Rubidium isopropoxide Rb(OiPr) sublimes under deep vacuum (10-6 Torr) despite of its polymeric nature, surprisingly it sublimes at higher temperature (200°C) than Cs analog (170°C). Due to its volatility, Rb(OiPr) is potentially applicable as MOCVD and ALD precursor for the growth of Rb-containing layers.
Rubidium tert-butoxide Rb(OtBu) is sublimable at 185-200°C/ 10-2 Torr.
Rb(OtBu) is promising as MOCVD and ALD precursor for the growth of Rb-containing thin films due to its volatility.
Synthesis:
Rubidium tert-butoxide was synthesized as adduct [RbOtBu·ButOH]∞ by the reaction of metallic Rb with ButOH in THF. The crystal structure of the one-dimensional ribbon chains [RbOtBu·tBuOH]∞ was determined by single-crystal XRD: it crystallizes from THF-n-pentane at −20°C in the triclinic space group, with unit cell dimension]: a = 9.886(2) Å; b = 9.914(2) Å; c = 6.640(1) Å; β = 90.46(1)° and Z = 2, as a one-dimensional chain linked by hydrogen-bonding. The alcohol adduct RbOtBu·ButOH]∞ undergoes an alkoxide ligand exchange process (rapid on the 1H NMR time scale at RT).
The unadducted species [RbOtBu]4
was easily obtained by sublimation of [RbOtBu·ButOH]∞. According to single-crystal XRD, [MOBut]4 crystallizes from toluene at −20°C in the cubic
space group P43M; with unit cell dimensions; a = 8.514(1) Å, and Z = 4, as cubane structures. The O-M-O angles in the cubane-like structured [RbOtBu]4 deviate only slightly from 90°, with O-M-O (89.11°)
and M-O-M (90.89°). [i]
[i] M.H. Chisholm, S.R. Drake, A.A. Naiini, W.E. Streib, Polyhedron, 1991, Vol. 10, Iss.3, p.337–345, “Synthesis and X-ray crystal structures of the one-dimensional ribbon chains [MOBut·ButOH]∞ and the cubane species [MOBut]4 (M = K and Rb)”
Rubidium tert-butoxide Rb(OtBu) was demonstrated as promising ALD precursor for the preparation Rb-contaning layers (Rb(OtBu) revealed similar behavior
as Li, Na and K analogues (tert-butoxides). In particular, the deposition of Rb–Ti–O and Rb–Nb–O films was performed, with Rb doping content up to 20% controllably
achieved in Rb:TiOx films, whereas in Rb:NbOx layers rubidium can be introduced as a major component. Rubidium t-butoxide Rb(OtBu) as ALD precursor allowed to obtain perovskite structure RbNbO3 stabilized on SrTiO3 (100) substrates (otherwise RbNbO3 is unattainable
in bulk systems under ambient conditions).[i]
[i] H.H. Sønsteby, K. Weibye, J.E. Bratvold, Ola Nilsen, Dalton Trans., 2017,46, 16139-16144, DOI: 10.1039/C7DT03753H, Rubidium containing thin films by atomic layer deposition
https://pubs.rsc.org/en/content/articlelanding/2017/dt/c7dt03753h/unauth#!divAbstract