Diantimony Complexes [Cp^R₂Mo₂(CO)₄(μ,η²‐Sb₂)] (Cp^R=C₅H₅, C₅H₄^tBu) as Unexpected Ligands Stabilizing Silver(I)_n (n=1–4) Monomers, Dimers and Chains

Abstract

Synthesis and reactivity of transition metal compounds bearing "naked" pnictogen atoms is an active research area with remarkable bonding patterns observed in the formed compounds. Within this field, intense investigations on the coordination behavior of complexes possessing P n and As n (2 � n � 5) moieties have been conducted. However, studies on heavier analogues have been ignored so far due to arduous challenges related to low yields and moderate air stability. Herein, we present the first in-depth study addressing the reactivity of organometallic complexes containing Sb-donor atoms with several Ag I salts. These reactions afforded twelve unprecedented aggregates as monomers, dimers as well as three-and four-membered chains of Ag I ions claimed in the literature to be inaccessible. Interatomic distances as well as computational evidence obtained with help of several different methods suggest the presence of Ag•••Ag interactions in all complexes containing more than one Ag I ion.

Potential of Mixed Dipnictogen Molybdenum Complexes in the Self-Assembly of Thallium Coordination Compounds

“…The dimer is stabilized by five AsSb ligands of E in which two of them each adopt a terminal η 2 -coordination mode while each of the other three units possess a bridging μ,η 2:1 -coordination mode, forming a paddle-wheel-like middle deck ( Scheme 3 c). As expected from the calculations, 36 μ,η 2:1 -coordination is favored over a μ,η 1:1 -coordination due to the comparably higher σ(E–E′) orbital energies going from As to Sb. Moreover, two of the three bridging units E form a η 1 -coordination via the lone pair of Sb, which is in accordance with the higher energy of the lone pair of Sb compared to the one of As ( Figure 1 ).…”

“…Moreover, two of the three bridging units E form a η 1 -coordination via the lone pair of Sb, which is in accordance with the higher energy of the lone pair of Sb compared to the one of As ( Figure 1 ). 36 All As–Sb bond lengths are slightly elongated [2.531(2)–2.651(3) Å] compared to free E (2.515(1) Å). 52 The As–Tl bond lengths are in the range of 3.148(2) to 3.498(3) Å and the Sb–Tl bond lengths are in between 3.526(2) and 3.874(2) Å, suggesting a partly distorted coordination of the respective σ(As–Sb) bond.…”

“…Even if the orbital energy of the σ­(P–Sb) bond is higher than for σ­(P–P) or σ­(P–As), no σ­(P–Sb) contribution to the Tl bonding is observed for C in [ C ] 2 Tl . Moreover, recently performed natural bond orbital calculations on the tetrahedranes A , D and F , show that the σ­(Sb–Sb) bond in F is higher in energy than the σ­(As–As) bond in D and the σ­(P–P) bond in A . This indicates clearly that the σ­(E–E) bond should be involved in the bonding to the unsaturated Tl I centers (Figure ).…”

“… Energy diagram of selected natural bond orbitals for compounds [{CpMo(CO) 2 } 2 (μ,η 2:2 -EE′)] (E, E′ = P, As, Sb); Figure was adapted with permission from ref ( 35 ) [Copyright 2024, Wiley-VCH], ref ( 36 ) [Copyright 2024, Wiley-VCH] and ref ( 39 ) [Copyright 2024, Wiley-VCH]. 35 , 36 , 39 …”

“…The tetrahedrane complexes [{CpMo­(CO) 2 } 2 (μ,η 2:2 -EE′)] [E = E′ = P ( A ); E = P, E′ = As ( B ); E = P, E′ = Sb ( C ); E = E′ = As ( D ); E = As, E′ = Sb ( E ); E = E′ = Sb ( F )], which are isolobal to the E 4 (E = P, As) tetrahedranes, are among the simplest in the series of E n ligand complexes, as their coordination behavior is more predictable due to only two E-donor atoms. Hence, our group studied the coordination chemistry of the homoleptic congeners [{CpMo­(CO) 2 } 2 (μ,η 2:2 -P 2 )] ( A ), ,, [{CpMo­(CO) 2 } 2 (μ,η 2:2 -As 2 )] ( D ) , and [{CpMo­(CO) 2 } 2 (μ,η 2:2 -Sb 2 )] ( F ) , in detail during the last years. Regarding the more elaborate heterodiatomic complexes [{CpMo­(CO) 2 } 2 (μ,η 2:2 -PE)] (E = As ( B ), Sb ( C )), only few reports on their coordination toward CuX (X = Cl, Br, I), (dppf)Cu (dppf = 1,1′-bis­(diphenylphosphino)-ferrocene) and M­[TEF] (M = Ag, Cu) as well as on their oxidation chemistry , are known.…”