Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA.
Chemistry. 2011 Jan 10;17(2):580-7. doi: 10.1002/chem.201001975. Epub 2010 Nov 5.
The reactions of nitrile complexes of the Re(6)(μ(3)-Se)(8) core-containing clusters, Re(6)(μ(3)-Se)(8)(PEt(3))(n)(CH(3)CN)(6-n) [n = 5 (1); n = 4, cis- (2) and trans- (3); n = 0 (4)], with organic azides C(6)H(5)CH(CH(3))N(3) and C(6)H(5)CH(2)N(3) produced the corresponding cationic imino complexes of the general formula Re(6)(μ(3)-Se)(8)(PEt(3))(n)(L)(6-n) [L = PhN=CHCH(3): n = 5 (5); n = 4, cis- (6) and trans- (7); n = 0 (8) and L = HN=CHPh: n = 5 (9); n = 4, cis- (10) and trans- (11)]. These novel complexes were characterized by NMR spectroscopy ((1)H and (31)P) and single-crystal X-ray diffraction. A mechanism involving the migration of one of the groups on the azido α-C atom to the α-N atom of the azido complex, concerted with the photo-expulsion of N(2), was invoked to rationalize the formation of the imino complexes. Density functional theory (DFT) calculations indicated that due to the coordination with and activation by the cluster core, the energy of the electronic transition responsible for the photo-decomposition of a cluster-bound azide is much reduced with respect to its pure organic counterpart. The observed geometric specificity was rationalized by using the calculated and optimized preferred ground-state conformation of the cluster-azido intermediates.
Re(6)(μ(3)-Se)(8)核簇合物的腈配合物的反应，Re(6)(μ(3)-Se)(8)(PEt(3))(n)(CH(3)CN)(6-n) [n = 5 (1); n = 4，顺式-(2)和反式-(3); n = 0 (4)]，与有机叠氮化物 C(6)H(5)CH(CH(3))N(3) 和 C(6)H(5)CH(2)N(3) 反应生成了相应的阳离子亚氨基配合物，通式为Re(6)(μ(3)-Se)(8)(PEt(3))(n)(L)(6-n) [L = PhN=CHCH(3): n = 5 (5); n = 4，顺式-(6)和反式-(7); n = 0 (8)和 L = HN=CHPh: n = 5 (9); n = 4，顺式-(10)和反式-(11)]。这些新的配合物通过 NMR 光谱((1)H 和 (31)P)和单晶 X 射线衍射进行了表征。提出了一个涉及迁移一个叠氮α-C 原子上的基团到叠氮配合物的α-N 原子的机制，同时伴随着 N(2)的光解吸，以合理化亚氨基配合物的形成。密度泛函理论(DFT)计算表明，由于与簇核的配位和活化，负责簇结合叠氮物光解的电子跃迁的能量相对于其纯有机对应物大大降低。观察到的几何特异性通过使用计算和优化的簇-叠氮化物中间体的首选基态构象来合理化。
