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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Isomerization in substitution processes of eyclometallated dimethylhaloplatinum(IV)complexes
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Isomerization in substitution processes of eyclometallated dimethylhaloplatinum(IV)complexes

机译：环乙基金属化二甲基卤化铂（IV）配合物的取代过程中的异构化

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Cyclomctallated imine platinum(IV)derivatives of general formula [PtX(Me)_2(C-N)(SMe_2)],being X = Br and Cl with C-N = CC_5H_4CH_2NCH(2,4,6-Me_3C_6H_2)(1 and 2);X = I with C-N =CC_5H_4CHNBzl(3);X = Br with C-N = CC_5H_4CHNPh and CC_5H_4CH_2N(2,4,6-Me_3C_6H_2)(4 and 5),and X = I with C-N = CC_5H_4CH_2N(2,4,6-Me_3C_6H_2)(6)have been characterised as having different fac(Me/Me/SMe_2)to mer(Mc/Mc/SMc_2)geometrical disposition ratios.The isomeric/ac(Me/Me/SMe_2)form is present at various percentages depending on the rigidity of the system,from a maximum of 100% for complexes 1 and 2 as proved from the X-ray crystal structure determination of both complexes and selective NOE experiments,to a minimum of 30% in the case of 3.SMe_2 by PPH_3 substitution has been studied for these fac complexes where,in comparison to similar compounds with a mer(Me/Me/SMe_2)disposition,the strong trans-influence of the methyl group is avoided.The results indicate that there are more important effects than the simple trans-influence of the methyl ligand,the reactions are found to be much faster than their equivalent with complexes with mer geometries.In some of the cases,the final phosphine substituted products show the full isomerization to expected less hindered mer(Me/Me/PPH_3)geometry,while in others,a mixture of the fac and mer arrangements is found in the final reaction products.For the 2,4,6Me_3QH_2-containing imines the isomerization takes place during substitution from a postulated pentacoordinated intermediate,for the remaining complexes the final reaction mixture is obtained in a process that takes place after substitution.For these two cases(products 3 and 4),the presence of an intermediate with a fac(Me/Me/PPH_3)geometry,that further evolves to the final mer complex,has been characterised by low temperature NMR,and the isomerization reactions have been studied as a function of temperature and pressure.The results agree with a process involving a very energetically demanding turnstile twist type reorganization of the molecule,after a significant degree of dissociation of the ligands(DELTA H= 109 and 100 kJ mol~(-1);DELTAS* = 88 and 49 J K~(-1)mol~(-1);DELTAV = 14.9 and 20.0 cm~3 mol~(-1)for compounds 3 and 4 respectively).
机译：通式[PtX（Me）_2（CN）（SMe_2）]的环杂亚甲基亚胺铂（IV）衍生物，X = Br和Cl，CN = CC_5H_4CH_2NCH（2,4,6-Me_3C_6H_2）（1和2）; X = = CN = CC_5H_4CHNBzl（3）; X = Br = CN = CC_5H_4CHNPh和CC_5H_4CH_2N（2,4,6-Me_3C_6H_2）（4和5），X = I CN = CC_5H_4CH_2N（2,4,6-Me_3C_6H_2 ）（6）的特征是fac（Me / Me / SMe_2）与mer（Mc / Mc / SMc_2）的几何构型比例不同。异构体/ ac（Me / Me / SMe_2）的形式取决于系统的刚性，从配合物1和2的X射线晶体结构确定和选择性NOE实验证明，对于配合物1和2最高为100％，对于PSM_3为3.SMe_2的情况，最低为30％已研究了这些fac配合物的取代反应，与具有mer（Me / Me / SMe_2）位置的类似化合物相比，避免了甲基的强反式影响。结果表明，与这些化合物相比，甲基丙烯酸具有更重要的影响。 s甲基配体的简单反式影响，发现该反应比具有巯基几何形状的配合物的反应要快得多。在某些情况下，最终的膦取代产物显示出完全异构化为预期较少受阻的巯基（Me / Me / PPH_3）几何形状，而在其他情况下，最终反应产物中则存在fac和mer排列的混合物。对于含2,4,6Me_3QH_2的亚胺，异构化发生在从假定的五配位中间体取代过程中，其余在取代后的过程中获得最终的反应混合物。对于这两种情况（产物3和4），存在具有fac（Me / Me / PPH_3）几何形状的中间体，该中间体进一步演化为最终产物mer配合物已通过低温NMR进行了表征，并且异构化反应已作为温度和压力的函数进行了研究。结果与一个过程非常耗费能量在配体显着解离后（ΔH = 109和100 kJ mol〜（-1）; DELTAS * = 88和49 JK〜（-1）mol〜（-1）的分子的扭曲类型重组;对于化合物3和4，DELTAV分别为14.9和20.0cm〜3mol〜（-1）。

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