Siloxane functionalized platinum(IV) pre-catalyst

Abstract

The present invention is a compound of Formula 1: where Ar, X, R1, R2, R3, R4, R7, x, y, and z, are defined herein. The present invention provides a pre-catalyst that decomposes quickly to a platinum state that promotes hydrosilylation upon irradiation with light of the appropriate wavelength.

Description

[0001] Siloxane Functionalized Platinum(IV) Pre-catalyst Background of the Invention The present invention relates to a photoactivated siloxane-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) decompose 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. 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) decompose 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. Summary of the Invention The present invention is a compound of Formula 1: where Ar is phenyl, naphthyl, or anthracenyl; X is a C2-C12 hydrocarbyl diradical; each R1is independently C1-C6-alkyl or phenyl; each R2is independently C1-C6-alkyl, C1-C6-alkoxy, Ar, NO2, acetyl, trifluoromethyl, or halo; each R3is independently C1-C6-alkyl, C1-C6-alkoxy, phenyl, or -(OSi(R5)2)wOSi(R6)3; each R4is independently C1-C6-alkyl, phenyl, or C1-C6-alkoxy; each R5is independently C1-C6-alkyl, phenyl, or OSi(R4)3; each R6is independently C1-C6-alkyl, phenyl, or C1-C6-alkoxy; each R7is independently H, methyl, ethyl, or phenyl; m is 0 or 1; x is from 0 to 5; y is from 0 to 4; and the sum of z + w is from 0 to 20. The present invention addresses a need in the art by providing a 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: where Ar is phenyl, naphthyl, or anthracenyl; X is a C2-C12 hydrocarbyl diradical; each R1is independently C1-C6-alkyl or phenyl; each R2is independently C1-C6-alkyl, C1-C6-alkoxy, Ar, NO2, acetyl, trifluoromethyl, or halo; each R3is independently C1-C6-alkyl, C1-C6-alkoxy, phenyl, or -(OSi(R5)2)wOSi(R6)3; each R4is independently C1-C6-alkyl, phenyl, or C1-C6-alkoxy; each R5is independently C1-C6-alkyl, phenyl, or OSi(R4)3; each R6is independently C1-C6-alkyl, phenyl, or C1-C6-alkoxy; each R7is independently H, methyl, ethyl, or phenyl; m is 0 or 1; x is from 0 to 5; y is from 0 to 4; and the sum of z + w is from 0 to 20. Preferably z is from 1 to 20. Preferably, each R4is methyl when z is from 1 to 20, and each R4is phenyl when z is 0; each R5is independently methyl, phenyl, or -OSi(OCH3)3; and each R7is H. The compound of the present invention is advantageously 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(trimethylsilyl)amide such as potassium or sodium bis(trimethylsilyl)amide or with an alkyl lithium such as n-butyl lithium to form the alkali metal salt of (R1)x-Cp (Intermediate A): Li-(R1)-Cp can then be contacted with another equivalent of R1-Br to form a further substituted cyclopentadiene, and the reaction can be repeated up to a (R1)5-substituted Cp-alkali metal. In a separate series of steps, a dibromomethylaryl compound such as dibromomethylbenzene is contacted with an alkenyl-functionalized Grignard reagent to form an alkenyl-functionalized bromomethylaryl compound, preferably an alkenyl-functionalized bromomethylbenzene (Intermediate B): for the compound of Formula 1 where X is a C3-C12 hydrocarbyl diradical. An analogous intermediate can be prepared where X is a C2 hydrocarbyl diradical by using the commercially available bromomethylstyrene as Intermediate B. In a separate series of steps, a tolyl-functionalized Grignard reagent such as (p-tolyl)magnesium bromide is contacted with a halide-functionalized dimethyl(vinyl)silyl compound such as chlorodimethyl(vinyl)silane to form a tolyl-functionalized dimethyl(vinyl)silyl compound: The tolyl-functionalized dimethyl(vinyl)silyl compound 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 (Intermediate B′), where each R7is H and m is 1:

[0002] Intermediate B or B′ is advantageously contacted with a siloxane containing Si-H functionality, in the presence of a platinum catalyst to form Intermediate C: Norbornadiene dimethyl platinum (II) ((NBD)PtMe2) is dissolved in suitable donor solvent such as pyridine, then contacted with Intermediate C under conditions sufficient to form an oxidative addition product, which is then contacted in the same reaction vessel with Intermediate A to form the compound of Formula 1: Ar is preferably or -(OSi(R5)2)wOSi(R6)3. R5is preferably methyl, phenyl, or -OSi(OCH3)3; each R6is preferably methyl; each R7is preferably H; and the sum of z + w is preferably from 1 to 15. In another aspect, w is 0; in another aspect, z is from 1 to 15. Specific examples of compounds of the present invention include the following:

[0003] ion of norbornadiene dimethyl platinum (II) and an N-donor solvent such as pyridines or quinolines with Intermediate C 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. 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. This efficiency is believed to arise from both the presence of the Pt-(R7)2Ar fragment, which provides a mechanism for a more facile homolytic cleavage and concomitant transformation of the pre-catalyst to the catalytically active Pt(0) state, and siloxane functionality, which promotes improved dispersion of the pre-catalyst in a siloxane medium. 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 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)-4-(but-3-en-1-yl)benzene 1,4-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 72 h. The reaction mixture was then removed from the glovebox and diluted with deionized water (25 mL) causing the heterogenous mixture to become homogeneous. 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, dried over MgSO4, filtered, and concentrated to a nearly colorless oil by rotary evaporation. The crude material was purified by flash chromatography using 100% hexanes as the solvent system. The desired product was collected in fractions 7 - 24.1H NMR and GC-MS was used to confirm purity. Yield: 2.6 g, 38.1 %.1H NMR (400 MHz, CDCl3) δ 7.35 – 7.26 (m, 2H), 7.17 (d, J = 7.9 Hz, 2H), 5.85 (ddt, J = 16.9, 10.2, 6.6 Hz, 1H), 5.10 – 4.95 (m, 2H), 4.50 (s, 2H), 2.71 (dd, J = 9.0, 6.7 Hz, 2H), 2.37 (qd, J = 7.2, 1.6 Hz, 2H).13C NMR (101 MHz, CDCl3) δ 142.47, 138.37, 137.97, 135.41, 129.17, 129.02, 128.47, 115.24, 114.94, 77.48, 77.36, 77.16, 76.84, 35.69, 35.41, 35.20, 35.11, 33.82.

[0004] Intermediate Example 3 – Preparation of 1-(4-(4-(Bromomethyl)phenyl)butyl)-1,1,3,3,3- pentamethyldisiloxane (Br-benzyl-MM) 1-(Bromomethyl)-4-(but-3-en-1-yl)benzene (1.00 g, 4.44 mmol, 1 equiv) was added to a 60-mL glass vial equipped with a septa cap and a magnetic stir bar. Karstedt's catalyst was added (3 drops of a 2 wt% Pt in xylenes solution) and the mixture was heated to 50 °C, followed by the dropwise addition of 1,1,1,3,3-pentamethyldisiloxane (MM') (0.87 mL, 4.44 mmol, 1 equiv). Stirring was continued at 50 °C for 24 h. The mixture was cooled to room temperature then diluted with hexanes (4 mL) and stirred with activated carbon for 5 – 10 min. The mixture was then passed through a 0.45-µm PTFE syringe filter and the volatiles were removed by rotary evaporation to afford a nearly colorless liquid. Yield: 1.62 g, 97.7 %.1H NMR (500 MHz, CDCl3) δ 7.32 (d, J = 8.1 Hz, 2H), 7.17 (d, J = 8.1 Hz, 2H), 4.52 (s, 2H), 2.65 – 2.57 (m, 2H), 1.73 – 1.57 (m, 2H), 1.50 – 1.29 (m, 2H), 0.66 – 0.46 (m, 2H), 0.08 (s, 9H), 0.06 (s, 6H).13C NMR (126 MHz, CDCl3) δ 143.55, 135.13, 129.12, 128.99, 35.57, 35.14, 33.93, 23.14, 18.35, 2.12, 0.52. Intermediate Example 4 – Preparation of 1-(4-(4-(Bromomethyl)phenyl)butyl)- polydimethylsiloxane (Br-benzyl-PDMS): 1-(Bromomethyl)-4-(but-3-en-1-yl)benzene (0.680 g, 3.02 mmol, 1 equiv) was added to a 60-mL glass vial with a septa cap along with a magnetic stir bar. Karstedt's catalyst was added (3 drops of a 2 wt% Pt in xylenes solution) and the mixture was heated to 50 °C followed by the dropwise addition of mono-hydride terminated polydimethylsiloxane material (dp = 10-12, Gelest, product code MCR-H07) (3.04 g, 3.02 mmol, 1 equiv). After 2 h, the mixture was cooled to ambient temperature, then diluted with hexanes (4 mL) and stirred with activated carbon for 5 – 10 min. The mixture was then passed through a 0.45-µm syringe filtered and the volatiles were removed in vacuo to afford a pale- yellow liquid.1H NMR characterization confirmed the identity of the target product. Yield: 3.47 g, 93.3 %.1H NMR (400 MHz, C6D6) δ 7.05 (d, J = 8.0 Hz, 2H), 6.95 (d, J = 7.8 Hz, 2H), 4.05 (s, 2H), 2.47 (t, J = 7.7 Hz, 2H), 1.58 (p, J = 7.4 Hz, 2H), 1.47 – 1.33 (overlapping resonances, 6H), 0.99 – 0.92 (overlapping resonances, 4H), 0.68 – 0.56 (overlapping resonances, 4H), 0.30 – 0.15 (overlapping resonances, 85H).13C NMR (101 MHz, C6D6) δ 143.20, 135.64, 129.37, 128.99, 35.73, 35.43, 33.54, 26.82, 25.93, 23.34, 18.47, 18.39, 14.09, 1.51, 1.44, 1.42, 0.45. Intermediate Example 5 – Preparation of 3-(4-(4-(bromomethyl)phenyl)butyl)-1,1,1,3,5,5,5- heptamethyltrisiloxane (Br-benzyl-MDM) 1-(Bromomethyl)-4-(but-3-en-1-yl)benzene (0.180 g, 0.80 mmol, 1 equiv) was added to a 60-mL glass vial with a septa cap along with a magnetic stir bar. Karstedt's catalyst was added (2 drops of a 2wt% Pt in xylenes) and the mixture was heated to 50 °C followed by the dropwise addition of 1,1,1,3,5,5,5-heptamethyltrisiloxane (MD′M) (0.217 mL, 0.80 mmol, 1 equiv). After 2 h, the mixture was cooled to ambient temperature, and the reaction mixture was diluted with hexanes (4 mL) and stirred with activated carbon for 5 – 10 min. The mixture was then passed through a 0.45-µm PTFE syringe filter and the volatiles were removed by rotary evaporation to afford a nearly colorless liquid. Yield: 0.338 g, 94.4 %.1H NMR (500 MHz, C6D6) δ 7.03 (d, J = 8.0 Hz, 2H), 6.93 (d, J = 8.4 Hz, 2H), 4.05 (s, 2H), 2.45 (t, J = 7.6 Hz, 2H), 1.57 (p, J = 7.5 Hz, 2H), 1.49 – 1.35 (m, 2H), 0.68 – 0.48 (m, 2H), 0.16 (s, 18H), 0.13 (s, 3H).13C NMR (126 MHz, C6D6) δ 143.15, 135.61, 129.35, 129.01, 35.70, 35.16, 33.56, 23.17, 17.96, 2.04, 0.06. Intermediate Example 6 – Preparation of dimethyl(p-tolyl)(vinyl)silane Chlorodimethyl(vinyl)silane (2.00 g, 16.58 mmol, 1 equiv) was combined with THF (30 mL) and a magnetic stir bar in a 100-mL glass jar. The colorless solution was stored at -25 °C for 1 h. Once cooled, a 1.0 M solution of p-tolylmagnesium bromide in THF (16.58 mL, 16.58 mmol, 1 equiv) was added slowly. The reaction mixture was then left to warm slowly to ambient temperature and continue stirring for 48 h, whereupon a portion of 1,4-dioxane (8 mL) was added, resulting in precipitation of colorless solids. The suspension was then passed through a Celite pad atop a disposable PTFE-frit filter and the volatiles were removed in vacuo, affording a pale-yellow liquid. Yield: 1.83 g, 62.6 %.1H NMR (400 MHz, C6D6) δ 7.49 – 7.42 (m, 2H), 7.11 – 7.04 (m, 2H), 6.30 (dd, J = 20.3, 14.6 Hz, 1H), 5.99 (dd, J = 14.6, 3.8 Hz, 1H), 5.74 (dd, J = 20.3, 3.8 Hz, 1H), 2.14 (s, 3H), 0.31 (s, 6H).13C NMR (101 MHz, C6D6) δ 138.95, 138.59, 134.36, 132.76, 129.01, 120.18, 21.47, -2.63. Intermediate Example 7 – Preparation of (4-(bromomethyl)phenyl)dimethyl(vinyl)silane Dimethyl(p-tolyl)(vinyl)silane (1.10 g, 6.24 mmol, 1 equiv) was combined with deoxygenated ethyl acetate (25 mL) that had been previously dried over molecular sieves, N- bromosuccinimide (1.11 g, 6.24 mmol, 1 equiv), azobisisobutyronitrile (0.205 g, 1.25 mmol, 1 equiv), and a magnetic stir bar in a 40-mL glass vial. The reaction mixture was then heated a total of 18 h at 70 °C, after which time the reaction mixture was cooled to ambient temperature and then concentrated in vacuo onto silica gel and purified by ISCO chromatography using 100 % hexanes at the solvent system. The desired product was isolated from fractions 5 - 11. Yield: 0.360 g, 22.6 %.1H NMR (400 MHz, C6D6) δ 7.35 (d, J = 8.0 Hz, 2H), 7.09 (d, J = 8.0 Hz, 2H), 6.21 (dd, J = 20.2, 14.6 Hz, 1H), 5.96 (dd, J = 14.6, 3.7 Hz, 1H), 5.67 (dd, J = 20.2, 3.7 Hz, 1H), 4.00 (s, 2H), 0.24 (s, 6H).13C NMR (101 MHz, C6D6) δ 138.96, 138.78, 137.88, 134.56, 133.16, 128.69, 128.67, 33.35, -2.88. Intermediate Example 8 – Preparation of 3-(2-((4-(bromomethyl)phenyl)dimethylsilyl)ethyl)- 1,1,1,3,5,5,5-heptamethyltrisiloxane (Br-benzyl-SiMe2-MDM) (4-(bromomethyl)phenyl)dimethyl(vinyl)silane (0.105 g, 0.41 mmol, 1 equiv) was added to a 30-mL glass vial with a septa cap along with a magnetic stir bar and toluene (2 mL). Karstedt's catalyst was added (1 drop of a 2 wt% Pt in xylenes) and the mixture was heated to 50 °C followed by the dropwise addition of 1,1,1,3,5,5,5-heptamethyltrisiloxane (MD′M) (0.112 mL, 0.41 mmol, 1 equiv). After 2 h, the mixture was cooled to ambient temperature, and the reaction mixture was diluted with hexanes (4 mL) and stirred with activated carbon for 5 min. The mixture was then passed through a 0.45-µm PTFE syringe filter and the volatiles were removed by rotary evaporation to afford a nearly colorless liquid. Yield: 0.183 g, 93.1 %.1H NMR (400 MHz, C6D6) δ 7.43 – 7.34 (m, 2H), 7.12 – 7.07 (m, 2H), 4.00 (s, 2H), 0.88 – 0.78 (m, 2H), 0.58 – 0.50 (m, 2H), 0.22 (s, 6H), 0.16 (s, 18H), 0.14 (s, 3H).13C NMR (101 MHz, C6D6) δ 139.73, 138.77, 134.31, 128.69, 33.36, 10.13, 7.49, 2.06, -0.77, -3.53. Example 1 – Preparation of CpPtMe2-benzyl-MM (NBD)PtMe2 (0.20 g, 0.63 mmol, 1 equiv) was combined with pyridine (5 mL) and a magnetic stir bar in a 20-mL glass vial in a nitrogen filled glovebox. The resulting golden yellow solution was allowed to stir at ambient temperature for 5 min, after which time Br-benzyl-MM (Intermediate 3, 0.235 g, 0.63 mmol, 1 equiv) was added dropwise. After stirring for another 4 h, NaCp (0.067 g, 0.76, 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 18 h. The volatiles were removed in vacuo and the residue was triturated with dichloromethane (DCM, 2 x 4 mL), extracted into DCM (3 x 5 mL), and filtered through a Celite pad, which was then washed with additional DCM (10 mL). The combined extracts were then concentrated in vacuo to afford a red / maroon oil. The material was then removed from the glovebox and extracted again into DCM (10 mL) and filtered through a Florisil pad, which was then washed with another 10 – 15 mL of DCM. The filtrate was concentrated to a red oil by rotary evaporation. The oil was taken up in hexanes (5 mL) and filtered through a Florisil pad, and the filtrate was concentrated to a nearly colorless oil. Yield: 0.272 g, 73.9 %.1H NMR (500 MHz, C6D6) δ 7.21 – 7.17 (m, 2H), 7.06 – 7.02 (m, 2H), 5.13 – 4.84 (m, 5H), 3.14 (m,2JPt-H= 97.2 Hz, 2H), 2.57 (t, J = 7.7 Hz, 2H), 1.80 – 1.60 (m, 2H), 1.52 – 1.39 (m, 2H), 1.22 (m,2JPt-H = 82.6 Hz, 6H), 0.73 – 0.46 (m, 2H), 0.14 (s, 9H), 0.12 (s, 6H).13C NMR (126 MHz, C6D6) δ 149.13, 138.85, 128.58, 128.44, 97.62, 35.80, 35.65, 23.40, 18.61, 11.52 (m,1JPt-C = 664.6 Hz), 2.17, 0.59, -17.98 (m,1JPt-C= 738.1 Hz).195Pt NMR (85 MHz, C6D6) δ -4968.89. Example 2 – Preparation of (CH3)5-CpPtMe2-(benzyl-MM) (NBD)PtMe2(0.130 g, 0.41 mmol, 1 equiv) was combined with pyridine (3 mL) and a magnetic stir bar in a 20-mL glass vial in a nitrogen filled glovebox. The resulting golden yellow solution was allowed to stir at ambient for 10 min, after which time Br-benzyl-MM (0.153 g, 0.41 mmol, 1 equiv) was added dropwise to the solution. After stirring for an another 3 h, Li(CH3)5Cp (0.070 g, 0.49, 1.2 equiv) was added to the reaction mixture directly as a solid at ambient temperature. Additional pyridine (2 mL) was added to facilitate quantitative transfer of all the Cp salt into the reaction vial. The reaction mixture was stirred at ambient temperature for another 2 h, after which time the reaction mixture was passed through a Celite pad atop a Florisil pad contained within a 0.45-µm PTFE syringe filter. The pads and filter were rinsed with hexanes (4 x 3 mL) and combined with the filtrate. The volatiles were then removed in vacuo and the residue was triturated with hexanes (2 x 4 mL) then extracted into hexanes (5 x 5 mL) and filtered again through a fresh Florisil pad and a 0.45-µm PTFE syringe. The extract was then concentrated in vacuo to afford a pale-yellow oil. The material was stored at -25 °C for 18 h and then extracted for a final time into hexanes (3 mL) then filtered through a fresh Florisil pad. The pad was washed with additional hexanes, and the filtrate was concentrated to a nearly colorless oil in vacuo. Yield: 0.180 g, 67.2 %.1H NMR (400 MHz, C6D6) δ 7.21 – 7.15 (m, 2H), 7.12 – 7.00 (m, 2H), 2.96 (m,2JPt-H = 99.6 Hz, 2H), 2.65 – 2.48 (m, 2H), 1.74 – 1.62 (m, 2H), 1.49 – 1.39 (m, 2H), 1.35 (m,3JPt-H = 6.4 Hz, 15H), 0.82 (m,2JPt-H = 78.9 Hz, 6H), 0.67 – 0.55 (m, 2H), 0.15 (s, 9H), 0.13 (s, 6H).13C NMR (126 MHz, C6D6) δ 145.89, 138.07, 128.35, 102.66, 35.86, 35.76, 23.30, 18.68, 12.33 (m,1JPt-C = 334.9 Hz), 7.47, 2.16, 0.61, -6.55 (m,1JPt-C = 371.5 Hz).195Pt NMR (85 MHz, C6D6) δ -5036.4. Example 3 – Preparation of CH3-CpPtMe2-(benzyl-PDMS) (NBD)PtMe2(0.148 g, 0.47 mmol, 1 equiv) was combined with pyridine (3 mL) and a magnetic stir bar in a 20-mL glass vial in a nitrogen filled glovebox. The resulting golden yellow solution was allowed to stir at ambient temperature for 10 min after which time Br-benzyl-PDMS (dp = 10-12, 0.574 g, 0.47 mmol, 1 equiv) was added dropwise to the solution. Additional pyridine (1 mL) was added to ensure quantitative transfer of the siloxane reagent to the reaction vial. After stirring for another 3 h, LiMeCp (0.048 g, 0.56, 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 another 2 h, after which time the reaction mixture was then passed through a celite pad atop a Fluorisil pad and filtered through a 0.45-µm PTFE syringe filter. The pads and filter were rinsed with hexanes (4 x 3 mL) and combined with the filtrate. The volatiles were then removed in vacuo and the residue was triturated with hexanes (3 x 3 mL) then extracted into hexanes (3 x 5 mL) and filtered through a fresh Fluorisil pad and a 0.45-µm PTFE syringe. The extract was then concentrated in vacuo to afford a pale-yellow oil. The material was stored at -25 °C for 18 h and then extracted for a final time into hexanes (3 mL) and filtered through a fresh Fluorisil pad, which was washed with another 5 - 7 mL of hexanes. The filtrate was then concentrated to a nearly colorless oil in vacuo. Yield: 0.420 g, 61.9 %.1H NMR (400 MHz, C6D6) δ 7.21 (d, J = 7.9 Hz, 2H), 7.05 (d, J = 7.9 Hz, 2H), 4.98 (t, J = 2.3 Hz, 2H), 4.70 (t, J = 2.4 Hz, 2H), 3.17 (m,2JPt-H = 97.5 Hz, 2H), 2.69 – 2.49 (m, 2H), 1.70 (p, J = 7.5 Hz, 2H), 1.51 – 1.32 (m, 3H), 1.16 (m,2JPt-H= 81.7 Hz, 6H), 0.99 – 0.89 overlapping multiplets, 4H), 0.73 – 0.57 (m, 4H), 0.32 – 0.15 (m, 85H).13C NMR (101 MHz, C6D6) δ 149.16, 138.66, 114.48, 98.58, 93.56, 35.83, 35.73, 26.82, 25.94, 23.39, 18.55, 18.39, 14.09, 11.49, 11.26 (m,1JPt-C = 663.3 Hz), 1.54, 1.51, 1.45, 1.43, 0.48, 0.46, -14.60 (m,1JPt-C = 740.6 Hz).195Pt NMR (86 MHz, C6D6) δ -4990.79. Example 4 – Preparation of CH3-CpPtMe2-(benzyl-MDM) (NBD)PtMe2(0.85 g, 0.27 mmol, 1 equiv) was combined with pyridine (2 mL) and a magnetic stir bar in a 20-mL glass vial in a nitrogen filled glovebox. The resulting golden yellow solution was allowed to stir at ambient for 20 min after which time Br-benzyl-MDM (0.120 g, 0.27 mmol, 1 equiv) in pyridine (0.5 mL) was added dropwise to the solution. After stirring for 2h at ambient temperature, solid LiMeCp (0.028 g, 0.32 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 2 h, then passed through a Celite pad atop a Fluorisil pad and a 0.45-µm PTFE syringe filter. The pads and filter were rinsed with hexanes (2 x 3 mL) and combined with the filtrate. The volatiles were then removed in vacuo and the residue was triturated with hexanes (3 x 3 mL) then extracted into hexanes (3 x 5 mL) and filtered through a fresh Fluorisil pad and a 0.45-µm PTFE syringe. The extract was then concentrated in vacuo to afford a pale-yellow oil. The material was stored at -25 C for 18 h and then extracted for a final time into hexanes (3 mL) and filtered through a fresh Fluorisil pad, which was washed with another 5 - 7 mL of hexanes. The filtrate was concentrated to a nearly colorless oil in vacuo. Yield: 0.101 g, 56.1 %.1H NMR (400 MHz, C6D6) δ 7.20 (d, J = 8.0 Hz, 2H), 7.04 (d, J = 8.1 Hz, 2H), 4.98 (t, J = 2.2 Hz, 2H), 4.69 (t, J = 2.3 Hz, 2H), 3.17 (m,2JPt-H = 97.5 Hz, 2H), 2.58 (dd, J = 9.5, 5.7 Hz, 2H), 1.70 (p, J = 7.4 Hz, 2H), 1.55 (s, 3H), 1.54 – 1.44 (m, 2H), 1.16 (m,2JPt-H= 81.7 Hz, 2H), 0.72 – 0.56 (m, 2H), 0.18 (s, 18H), 0.14 (s, 3H).13C NMR (101 MHz, C6D6) δ 149.11 (m,2JPt-C = 58.3 Hz), 138.63, 114.48, 98.58, 93.55, 35.84, 35.51, 23.30, 18.03, 11.49, 11.26 (m,1JPt-C= 663.2 Hz), 2.08, 0.08, -14.59 (m,1JPt-C = 740.6 Hz).195Pt NMR (86 MHz, C6D6) δ -4991.45. Example 5 – Preparation of CH3-CpPtMe2-(benzyl-SiMe2-MDM) (NBD)PtMe2 (0.082 g, 0.26 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 Br-benzyl-SiMe2-MDM (0.123 g, 0.26 mmol, 1 equiv) was added dropwise. 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 (0.027 g, 0.31 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 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. The combined filtrates were then concentrated in vacuo to afford a yellow liquid that was re-extracted into hexanes (6 mL) and filtered for a final time through a Florisil pad and a 0.20-µm PTFE syringe filter, affording a pale-yellow solution. The solution was then concentrated to a pale-yellow liquid. Yield: 0.091 g, 50.2 %.1H NMR (400 MHz, C6D6) δ 7.51 – 7.41 (m, 2H), 7.31 – 7.20 (m, 2H), 4.94 (t, J = 2.2 Hz, 2H), 4.66 (t, J = 2.3 Hz, 2H), 3.15 (m,2JPt-H= 99.1 Hz, 2H), 1.52 (d, JPt-H= 6.3 Hz, 3H), 1.15 (m,2JPt-H = 81.6 Hz, 6H), 0.93 – 0.86 (m, 2H), 0.66 – 0.58 (m, 2H), 0.31 (s, 6H), 0.17 (s, 18H), 0.16 (s, 3H).13C NMR (101 MHz, C6D6) δ 152.81 (d, J = 58.6 Hz), 134.19 (JPt-C= 15.4 Hz), 133.81 (JPt-C = 13.9 Hz), 114.47 (JPt-C = 14.3 Hz), 98.58, 93.46, 11.41, 11.31 (m,1JPt-C = 662.2 Hz), 10.32, 7.87, 2.10, -0.75, -3.25 (JPt-C= 51.3 Hz), -14.50 (m,1JPt-C= 736.2 Hz).195Pt NMR (85 MHz, C6D6) δ -5003.26. The compounds of Examples 1-5 (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. Table 1 – Polyorganosiloxane Formulations Formulation Example No. 1 2 3 4 5 P l 1 b 9892 9879 9865 9878 9878 90 33 % 45 Ge 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.

[0005] Table 2 – Cure Times for Formulations Formulation Example No. Pre-catalyst Gel Point Time (min) eactivity, as evidenced by gel point times of < 30 min.

Claims

Claims:

1. A compound of Formula 1:where Ar is phenyl, naphthyl, or anthracenyl; X is a C2-C12 hydrocarbyl diradical; each R1is independently C1-C6-alkyl or phenyl; each R2is independently C1-C6-alkyl, C1-C6-alkoxy, Ar, NO2, acetyl, trifluoromethyl, or halo; each R3is independently C1-C6-alkyl, C1-C6-alkoxy, phenyl, or -(OSi(R5)2)wOSi(R6)3; each R4is independently C1-C6-alkyl, phenyl, or C1-C6-alkoxy; each R5is independently C1-C6-alkyl, phenyl, or OSi(R4)3; each R6is independently C1-C6-alkyl phenyl, or C1-C6-alkoxy; each R7is independently H, methyl, ethyl, or phenyl; m is 0 or 1; x is from 0 to 5; y is from 0 to 4; and the sum of z + w is from 0 to 20.

2. The compound of Claim 1 where Ar is phenyl; each R1is independently C1-C4-alkyl or phenyl; each R2is H; each R3is independently methyl, phenyl, or -(OSi(R5)2)wOSi(R6)3; each R4is methyl when z is from 1 to 20, and each R4is phenyl when z is 0; each R5is independently methyl, phenyl, or -OSi(OCH3)3; and each R7is H.

3. The compound of Claim 2 where X is a C2-C4 hydrocarbyl diradical; and y is 0, 1, or 2.

4. The compound of Claim 3 where w is 0; and each R3is independently methyl, phenyl, or Si(OCH3)3.

5. The compound of any of Claims 1 to 4 where each R3is methyl or phenyl; and z is from 1 to 15.

6. The compound of Claim 5 which is selected from the groups consisting of7. The compound of Claim 5 which is selected from the group consisting of: H Si Si O Pt nd .

8. A method comprising the steps of a) contacting a solution of norbornadiene dimethyl platinum (II) and an N-donor solvent with Intermediate C:under conditions sufficient to form 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 Ar is phenyl, naphthyl, or anthracenyl; X is a C2-C12 hydrocarbyl diradical; each R1is independently C1-C6-alkyl or phenyl; each R2is independently C1-C6-alkyl, C1-C6-alkoxy, Ar, NO2, acetyl, trifluoromethyl, or halo; each R3is independently C1-C6-alkyl, C1-C6-alkoxy, phenyl, or -(OSi(R5)2)wOSi(CH3)3; each R4is independently C1-C6-alkyl, phenyl, or C1-C6- alkoxy; each R5is independently C1-C6-alkyl, phenyl, or OSi(R4)3; each R6is independently C1-C6-alkyl, phenyl, or C1-C6-alkoxy; each R7is independently H, methyl, ethyl, or phenyl; m is 0 or 1; x is from 0 to 5; y is from 0 to 4; and the sum of z + w is from 0 to 20.

9. The method of Claim 8 where the N-donor solvent in pyridine, Ar is phenyl; X is a C2-C12 hydrocarbyl diradical; each R1is independently C1-C4-alkyl or phenyl; each R2is H; each R3is independently methyl, methoxy, phenyl, or -(OSi(R5)2)wOSi(CH3)3; each R4is methyl when z is from 1 to 20, and each R4is phenyl when z is 0; each R5is independently -OSi(OCH3)3, methyl, or phenyl; and each R7is H.

Images