Syntheses and Structures of Sterically Congested Linear and Branched Cobalta[n]triangulanes

Abstract

Treatment of {eta(5):eta(1)[2-(di-tert-butylphosphanyl-P)ethyl]cyclopentadienyl}cobalt(I) chloride (5) with methylenecyclopropane (3) or bicyclopropylidene (4), as well as with their spirocyclopropanated analogues methylenespiropentane (7), cyclopropylidenespiropentane (10), or 7,7'-bi(dispiro[2.0.2.1]heptylidene) (15) in the presence of sodium amalgam at -50 degrees C, furnished the stable cobalt complexes 6, 9, 8, 11, and 16, respectively, in 72, 83, 84, 86, and 54 % isolated yield, respectively. The complexes 14 and 16 were also obtained by ligand exchange of the ethene complex {eta(5):eta(1)[2-(di-tert-butylphosphanyl-P)ethyl]cyclopentadienyl}(eta(2)-ethene)cobalt(I) (12) with 13 and 15 in 79 and 52 % yield, respectively. The X-ray crystal-structure analyses of complexes 9, 14, and 16, as well as the NMR-spectroscopic data of all complexes, reveal that they can be regarded as linear and branched cobalta[n]triangulanes. The thermal stability of complexes 6, 8, and 9 up to 109, 145, and 160 degrees C was determined by differential thermal analysis-thermogravimetry (DTA-TG) analysis.

Syntheses, Structural Characterization, and Kinetic Investigations of Metalla[3]triangulanes: Isoelectronic Nickel(0) and Copper(I) Complexes with Bicyclopropylidene (bcp) and Dicyclopropylacetylene (dcpa) as Ligands

“…In addition, a severe bending of the cyclopropane moieties is revealed in the molecular structure. This is a consequence of the strong back‐bonding effect [9,10] which also leads to a remarkably longer double bond [1.422(4) Å, 9.0 %] of the coordinated ligand (Table 1) in comparison to the free molecule of 1 [1.304(2) Å] [4,22] . Interestingly, the elongation of the C=C distances in 1,5‐cyclooctadiene [1.340(3) Å], [23] ethylene [1.337(2) Å], butadiene [1.342(1) Å], [24] and styrene [1.325(2) Å] [25] upon formation of similar nickel complexes is equal to Δ=0.053, [26] 0.055, [27] 0.073, [28] and 0.118 Å [27] .…”

The First Cyclopentadienylalkylphosphane Nickel Chelates: Synthesis, Structures, and Reactions

“…Furthermore, such chelate complexes show enhanced stability relative to the corresponding unchelated analogues. This makes possible the formation of stable complexes with unusual ligands, such as cyclopropene and cyclopropenone acetal complexes 1 and 2 , [2, 3] methylenecyclopropane and bicyclopropylidene complexes 3 ,4, 5 as well as spirocyclopropane derivatives such as 4 5 with the cobalt chelate system, which has been investigated in our group for some time.…”

The First Late‐Transition‐Metal Cyclopentadienyl Chelate Complexes with Silylphosphane or Secondary Phosphane Tethers

“…The respective ligand system is generated by nucleophilic opening of spiro[2.4]hepta-4,6diene with lithium tert-butylphosphide. Cyclopentadienyl chelate complexes with anionic tethers.In the context of our interest in cyclopentadienylalkylphosphane chelates of late-transition-metals such as cobalt [17][18][19][20][21][22][23][24][25][26][27][28][29] and nickel, [11,13] we noticed that phosphido chelates such as 9 are comparatively rare and known only for early-transition-metals such as group 4 metals, [15,[30][31][32][33] lanthanides, [34] or niobium. Treatment of lithium tert-butylphosphide with tert-butylchlorodimethylsilane or with chlorotriisopropylsilane affords the respective secondary silylphosphanes.…”