The structure of trans-chloro(dinitrogen)bis(tri-isopropylphosphine)-rhodium(I): an X-ray study of the structure in the solid state and a nuclear magnetic resonance study of the structure in solution

Abstract

The crystal structure of [RhCl(N₂)(PPrⁱ₃)₂] has been redetermined at –160 °C. In contrast to the results of a previous structure determination, we conclude that a scattering model in which the N₂ ligand is end-on (η¹) co-ordinated is fully consistent with the data. Such end-on co-ordination is confirmed in solution at +30 °C from the ³¹P and ¹⁵N n.m.r. spectra of a ¹⁵N₂ labelled sample. The material crystallizes in the space group P2₁/c(C⁵_2h) of the monoclinic system in a cell of dimensions a= 8.062(2), b= 8.883(2), c= 16.431(4)Å, β= 92.45(1)°, Z= 2; the final R and R′ are 0.024 and 0.031, respectively, based on the full-matrix refinement of 124 variables and 3 597 observations. The ³¹P n.m.r. spectrum of the ¹⁵N₂-labelled complex shows a doublet of doublets, J_{P – Rh} 122.3 and J_p–¹⁵N 4.25 Hz, and proves the N₂ co-ordination to be η¹ in solution. The ¹⁵N n.m.r. spectrum of the labelled complex is also consistent with η¹-co-ordination: J_15N(1)–Rh 28, J_{15N(1)–¹⁵N(2)} 4, J_15N(1)–P 4, J_15N(2)–Rh 4 Hz; δ_N(1) 269 and δ_N(2) 302 p.p.m.(downfield from external ¹⁵NH₄⁺).