Metal‐only Lewis Pairs of Rhodium with s, p and d‐Block Metals

Abstract

Metal‐only Lewis pairs (MOLPs) in which the two metal fragments are solely connected by a dative M→M bond represent privileged architectures to acquire fundamental understanding of bimetallic bonding. This has important implications in many catalytic processes or supramolecular systems that rely on synergistic effects between two metals. However, a systematic experimental/computational approach on a well‐defined class of compounds is lacking. Here we report a family of MOLPs constructed around the RhI precursor [(η5‐C5Me5)Rh(PMe3)2] (1) with a series of s, p and d‐block metals, mostly from the main group elements, and investigate their bonding by computational means. Among the new MOLPs, we have structurally characterized those formed by dative bonding between 1 and MgMeBr, AlMe3, GeCl2, SnCl2, ZnMe2 and Zn(C6F5)2, as well as spectroscopically identified the ones resulting from coordination to MBArF (M=Na, Li; BArF−=[B(C6H2‐3,5‐(CF3)2)4]−) and CuCl. Some of these compounds represent unique examples of bimetallic structures, such as the first unambiguous cases of Rh→Mg dative bonding or base‐free rhodium bound germylene and stannylene species. Multinuclear NMR spectroscopy, including 103Rh NMR, is used to probe the formation of Rh→M bonds. A comprehensive theoretical analysis of those provides clear trends. As anticipated, greater bond covalency is found for the more electronegative acids, whereas ionic character dominates for the least electronegative nuclei, though some degree of electron sharing is identified in all cases.

Zintl cluster supported low coordinate Rh(i) centers for catalytic H/D exchange between H2and D2

“…Thus their reactivity is predicted to mimic that of more traditional organometallic nucleophiles such as Cp*Rh(PMe 3 ) 2 . 29…”

Synthesis and reactivity of heterometallic complexes containing Mg- or Zn-metalloligands

“…20 In addition, the Grignard reagent MeMgBr could be regarded as a metal Lewis acidic fragment that interacts with the metal Lewis base (η 5 -C 5 Me 5 )Rh(PMe 3 ) 2 16 to access metal-only Lewis pairs 17 (Scheme 6), which represent highly unusual examples containing unsupported Rh–Mg dative bonds. 21…”

“…Later, Campos et al reported a series of heterobimetallic Zn–TM complexes, such as (bhq) 2 PdZn(C 6 F 5 ) 2 (bhq: cis -bis(1,10-benzo[ h ]quinolinato) 46a , (bhq) 2 PdZn(C 6 H 5 ) 2 46b , (η 5 -C 5 Me 5 )Rh(PMe 3 ) 2 ZnMe 2 47a , and (η 5 -C 5 Me 5 )Rh(PMe 3 ) 2 Zn(C 5 F 5 ) 2 47b (Scheme 15), from the reactions of different non-hydride transition metal complexes with dialkyl zinc compounds. 21,40 Recently, heterobimetallic Zn–Pt complexes, (Cy 3 P) 2 PtZnBr 2 48a and ( t Bu 3 P) 2 PtZn(C 6 F 5 ) 2 48b , bearing Pt–Zn dative bonds were synthesized through the reactions of Pt(PR 3 ) 2 (R = Cy, t Bu) with ZnBr 2 and Zn(C 6 F 5 ) 2 , respectively. 41…”

Revealing the Role of the Cyaphide Ion as a Bridging Ligand in Heterometallic Complexes

“…Encouraged by this finding, we sought to apply this protocol to another transition metal. The rhodium(I) piano‐stool complex Rh(Cp*)(PMe 3 ) 2 is known to react as a metal‐centered Lewis base, [24] therefore we reasoned that it too would be an appropriate precursor to bridging cyaphido complexes. Heating a mixture of A and Rh(Cp*)(PMe 3 ) 2 at 80 °C overnight results in the liberation of trimethylphosphine (observed by 31 P{ 1 H} NMR spectroscopy), and the formation of the gold(I)/rhodium(I) bridging cyaphide complex Au(IDipp)(μ 2 −C≡P)Rh(Cp*)(PMe 3 ) ( 3 ; Scheme 2).…”