Mixed‐Metal Lanthanide–Iron Triple‐Decker Complexes with a cyclo‐P₅ Building Block

Abstract

Triple-and multidecker sandwich complexes have been discussed in the last decades for their unique electrical and magnetic properties. The organic spacer between the metals may facilitate intermetallic electronic communication, which has a high potential for molecular electronics.[1] A number of one-dimensional organometallic sandwich molecular wires (SMWs) have been extensively studied. Thus, the multilayer vanadium-arene (Ar) organometallic complexes [V n (Ar) m ], which can be produced in a molecular beam by laser vaporization, are a class of one-dimensional molecular magnets.[2] Ferrocene-based molecular wires have been synthesized in the gas phase and characterized by mass spectroscopy.[3] It was calculated that these compounds have half-metallic properties with 100 % negative spin polarization near the Fermi level in the ground state.[4] In contrast to this investigation in the gas phase, studies on related organometallic triple-and multidecker sandwich complexes containing f-block elements (lanthanides or actinides) in condensed phase remain rare;[5] studies were mostly on the cyclooctatetraene ligand and its derivatives. The only rare-earth-element triple-decker complex with heterocycles is the low-valent scandium 1,3,5-triphosphabenzene complex [{(h 5 -P 3 C 2 tBu 2 )Sc} 2 (m-h 6 :h 6 -P 3 C 3 tBu 3 )], which was obtained by cocondensation of scandium vaporized in an electron beam with an excess of the phosphaalkyne tBuCP.[6] Apart from organometallic compounds, triple-and multidecker sandwich complexes of the 4f elements consisting of "salen" type Schiff base ligands, [7] phthalocyanines, and porphyrins have been extensively studied because these compounds exhibit tunable spectroscopic, electronic, and redox properties, and different extents of intramolecular p-p interactions.[8] Despite these promising physical properties further investigations on 4f elements based triple-and multidecker sandwich complexes are obviously hampered by the limited variety of ligands that have been attached to the metal centers to date. Based on these considerations, we present herein mixed d/f-block-metal triple-decker complexes with a purely inorganic all-phosphorus middle deck.In contrast to d-block chemistry, where purely inorganic ring systems of Group 15 elements such as P 5 and P 6 , [9] As 5 , [9c] and Sb 5 [10] are well-established, there is no analogy with the fblock elements to date. On the other hand, it was shown only recently that rare-earth elements can stabilize highly reactive main-group species such as N 2 3À .[11] Although some heavier Group 15-lanthanide compounds, such as phosphides (Ln À PR 2 ), [12] arsenides (Ln À AsR 2 ), [12d, 13] stibides (Ln À Sb 3 ), [14] and bismutides (LnÀBiÀBiÀLn) [15] are known, the first molecular polyphosphide of the rare-earth elements, [(Cp* 2 Sm) 4 P 8 ] (Cp* = h 5 -C 5 Me 5 ), was recently synthesized. [16] The structure of the complex is very rare and can be described as a realgartype P 8 4À ligand trapped in a cage of four samarocenes. As no triple-decker sandw...

P4 Activation by Lanthanum and Lutetium Naphthalene Complexes Supported by a Ferrocene Diamide Ligand

“…For La2-naph, the corresponding proton chemical shifts were at 4.3 and 2.7 ppm, each shifted upfield by about 1 ppm. However, the 13 C chemical shifts for La2-naph were similar to the other metal naphthalene complexes. The reason for the unexpected proton upfield shifting for La2-naph is not clear to us now, especially since the 13 C chemical shifts were in the normal range.…”

“…Compounds La2-naph and Lu2-naph were characterized by 1 H and 13 C NMR spectroscopy and elemental analysis. While the proton chemical shifts of Lu2-naph were close to the corresponding proton chemical shifts of Y2-naph and Sc2-naph, the proton chemical shifts of the naphthalene fragment in La2-FULL PAPER naph were significantly upfield compared to the other three metal naphthalene complexes.…”

“…1 H NMR (500 MHz, C7D8, 25 °C) δ, ppm: broad peaks centered at 4.11, 3.81, and 3.28 (br, 24H total, CH on Cp rings), 3.97 (br s, 6H, CH2O on THF), 3.56 (br s, 6H, CH2O on Et2O), 1.55 (br s, 6H, CH2CH2O on THF), 1.14 (br s, 9H, CH3CH2O on Et2O), 1.10 (s, 54H, (CH3)3C), and 0.44 (br s, 36H, SiCH3). 13 Supporting Information (see footnote on the first page of this article): Experimental details, NMR spectra, and X-ray data.…”

“…[5,6] On the contrary, early transition metal mediated P4 activation is much less investigated and rare-earth examples are rare. [7][8][9][10][11][12][13] Roesky et al reported the formation of (Cp * 2Sm)4P8 from slow vapour transfer of P4 into a toluene solution of Cp * 2Sm. [12] Our group recently reported a direct P4 activation by well defined scandium and yttrium naphthalene or anthracene complexes under ambient conditions.…”

Rare Earth Arene-Bridged Complexes Obtained by Reduction of Organometallic Precursors

“…Among early transition metals, rare earths are more Lewis acidic, leading to a more pronounced mismatch in binding between their ions and phosphorous anions (Cui et al, 2008;Lv et al, 2011;Masuda et al, 2008). All known examples of lanthanide (Chart 22) (Konchenko et al, 2009;Li et al, 2011) and actinide (Scherer et al, 1991;Stephens, 2004) mediated P4 activation had involved low-valent metal complexes prior to our reports. For example, (Cp*2Sm)4P8 was obtained by vapor transfer of P4 to a toluene solution of Cp*2Sm over the course of a week in a low yield (ca.…”