Platinum Complexes of Alkynyl-Substituted Dimethyldihydropyrenes

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• 作者：Pengrong Zhang ; David J. Berg ; Reginald H. Mitchell ; Allen Oliver ; Brian Patrick
• 刊名：Organometallics
• 出版年：2012
• 出版时间：December 10, 2012
• 年：2012
• 卷：31
• 期：23
• 页码：8121-8134
• 全文大小：592K
• 年卷期：v.31,no.23(December 10, 2012)
• ISSN：1520-6041

文摘

A series of photochromic dimethyldihydropyrenes (DHP) bearing ethyne substituents in the 4-position (^RDHP-C鈮H; R = H (4), acetyl (5), benzoyl (6), 1-naphthoyl (7), benzo[e] (8)) were prepared for use as precursors to ethynyl ligands. Dehydrohalogenation of the adduct of these ethynes with various PtCl₂(L)₂ complexes afforded a series of cis and trans square-planar bis(DHP-ethynyl) platinum complexes, (^RDHP-C鈮)₂Pt(L)₂ (cis, R = H, L₂ = PEt₃ (9), acetyl, PEt₃ (10), benzoyl, PEt₃ (11), 1-naphthoyl, PEt₃ (12), benzo[e], PEt₃ (13), benzoyl, PPh₃ (14), benzo[e], PPh₃ (15); trans, R = H, L₂ = dppe (16), benzo[e], dppe (17), acetyl, bipy (18), 1-naphthoyl, bipy (19), H, phen (20)). The DHP-ethynes bearing acyl and benzo[e] substituents on the DHP (5鈥?b>8) and their platinum complexes (10鈥?b>19) are photochromic and undergo ring opening to the related cyclophanediene (CPD) isomer on irradiation with visible light (位 >550 nm). In the case of the benzo[e]DHP 8, adding a 4-ethynyl substituent increases the rate of photo-opening 4-fold; however, in the acylDHP series 5鈥?b>7, addition of a 4-ethynyl group slows the rate of photo-opening by a factor of about 4. The platinum complexes generally open more slowly than the corresponding alkyne precursors, again by a factor of about 4. The rate of photo-opening does not appear to be affected significantly by the nature of the ancillary ligands or the metal geometry, suggesting that there is poor electronic communication between the platinum center and the DHP 蟺 system. The thermal back-reaction from the open CPD to closed DHP form is about 50% faster for the metal complexes than for the DHP-ethyne precursor. The platinum complexes and the DHP-ethynes were characterized by NMR and IR spectroscopy and MS and by X-ray crystallography for metal complexes 10, 11, 14, 15, and 17.