Polymerization Isomerism in [{MFe(CO)₄}_n]ⁿ⁻ (M = Cu, Ag, Au; n = 3, 4) Molecular Clusters Supported by Metallophilic Interactions

Abstract

Triangular clusters [{MFe­(CO)4}3]3– (M = Cu, 4; Ag, 5; Au, 6) were selectively obtained by heating Fe­(CO)4(MIMes)2 (M = Cu, 1; Ag, 2; Au, 3; IMes = C3N2H2(C6H2Me3)2). 1–3 were synthesized by reacting Na2[Fe­(CO)4]·2thf with 2 equiv of M­(IMes)­Cl. As previously described, the direct reactions of Na2[Fe­(CO)4]·2thf with one equivalent of M­(I) salts resulted in the triangular cluster [{CuFe­(CO)4}3]3– for Cu, whereas the square clusters [{MFe­(CO)4}4]4– were formed for Ag and Au. Thus, depending on the synthetic protocol adopted, both the triangular [{MFe­(CO)4}3]3– and square [{MFe­(CO)4}4]4– polymerization isomers can be selectively obtained, at least for Ag and Au. Polymerization isomerism, that is two compounds having the same elemental compositions but different molecular weights, was investigated in [{MFe­(CO)4} n ] n− (n = 3, 4; M = Cu, Ag, Au) by means of structural and theoretical methods and the role of metallophilic interactions was computationally studied by means of the atoms-in-molecules (AIM) approach.

First Copper(I) and Silver(I) Complexes Containing Phosphanylphosphido Ligands

“…The NBO analysis revealed the weak interactions between adjacent silver atoms (10–15 kcal · mol –1 ). The distances in 2 are comparable to these observed in [Ag 2 (NO 3 ) 2 ‐{C 4 H 2 S(CONMe‐4‐C 5 H 4 N) 2 } 2 ], [Ag 2 (CF 3 CO 2 ) 2 {C 4 H 2 S(CONMe‐4‐C 5 H 4 N) 2 } 2 ] (intermolecular Ag ··· Ag = 3.48 Å) and are longer than these observed in [Ag 4 {Fe(CO) 4 } 4 ] 4– (3.036(1)–3.334(1) Å) . The arrangement around P2 and P4 atoms in 1 (∑P2 = 317.46(14)° and ∑P4 = 319.19(15)°) and P2, P4, P6 and P8 in 2 (∑P2 = 318.4(2)°, ∑P4 = 320.9(3)°, ∑P6 = 317.1(3)° and ∑P8 = 319.1(2)°) is clearly pyramidal.…”

A Comparative Experimental and Computational Study of Heterometallic Fe‐M (M = Cu, Ag, Au) Carbonyl Clusters Containing N‐Heterocyclic Carbene Ligands

“…Crystal data of the new salts were included as Supporting Information and deposited within the Cambridge Crystallographic Datacenter for sake of completeness. All these salts contained the [Ag 3 Fe 3 (CO) 12 ] 3– ( 7 ), [Ag 4 Fe 4 (CO) 16 ] 4– ( 8 ), and [Ag 5 Fe 4 (CO) 16 ] 3– ( 9 ) cluster anions, that were already described in the literature (Figures S33–S35 in Supporting Information). Their formation suggested that the Ag–IMes bond was mainly broken during work‐up, leading to homoleptic Ag–Fe–CO clusters.…”

“…In particular, attempting the isolation of 3 , crystals of [NEt 4 ] 2 [Ag(IMes) 2 ][Ag 3 Fe 3 (CO) 12 ] · solv, [NEt 4 ] 2 [HIMes] 2 [Ag 4 Fe 4 (CO) 16 ], [NEt 4 ] 4 [Ag 4 Fe 4 (CO) 16 ] · 2CH 3 CN and [NEt 4 ] 3 [Ag 5 Fe 4 (CO) 16 ] were obtained. Crystal data of the new salts were included as Supporting Information and deposited within the Cambridge Crystallographic Datacenter for sake of completeness.…”

“…Compounds 11 – 14 were spectroscopically characterized by means of IR, 1 H and 13 C{ 1 H} NMR techniques after work‐up of the reaction mixtures (see Experimental Section and Figures S13–S20 and S41–S42 in the Supporting Information). The molecular structures of 11 and 13 were previously included in a communication but not discussed in detail (see Figures S36 and S37 in Supporting Information) . Moreover, the molecular structure of the new species 12 was crystallographically determined as its 12· 2thf solvate (Figure and Table ).…”

“…In this sense, we recently reported that the thermal decomposition of the heterometallic Fe(CO) 4 {M(IMes)} 2 complexes (IMes = C 3 N 2 H 2 (C 6 H 2 Me 3 ) 2 ; M = Cu, Ag, Au) resulted in the triangular [M 3 Fe 3 (CO) 12 ] 3– clusters . Furthermore, the direct reaction of Na 2 [Fe(CO) 4 ] · 2thf with M(I) salts afforded the same triangular [Cu 3 Fe 3 (CO) 12 ] 3– cluster in the case of Cu, whereas the square species [M 4 Fe 4 (CO) 16 ] 4– where obtained for Ag and Au , .…”