Lanthanide−Transition-Metal Carbonyl Complexes. 1. Syntheses and Structures of Ytterbium(II) Solvent-Separated Ion Pairs and Isocarbonyl Polymeric Arrays of Tetracarbonylcobaltate

Abstract

Transmetalation reactions of metallic ytterbium with Hg[Co(CO)(4)](2) in the coordinating solvents pyridine and THF yield the solvent-separated ion pairs [Yb(L)(6)] [Co(CO)(4)](2) (1a, L = Pyr; 2a, L = THF). The IR spectrum of 1a in pyridine indicates that the tetracarbonylcobaltate anion is not directly bonded to the divalent Yb cation owing to the strong coordinating ability of pyridine. On the other hand, IR spectra of 2a in THF are concentration dependent. In dilute solutions there is an equilibrium between the solvent-separated ion pair and a weak contact ion pair. Higher concentrations of 2a facilitate the formation of a tight ion pair that has a low-frequency isocarbonyl absorption. Remarkably, complexes 1a and 2a are easily transformed in toluene into the two-dimensional sheetlike arrays [(Pyr)(4)Yb[(mu-CO)(2)Co(CO)(2)](2)](infinity) (1b) and [(THF)(2)Yb[(mu-CO)(3)Co(CO)](2).Tol](infinity) (2b). The two-dimensional frameworks are supported by isocarbonyl linkages. Infrared spectra of toluene solutions substantiate the existence of the isocarbonyl bridges with low-frequency absorptions at 1780 cm(-1). Compounds 1b and 2b belong to a rare class of lanthanide-transition-metal carbonyl extended arrays, only three others of which have been structurally established. Dissolving 1b in pyridine regenerates 1a, but the complete conversion of 2b into 2a cannot be achieved. Crystal data: 1a.Pyr is monoclinic, P2(1)/c, a = 11.171(1) A, b = 11.925(1) A, c = 33.978(1) A, beta = 95.10(1) degrees, Z = 4; 2a is monoclinic, C2/c, a = 17.724(1) A, b = 12.468(1) A, c = 18.413(1) A, beta = 100.34(1) degrees, Z = 4; 1b is monoclinic, C2/c, a = 11.047(1) A, b = 13.423(1) A, c = 21.933(1) A, beta = 103.49(1) degrees, Z = 4; 2b is monoclinic, C2/c, a = 28.589(1) A, b = 7.223(1) A, c = 14.983(1) A, beta = 118.90(1) degrees, Z = 4.

The “Noncoordinating” Anion Tf2N− Coordinates to Yb2+: A Structurally Characterized Tf2N− Complex from the Ionic Liquid [mppyr][Tf2N]

“…Bond lengths of 210–217 pm are found in aryloxo–ytterbium complexes, while YbO bond lengths in bridging aryloxo ligands lie in the range 224–234 pm 14. YbO bond lengths of 238–239 pm are reported for [Yb(thf) 6 ] 2+ with neutral tetrahydrofuran as a ligand 15. Unfortunately there are no structural data for Yb II –1,3‐diketone complexes available for comparison.…”

Molecular Active Sites in Heterogeneous Ir–La/C-Catalyzed Carbonylation of Methanol to Acetates

“…However, the metal−metal bond distances in these complexes exceed 5 Å. 16,17 Complexes involving the less common covalent metal− metal bonding mode (Ln−M−CO) possess metal−metal bond lengths of ∼3 Å that are typical of transition metal−lanthanide bonds. 18−21 The two remaining possible bonding modes, a halide bridged structure without a metal−metal bond or the ion pair [(solvent) 4 LaCl 2 ] + [Ir(CO) 2 I 2 ] − , can also be discounted.…”

“…The most common bonding mode is an isocarbonyl complex, Ln–OC–M (Ln = lanthanide and M = transition metal), wherein the lanthanide acts as a Lewis acid and is bound to the oxygen of one or more of the carbonyl ligands. However, the metal–metal bond distances in these complexes exceed 5 Å. , Complexes involving the less common covalent metal–metal bonding mode (Ln–M–CO) possess metal–metal bond lengths of ∼3 Å that are typical of transition metal–lanthanide bonds. − The two remaining possible bonding modes, a halide bridged structure without a metal–metal bond or the ion pair [(solvent) 4 LaCl 2 ] + [Ir(CO) 2 I 2 ] − , can also be discounted. The former motif displays metal–metal distances of ∼4 Å or more, and the latter display even larger metal–metal distances.…”

OP02.04: Cardiac biometry and function in fetuses with intracardiac echogenic foci

“…In Aryloxo‐Ytterbium‐Komplexen werden Bindungslängen von 210–217 pm gefunden, die Abstände zwischen dem Ytterbiumatom und den Sauerstoffatomen der verbrückenden Aryloxo‐Liganden liegen zwischen 224 und 234 pm 14. Mit neutralem Tetrahydrofuran als Liganden wurden Yb‐O‐Abstände von 238–239 pm für [Yb(thf) 6 ] 2+ gefunden 15. Leider existieren keine Strukturdaten von Yb II ‐1,3‐Diketonat‐Komplexen zum Vergleich.…”