Dougan Sarah J, Melchart Michael, Habtemariam Abraha, Parsons Simon, Sadler Peter J
School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, U.K.
Inorg Chem. 2006 Dec 25;45(26):10882-94. doi: 10.1021/ic061460h.
Ru(II) eta6-arene complexes containing p-cymene (p-cym), tetrahydronaphthalene (thn), benzene (bz), or biphenyl (bip), as the arene, phenylazopyridine derivatives (C5H4NN:NC6H5R; R = H (azpy), OH (azpy-OH), NMe2 (azpy-NMe2)) or a phenylazopyrazole derivative (NHC3H2NN:NC6H5NMe2 (azpyz-NMe2)) as N,N-chelating ligands and chloride as a ligand have been synthesized (1-16). The complexes are all intensely colored due to metal-to-ligand charge-transfer Ru 4d6-pi* and intraligand pi -->pi* transitions (eta = 5000-63 700 M-1 cm-1) occurring in the visible region. In the crystal structures of [(eta6-p-cym)Ru(azpy)Cl]PF6 (1), [(eta6-p-cym)Ru(azpy-NMe2)Cl]PF6 (5), and [(eta6-bip)Ru(azpy)Cl]PF6 (4), the relatively long Ru-N(azo) and Ru-(arene-centroid) distances suggest that phenylazopyridine and arene ligands can act as competitive pi-acceptors toward Ru(II) 4d6 electrons. The pKa* values of the pyridine nitrogens of the ligands are low (azpy 2.47, azpy-OH 3.06 and azpy-NMe2 4.60), suggesting that they are weak sigma-donors. This, together with their pi-acceptor behavior, serves to increase the positive charge on ruthenium, and together with the pi-acidic eta6-arene, partially accounts for the slow decomposition of the complexes via hydrolysis and/or arene loss (t(1/2) = 9-21 h for azopyridine complexes, 310 K). The pKa* of the coordinated water in [(eta6-p-cym)Ru(azpyz-NMe2)OH2]2+ (13A) is 4.60, consistent with the increased acidity of the ruthenium center upon coordination to the azo ligand. None of the azpy complexes were cytotoxic toward A2780 human ovarian or A549 human lung cancer cells, but several of the azpy-NMe2, azpy-OH, and azpyz-NMe2 complexes were active (IC50 values 18-88 microM).
已合成了含有对异丙基苯（p-cym）、四氢萘（thn）、苯（bz）或联苯（bip）作为芳烃配体、苯基偶氮吡啶衍生物（C5H4NN:NC6H5R；R = H（azpy）、OH（azpy-OH）、NMe2（azpy-NMe2））或苯基偶氮吡唑衍生物（NHC3H2NN:NC6H5NMe2（azpyz-NMe2））作为N,N-螯合配体以及氯离子作为配体的钌（II）η6-芳烃配合物（1 - 16）。由于在可见光区域发生金属到配体的电荷转移Ru 4d6-π和配体内π→π跃迁（ε = 5000 - 63700 M-1 cm-1），这些配合物都具有强烈的颜色。在[(η6-p-cym)Ru(azpy)Cl]PF6（1）、[(η6-p-cym)Ru(azpy-NMe2)Cl]PF6（5）和[(η6-bip)Ru(azpy)Cl]PF6（4）的晶体结构中，相对较长的Ru-N(azo)和Ru-(芳烃质心)距离表明苯基偶氮吡啶和芳烃配体可作为对Ru(II) 4d6电子的竞争性π-受体。配体吡啶氮的pKa值较低（azpy为2.47，azpy-OH为3.06，azpy-NMe2为4.60），表明它们是弱σ-供体。这与它们的π-受体行为一起，增加了钌上的正电荷，并与π-酸性的η6-芳烃一起，部分解释了配合物通过水解和/或芳烃损失的缓慢分解（对于偶氮吡啶配合物，t(1/2) = 9 - 21 h，310 K）。[(η6-p-cym)Ru(azpyz-NMe2)OH2]2+（13A）中配位水的pKa为4.60，这与钌中心与偶氮配体配位后酸度增加一致。没有一种azpy配合物对A2780人卵巢癌细胞或A549人肺癌细胞具有细胞毒性，但几种azpy-NMe2、azpy-OH和azpyz-NMe2配合物具有活性（IC50值为18 - 88 μM）。
