Synthesis and Chemistry of Bis(borylphosphino)silanes and -germanes

Abstract

The reactions of Me(2)SiCl(2), Ph(2)SiCl(2), and Ph(2)GeCl(2) with LiP(H)B(N(i)Pr(2))(2) in a 1:2 ratio and the reaction of Ph(2)SiCl(2) with LiP(H)B(N(i)Pr(2))[N(SiMe(3))(2)] in a 1:2 ratio give good yields of the respective diphosphinosilanes, Me(2)Si[P(H)B(N(i)Pr(2))(2)](2), Ph(2)Si[P(H)B(N(i)Pr(2))(2)](2), Ph(2)Ge[P(H)B(N(i)Pr(2))(2)](2), and Ph(2)Si[P(H)B(N(i)Pr(2))[N(SiMe(3))(2)]](2). These species, when combined with BuLi in a 1:2 ratio, give lithium diphosphinosilanes and -germanes of the general type (DME.Li)(2){[PB(NR(2))(2)](2)ER'(2)}. All of the species have been characterized by spectroscopic methods. The molecular structures of three of the lithio compounds, (DME.Li)(2){[PB(N(i)Pr(2))(2)](2)SiPh(2)} (11), (DME.Li)(2){[PB(N(i)Pr(2))N(SiMe(3))(2)](2)SiPh(2)} (15), and (DME.Li)(2){[PB(N(i)Pr(2))(2)](2)GePh(2)} (13), have been determined by X-ray diffraction techniques. 11 crystallized in the triclinic space group P&onemacr; with a = 11.071(2) Å, b = 14.937(3) Å, c = 18.080(4) Å, alpha = 91.31(3) degrees, beta = 101.23(3) degrees, gamma = 109.95(3) degrees, and Z = 2, and 13 crystallized in the triclinic space group P&onemacr; with a = 11.083(1) Å, b = 14.978(2) Å, c = 18.134(2) Å, alpha = 91.17(1) degrees, beta = 101.43(1) degrees, gamma = 110.05(1) degrees, and Z = 2. 15 crystallized in the monoclinic space group P2(1)/n with a = 11.939(2) Å, b = 24.516(3) Å, c = 21.572(3) Å, beta = 101.52(1) degrees, and Z = 4. The reactions of the lithio compounds were surveyed with R(2)ECl(2) reagents. The metathesis reactions are sluggish, but the 1:1 reaction of (DME.Li)(2){[PB(N(i)Pr(2))(2)](2)GePh(2)} with (t)Bu(2)SnCl(2) gave the four-membered-ring compound The 1:2 reaction of Me(2)(Cl)SiSi(Cl)Me(2) with LiP(H)B(N(i)Pr(2))(2) yielded the (borylphosphino)silane [Me(2)SiP(H)B(N(i)Pr(2))(2)](2).

Monomeric phosphinoboranes

“…It has been applied to the synthesis of the bulky phosphinoboranes 23a-c [18,54], 25 [26] and 26a-d [55] whose properties and reactivity have been extensively studied (see Section 4.3) as well as the borylphosphines 27 [56], 28 [57], 30 [58] and 31a-c and 32 [59] which have been used as ligands (see Section 4.4).…”

Hydrophosphination of boron–boron multiple bonds

“…due to p-donor or carborane substituents) and phosphorus thus retains its lone pair and tetrahedral geometry, are highly electron rich h 1 ligands for transition metal complexes. [9][10][11] By far the most common route for the construction of P-B bonds is salt elimination [12][13][14][15][16][17][18][19] using an alkali metal phosphide, MPR 2 , and a haloborane (Scheme 1A), although other routes are known, including nucleophilic addition of a boryl anion to a chlorophosphine (B), 20 elimination of silyl halide (C), 10,11,21 and cross-coupling of a B-I species with secondary phosphines using a palladium catalyst (D). 9 Of the different synthetic options for the construction of phosphorus-carbon bonds, hydrophosphination of unsaturated carbon substrates has gained popularity in recent years.…”

Exploration of Novel α,ω‐Substituted Diphosphatrisilanes by Combining Experimental Methods and DFT Calculations

“…[7] There is also one tetraphenylated diphosphasilane known, [Ph 2 P-SiMe 2 -] 2 , synthesized by Hassler. [3] The addition of a boron moiety as a substituent on the phosphorus, led to an additional type A silicon ligand, {[(iPr 2 N) 2 B]PH-SiMe 2 -} 2 , [8] which was suitable for coordination as seen in a molybdenum tetracarbonyl complex {[(iPr 2 N) 2 B]PH-SiMe 2 -} 2 Mo(CO) 4 . [9] Coordination of diphosphasilanes B is even less explored; cleavage of the hydrogen of [PhPH-SiMe 2 -] 2 and subsequent reaction with transition metals led to cyclic compounds of the type {-SiMe 2 -PPh-M-PPh-SiMe 2 -}.…”

“…Diphosphasilanes synthesized by hypersilylphosphane coupling (R = H, Li, TMS). [16] Further expanding on the pathway used by Flock, a novel 2,4-dihydrogenated phosphapentasilane precursor (7) and a 2,4-dihalogenated phosphapentasilane precursor (8), containing three silicon atoms in the backbone, were synthesized (Figure 3). The usefulness of this precursor used as reaction partner with alkali metal phosphanides to form novel α,ω-phosphorus substituted diphosphanes will be highlighted.…”

“…All the work is supported by DFT calculations to aquire NMR data as well as structural properties of minimum structures. In addition, the spatial arrangement of the calculated minima structures of the compounds will be compared with the single-crystal X-ray structures of the novel 2,4-dihydroand dichloropentasilanes (7,8).…”