The Stabilisation of Monomeric Parent Compounds of Phosphanyl‐ and Arsanylboranes

Abstract

The structures of the parent compounds of phosphanyl- and arsanylboranes, H(2)BPH(2) and H(2)BAsH(2), were calculated by DFT-B3LYP methods. Such compounds have not previously been obtained preparatively. By applying the concept of Lewis acid/base stabilisation, [(CO)(5)W(H(2)EBH(2).NMe(3))] (E=P (3), As (4)) derivatives have been synthesised by the metathesis reactions between Li[(CO)(5)WEH(2)] and ClH(2)BNMe(3) (E=P, As). Comprehensive thermodynamic studies on these systems verify the high stability of the Lewis acid/base stabilised complexes. Unexpected based on the thermodynamic calculations, UV radiation of the phosphanylborane 3 leads to the dinuclear phosphanido-bridged complex [(CO)(8)W(2)(mu-PHBH(2).NMe(3))(2)] (5) by H(2) and CO elimination.

Main Group Lewis Acid/Base‐Stabilised Phosphanylboranes

“…(6) Only in the mass spectrum of 5 is the molecular ion peak detected. In the case of 1, 4 and 5 the highest peak is that of the Lewis acid [E(C 6 for the B-H stretching modes and the P-H stretching frequencies appear between 2320 cm -1 and 2440 cm -1 . The 19 F NMR spectra of the products show the three separated resonances for ortho-, meta-and para-fluorine atoms.…”

“…[7] The Lewis acid stabilised phosphanylboranes that we synthesised carry transition metal carbonyls as the Lewis acid. [6] In contrast, less is known about main group Lewis acid stabilised group 13/15 compounds. [5,7,8] ence on the reactivity of the phosphanylboranes [Equation (1)].…”

“…[15][16][17] www.eurjic.org Metalation of (C 6 F 5 ) 3 GaPPhH 2 3 as well as of (C 6 F 5 ) 3 -BPPhH 2 with nBuLi leads to [(C 6 F 5 ) 3 EPPhHLi] which were then treated with ClBH 2 NMe 3 to yield colourless crystals of (C 6 F 5 ) 3 BPPhHBH 2 NMe 3 (4) and (C 6 F 5 ) 3 GaPPhHBH 2 -NMe 3 (5), respectively [Equation (6)]. (6) Only in the mass spectrum of 5 is the molecular ion peak detected. In the case of 1, 4 and 5 the highest peak is that of the Lewis acid [E(C 6 for the B-H stretching modes and the P-H stretching frequencies appear between 2320 cm -1 and 2440 cm -1 .…”

“…For example, photolysis of compound D leads to a dimer with elimination of CO and H 2 . [6] Furthermore, the reaction of D with iodine leads to oxidation of the tungsten atom with concomitant loss of CO and not, as expected, to halogenation of the phosphorus atom. [9] (1)…”

“…By this way the lone pair of the pnicogen is occupied by a Lewis acid (LA) and the Group 13 element is coordinated by a Lewis base (LB) (B). [6] Recently we were able to synthesise the first phosphanylborane C, which is stabilised only by a Lewis base. [7] The Lewis acid stabilised phosphanylboranes that we synthesised carry transition metal carbonyls as the Lewis acid.…”