An H‐Substituted Rhodium Silylene

Abstract

Divergent reactivity of organometallic rhodium(I) complexes, which led to the isolation of neutral rhodium silylenes, is described. Addition of PhRSiH2 (R=H, Ph) to the rhodium cyclooctene complex (iPrNNN)Rh(COE) (1‐COE; iPrNNN=2,5‐[iPr2P=N(4‐iPrC6H4)]2N(C6H2)−, COE=cyclooctene) resulted in the oxidative addition of an Si−H bond, providing rhodium(III) silyl hydride complexes (iPrNNN)Rh(H)SiHRPh (R=H, 2‐SiH2Ph; Ph, 2‐SiHPh2). When the carbonyl complex (iPrNNN)Rh(CO) (1‐CO) was treated with hydrosilanes, base‐stabilized rhodium(I) silylenes κ2‐N,N‐(iPrNNN)(CO)Rh=SiRPh (R=H, 3‐SiHPh; Ph, 3‐SiPh2) were isolated and characterized using multinuclear NMR spectroscopy and X‐ray crystallography. Both silylene species feature short Rh−Si bonds [2.262(1) Å, 3‐SiHPh; 2.2702(7) Å, 3‐SiPh2] that agree well with the DFT‐computed structures. The overall reaction led to a change in the iPrNNN ligand bonding mode (κ3→κ2) and loss of H2 from PhSiRH2, as corroborated by deuterium labelling experiments.

Different Reactivities of (5-Ph2P-Ace-6-)2MeSiH toward the Rhodium(I) Chlorides [(C2H4)2RhCl]2 and [(CO)2RhCl]2. Hirshfeld Atom Refinement of a Rh–H···Si Interaction

“…The observed 1 J (Rh–H) value is similar to the J value of 27 Hz reported for a Rh­(III) complex derived from the pincer ligand II′ (Scheme ), namely [Cy 2 P­( o -C 6 H 4 )] 2 SiMe-Rh­(H)­Cl, but slightly larger than e.g. in rhodium­(III) silyl hydrides of the type ( i Pr NNN)­Rh­(H)­SiHRPh ( i Pr NNN = 2,5-[ i Pr 2 P = N­(4- i PrC 6 H 4 )] 2 N­(C 6 H 2 ) − ) reported at 26 Hz (R = H) and 26 Hz (R = Ph) . They are also marginally larger than in the phosphinodisilane [RhH­{κ 3 ( P , Si , Si )-PhP­( o -C 6 H 4 CH 2 Si i Pr 2 ) 2 }] with 1 J (Rh–H) = 25 Hz or in Xantphos rhodium­(III) species of the type RhHX 1 X 2 {xant­(P i Pr 2 ) 2 } (X 1 , X 2 = H, Cl, OTf; xant = 9,9-Me 2 -4,5-( i Pr 2 P) 2 -C 12 H 6 O) binding one or two hydrides, giving rise to J couplings of 24–26 Hz .…”

An Iminophosphonamido‐Chlorosilylene as a Strong σ‐Donating NHSi Ligand: Synthesis and Coordination Chemistry

“…[14a] Notably, a donor-accepter Rh1!Si1 backdonation (18.31 kcal mol À1 ) was confirmed by second-order perturbation theory. This value is comparable to the corre- 5), Rh1-Cl1 2.3726( 7), Si1-Cl2 2.1146( 7), N1-Si1 1.8265( 15), N2-Si1 1.8249( 16); Si1-Rh1-Si1* 94.03( 3), Si1-Rh1-Cl1 132.985 (13). sponding back-donation energies (22.9 and 20.8 kcal mol À1 ) from osmium to silicon atoms in a silylyne-osmium complex reported by Tilley and Hall.…”

“…The SiÀRh bond lengths involving the chlorosilylene ligands [Si2-Rh1: 2.342(1) ; Si3-Rh1: 2.322 (1) ] are comparable to those reported for NHSicoordinated Rh I complexes [2.2273(7)-2.3289(6) ]. [9] It is noteworthy that the Si1-Rh1 bond [2.133(1) ] is still shorter than those observed in intramolecular base-stabilized silylene complexes of the type k 2 -N,N-( iPr NNN)(CO)Rh=SiRPh [R = H: 2.262(1) ; R = Ph: 2.2702( 7) ; iPr NNN = 2,5-[ i Pr 2 P = N(4-i PrC 6 H 2 )] 2 N(C 6 H 2 ) À ] [13] and N-hetero-Rh-metallacyclic silylenes [2.138( 1)-2.182( 1) ], which exhibit significant Rh!Si p-back-donation character. [14] Consequently, this bonding feature clearly indicates a Si = Rh double bond character.…”

“…All hydrogen atoms and one solvent molecule are omitted for clarity. Selected bond lengths [] and angles [8]: Rh1-Si1 2.1605(5), Rh1-Cl1 2.3726(7), Si1-Cl2 2.1146(7), N1-Si1 1.8265(15), N2-Si1 1.8249(16); Si1-Rh1-Si1* 94.03(3), Si1-Rh1-Cl1 132.985(13).…”

An Iminophosphonamido‐Chlorosilylene as a Strong σ‐Donating NHSi Ligand: Synthesis and Coordination Chemistry

“…The Si−Rh bond lengths involving the chlorosilylene ligands [Si2‐Rh1: 2.342(1) Å; Si3‐Rh1: 2.322(1) Å] are comparable to those reported for NHSi‐coordinated Rh I complexes [2.2273(7)–2.3289(6) Å] [9] . It is noteworthy that the Si1‐Rh1 bond [2.133(1) Å] is still shorter than those observed in intramolecular base‐stabilized silylene complexes of the type κ 2 ‐ N , N ‐( i Pr NNN)(CO)Rh=SiRPh [R=H: 2.262(1) Å; R=Ph: 2.2702(7) Å; i Pr NNN=2,5‐[ i Pr 2 P=N(4‐ i PrC 6 H 2 )] 2 N(C 6 H 2 ) − ] [13] and N ‐hetero‐ Rh ‐metallacyclic silylenes [2.138(1)–2.182(1) Å], which exhibit significant Rh→Si π‐back‐donation character [14] . Consequently, this bonding feature clearly indicates a Si=Rh double bond character.…”