Reaction of 8-bromo-7-ethyl-3-methylxanthine 1 with zerovalent group 10 metal complexes gave via an oxidative addition of the C–Br bond the neutral complexes trans -[ 2 ] (M = Pd) and trans -[ 3 ] (M = Pt) bearing a theobromine-derived azolato ligand. While the oxidative addition to [Pd 0 (PPh 3 ) 4 ] gave exclusively trans -[ 2 ], the reaction with the more substitution-inert [Pt 0 (PPh 3 ) 4 ] yielded after 1 day the kinetic product cis -[ 3 ], which was converted under heating for a total of 3 days completely into the thermodynamically more stable complex trans -[ 3 ]. Treatment of trans -[ 2 ], trans -[ 3 ] or the mixture of cis -/ trans -[ 3 ] with the proton source HBF 4 ⋅Et 2 O led to complexes trans -[ 4 ]BF 4 , trans -[ 5 ]BF 4 and a mixture of cis / trans -[ 5 ]BF 4 with retention of the original ratio of cis to trans , respectively. The molecular structures of the azolato complexes trans -[ 2 ] and trans -[ 3 ] and of the theobromine derived p NHC complexes trans -[ 4 ]BF 4 and trans -[ 5 ]BF 4 have been determined by X-ray diffraction studies.

中文翻译：

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将8-溴代可可溴衍生物氧化添加到d10金属中

8-溴-7-乙基-3-甲基黄嘌呤1与零价10族金属配合物的反应通过C-Br键的氧化加成得到中性配合物反式-[2]（M = Pd）和反式-[3] （M = Pt）带有可可碱衍生的偶氮杂配体。氧化添加到[Pd 0（PPh 3）4]时只产生反式-[2]，与取代度更高的[Pt 0（PPh 3）4]的反应在1天后产生了动力学产物顺式-[3 ]，将其在加热下总共加热3天完全转化为热力学上更稳定的复合物反式[[3]]。用质子源HBF 4⋅Et2 O处理反式-[2]，反式-[3]或顺式-/反式-[3]的混合物可生成反式-[4] BF 4，反式-[5 ] BF 4和顺式/反式-[5] BF 4的混合物，分别保留了顺式与反式的原始比例。