Synthesis, structure, and reactivity of doubly trans-spanning bis(dialkyl selenide) complexes; a new route to diselenamacrocycles via alkene metathesis in metal coordination spheres
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© 2018 Elsevier B.V. The reaction of selenium with NaBH4 and Br(CH2)6CH=CH2 (2.0 equiv each) gives the dialkyl selenide Se((CH2)6CH=CH2)2 (91% after workup) which is combined with PtCl2 (0.5 equiv, toluene) to give trans-PtCl2(Se((CH2)6CH=CH2)2)2 (10, 85%). The reaction of 10 and Grubbs' first generation catalyst yields macrocyclic[Figure presented] (11, 60%) as a mixture of syn/anti isomers with respect to the selenium lone pairs. The reaction of 11 and Ph2Zn gives the diphenyl complex[Figure presented] (12, 86%; mixture of isomers). When 11 is treated with H2 under conditions that hydrogenate related diphosphine complexes (5 bar, 50 °C, (Ph3P)3RhCl or PtO2, CH2Cl2), no reaction occurs. Under more forcing conditions, (8 bar, 85 °C, Pd/C, C2H5OH), 11 and 12 give the demetalated diselenamacrocycle Se(C14H28)2Se (13; 72-67%). The crystal structures of 11 and 12 show anti selenium lone pairs and trans C=C linkages; that of 13 exhibits columns of extended macrocycles.
author list (cited authors)
Joshi, H., Kharel, S., Bhuvanesh, N., & Gladysz, J. A.