A simple molecule with a complex crystal structure: interplay of ³¹P solid‐state NMR spectroscopy and single‐crystal x‐ray diffraction in the structure determination of a ruthenium diphosphine diamine complex

Abstract

A comprehensive 31P solid-state NMR study of Ru(eta1-Ph2PCH2CH2OCH3)2(eta2-en)Cl2 (en = ethylenediamine) (1), by 1D (contact time variation, inversion-recovery, SPARTAN) and 2D techniques (homonuclear J-resolved, SECSY) indicated that the crystal structure of 1 should be complex. The single-crystal x-ray structure determination confirmed the presence of eight independent molecules in the asymmetric unit, with 31P isotropic chemical shifts in the range 27.3-40.1 ppm, while the spans of the phosphorus chemical shift tensors are of the order of 170 ppm. Based on unique structural features and NMR data, one molecule has been tentatively assigned.

Bonding modes of stanna-closo-dodecaborate: η1(Sn) to η3(BH) rearrangement reactions in zwitterionic stanna-closo-dodecaborate ruthenium complexes

“…Reported literature values for the 31 P chemical shift tensors of octahedral ruthenium phosphane complexes are limited to RuCl 2 (g 1 -Ph 2 PCH 2 CH 2 OCH 3 ) 2 (g 2 -en) which crystallizes from dichloromethane with eight independent molecules in the asymmetric unit and exhibits values of d 11 in the range 95 ppm to 109 ppm and values of d 33 in the range −75 ppm to −60 ppm. 16 For the most part the values reported here are similar to the literature values. The exceptions are the value for d 11 of 160 ppm of the signal at d iso = 48.7 ppm of compound 4 which is significantly shifted to higher frequency and the values of d 33 (−31 ppm and −35 ppm) of compound 6b which are also shifted to higher frequency compared to the reported values.…”

“…The large differences of the chemical shifts between the three phosphorus atoms are remarkable. The scalar coupling between the phosphorus atoms could be resolved using a homonuclear 2D J-resolved 31 P VACP/MAS experiment 16 and amounts to 2 J(P,P) = 29 Hz and 49 Hz. The 119 Sn HPDEC/MAS NMR spectrum of 4 displays one broad doublet with 2 J( 119 Sn,P) = 1592 Hz at −304 ppm and is therefore shifted to higher frequency compared to 6b (Table 2).…”

Sol−Gel Processed Diamine(diphosphine)ruthenium(II) Complexes for the Catalytic Hydrogenation of α,β-Unsaturated Ketones1,2

“…complicated, covering a range of chemical shifts from 27.3 to 40.1 ppm. 36 In summary the broad range of chemical shifts in the 31 P CP/MAS spectra of X1-X4 is fully compatible with the ruthenium diamine diphosphine complex of 6T 0 . However, different structures have to be considered.…”

Quantifying hydrogen-bonding strength: the measurement of 2hJNN couplings in self-assembled guanosines by solid-state 15N spin-echo MAS NMR

“…[17][18][19][20][21][22][23][24][25][26][27][28][29] In particular, work on the precise measurement of J couplings in the solid state by spin-echo modulation has recently received increased attention. [30][31][32][33][34][35][36][37][38][39][40][41] J couplings are not normally resolved in ordinary 1-D solidstate NMR spectra, since the observed linewidth is usually larger than the magnitude of the coupling. However, a simple t/2-p-t/2 spin-echo MAS experiment can be used to refocus evolution due to all terms that appear as offsets, e.g.…”

“…The spin-echo MAS technique has been applied widely, in particular for the 100% natural abundant 31 P nucleus in inorganic chemistry and materials applications. 4,7,24,31,33,36,38,39,41,44,[47][48][49][50][51][52][53][54][55] Recently, the spin-echo experiment has been applied to organic systems. 24,30,32,34,35,37,40,41 For example, studies carried out on partially 13 C-labelled samples of wood have provided accurate determinations of 1 J CC couplings in cellulose even in the presence of considerable disorder.…”