The first osmaboranes and a new iridatetraborane

Degradation and modification of metallaboranes

“…Over a period of a few days these peaks grew in intensity and were assigned to the species 6b and 8b. This was also confirmed by 31 P{ 1 H}-NMR spectrum which additionally showed the presence of 1 and the nido -osmapentaborane cluster, (PPh 3 ) 2 (CO)OsB 4 H 8 (3). The presence of these products was expected, since the equilibration of 7b to 6b would release 1, and 3 would be formed when 7b degraded to 8b.…”

“…Chemical shifts are reported in ppm for CDCl 3 solutions, unless otherwise stated, to low field (high frequency) of Et 2 O ×/BF 3 for 11 B, of SiMe 4 for 1 H and of 85% H 3 PO 4 for 31 P. Mass spectra were measured on a JEOL MStation JMS700. Elemental analyses were carried out by Atlantic Microlabs Inc., Norcross, GA. B 5 H 9 was obtained from laboratory stock, and distilled on a high vacuum line before use, and [2,2,2-(PPh 3 ) 2 (CO)-nido -2-OsB 5 H 9 ] was prepared according to the literature method [3]. BH 3 ×/thf was used as received and the bidentate phosphines [Fe(C 5 H 4 PPh 2 ) 2 ] (dppf) [4], [PPh 2 C 6 H 4 PPh 2 ] (1,4 arphos) [5], and [PPh 2 CH 2 C 6 H 4 CH 2 PPh 2 ] (dppx) [6] were prepared according to literature methods.…”

[(CO)H(PPh3)2-arachno-OsB3H8]

“…The reaction between LiBsH8 and [OsHCI(CO)(PPh3)3] was carried out on a 0.5 mmol scale in tetrahydrofuran (thf) solution essentially according to the literature method (Bould et al, 1983) using the same conditions and similar procedures. Compound (I) was obtained as follows: the thf was removed under vacuum, the solid obtained redissolved in CH2Cl2/pentane solution (1:3), filtered through silica gel, the filtrate applied to a preparative thin-layer-chromatography plate and developed using diethyl ether/pentane (1:1) as the mobile phase giving two bands (under UV illumination) at Rf = 0.8 (identified by NMR spectroscopy as Ph3PBH3) and Rf = 0.5 [compound (I), 9 mg, 0.011 mmol, 2% yield].…”

“…During our investigations of the chemistry of metallaboranes, we have prepared the osmahexaborane (CO)(PPh3)2OsBsH9, which is available in ca 80% yield from the reaction of LiBsH8 and OsHCI(CO)(PPh3)3 (Bould, Greenwood & Kennedy, 1983). We have found that the residues from the preparation show, from liB NMR, evidence of other metallaborane products and we have attempted to identify some of these.…”

“…The products include the title compound, (I), an arachnoosmatetraborane cluster, and what appear to be a novel arachno-osmapentaborane cluster and a novel nidoosmadecaborane cluster. Compound (I) is formed in a very low yield (2%) and is more conveniently available in 65% yield from the reaction of T1B3H8 and OsHCI(CO)(PPh3)3 (Bould et al, 1983).…”