Benzyl or allyl functionalized platinum(IV) pre-catalyst

Abstract

The present invention is a compound of Formula (1): where R1, R2, R3, and x are as defined herein. The compound of the present invention is useful as a pre-catalyst for hydrosilylation reactions.

Description

[0001] Benzyl or Allyl Functionalized Platinum(IV) Pre-catalyst Background of the Invention The present invention relates to a photoactivated benzyl or allyl functionalized platinum(IV) (Pt(IV)) pre-catalyst, particularly for hydrosilylation reactions. Hydrosilylation is commonly used in the silicones industry for the synthesis of silicone polymers and cross-linked materials. UV-initiated hydrosilylation using a photoactive pre-catalyst is becoming more popular as the energy input needed to trigger the reaction is low relative to thermally activated approaches. Pt(IV) species such as cyclopentadienyltrimethylplatinum and its analogs are known as photoactive pre-catalysts (see US 4,510,094; US 8,088,878; and US 10,392,479) for hydrosilylation; Pt(IV) decomposes under UV irradiation to form the catalytically active Pt(0) species. Nevertheless, these known pre-catalysts are often undesirably volatile, and reactions using these pre-catalysts tend to be sluggish. There is a need, therefore, to discover pre-catalysts that enhance reactivity and that exhibit favorable volatility profiles. Summary of the Invention The present invention is a compound of Formula 1: where x is from 0 to 5; each R1is independently C1-C6-alkyl or phenyl; each R2is independently H, methyl, ethyl, or phenyl; and R3is either of the following fragments: where each R4is C1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, y, (vinyl)silyl, or C2-C12- alkenyl; each R6is independently C1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, NO2, acetyl, halo, dimethyl(vinyl)silyl, or C2-C12-alkenyl; and each y is independently from 0 to 5. The present invention addresses a need in the art by providing a nonvolatile Pt(IV) pre-catalyst that decomposes rapidly to the catalytically active Pt(0) state under light irradiation. Detailed Description of the Invention The present invention is a compound of Formula 1: Formula 1 where x is from 0 to 5; each R1is independently C1-C6-alkyl or phenyl; each R2is independently H, methyl, ethyl, or phenyl; and R3is either of the following fragments: where each R4is C1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, NO2, acetyl, halo, aryl-(R6)y, dimethyl(vinyl)silyl, or C2-C12- alkenyl; each R6is independently C1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, NO2, acetyl, halo, dimethyl(vinyl)silyl, or C2-C12-alkenyl; and each y is independently from 0 to 5. US 4,510,094 (Drahnak column 3, lines 33-44) reports the preparation of (η5-cyclopentadienyl)trimethylplatinum ((Cp)trimethylplatinum) complexes by the addition of a solution of cyclopentadienylsodium in THF to trimethylplatinum iodide in benzene according to the procedure of Robinson and Shaw (J. Chem, Soc.1965, 1529). Furthermore, Drahnak recites (Cp)dimethylbenzylplatinum (column 4, line 58, (Cp)Me2BzPt) as a representative compound of the invention; nevertheless, no details of its preparation are disclosed; consequently, the present inventors have been unable to prepare (Cp)Me2BzPt and its analogs, without extensive experimentation not taught or suggested by Drahnak. It has now been discovered that the compound of the present invention can be prepared using the following steps. In a first step, an alkali metal cyclopentadiene such as sodium cyclopentadiene (Na-Cp) is contacted with R1-Br to form an alkyl or phenyl substituted cyclopentadiene (R1)x-Cp. Examples of preferred R1groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and t-butyl groups. (R1)x-Cp is then contacted with an alkali metal bis(tetramethylsilyl)amide such as potassium or sodium bis(tetramethylsilyl)amide or with an alkyl lithium such as n-butyl lithium to form the alkali metal salt of (R1)x-Cp (Intermediate A): In a separate series of steps, a tolyl-functionalized Grignard reagent such as (o-tolyl)magnesium bromide can be contacted with a halide-functionalized dimethyl(vinyl)silyl compound such as chlorodimethyl(vinyl)silane to form a tolyl-functionalized dimethyl(vinyl)silyl compound, which can then be treated with a brominating agent such as N-bromosuccinimide (NBS) in the presence of a radical initiator such as azobisisobutyronitrile (AIBN) to generate a dimethyl(vinyl)silyl-functionalized bromomethylbenzene BrCH2-phenyl-SiMe2Vi: Li-(R1)-Cp substituted cyclopentadiene, and the reaction can be repeated up to an (R1)5-substituted Cp-alkali metal salt. The compound of Formula 1 where R3is phenyl-(R5)y can be prepared as follows: Norbornadiene dimethyl platinum (II) (NBD)PtMe2is dissolved in a suitable donor solvent such as pyridine, then contacted with a benzyl bromide (Br-C(R2)2phenyl(R5)y) where y is 0 to 5, preferably, 1, 2, or 3, then contacted with Intermediate A in the same reaction vessel to form a compound of the present invention. where each R1is preferably independently C1-C4-alkyl or phenyl; each R2is preferably H. In one embodiment, each R5is independently methyl, trifluoromethyl, nitro, but-3-ene-1-yl, methoxy, or aryl-(R6)y, where aryl is phenyl, naphthyl, or anthracenyl. Specific examples of compounds of this embodiment of the present invention include the following: The alkenyl group, can be prepared analogously, by contacting the (NBD)PtMe2 / pyridine mixture with a bromoalkene such as 1-bromo-3-methylbut-2-ene under similar reaction conditions to form the following compound: where each R1is preferably and each R2is preferably H. In another aspect, the present invention is a method comprising the steps of contacting a solution of norbornadiene dimethyl platinum (II) and an N-donor solvent such as pyridines or quinolines with Br-C(R2)2phenyl(R5)y under conditions suitable for forming an oxidative addition intermediate, then contacting the oxidative addition intermediate with Intermediate A under conditions suitable for forming the compound of Formula 1. In this aspect, y is from 0 to 5. Suitable pyridines include pyridine, 4-methylpyridine, 4-t-butylpyridine, 4-methoxypyridine, and 4-dimethylaminopyridine. Suitable quinolines include quinoline, 8-methylquinoline, and 8-methoxyquinoline. The compound of the present invention is a Pt(IV) pre-catalyst that exhibits excellent efficiency for promoting UV-triggered hydrosilylation chemistry. The relatively low vapor pressure of the pre-catalyst is also beneficial because the amount of pre-catalyst needed to initiate hydrosilylation is lower due to its decreased volatility. Examples In the following examples, Cp refers to an unsubstituted cyclopentadiene ring, Cp* refers to a pentamethyl substituted cyclopentadiene ring,MeCp refers to a monomethyl substituted cyclopentadiene ring, 2,6-Me2Bz refers to 2,6-dimethylbenzyl, 4-CF3Bz refers to 4-trifluoromethylbenzyl, 3-Me-2-Bu refers to 3-methylbut-2-enyl, 2-BuBz refers to 2-(but-3-en- 1-yl)benzyl, 2-PhBz refers to 2-phenylbenzyl, and 2-SiMe2ViBz refers to 2-dimethyl(vinyl)silyl. Intermediate Example 1 – Preparation of (NBD)PtMe2 (NBD)PtMe2was prepared using an adapted procedure from Eur. J. Inorg. Chem.2015, 2015, 226–239, wherein deionized water was used to quench the reaction rather than concentrated HCl. NMR spectroscopy of the obtained product matched that previously reported. Intermediate Example 2 – Preparation of 1-(Bromomethyl)-2-(but-3-en-1-yl)benzene 1,2-Bis(bromomethyl)benzene (8.00 g, 30.31 mmol, 1 equiv) was combined with diethyl ether (50 mL), THF (20 mL), and a magnetic stir bar in a 250-mL glass jar inside a nitrogen-filled glove box. The resulting colorless suspension was stored at -25 °C for 1 h prior to the dropwise addition of a 1.0 M solution of allylmagnesium bromide in diethyl ether (28.8 mL, 28.8 mmol, 0.95 equiv) to the suspension. The resulting gray suspension was allowed to warm to ambient temperature and stirred vigorously for 4 h. The reaction mixture was then removed from the glove box and diluted with deionized water (25 mL). The resulting biphasic mixture was transferred to a separatory funnel and the organic layer was washed with water (2 x 10 mL) and brine (2 x 10 mL). The organic layer was collected, concentrated on silica gel, and purified by column chromatography using 100% hexanes as the mobile phase. Fractions 3-5 were combined and concentrated to a colorless liquid. Yield: 2.33 g, 34.0 %.1H NMR (400 MHz, C6D6) δ 7.06 – 6.94 (m, 2H), 6.90 (t, J = 7.4 Hz, 2H), 5.72 (ddt, J = 16.9, 10.2, 6.6 Hz, 1H), 5.05 – 4.85 (overlapping resonances, 2H), 4.12 (s, 2H), 2.68 – 2.56 (m, 2H), 2.31 – 2.13 (m, 2H).13C NMR (101 MHz, C6D6) δ 140.90, 137.95, 135.88, 130.87, 129.91, 129.06, 126.70, 115.35, 34.95, 31.82, 31.65. Intermediate Example 3 – Preparation of dimethyl(o-tolyl)(vinyl)silane Chlorodimethyl(vinyl)silane (4.00 g, 33.15 mmol, 1 equiv) was combined with THF (75 mL) and a magnetic stir bar in a 150-mL glass jar. The colorless solution was stored at -25 °C for 1 h. Once cooled, a 2.0 M solution of o-tolylmagnesium bromide in THF (16.58 mL, 33.15 mmol, 1 equiv) was added slowly. The reaction mixture was then allowed to warm slowly to ambient temperature with continue stirring for 24 h. A portion of 1,4-dioxane (20 mL) was added to the reaction mixture. The resulting suspension was allowed to stir at ambient temperature for 1 h and was then passed through a Celite pad atop a disposable PTFE-frit filter. The pale-yellow filtrate was concentrated in vacuo, affording a pale-yellow residue. The residue was extracted into hexanes (40 mL) and filtered sequentially through a 0.45-µm and a 0.20-µm PTFE syringe filter, affording a pale-yellow solution. The solution was stored at -25 °C for 48 h, leading to the precipitation of colorless solids. The solids were filtered off using a 0.20-µm PTFE syringe filter. The filtrate was concentrated to a pale-yellow liquid. Yield: 3.95 g, 67.6 %.1H NMR (400 MHz, C6D6) δ 7.52 (dd, J = 7.3, 1.6 Hz, 1H), 7.22 – 7.14 (m, 1H), 7.10 (t, J = 7.3 Hz, 1H), 7.04 (d, J = 7.5 Hz, 1H), 6.30 (dd, J = 20.3, 14.6 Hz, 1H), 5.95 (dd, J = 14.6, 3.7 Hz, 1H), 5.69 (dd, J = 20.3, 3.7 Hz, 1H), 2.33 (s, 3H), 0.33 (s, 6H).13C NMR (101 MHz, C6D6) δ 143.97, 139.06, 136.47, 135.33, 132.39, 130.18, 129.83, 125.41, 23.24, -1.84. Intermediate Example 4 – Preparation of (2-(bromomethyl)phenyl)dimethyl(vinyl)silane Dimethyl(o-tolyl)(vinyl)silane (3.00 g, 17.01 mmol, 1 equiv) was combined with deoxygenated ethylacetate (75 mL, previously dried over molecular sieves), NBS (3.03 g, 17.01 mmol, 1 equiv), AIBN (0.559 g, 3.40 mmol, 0.2 equiv), and a magnetic stir bar in a 150-mL glass jar. The reaction mixture was then heated at 70 °C for 18 h. After cooling to ambient temperature, the reaction mixture was filtered through a Celite pad atop a disposable PTFE filter frit. The pad was washed with hexanes (2 x 15 mL). The combined washes and filtrate were then concentrated onto silica gel and purified by ISCO chromatography using 100 % hexanes at the mobile phase. The desired product was isolated from fractions 3-9. Yield: 1.12 g, 25.8 %.1H NMR (500 MHz, C6D6) δ 7.38 (dd, J = 7.5, 1.5 Hz, 1H), 7.22 (dd, J = 7.6, 1.3 Hz, 1H), 7.07 (td, J = 7.5, 1.5 Hz, 1H), 7.00 (td, J = 7.4, 1.3 Hz, 1H), 6.33 – 6.22 (m, 1H), 5.97 – 5.87 (m, 1H), 5.66 (dd, J = 20.3, 3.5 Hz, 1H), 4.38 (s, 2H), 0.33 (s, 6H).13C NMR (126 MHz, C6D6) δ 143.96, 138.62, 137.35, 135.60, 133.06, 131.46, 130.18, peak obscured by NMR solvent, 34.58, -1.46. Example 1 – Preparation of CpPtMe2(2,6-Me2Bz) (NBD)PtMe2(84 mg, 0.265 mmol) and pyridine (3 mL) charged into a vial equipped with a magnetic stir bar. The mixture was stirred for 1 h at room temperature in a nitrogen-filled glovebox. 2,6-Dimethylbenzyl bromide (Me2BzBr, 53 mg, 0.265 mmol) was then added to the vial, and the solution was stirred for 1 h. Additional Me2BzBr (15 mg) was added to the vial and stirring was continued overnight. Additional Me2BzBr (15 mg) was added, and the mixture was heated to 45 °C and stirring was continued overnight. The mixture was charged with NaCp solution (2.4 M in THF, 110 µL, 0.265 mmol) and stirring was continued at room temperature for 2 h. The mixture was then heated to 45 °C and stirring was continued overnight. The mixture was dried in vacuo, charged with Et2O, and filtered through a syringe filter, and dried in vacuo. The red residue was then taken up in CH2Cl2 and passed through a Florisil pad. The filtrate was collected and dried, resulting in a red solid (43 mg, 39%).1H NMR (400 MHz, C6D6) δ 6.94 (m, 3H, Ar), 4.81 (m, 5H, Cp), 2.67 (m, 2H, Pt-CH2, 96 Hz), 2.26 (m, 6H, Me), 1.27 (m, 6H, Pt-CH3, 82 Hz) ;13C NMR (101 MHz, C6D6) δ 150.74, 134.55, 124.78, 97.91, 20.28, 9.89 (1JPt-C = 678 Hz), -18.85 (1JPt-C = 724 Hz);195Pt NMR (85 MHz, C6D6) δ -5009.62. Example 2 – Preparation of Cp*PtMe2(4-CF3Bz) (NBD)PtMe2(60 mg, 0.189 mmol) was combined with pyridine (5 mL) in a 20-mL vial equipped with a magnetic stir bar and stirred for 10 min in a nitrogen-filled glovebox. 4-Trifluoromethylbenzyl bromide (45 mg, 0.189 mmol) was then added to the mixture and stirring was continued for 1.5 h, after which time LiCp* (34 mg, 2.36 mmol) was added. The mixture was heated to 45 °C and stirring was continued overnight. The red mixture was dried in vacuo, followed by the addition of CH2Cl2; the resulting solution was filtered through a Florisil pad, and the light-yellow filtrate was concentrated in vacuo to afford 80 mg (82 %) of the title compound as a yellow oil.1H NMR (C6D6, 400 MHz) δ 7.36 (d, 2H, Ar), 6.97 (d, 2H, Ar), 2.79 (pt, 2H, CH2,2JPt-H= 84 Hz), 1.20 (s, 15H, Cp*), 0.69 (pt, 6H, Pt-CH3,2JPt-H= 60 Hz);13C NMR (100 MHz) δ 153.50, 125.78 (q), 125.68 (q), 124.84 (m), 102.68, 11.31 (1JPt-C = 667 Hz), 7.25, - 6.24 (1JPt-C= 730 Hz);19F NMR (471 MHz, C6D6) δ -61.52;195Pt NMR (85.5 MHz) δ -5060.66. Example 3 – Preparation of Cp*PtMe2(3-Me-2-Bu) (NBD)PtMe2 (67 mg, 0.211 mmol) and pyridine (5 mL) were charged into a 20-mL vial equipped with a stirring bar and stirred for 10 min in a nitrogen-filled glovebox. Prenyl bromide (25 µL, 0.211 mmol) was then added and the mixture was stirred for 1.5 h, after which time LiCp* (39 mg, 0.275 mmol) was added. The mixture was heated to 45 °C and stirring was continued overnight. The red mixture was dried in vacuo, charged with CH2Cl2, and filtered through a Florisil pad. The light-yellow filtrate was concentrated in vacuo to afford 65 mg (72%) of the title compound as a yellow oil.1H NMR (C6D6, 400 MHz): δ 5.37 (m, 1H, CH), 2.41 (ptd, 2H, CH2,2JPt-H = 100Hz,2JH-H = 12 Hz), 1.79 (m, 3H, CH3), 1.74 (m, 3H, CH3), 1.52 (m, 15H, Cp*), 0.77 (pt, 6H, Pt-CH3,2JPt-H= 80Hz);13C NMR (C6D6, 100 MHz) δ 130.18, 125.44, 102.51, 26.09, 18.65, 7.82, 6.85, -8.17;195Pt NMR (C6D6, 85.5 MHz) δ -5073.39. Example 4 – Preparation ofMeCpPtMe2(2-BuBz) (NBD)PtMe2 (0.118 g, 0.37 mmol, 1 equiv) and pyridine (3 mL) were charged into a 20-mL vial equipped with a magnetic stir bar and stirred for 20 min at ambient temperature in a nitrogen glove box. 1-(Bromomethyl)-2-(but-3-en-1-yl)benzene (0.084 g, 0.37 mmol, 1 equiv) was added dropwise followed by the addition of pyridine (1 mL) to ensure quantitative transfer of the reagent to the reaction vial. After stirring at ambient temperature for 4 h, LiMeCp (0.038 g, 0.45 mmol, 1.2 equiv) was added to the reaction mixture directly as a solid at ambient temperature. The reaction mixture was stirred at ambient temperature for 1 h, whereupon the reaction mixture was passed through a Celite pad and a 0.45-µm PTFE syringe filter. The Celite pad was rinsed with hexanes (2 x 3 mL) and the washings were combined with the filtrate. The volatiles were then removed in vacuo and the purple residue was stored at -25 °C for 18 h. The residue was then triturated with hexanes (2 x 2 mL) and then extracted into hexanes (2 x 10 mL) and passed through a Fluorisil pad and two sequential 0.20-µm PTFE syringe filters. The filtrate was then concentrated in vacuo to afford a pale-yellow liquid. The liquid was extracted a final time into hexanes (6 mL), passed through a Fluorisil pad and a 0.20-µm PTFE syringe filter, and concentrated in vacuo to a nearly colorless liquid. Yield: 0.110 g, 65.8 %.1H NMR (500 MHz, C6D6) δ 7.29 – 7.20 (m, 1H), 7.10 – 6.91 (overlapping resonances, 3H), 5.92 (ddt, J = 16.9, 10.2, 6.6 Hz, 1H), 5.11 (dq, J = 17.0, 1.7 Hz, 1H), 5.01 (ddt, J = 9.2, 2.2, 1.1 Hz, 1H), 4.82 (t, J = 2.1 Hz, 2H), 4.60 (t, J = 2.4 Hz, 2H), 3.02 (m,2JPt-H= 97.6 Hz, 2H), 2.86 – 2.67 (m, 2H), 2.49 – 2.35 (m, 2H), 1.52 (m, JPt-H = 6.3 Hz, 3H), 1.18 (m,2JPt-H = 81.2 Hz, 6H).13C NMR (101 MHz, C6D6) δ 150.50 (JPt-C= 60.9 Hz), 138.93, 137.71 (JPt-C= 22.7 Hz), 129.87 (JPt-C= 22.0 Hz), 129.17 (JPt-C = 14.7 Hz), 126.18 (JPt-C = 14.7 Hz), 125.01 (JPt-C = 15.8 Hz), 114.90, 114.44, 98.90, 93.41, 35.57, 33.01, 11.43, 9.99 (1JPt-C = 675.3 Hz), -14.74 (1JPt-C = 732.1 Hz).195Pt NMR (86 MHz, C6D6) δ -4986.46. Example 5 – Preparation ofMeCpPtMe2(2-PhBz) (NBD)PtMe2(0.143 g, 0.45 mmol, 1 equiv) was combined with pyridine (2 mL) and a magnetic stir bar in a 30-mL glass vial. The resulting pale-yellow solution was allowed to stir at ambient for 20 min, whereupon 2-(bromomethyl)-1,1'-biphenyl (0.111 g, 0.45 mmol, 1 equiv) was added directly as a solid. Additional pyridine (1 mL) was added to ensure quantitative transfer of the bromomethyl reagent to the reaction vial. After stirring for 2 h total, LiMeCp (0.047 g, 0.54 mmol, 1.2 equiv) was added to the reaction mixture directly as a solid at ambient temperature. The reaction mixture was allowed to continue stirring at ambient temperature for 1 h, after which time volatiles were removed in vacuo. Hexanes was added to the residue, affording a suspension that was then stirred for 1h at ambient temperature. The suspension was then passed through a Florisil pad and a 0.45-µm PTFE syringe filter. The filtration pad was rinsed with hexanes (2 x 5 mL) and combined with the filtrate. This extraction and filtration were repeated two more times. The combined pale-yellow filtrates were then concentrated in vacuo to afford a yellow liquid that was stored at -25 °C overnight. The material was re- extracted into hexanes (6 mL) and filtered again through a Florisil pad and a 0.20-µm PTFE syringe filter. The solution was then concentrated to a nearly colorless, thick liquid. Yield: 0.111 g, 52.2 %.1H NMR (400 MHz, C6D6) δ 7.45 – 7.36 (overlapping resonances, 3H), 7.28 – 7.20 (overlapping resonances, 2H), 7.19 – 7.12 (overlapping resonances, 2H), 7.10 (td, J = 7.5, 1.6 Hz, 1H), 7.01 (td, J = 7.4, 1.5 Hz, 1H), 4.83 – 4.73 (m, 2H), 4.60 – 4.51 (m, 2H), 3.29 (m,2JPt-H= 102.1 Hz, 2H), 1.49 (m, JPt-H= 6.3 Hz, 3H), 0.95 (m,2JPt-H= 81.4 Hz, 6H).13C NMR (101 MHz, C6D6) δ 149.72 (JPt-C = 59.1 Hz), 143.29, 140.04 (JPt-C = 25.0 Hz), 130.90, 130.60 (JPt-C= 15.4 Hz), 130.14 (JPt-C= 4.1 Hz), 127.29 (JPt-C= 14.6 Hz), 126.91, 124.77 (JPt-C= 16.1 Hz), 114.87 (JPt-C = 15.6 Hz), 98.69, 92.69, 11.42, 8.72 (1JPt-C = 678.6 Hz), -14.73 (1JPt-C =732.0 Hz).195Pt NMR (85 MHz, C6D6) δ -4984.80. Example 6 – Preparation ofMeCpPtMe2(2-SiMe2ViBz) (NBD)PtMe2 (0.123 g, 0.39 mmol, 1 equiv) was combined with pyridine (2 mL) and a magnetic stir bar in a 30-mL glass vial. The resulting pale-yellow solution was allowed to stir at ambient for 20 min, after which time (2-bromomethyl)phenyl)dimethyl(vinyl)silane (0.087 g, 0.39 mmol, 1 equiv) was added dropwise. Additional pyridine (1 mL) was then added. After stirring for 2 h total, LiMeCp (0.040 g, 0.47 mmol, 1.2 equiv) was added to the reaction mixture directly as a solid at ambient temperature. The reaction mixture was allowed to continue stirring at ambient temperature for 1 h, whereupon the volatiles were removed in vacuo. Hexanes was added to the residue, affording a suspension that was then stirred for 1 h at ambient temperature. The suspension was then passed through a Florisil pad and a 0.45-µm PTFE syringe filter. The filtration pad was rinsed with hexanes (2 x 5 mL) and combined with the filtrate. The extraction and filtration were repeated two more times. The combined yellow filtrates were then concentrated in vacuo to afford an orange liquid that was stored at -25 °C overnight. The material was re-extracted into hexanes (6 mL) and filtered again through a Florisil pad and a 0.20-µm PTFE syringe filter, affording a pale-yellow solution. The solution was then concentrated to a thick yellow liquid. Yield: 0.082 g, 44.1 %.1H NMR (400 MHz, C6D6) δ 7.49 – 7.37 (overlapping resonances, 2H), 7.15 – 7.11 (m, 1H), 6.99 (tt, J = 8.2, 2.8 Hz, 1H), 6.49 (dd, J = 20.3, 14.6 Hz, 1H), 6.01 (dd, J = 14.6, 3.6 Hz, 1H), 5.80 (dd, J = 20.3, 3.7 Hz, 1H), 4.84 (t, J = 2.2 Hz, 2H), 4.65 (t, J = 2.3 Hz, 2H), 3.23 (m,2JPt-H = 96.0 Hz, 2H), 1.53 (m, JPt-H = 6.0 Hz, 3H), 1.22 (m,2JPt-H= 80.8 Hz, 6H), 0.47 (s, 6H).13C NMR (101 MHz, C6D6) δ 158.73 (JPt-C= 60.3 Hz), 140.03, 135.00 (JPt-C = 10.3 Hz), 132.93, 131.90, 130.90 (JPt-C = 23.6 Hz), 129.32 (JPt-C= 12.1 Hz), 124.16 (JPt-C= 13.6 Hz), 114.85 (JPt-C= 15.4 Hz), 99.21, 93.46, 15.62 (1JPt-C= 688.3 Hz), 11.43, -1.11, -14.87 (1JPt-C = 730.6 Hz).195Pt NMR (85 MHz, C6D6) δ -4981.10. Examples 1-6 (Pre-catalysts) were combined separately with methyl trimethoxy silane (XIAMETER™ OFS-6070 Silane (MTM)). Each pre-catalyst + MTM mixture was added to a pre-mixed blend of a vinyl-terminated polydimethylsiloxane (XIAMETER™ RBL-9119 Polymer (Polymer 1)) and a trimethylsilyl-terminated methylhydrosiloxane-dimethylsiloxane copolymer (DOWSIL™ 6-3570 Polymer (Polymer 2). Each composition was mixed at 2000 rpm for 30 s. (XIAMETER and DOWSIL are Trademarks of The Dow Chemical Company or its Affiliates.) Table 1 illustrates the formulations. Formulation 1 used the compound of Example 1; Formulation 2 used the compound of Example 2, etc. Pre-catalyst + Solvent amounts were tuned to achieve a concentration of elemental Pt of 18 ppm for each formulation. The pre-catalyst concentration in MTM refers to the weight % concentration of the pre-catalyst.

[0002] Table 1 – Polyorganosiloxane Formulations 88 90 23 % 45 Gel Point Determination The gel point times for each sample was measured using the following UV-rheology test: UV-activated hydrosilylation cure tests were carried out using an MCR-302 Rheometer equipped with a UV irradiation accessory. Broadband UV of a wavelength between 250 and 450 nm was irradiated, and 4 J / cm2of UV dose was applied (100 mW / cm2x 40 sec). Sample thickness was initially set at 0.3 mm. To generate cure profiles, viscoelastic properties were monitored applying oscillatory shearing within linear viscoelastic regions at 10 rad / sec. Then, the gel times were determined from the G’-G” crossover points. Table 2 illustrates the gel point times for each formulation. Table 2 – Gel Point Times for Formulations Formulation Example No. Pre-catalyst Gel Point Time (min) d by gel point times of < 30 min.

Claims

Claims:

1. A compound of Formula 1:Formula 1 where x is from 0 to 5; each R1is independently C1-C6-alkyl or phenyl; each R2is independently H, methyl, ethyl, or phenyl; and R3is either of the following fragments:where each R4is C1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, NO2, acetyl, halo, aryl-(R6)y, dimethyl(vinyl)silyl, or C2-C12- alkenyl; each R6is independently C1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, NO2, acetyl, halo, dimethyl(vinyl)silyl, or C2-C12-alkenyl; and each y is independently from 0 to 5.

2. The compound of Claim 1 where each R1is independently C1-C4-alkyl or phenyl; each R2is H; and R3is represented by the following fragment: where each R5is independently phenyl-(R6)y, dimethyl(vinyl)silyl, but-3-ene-1-yl, or nitro; each R6is methyl, methoxy, trifluoromethyl, but-3- ene-1-yl, dimethyl(vinyl)silyl, or nitro; and each y is independently 0, 1, 2, or 3.

3. The compound of Claim 2 which is selected from the group consisting of: .

4. The compound of Claim 3 which is: .

5. The compound ofor phenyl; each R2is H; and R3is represented by the following fragment: .

6. The compound of Claim 5 which is:.

7. A method comprising theof norbornadiene dimethyl platinum (II) and an N-donor solvent with Br-C(R2)2phenyl(R5)y under conditions sufficient toform an oxidative addition product, then b) contacting the oxidative addition product with Intermediate A:under conditions sufficient to form the product of Formula 1:Formula 1 where x is from 0 to 5; each R1is independently C1-C6-alkyl or phenyl; each R2is independently H, methyl, ethyl, or phenyl; and R3is either of the following fragments: where each R4isC1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, NO2, acetyl, halo, aryl-(R6)y, dimethyl(vinyl)silyl, or C2-C12- alkenyl; each R6is independently C1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, NO2, acetyl, halo, dimethyl(vinyl)silyl, or C2-C12-alkenyl; and each y is independently from 0 to 5.

8. The method of Claim 7 where the N-donor solvent in pyridine, each R1is independently C1-C4-alkyl or phenyl; each R2is H; and each R3is the following fragment:where y is 0, 1, 2, or 3; and each R5is independently methyl, methoxy, trifluoromethyl, but-3- ene-1-yl, phenyl, dimethyl(vinyl)silyl, or nitro.

9. The method of Claim 7 where each R1is independently C1-C4-alkyl or phenyl; each R2is H; and each R3is the following fragment: .

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