Synthesis, properties, and X-ray crystal structure of trans-dichlorotetrakis-(1,3-diethylimidazolidin-2-ylidene)ruthenium(II), a neutral tetracarbenemetal complex

Abstract

Oligocarbeneruthenium(II) complexes, having a high Ru–C_carb rotational barrier, have been obtained from [RuCl₂(PPh₃)₃] and an electron-rich olefin [[graphic omitted]R]₂(L^R)₂(R = Me or Et); these include (i) the unusual (X-ray determined) neutral trans-[RuCl₂(L^R)₄], (R = Et), which with CO afford trans-[Ru(CO)Cl₂(L^R)₃](R = Et) or trans-[Ru(CO)Cl(L^R)₄]⁺Cl^–(R = Me), (ii) the tri-µ-halogeno-[Ru₂X₃(L^R)₆]⁺X^–(X = Cl or I), and (iii)trans-[RuCl(L^R)₄(PF₃)]⁺Y^–(Y = Cl or BF₄) in which there is long-range FH coupling (⁶J).