Synthesis, structure, and reactivity of doubly trans-spanning bis(dialkyl selenide) complexes; a new route to diselenamacrocycles via alkene metathesis in metal coordination spheres

Publication date: Available online 31 August 2018Source: Journal of Organometallic ChemistryAuthor(s): Hemant Joshi, Sugam Kharel, Nattamai Bhuvanesh, John A. GladyszAbstractThe 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 trans-PtCl2(Se((CH2)6CH = CH(CH2)6)2Se) (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 trans-PtPh2(Se((CH2)6CH = CH(CH2)6)2Se) (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.Graphical abstractThe title compounds are accessed by the reaction of Grubbs' first generation catalyst and platinum(II) dichloride complexes with trans dialkyl selenide ligands Se((CH2)6CH = CH2)2, and subsequent substitution of the chloride ligands. They are isolated as mixtures of ...

Source: Journal of Organometallic Chemistry - September 1, 2018 Category: Chemistry Source Type: research