Neutral and cationic enantiopure group 13 iminophosphonamide complexes

Synthesis and reactivity of enantiopure iminophosphonamide ligand L-H (L = [Ph$_{2}$P{N(R)CH(CH$_{3}$)Ph}$_{2}$]) with group 13 metal compounds has been investigated. The reaction of L-H with LiAlH$_{4}$ afforded the aluminium monohydride complex [L$_{2}$AlH]. The monochloride complexes [L$_{2}$MCl] (M = Al, Ga) were accessed by reacting corresponding MCl$_{3}$ (M = Al, Ga) with L-Li. Furthermore, the tetracoordinated aluminium cation [L$_{2}$Al]$^{+}$[GaCl$_{4}$]$^{-}$ and gallium cation [L$_{2}$Ga]$^{+}$[AlCl$_{4}$]$^{-}$ were obtained by chloride abstraction from [L$_{2}$MCl] (M = Al, Ga), respectively. The title complexes represent the first examples of enantiopure group 13 metal complexes coordinated by chiral iminophosphonamides. All complexes have been characterized by single crystal X-ray diffraction, multinuclear NMR, EA and IR studies

A Phosphine Functionalized β‐Diketimine Ligand for the Synthesis of Manifold Metal Complexes

One-size-fits-all: A β-diketimine ligand and its corresponding anion, forming a PNNP-type pocket, can stabilize various coordination polyhedral. A complete series of complexes forming seven different coordination polyhedral and coordination numbers ranging from 2 to 6 were realized. A bis(diphenyl)-phosphine functionalized β-diketimine (PNac-H) was synthesized as a flexible ligand for transition metal complexes. The newly designed ligand features symmetrically placed phosphine moieties around a β-diketimine unit, forming a PNNP-type pocket. Due to the hard and soft donor atoms (N vs. P) the ligand can stabilize various coordination polyhedra. A complete series ranging from coordination numbers 2 to 6 was realized. Linear, trigonal planar, square planar, tetrahedral, square pyramidal, and octahedral coordination arrangements containing the PNac-ligand around the metal center were observed by using suitable metal sources. Hereby, PNac-H or its anion PNac− acts as mono-, bi- and tetradendate ligand. Such a broad flexibility is unusual for a rigid tetradentate system. The structural motifs were realized by treatment of PNac-H with a series of late transition metal precursors, for example, silver, gold, nickel, copper, platinum, and rhodium. The new complexes have been fully characterized by single crystal X-ray diffraction, NMR, IR, UV/Vis spectroscopy, mass spectrometry as well as elemental analysis. Additionally, selected complexes were investigated regarding their photophysical properties. Thus, PNac-H proved to be an ideal ligand platform for the selective coordination and stabilization of various metal ions in diverse polyhedra and oxidation states

Synthesis of Unprecedented 4d/4f‐Polypnictogens

A series of 4d/4f‐polyarsenides, ‐polyarsines and ‐polystibines was obtained by reduction of the Mo‐pnictide precursor complexes [{Cp$^{t}$Mo(CO)$_{2}$}$_{2}$(μ,η$^{2:2}$‐E$_{2}$)] (E=As, Sb; Cp$^{t}$=tBu substituted cyclopentadienyl) with two different divalent samarocenes [Cp*$_{2}$Sm] and [(Cp$^{Me4nPr}$)$_{2}$Sm]. For the reductive conversion of the Mo‐stibide only one product was isolated, featuring a planar tetrastibacyclobutadiene moiety as an unprecedented ligand for organometallic compounds. For the corresponding Mo‐arsenide a tetraarsacyclobutadiene and a second species with a side‐on coordinated As$_{2}$$^{2−}$ anion was isolated. The latter can be considered as reaction intermediate for the formation of the tetraarsacyclobutadiene

Alkali Metal Complexes of a Bis(diphenylphosphino)methane Functionalized Amidinate Ligand: Synthesis and Luminescence

A novel bis(diphenylphosphino)methane (DPPM) functionalized amidine ligand (DPPM−C(N-Dipp)$_{2}$H) (Dipp=2,6-diisopropylphenyl) was synthesized. Subsequent deprotonation with suitable alkali metal bases resulted in the corresponding complexes [M{DPPM−C(N-Dipp)$_{2}$}(Ln)] (M=Li, Na, K, Rb, Cs; L=thf, Et$_{2}$O). The alkali metal complexes form monomeric species in the solid state, exhibiting intramolecular metal-π-interactions. In addition, a caesium derivative [Cs{PPh$_{2}$CH$_{2}$-C(N-Dipp)$_{2}$}]$_{6}$ was obtained by cleavage of a diphenylphosphino moiety, forming an unusual six-membered ring structure in the solid state. All complexes were fully characterized by single crystal X-ray diffraction, NMR spectroscopy, IR spectroscopy as well as elemental analysis. Furthermore, the photoluminescent properties of the complexes were thoroughly investigated, revealing differences in emission with regards to the respective alkali metal. Interestingly, the hexanuclear [Cs{PPh$_{2}$CH$_{2}$-C(N-Dipp)$_{2}$}]$_{6}$ metallocycle exhibits a blue emission in the solid state, which is significantly red-shifted at low temperatures. The bifunctional design of the ligand, featuring orthogonal donor atoms (N vs. P) and a high steric demand, is highly promising for the construction of advanced metal and main group complexes

Introduction of plumbole to f-element chemistry

Herein, we present the synthesis and characterization of heteroleptic lanthanide complexes bearing a dianionic η5-plumbole ligand in their coordination sphere. The reaction proceeds via a salt elimination reaction between the dilithioplumbole ([Li(thf)]$_2$[1,4-bis-tert-butyl-dimethylsilyl-2,3-bis-phenyl-plumbolyl] = [Li$_2$(thf)$_2$(η$^5$-L$^Pb$)]) and specifically designed [Ln(η$^8$-COT$^TIPS$)BH$_4$] precursors (Ln = lanthanide, La, Ce, Sm, Er; COT$^TIPS$ = 1,4-bis-triisopropylsilyl-cyclooctatetraenyl), that are capable of stabilizing a planar plumbole moiety in the coordination sphere of different trivalent lanthanide ions. In-depth ab initio calculations show that the aromaticity of the dianionic plumbole is retained upon coordination. Electron delocalization occurs from the plumbole HOMO to an orbital of mainly d-character at the lanthanide ion. The magnetic properties of the erbium congener were investigated in detail, leading to the observation of magnetic hysteresis up to 5 K (200 Oe s$^−1$), an unequivocal proof for single molecule magnet behavior in this system. The magnetic behavior of the erbium species can be modulated by manipulating the position of the lithium cation in the complex, which directly influences the bonding metrics in the central [(η$^5$-L$^Pb$)Er(η$^8$-COT$^TIPS$)]− fragment. This allowed us to assess a fundamental magneto-structural correlation in an otherwise identical inner coordination sphere

d/f‐Polypnictides Derived by Non‐Classical Ln (2+) Compounds: Synthesis, Small Molecule Activation and Optical Properties

Reduction chemistry induced by divalent lanthanides has been primarily focused on samarium so far. In light of the rich physical properties of the lanthanides, this limitation to one element is a drawback. Since molecular divalent compounds of almost all lanthanides have been available for some time, we used one known and two new non-classical reducing agents of the early lanthanides to establish a sophisticated reduction chemistry. As a result, six new d/f-polyphosphides or d/f-polyarsenides, [K(18-crown-6)] [Cp ''(2)Ln(E-5)FeCp*] (Ln=La, Ce, Nd; E=P, As) were obtained. Their reactivity was studied by activation of P-4, resulting in a selective expansion of the P-5 rings. The obtained compounds [K(18-crown-6)] [Cp ''(2)Ln(P-7)FeCp*] (Ln=La, Nd) are the first examples of an activation of P-4 by a f-element-polypnictide complex. Additionally, the first systematic femtosecond (fs)-spectroscopy investigations of d/f-polypnictides are presented to showcase the advantages of having access to a broader series of lanthanide compounds

3d-4f heterometallic complexes by the reduction of transition metal carbonyls with bulky Ln(II) amidinates

The redox chemistry between divalent lanthanide complexes bearing bulky amidinate ligands has been studied with 3d transition metal carbonyl complexes (iron and cobalt). The reaction of [(DippForm)(2)Sm-II(thf)(2)] (DippForm = N,N '-bis(2,6-diisopropylphenyl)formamidinate) with [Co-2(CO)(8)] resulted in the formation of a tetranuclear Sm-Co complex, [{(DippForm)(2)Sm-III(thf)}(2){(mu-CO)(2)Co(CO)(2)}2]. The product of the reaction of [(DippForm)(2)Yb-II(thf)(2)] and [Co-2(CO)(8)] gives the dinuclear Yb-Co complex [{(DippForm)(2)Yb-III(thf)}{(mu-CO)Co(CO)(3)}] in toluene. The reaction of [(DippForm)(2)Sm-II(thf)(2)] was also carried with the neighbouring group 8 carbonyl complexes [Fe-2(CO)(9)] and [Fe-3(CO)(12)], resulting in a pentanuclear Sm-III-Fe complex, [{(DippForm)(2)Sm-III}(2){(mu(3)-CO)(2)Fe-3(CO)(9)}], featuring a triangular iron carbonyl cluster core

Synthesis of Unprecedented 4d/4f‐Polypnictogens

A series of 4d/4f-polyarsenides, -polyarsines and -polystibines was obtained by reduction of the Mo-pnictide precursor complexes [{(CpMo)-Mo-t(CO)(2)}(2)(mu,eta(2:2)-E-2)] (E=As, Sb; Cp-t=tBu substituted cyclopentadienyl) with two different divalent samarocenes [Cp*Sm-2] and [(Cp-Me4nPr)(2)Sm]. For the reductive conversion of the Mo-stibide only one product was isolated, featuring a planar tetrastibacyclobutadiene moiety as an unprecedented ligand for organometallic compounds. For the corresponding Mo-arsenide a tetraarsacyclobutadiene and a second species with a side-on coordinated As-2(2-) anion was isolated. The latter can be considered as reaction intermediate for the formation of the tetraarsacyclobutadiene