Styrene Polymerization under Ambient Conditions by using a Transient 1,3,2-Diazaphospholane-2-oxyl Complex

A combined theoretical and experimental study on the formation and reactivity of a P-OTEMP (P-bound TEMPO (TEMPO=2,2,6,6-tetramethyl-piperidin-1-oxyl)) substituted 1,3,2-diazaphospholane W(CO)₅ complex is presented, including DFT-based mechanistic details. The complex possesses a thermally labile O-N bond that cleaves homolytically yielding the transient 1,3,2-diazaphospholane-2-oxyl complex [(CO)₅ W(R₂ PO^. )], which acts as a radical initiator for styrene polymerization under ambient conditions.

Synthesis, crystal structure and catalytic activity in reductive amination of di-chlorido-(η6-p-cymene)(2'-di-cyclo-hexyl-phosphanyl-2,6-di-meth-oxy-biphen-yl-κP)ruthenium(II)

The title compound, [RuCl2(C10H14)(C26H35O2P)] (I), crystallizes in the monoclinic space group P21/c with two crystallographically independent mol-ecules (A and B) in the asymmetric unit. The geometries of both mol-ecules are very similar and distinguished only by the twist angles of the two benzene rings in the phosphine substituents [89.54 (14) and 78.36 (14)° for mol-ecules A and B, respectively]. The Ru atoms have classical pseudo-tetra-hedral piano-stool coordination environments. The conformation of each mol-ecule is stabilized by intra-molecular C-H⋯O and C-H⋯Cl hydrogen bonds and C-H⋯π inter-actions. The two mol-ecules are linked by a C-H⋯Cl hydrogen bond. In the crystal, the mol-ecules are further linked by C-H⋯ π inter-actions, forming -A-B-A-B- chains propagating along the a-axis direction. Complex I is an active catalyst for reductive amination reaction. The catalytic activity of this complex can be explained by the lability of the p-cymene ligand, which can be replaced by two-electron ligands such as CO or amine.