烯烃,炔烃,1,2-和1,3-二烯与[MR(NN)(MeCN)] +(M = Pt或Pd; R =烃基; N = N =二齿氮配体)反应生成R-取代的衍生物。将有机片段通常在η保持在金属环境中1或η 3协调,除在用Pd烯烃的反应(II)复合体。在这种情况下,通过相对快速的β-消除过程由Pd-烷基中间体产生游离的R-取代的烯烃。在单取代的烯烃(丙烯或苯乙烯)与同源的Pt和Pd络合物之间的反应中检测到不同的区域化学。Pt-C键始终与末端未取代的烯烃碳形成,而对于内部碳,尤其是在被Pd物种观察到被苯基取代的情况下,尤其倾向于内部碳。中性[MClR(NN)]的反应性明显较低。在这种情况下,当M = Pt时,不饱和有机底物通常会添加到金属中,从而提供相当稳定的tbp五配位络合物。
Carbon-carbon bond formation in cationic aryl-olefin-platinum(II) complexes
摘要:
Cationic five-coordinate [Pt(3-R1-4-R2-C6H3)(MeCN)(6-Me-py-2-CH=NPh)(C2H4)]+ complexes (R1, R2 = H, Me, OMe) undergo an unexpected rearrangement at 0-degrees-C in chloroform solution, affording, after treatment with aqueous LiCl, the neutral four-coordinate species [Pt(2-Et-4-R1-5-R2-C6H2)Cl(6-Me-py-2-CH=NPh)]. Pt-C(aryl) bond breaking and making is involved in the whole process, resulting in a 1,2-shift of the platinum atom to an adjacent position of the benzene ring. The same compound is obtained, together with products deriving from a typical insertion, when an equimolar amount of ethylene is added to a chloroform solution of [Pt(3-R1-4-R2-C6H3)(MeCN)(6-Me-py-2-CH=NPh)]+ at 0-degrees-C. When higher (>3) ethylene/Pt ratios are used, only the five-coordinate [Pt(3-R1-4-R2-C6H3CH2CH2)Cl(6-Me-py-2-CH= NPh)(C2H4)] complex is isolated. As the experimental data rule out the possibility of a (2-arylethyl)platinum to (2-ethylaryl)platinum rearrangement, different reaction paths are suggested for the two processes. When the two reactions are combined in a "one-pot' sequence, a regiocontrolled double alkylation of the aryl system can be obtained. The behavior of substrates containing bidentate nitrogen ligands having different five-coordination stabilizing effects is examined, and data concerning the reactions of propene and styrene are reported.