Reversible Small-Molecule Interactions with Coordinatively Unsaturated Metal Centers Held in Metallathiaborane Clusters

Abstract

The metallathiaboranes [8,8-(dppe)-nido-8,7-NiSB9H11] [1, dppe = bis(diphenylphosphanyl)ethane], [7-Et-8,8-(dppe)-nido-8,7-NiSB9H10] (2), [9-Et-8,8-(dppe)-nido-8,7-NiSB9H10] (3) and [2,2-(dppe)-closo-2,1-NiSB8H8] (4) are isolated from the reactions between Cs[arachno-SB9H12], Li[BHEt3] and [NiCl2(dppe)] at low temperature in yields of 30, 1, 0.1 and <1 %, respectively. The arachno-nickellathiadecaborane [6,6-(dppe)-arachno-6,9-NiSB8H10] (5) is isolated from the reaction between [(N,N,N′,N′-tetramethylnaphthalene-1,8-diamine)H][SB8H11], Li[BHEt3] and [NiCl2(dppe)] at low temperature (75 % yield). Compound 1 reversibly takes up NH3 in solution, and the characterization of the resulting compound is discussed. Compound 5 shows no interactions with ammonia but does reversibly take up CO to give [6,6,6-(CO)(dppe)-arachno-6,9-NiSB8H10] (7). The CO molecule is very weakly bound and is lost readily even in the solid state. Similarly to 1, the isonido-iridathiaundecaboranes [(L)2-H-isonido-IrSB9H9] (L = PMe3 and PMe2Ph) also reversibly takes up NH3 to afford [8,8,8-(PMe3)2(NH3)-nido-8,7-IrSB9H10]·NH3 (8) and [8,8,8-(PMe2Ph)2(NH3)-nido-8,7-IrSB9H10] (9) quantitatively. The ferrathiaborane compound [1,1,3-(dppe)2-1,2-closo-FeSB9H9] (11) was isolated in trace yield when [FeCl2(dppe)] was used as the starting metal complex. When appropriate, the compounds were characterized by single-crystal X-ray diffraction studies, multielement NMR spectroscopy together with DFT gauge including atomic orbitals (GIAO) chemical-shielding calculations, IR spectroscopy and elemental analysis.