Schanze.4i,7 While various chromophores were employed in previous studies including thiophene and its derivatives,8 perylenebis(dicarboximide),9 phthalocyanine,10 and porphyrin and C60 derivatives,11 tetracene and pentacene, which are heavily © 2012 American Chemical Society

studied in optoelectronics and photovoltaics, had not been widely used in the construction of multichromophoric systems. This was mainly due to the thermal instability of the organic molecules and lack of suitable synthetic entries. However, these problems were circumvented by the ground-breaking syntheses of 5,12-bis[(triisopropylsilyl)ethynyl]tetracene12 (TIPS-T) and 6,13-bis[(triisopropylsilyl)ethynyl]pentacene13 (TIPS-P) by Anthony et al., which not only are stable and soluble but also can function as ligands in forming complexes with Au(I) or Pt(II) ions.14 Our previous studies on the binuclear Pt complexes of TIPS-T, bis-trans-[Pt(PEt3)2I]-5,12-diethynyltetracene (Pt2T, Scheme 1),14 and TIPS-P, bis-trans-[Pt(PEt3)2L]-6,13-diethynylpentacene (Pt2P),15 showed that the collective effect of platination and alkynylation could red-shift the fluorescence of tetracene and pentacene by 0.57 and 0.34 eV, respectively. In addition, platination of 6,13-diethynylpentacene can push the pentacene-based fluorescence to the nearinfrared region.15 Herein we report the synthesis, structures, and spectroscopy of two Pt-conjugated homobichromophoric complexes containing two tetracenyl rings (T-Pt-T) and two pentacenyl rings (P-Pt-P) and a heterobichromophoric complex containing one tetracenyl ring and one pentacenyl ring (T-Pt-P) (Scheme 1). The monochromophoric building blocks T-Pt-I and P-Pt-I were derivatized to form phenylacetylide complexes T-Pt-Ac and P-Pt-Ac, and the former was characterized by X-ray crystallography. Received: August 23, 2012 Published: October 31, 2012 7522

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Scheme 1

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refined for the rest of the non-hydrogen atoms. The hydrogen atoms were placed in their ideal positions. Two of the isopropyl groups in TPt-Ac are disordered, with the terminal carbon atoms occupying two positions with occupancy ratios of 74:26 and 35:65. The asymmetric unit of P-Pt-I contains four molecules. Two triethylphosphine groups and one isopropyl group are disordered into two positions with occupancy ratios of 50:50. The carbon atoms of the disordered triisopropylsilyl groups in P-Pt-P were refined isotropically with restraints in bond lengths. Selected crystal data are given in Table 1. Synthesis. trans-[I(Et3P)2PtII]{5-ethynyl-12-[(triisopropylsilyl)ethynyl]tetracene} (T-Pt-I). In a 500 mL Schlenk flask were charged trans-PtI2(PEt3)2 (800 mg, 1.2 mmol), iPr2NH (10 mL), 5,12bis[(triisopropylsilyl)ethynyl]tetracene (600 mg, 1.0 mmol), CuI (10 mg), and CH2Cl2 (100 mL). To the stirred mixture was added dropwise a CH2Cl2 solution (150 mL) of Bu4NF (100 mg, 0.3 mmol) over 5 h. The resulting solution was stirred overnight, and then the solvent was removed by rotavaporation. The dark red product was collected from column chromatography (silica gel, 20 cm × 4 cm column, hexane/dichloromethane 4/1). Yield: 140 mg, 11%. Anal. Calcd for T-Pt-I (C43H61IP2PtSi): C, 52.17; H, 6.21. Found: C, 52.13; H, 5.43. 1H NMR (500 MHz, CDCl3): δ 9.35 (s, 1H, H6), 9.28 (s, 1H, H11), 8.70 (d, J = 8.9 Hz, 1H, H4), 8.61 (d, J = 8.2 Hz, 1H, H1), 8.00 (d, J = 8.9 Hz, 1H, H7), 7.96 (d, J = 7.0 Hz, 1H, H10), 7.51 (t, J = 8.2 Hz, 1H, H3), 7.45−7.42 (m, 3H, H2,8,9), 2.26−2.23 (m, 12H, PCH2CH3), 1.34−1.21 (m, 39H, PCH2CH3, iPr). 31P{1H} NMR (202.4 MHz, CDCl3): δ 9.66 (s, 1JPt−P = 2309 Hz). MALDI-TOF-MS: m/z 989.2, [M]+. trans-[(C 6 H 5 CC)(Et3 P) 2 Pt II ]{5-ethynyl-12-[(triisopropylsilyl)ethynyl]tetracene} (T-Pt-Ac). In a 50 mL Schlenk flask were charged

EXPERIMENTAL SECTION

General Methods. All syntheses were carried out under a N2 atmosphere. All the solvents used for syntheses and spectroscopic measurements were purified according to the literature procedures.16 trans-Pt(PEt3)2I2,17 5,12-bis[(triisopropylsilyl)ethynyl]tetracene,12 and 6,13-bis[(triisopropylsilyl)ethynyl]pentacene18 were prepared according to reported procedures. Physical Methods. The UV/vis absorption and emission spectra of the complexes were recorded on a Hewlett-Packard HP8452A diode array spectrophotometer and a Perkin-Elmer LS-50D fluorescence spectrophotometer, respectively. Emission lifetimes were recorded on a Horiba Jobin-Yvon Fluorolog FL-1057 fluorescence spectrometer. Cresyl violet was used as a standard in measuring the emission quantum yields.19 1H and 31P{1H} NMR spectra were recorded on a Bruker ACF 500 spectrometer. 1H−1H COSY spectra were recorded on a Bruker DRX500 NMR spectrometer with a 5 mm Cryo TXI Probe. All chemical shifts are quoted relative to SiMe4 (1H) or H3PO4 (31P). Elemental analyses of the complexes were carried out in the microanalysis laboratory in the Department of Chemistry at the National University of Singapore. X-ray Crystallography. The diffraction experiments were carried out on a Bruker AXS SMART CCD three-circle diffractometer with a sealed tube at 223 K using graphite-monochromated Mo Kα radiation (λ = 0.710 73 Å). The software used were as follows: SMART20a for collecting frames of data, indexing reflection and determination of lattice parameters, SAINT20a for integration of intensity of reflections and scaling, SADABS20b for empirical absorption correction, and SHELXTL20c for space group determination, structure solution, and least-squares refinements on |F|2. Anisotropic thermal parameters were 7523

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Table 1. Crystal Data for T-Pt-Ac, P-Pt-I, T-Pt-T·CH2Cl2, and P-Pt-P T-Pt-Ac empirical formula formula wt cryst syst space group unit cell dimens a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z calcd density (g cm−3) abs coeff (mm−1) F(000) cryst size (mm3) θ range for data collection (deg) index ranges

no. of rflns collected no. of indep rflns (R(int)) max, min transmission no. of data/restraints/params final R indicesa (I > 2σ(I)) R1 wR2 goodness of fit (GOF)b largest diff peak, hole (e Å−3)

P-Pt-I

T-Pt-T·CH2Cl2

P-Pt-P

C51H66P2PtSi 964.16 triclinic P1̅

C47H63I P2PtSi 1039.49 monoclinic P21/c

C75H94Cl2P2PtSi2 1379.61 monoclinic C2/c

C82H96P2PtSi2 1394.80 triclinic P1̅

9.680(3) 16.350(5) 17.323(6) 62.204(7) 78.902(8) 86.599(8) 2378.6(14) 2 1.346 3.074 988 0.60 × 0.06 × 0.04 1.35−27.50 −12 ≤ h ≤ 12 −21 ≤ k ≤ 21 −22 ≤ l ≤ 22 31 128 10 880 (0.1157) 0.8869, 0.2599 10 880/30/526

30.112(2) 25.0907(17) 24.4373(19) 90 91.597(3) 90 18456(2) 16 1.496 3.835 8312 0.58 × 0.20 × 0.16 1.06−25.00 −35 ≤ h ≤ 35 −29 ≤ k ≤ 18 −29 ≤ l ≤ 29 109 398 32 492 (0.0732) 0.3334, 0.2161 34 292/262/2044

38.117(5) 11.0180(14) 17.077(2) 90 103.170(3) 90 6994.2(16) 4 1.310 2.203 2856 0.50 × 0.08 × 0.08 2.19−27.50 −29 ≤ h ≤ 49 −14 ≤ k ≤ 14 −22 ≤ l ≤ 21 24 101 8012 (0.0683) 0.8435, 0.4055 8012/0/384

7.2711(13) 11.622(2) 21.039(4) 86.290(4) 81.186(4) 81.257(4) 1734.9(5) 1 1.335 2.147 724 0.10 × 0.10 × 0.06 1.96−27.50 −9 ≤ h ≤ 9 −15 ≤ k ≤ 9 −27 ≤ l ≤ 27 11 898 7879 (0.0532) 0.7456, 0.5876 7879/212/395

0.0787 0.1504 1.032 3.006, −1.818

0.0542 0.1258 0.941 3.674, −1.374

0.0469 0.0994 1.041 1.806, −2.378

0.0607 0.1288 1.076 2.932, −1.640

R1 = (||Fo| − |Fc||)/(|Fo|); wR2 = [w(Fo2 − Fc2)/w(Fo4)]1/2. bGOF = [(w(Fo2 − Fc2)2/(n − p)]1/2. For all crystal determinations, the scan type and wavelength of radiation used are ω and 0.710 73 Å, respectively.

a

(m, 12H, PCH2CH3), 1.37−1.36 (m, 21H, iPr), 1.29−1.23 (m, 18H, PCH2CH3). 31P{1H} NMR (202.4 MHz, CDCl3): δ 9.75 (s, 1JPt−P = 2312 Hz). ESI-MS: m/z 1039.2, [M]+. trans-[(C 6 H 5 CC)(Et3 P) 2 Pt II ]{6-ethynyl-13-[(triisopropylsilyl)ethynyl]pentacene} (P-Pt-Ac). In a 50 mL Schlenk flask were charged P-Pt-I (40 mg, 0.04 mmol), NEt3 (5 mL), CuI (5 mg), and CH2Cl2 (15 mL). To the stirred mixture was added phenylacetylene (0.1 mL, 0,9 mmol). The resulting solution was stirred overnight, and all the solvents were reduced to dryness. The dark green product was collected from column chromatography (silica gel, 10 cm × 2 cm column, hexane/dichloromethane 8/3 v/v). Yield: 18 mg, 46%. Anal. Calcd for P-Pt-Ac (C55H68P2PtSi): C, 65.13; H, 6.76. Found: C, 65.20; H, 6.36. 1H NMR (500 MHz, CDCl3): δ 9.41 (s, 2H, H5,7), 9.26 (s, 2H, H12,14), 7.97−7.92 (m, 4H, H1,4,8,11), 7.37−7.35 (m, 6H, H2,3,9,10, oC6H5), 7.27−7.24 (m, 2H, m-C6H5), 7.16 (t, 1H, p-C6H5), 2.29−2.23 (m, 12H, PCH2CH3), 1.37−1.26 (m, 39H, PCH2CH3, iPr). 31P{1H} NMR (202.4 MHz, CDCl3): δ 12.55 (s, 1JPt‑P = 2361 Hz). MALDITOF-MS: m/z 1014.3, [M]+. trans-[(Et 3 P) 2 Pt II ]bis{5-ethynyl-12-[(triisopropylsilyl)ethynyl]tetracene} (T-Pt-T). 5,12-Bis[(triisopropylsilyl)ethynyl]tetracene (350 mg, 0.6 mmol), CH2Cl2 (50 mL), trans-PtI2(PEt3)2 (50 mg, 0.08 mmol), iPr2NH (5 mL), and CuI (5 mg) were added into a 250 mL Schlenk flask. To the stirred mixture was added slowly a CH2Cl2 solution (70 mL) of Bu4NF (52 mg, 0.17 mmol) over 5 h. The resulting solution was stirred overnight, and all the solvents were reduced to dryness. The dark red product was collected from column chromatography (silica gel, 20 cm × 4 cm column, hexane/ dichloromethane 4/1 v/v). Yield: 45 mg, 46%. Dark red crystals of T-Pt-T were obtained from CH2Cl2/MeOH at room temperature. Anal. Calcd for T-Pt-T (C74H92P2PtSi2): C, 68.65; H, 7.16. Found: C,

T-Pt-I (200 mg, 0.2 mmol), NEt3 (5 mL), CuI (5 mg), and CH2Cl2 (30 mL). After addition of phenylacetylene (0.2 mL, 1.9 mmol) the solution was stirred overnight and then the solvent was removed to give a dark red solid. The product was isolated from column chromatography (silica gel, 15 cm × 2 cm column, hexane/ dichloromethane 2/1 v/v). Yield: 160 mg, 82%. X-ray-quality crystals of T-Pt-Ac were grown by slow evaporation of a CH2Cl2/EtOH solution. Anal. Calcd for T-Pt-Ac (C51H66P2PtSi): C, 63.53; H, 6.90. Found: C, 63.25; H, 7.31. 1H NMR (500 MHz, CDCl3): δ 9.41 (s, 1H, H6), 9.26 (s, 1H, H11), 8.76 (d, J = 8.2 Hz, 1H, H4), 8.59 (d, J = 8.9 Hz, 1H, H1), 8.00 (d, J = 8.2 Hz, 1H, H7), 7.97 (d, J = 7.0 Hz, 1H, H10), 7.50 (t, J = 8.9 Hz, 1H, H3), 7.42−7.40 (m, 3H, H2,8,9), 7.34 (d, J = 7.6 Hz, 2H, o-C6H5), 7.25 (t, J = 8.2 Hz, 2H, m-C6H5), 7.15 (t, J = 7.6 Hz, 1H, p-C6H5), 2.24−2.21 (m, 12H, PCH2CH3), 1.32−1.26 (m, 39H, PCH2CH3, iPr). 31P{1H} NMR (202.4 MHz, CDCl3): δ 12.41 (s, 1 JPt−P = 2364 Hz). MALDI-TOF-MS: m/z 963.3, [M]+. trans-[I(Et 3 P) 2 Pt II ]{6-ethynyl-13-[(triisopropylsilyl)ethynyl]pentacene} (P-Pt-I). In a 250 mL Schlenk flask were charged transPtI2(PEt3)2 (600 mg, 0.9 mmol), iPr2NH (5 mL), 6,13-bis[(triisopropylsilyl)ethynyl]pentacene (200 mg, 0.3 mmol), CuI (5 mg), and CH2Cl2 (40 mL). To the stirred mixture was added dropwise a CH2Cl2 solution (100 mL) of Bu4NF (50 mg, 0.2 mmol) over 5 h. The resulting solution was stirred overnight, and all the solvents were reduced to dryness. The dark green product was collected from column chromatography (silica gel, 20 cm × 4 cm column, hexane/ dichloromethane 4/1 v/v). Yield: 100 mg, 12%. Dark green crystals of P-Pt-I were obtained from CH2Cl2/MeOH at −20 °C. Anal. Calcd for P-Pt-I (C47H63IP2PtSi): C, 54.28; H, 6.11. Found: C, 54.13; H, 6.36. 1 H NMR (500 MHz, CDCl3): δ 9.34 (s, 2H, H5,7), 9.28 (s, 2H, H12,14), 7.97−7.91 (m, 4H, H1,4,8,11), 7.38−7.36 (m, 4H, H2,3,9,10), 2.29−2.26 7524

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68.27; H, 7.23. 1H NMR (500 MHz, CDCl3): δ 9.49 (s, 2H, H6), 9.29 (s, 2H, H11), 8.83 (d, J = 8.9 Hz, 2H, H4), 8.62 (d, J = 8.8 Hz, 2H, H1), 8.03 (m, 4H, H7,10), 7.53 (t, J = 7.6 Hz, 2H, H3), 7.48−7.37 (m, 6H, H2,8,9), 2.28−2.25 (m, 12H, PCH2CH3), 1.37−1.26 (m, 60H, PCH2CH3, iPr). 31P{1H} NMR (202.4 MHz, CDCl3): δ 13.20 (s, 1 JPt−P = 2356 Hz). MALDI-TOF-MS: m/z 1294.5, [M]+. trans-[(Et 3 P) 2 Pt II ]bis{6-ethynyl-13-[(triisopropylsilyl)ethynyl]pentacene} (P-Pt-P). In a 250 mL Schlenk flask were charged 6,13bis[(triisopropylsilyl)ethynyl]pentacene (200 mg, 0.3 mmol), CH2Cl2 (70 mL), trans-PtI2(PEt3)2 (30 mg, 0.05 mmol), iPr2NH (5 mL), and CuI (5 mg). To the stirred mixture was added a CH2Cl2 solution (80 mL) of Bu4NF (36 mg, 0.1 mmol) over 5 h. The resulting solution was stirred overnight, and the dark green product was isolated from column chromatography (silica gel, 20 cm × 4 cm column, hexane/ dichloromethane 4/1). Yield: 30 mg, 47%. Dark green crystals of P-PtP were obtained from CHCl3/EtOH at room temperature. Anal. Calcd for P-Pt-P (C82H96P2PtSi2): C, 70.61; H, 6.94. Found: C, 70.30; H, 6.76. 1H NMR (500 MHz, CDCl3): δ 9.50 (s, 4H, H5,7), 9.30 (s, 4H, H12,14), 8.02−7.98 (m, 8H, H1,4,8,11), 7.41−7.39 (m, 8H, H2,3,9,10), 2.37−2.34 (m, 12H, PCH2CH3), 1.43−1.38 (m, 60H, PCH2CH3, iPr). 31 1 P{ H} NMR (202.4 MHz, CDCl3): δ 13.42 (s, 1JPt−P = 2345 Hz). MALDI-TOF-MS: m/z 1394.6, [M]+. trans-[(Et 3 P) 2 Pt II ]{5-ethynyl-12-[(triisopropylsilyl)ethynyl]tetracene}{6-ethynyl-13-[(triisopropylsilyl)ethynyl]pentacene} (T-PtP). In a 250 mL Schlenk flask were charged 5,12-bis[(triisopropylsilyl)ethynyl]tetracene (240 mg, 0.4 mmol) and CH2Cl2 (50 mL). To the stirred mixture was added dropwise a CH2Cl2 solution (70 mL) of Bu4NF (17 mg, 0.05 mmol) over 6 h, and then P-Pt-I (50 mg, 0.05 mmol), iPr2NH (5 mL), and CuI (5 mg) were quickly added. The resulting solution was stirred overnight, and the dark purple product was collected from column chromatography (silica gel, 20 cm × 4 cm column, hexane/dichloromethane 4/1). Yield: 54 mg, 84%. Anal. Calcd for T-Pt-P (C78H94P2PtSi2): C, 69.66; H, 7.05. Found: C, 69.54; H, 6.84. 1H NMR (500 MHz, CDCl3): δ 9.51 (s, 1H, H6-tetracene), 9.49 (s, 2H, H5,7-pentacene), 9.30 (s, 1H, H11-tetracene), 9.29 (s, 2H, H12,14-pentacene), 8.85 (d, J = 8.8 Hz, 1H, H4-tetracene), 8.63 (d, J = 8.8 Hz, 1H, H1-tetracene), 8.07−8.03 (m, 2H, H7,10-tetracene), 8.00− 7.98 (m, 4H, H1,4,8,11-pentacene), 7.54 (t, J = 6.9 Hz, 1H, H3tetracene), 7.49−7.44 (m, 3H, H2,8,9-tetracene), 7.40−7.38 (m, 4H, H2,3,9,10-pentacene), 2.33−2.28 (m, 12H, PCH2CH3), 1.41−1.33 (m, 60H, PCH2CH3, iPr). 31P{1H} NMR (202.4 MHz, CDCl3): δ 13.30 (s, 1 JPt−P = 2349 Hz). MALDI-TOF-MS: m/z 1344.6, [M]+.

Structures. The 1H NMR spectra of all the complexes show signals for the isopropyl and aromatic H atoms. For all the tetracenyl and pentacenyl rings in the complexes, only one of their two ethynyl groups is coordinated to the Pt ion. As a result, the two sides of the rings are nonequivalent, giving rise to two sets of signalsthe signals for the protons on the side of the Pt ion (H3,4,6,7,8 for the tetracenyl ring and H3,4,5,7,8,9 for the pentacenyl ring) and those on the side of the Si(iPr)3 group (H1,2,9,10,11 for the tetracenyl ring and H1,2,10,11,12,14 for the pentacenyl ring). Each set of tetracenyl protons comprises one singlet (H6/11) and four doublet of doublets (H1/4, H2/3, H7/10 and H8/9), and each set of pentacenyl protons is composed of one singlet (H5,7/12,14) and two doublet of doublets (H1,11/4,8 and H2,10/3,9). Due to the inductive effect of the Pt ion, the signals for the protons on the side of the metal ion are invariably more downfield than those on the other side. In addition, the former signals were more sensitive to a change in the auxiliary ligands of the Pt ion. These effects are useful in assignment of the signals. The 1H NMR spectrum of T-Pt-P exhibited four sets of signals for the tetracenyl and pentacenyl rings, which were assigned with the aid of the 1H−1H COSY spectrum of the complex (Supporting Information, Figure S1). The 31P{1H} spectra of all the complexes exhibited a singlet (δ 9.66−13.42) flanked with 195Pt satellites with 1JPt−P coupling constant of 2309−2364 Hz. The ORTEP plots of T-Pt-Ac, P-Pt-I, T-Pt-T, and P-Pt-P are shown in Figures 1−4, respectively, and selected bond lengths and angles are given in Tables 2−5. The crystal structure of T-Pt-Ac (Figure 1, Table 2) shows a Pt ion coordinated to the two acetylide groups and two trans-oriented PEt3 ligands, forming a distorted-square-planar geometry.

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RESULTS AND DISCUSSION Synthesis. The crux of the successful syntheses of the bichromophoric molecules described in this work was the monodesilylated T-SiH and P-SiH, which were generated by reacting a large excess of TIPS-T and TIPS-P with tetrabutylammonium fluoride (TBAF), respectively. Addition of TBAF had to be very slow in order to minimize double desilylation. Unreacted acenes could be easily recycled by column chromatography, in which TIPS-T and TIPS-P were eluted first as deep red and deep blue bands, respectively. As TSiH and P-SiH were highly unstable, they were generated in situ and immediately reacted with excess trans-Pt(PEt3)2I2 that was already present in the solution to form T-Pt-I and P-Pt-I. The side products of the reactions are T-Pt-T (yield 104 M−1 cm−1) throughout the entire visible region, except the range of ∼400−490 nm (ε ≈ (5−9) × 103 M−1 cm−1). Emission Spectroscopy. All complexes are photoluminescent in solution except P-Pt-P and their solution emission spectra are shown in Figures 9−11, and the lifetimes (τ) and quantum yields (Φ) of the emissions are given in Table 7. The complexes exhibit emission lifetimes in the nanosecond domain and small Stokes shifts (