Beiträge zur Chemie des Bors, 215. Darstellung und Reaktionen monomerer Tetraorganylphosphanylborane

Contributions to the Chemistry of Boron, 215 [1] . – Synthesis and Reactions of Monomeric Tetraorganyl‐phosphanyl‐boranes The reaction of diorganyl‐chloroboranes with lithium diorganyl‐or lithium bis(trimethylsilyl)phosphides leads to the monomeric phosphanylboranes t Bu 2 BP t Bu 2 ( 1 ), t Bu 2 BP(SiMe 3 ) 2 ( 2 ), 9‐BBNP t Bu 2 ( 3 ), 9‐BBNP(SiMe 3 ) 2 ( 4 ), and Cy 2 BP t Bu 2 ( 5 ). These species were studied by NMR‐spectroscopic methods. For further characterization reactions of the compounds 1, 3 , and 5 have been investigated. Heating of 1 and 5 results in the formation of the dimeric phosphanylboranes t Bu(H)BP t Bu 2 ( 8 ) and Cy(H)BP t Bu 2 ( 9 ) by dehydroboration. Dimers 8 and 9 are present as cis ‐ and trans 1‐isomers as confirmed by X‐ray structure analyses. The trans 1‐isomer of 9 shows a planar (BP) 2 four‐membered ring, whereas the ring of the cis 1‐isomer of 8 is slightly folded. Furthermore, the reaction of 3 with 9H‐9‐BBN yields (μ1‐H)(μ‐ t Bu 2 P)[9‐BBN] 2 ( 14 ), whose bridged structure is proven by a crystal structure analysis. Oxidation of the phosphorus atom in 3 with sulfur leads to the S 1‐boryl thiophosphinate t Bu 2 (S)PS‐9‐BBN ( 16 ).