Sodium Hydro(isothiocyanato)borates: Synthesis and Structures

Abstract

Sodium thiocyanate reacts in THF solution with 18‐crown‐6 to give the molecular compound Na(18‐crown‐6)(THF)NCS (3) with the N atom of the NCS anion oriented towards Na+. The same reaction with 15‐crown‐5 yields the ion pair Na(15‐crown‐5)NCS (4). In contrast, Na(NCS)(py)4, obtained by treating a solution of Na(H3BNCS) in THF with pyridine, yields Na(py)4(NCS) (5), which has a chain structure with hexacoordinate Na atoms coordinated to five N atoms and an S atom. Na(NCS) in THF adds 1 equiv. of BH3 to give Na(H3BNCS)·nTHF. Addition of 18‐crown‐6 to this solution yields crystals of the salt [Na(18‐crown‐6)(THF)2][H3BNCS] (1), as shown by X‐ray crystallography. Both the cation and the anion show site disorder. However, when 15‐crown‐5 is used for complexation, the salt [Na(15‐crown‐5)(THF)][H3BNCS] (2) can be isolated. Its anion shows an almost linear B−N−C−S unit. Only a mixture of (catecholato)(isothiocyanato)borates results on treating Na(NCS) in THF with catecholborane. However, the borate Na[catB(NCS)2] is readily formed by adding Na(NCS) to B‐(isothiocyanato)catecholborane. Single crystals of this compound were obtained as the salt [Na(18‐crown‐6)(THF)2][catB(NCS)2] (6). On the other hand, the reaction of Na(NCS) with 9‐borabicyclo[3.3.1]nonane (9‐BBN) in THF yields Na[(9‐BBN)NCS)]·nTHF, and, on addition of 18‐crown‐6, the complex [Na(18‐crown‐6)(THF)2][(9‐BBN)NCS] was isolated. Suitable crystals for X‐ray structure determination were, however, only obtained by crystallization from tetrahydropyran. This solvate has the rather unusual structure [Na(18‐crown‐6)(thp)2][{(9‐BBN)NCS}2Na(thp)4] (8). The sodiate anion has an Na atom coordinated by two S and four O atoms. DFT calculations support these experimental results: The (isothiocyanato)borates are more stable than the thiocyanato isomers. For the latter a bent structure of the B−S−C−N unit with a B−S−C bond angle of 105.7° is predicted. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Metallated [3]Ferrocenophanes Containing P3M Bridges (M = Li, Na, K) §

“…The coordination sphere of sodium was completed by one molecule of [15]-crown-5. The respective Na-O distances lay in the range of 2.453(2) Å to 2.607(2) Å, with an average distance of 2.498(2) Å, which matched values known in literature [18][19][20][21][22][23]. In contrast to the number of published potassium triphosphanides, characterized sodium triphosphanides are scarce.…”

Design of new heteroscorpionate ligands and their coordinative ability toward Group 4 transition metals; an efficient synthetic route to obtain enantiopure ligands

“…However, the short C(5)-S(1) bond [1.622(8) A ˚] is indicative of a double bond, with both distances consistent with those in other terminal isothiocyanates. 20, 21 Some of the prepared scorpionate lithium compounds were used for the synthesis of new titanium, zirconium and hafnium complexes. Thus, 1-8 reacted with [TiCl 4 (THF) 2 ] or [MCl 4 ] (M = Zr, Hf) to give complexes of stoichiometry [MCl 3 {j 3 -NNE(H)}]Cl (13-36) as white or yellow solids (Scheme 4).…”

Brønsted acid-promoted C–F bond activation in [P,S]-ligated neutral and anionic perfluoronickelacyclopentanes

“…The sodium cation is bound by two THF molecules in addition to the six oxygen atoms of 18-Crown-6, making it an octacoordinate metal centre. 18 Owing to the imparted electron density from the thiolate group and the basic nature of 7, we directed our attention to its reactivity with a range of different acids, aiming to develop new strategies for C-F bond functionalization. Of particular interest were Brønsted acids, as these have previously demonstrated reactivity with cobalt perfluorocyclobutanes, 19 nickel hexafluoropropene complexes, 20 and more recently with a three-coordinate perfluoronickelacyclopentane-NHC complex.…”