Structure of a Crystalline Alkali‐Metal Cyclopentadienide

Abstract

The solid potassium trimethylsilylcyclopentadienide 1 may be viewed as a “supersandwich” complex. It represents the first base‐free alkali‐metal cyclopentadienide to be obtained in crystalline form. Complex 1 contains parallel‐arranged, one‐dimensional, infinite structural units in which the potassium atoms (black) and the cyclopentadienyl rings (pentahapto‐bonded on both sides) alternate. Weak interactions exist between the strands.

Synthesis and Structural Characterization of Lithium, Potassium, Magnesium, and Heavier Group 14 Metal Complexes Derived from 2-Quinolyl-Linked (Thiophosphorano)methane

“…The potassium atom is bonded to the sulfur atom and nitrogen atom of the ligand and coordinated to the quinolyl carbon atoms of two ligands and the methine carbon of another ligand. The average K−C distance of 3.251 Å is slightly longer than those in [K{η 5 -C 5 H 4 (SiMe 3 )}] ∞ (3.027 Å) 26 29 It is noteworthy that the potassium atom is stabilized by a hard nitrogen atom and a soft sulfur atom as well as carbon atoms from the ligands without coordination to any solvent molecules. This is rarely found in the literature.…”

“…From the X-ray structure of compound 9, there is a 3.622 Å aromatic π-stacking interaction between two quinolyl rings, which further stabilizes the "open-box" framework structure. 25 Compound 10 consists of two lead atoms bridged by two methanediide carbon atoms, forming a 1,3-Pb 2 C 2 four- [Sn{μ 2 -C( i Pr 2 PS)(C 9 H 6 N-2)}] 2 (11) Sn(1)−N(1) 2.316(5) Sn(2)−N(2) 2.298(6) Sn(1)−C (10) 2.337 (7) Sn(2)−C(10) 2.318(7) Sn(1)−C (26) 2.326 (7) Sn(2)−C(26) 2.317 (7) 13 while the Pb(1)−S(2) distance of 3.141(3) Å is much longer than the reported value, suggesting that a bonding interaction between the Pb(1) and S(2) atoms is not present. The Pb−Pb distance of 3.405 Å is longer than the sum of covalent radii (3.08 Å) but is significantly shorter than the sum of van der Waals radii (4.04 Å), which indicates that a weak lead− lead interaction may be present in 10.…”

Preparation, Molecular Structure and Catalytic Behavior of (ArO)2Yb(NPh2)2K(THF)4(Ar=C6H2‐t‐Bu3‐2,4,6)

“…21 The potassium ion interacts in η 2 -fashion with C(45) and C(46) as well as C(51) and C(52), and these K-C(arene) lengths (average 0.3326(8) and 0.3361(7) nm respectively) are in the range expected for K-C(arene) interactions (0.3275-0.359 nm). 22 These lengths are a little longer than the K-C lengths observed in the alkali metal-cyclopentadienyl structures of K[C 5 H 4 (SiMe 3 )] (the shortest 0.2988(10) nm) 23 and K[C 5 (CH 2 Ph) 5 ](THF) 3 (the shortest 0.2968(5) nm). 24 When the η 2 -coordinated C(45) and C(46) atoms were considered to be a ligand, the dis- …”

catena-Poly[[(tetrahydrofuran-κO)potassium]-μ-(η5:η5)-2,3,4,5-tetramethyl-1-n-pentylcyclopentadienyl]

“…A nonparallel arrangement of the five-membered rings of the -Cp ligands essentially makes two additional coordination sites of the metal ion accessible for binding ancillary ligands. In NIBSOG and in KC 5 H 4 Si(CH 3 ) 3 (FOGMET; Jutzi et al, 1987), two rare examples of solventfree polymeric potassium complexes with nonbulky -Cp ligands, interchain Cp-K interactions complete the coordination environment of potassium. In connection with (I), it is interesting to note that a mono-and a ditetrahydrofuran adduct of KCp*, i.e.…”