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[Display omitted] Treatment of 1,4-diazabutadienes (DADs) of formula DippN=C(R)C(R)=NDipp (Dipp = 2,6-Pr 2 iC 6 H 3 , R = H or Me) with 2 or 1 equiv. of potassium metal in THF leads to the corresponding dianions (DAD2–) or radical anions (DAD•−), respectively. The subsequent salt metathesis between LnCl3 (Ln = Tb or Er) and the above dianions affords dimeric monochlorido complexes [(DAD2–)Ln(THF) 2 (μ-Cl)] 2 with bridging chlorine atoms between the lanthanides. The reaction of the radical anion species with LnCl3, if R = H, gives monomeric dichlorido complexes (DAD•−)Ln(THF) 2 Cl 2 ; however, if R = Me, the activation of one methyl group occurs, which in the reaction with TbCl3 leads to the formation of a product with shifted double bonds [DippN=C(Me)C(=CH 2)N(Dipp)]Tb(THF) 2 Cl 2. [ABSTRACT FROM AUTHOR]

A series of new half-sandwich bis(alkyl) rare-earth metal complexes coordinated by a sterically demanding 1,3,6,8-tetra-tert-butyl-carbazol-9-yl ligand [tBu4Carb]La(CH2C6H5)2(THF) (1-La), [tBu4Carb]Ln(o-NMe2C6H4CH2)2 (Ln = Sc (2-Sc), Y (2-Y), La (2-La), [tBu4Carb]Ln(CH2SiMe3)2(THF) (Ln = Sc (3-Sc), Y (3-Y)), were synthesized. 1-La, 2-La, and 2-Y were prepared by an alkane elimination protocol, while 2-Sc, 3-Sc, and 3-Y became accessible only when salt metathesis reactions of tBu4CarbK with R2Ln(THF)n+[BPh4]− were employed. X-ray analysis revealed that in all complexes the carbazolyl ligand exhibits π-coordination with metal ions. 2-Sc and 3-Sc when activated with [Ph3C][B(C6F5)4] demonstrate excellent activity in α-olefin (octene-1, nonene-1, decene-1 and 1,1-diphenyl-but-1-ene) polymerization. When H2 was used as a chain transfer agent (1 bar, rt) in the presence of 3-Sc/[Ph3C][B(C6F5)4] or 2-Y, 2-La olefin hydrogenation occurred with quantitative conversion. [ABSTRACT FROM AUTHOR]

The reactions of 1,3,5‐triazapentadiene 2,6‐iPr2C6H3NC(Ph)NC(Ph)NHC6H3iPr2‐2,6 (1) with Ln(CH2SiMe3)3(THF)2 (Ln=Y, Lu) in hexane afford bis(alkyl) complexes [2,6‐iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2‐2,6]Ln(CH2SiMe3)2(THF) (Ln=Y (2), Lu (3)) in 58 (2) and 62 (3) % yields. The X‐ray diffraction study revealed that in 3 the triazapentadienyl ligand coordinates with the Lu3+ ion in "amidinate" fashion resulting in the formation of a four‐membered metallocycle. In contrast, the reaction of 1 with the scandium analogue Sc(CH2SiMe3)3(THF)2 in toluene proceeds with the cleavage of C−N bond of 1,3,5‐triazapentadiene and leads to the formation of a dinuclear monoalkyl complex [{μ2‐2,6‐iPr2C6H3NC(Ph)N}Sc(CH2SiMe3)(THF)]2 (4) in 43 % yield. Complex 4 features κ2‐N,N‐coordination of the residual dianionic {μ2‐2,6‐iPr2C6H3NC(Ph)N}2− ligand μ‐bridging two Sc3+ centers. Alkyl complexes 2–4 were evaluated as pre‐catalysts for isoprene polymerization and hydrosilylation of unsaturated substrates with PhSiH3. [ABSTRACT FROM AUTHOR]

Bis(alkyl) complexes [(2,6‐Me2C6H3)NC(tBu)N(C6H4−2‐OMe)]M(CH2C6H4−2‐NMe2)2 (M=Sc (4), Y (5)), [(2‐OMe−C6H4N)2C(tBu)]Y(CH2SiMe3)2(THF)2 (6), supported by N,N,O‐tridentate (4, 5) and N,N,O,O‐tetradentate (6) amidinate ligands were synthesized by the alkane elimination approach reacting tris(alkyl) rare‐earth species M(R)3Xn (R=Me3SiCH2, X=THF, n=2; R=CH2C6H4−2‐NMe2, n=0) with one equivalent of amidine (2,6‐Me2C6H3)N=C(tBu)−NH(C6H4−2‐OMe) (1) or (2‐MeO−C6H4)N=C(tBu)−NH(C6H4−2‐OMe) (2). The reaction of amidine 2 with equimolar amount of Y(CH2C6H4−2‐NMe2)3 in toluene unexpectedly results in the addition of N,N‐dimethylaminobenzyl group to C=N bond of one amidinate fragment, ligand disproportionation and the formation of novel bis(amide)amidinate complex [(2‐OMe−C6H4N)2C(tBu)CH2C6H4−2‐NMe2]Y[(2‐OMe−C6H4N)2C(tBu)] (7). Complexes 4–6 were evaluated as catalysts for α‐olefins and isoprene polymerization. [ABSTRACT FROM AUTHOR]

New diphenylmethane [4‐tBu‐2‐(C3H2N2Me‐1)C6H3]2CH2 (1) bearing pendant imidazolyl groups in ortho‐positions of aromatic rings of diphenylmethane skeleton was synthesized using Stille cross‐coupling reaction between bis(4‐(tert‐butyl)‐2‐iodophenyl)methane and Bu3Sn(C3H2N2Me) in the presence of Pd(PPh3)4. Potassium diphenylmethanide [{[4‐tBu‐2‐(C3H2N2Me‐1)C6H3]2CH}K(OEt2)]2 (2K) was prepared by treatment of 1 with an equimolar amount of Lochmann‐Schlosser super base. Rare‐earth metal heteroalkyl complexes {[4‐tBu‐2‐(C3H2N2Me‐1)C6H3]2CH}Ln(CH2SiMe3)2(THF)n (Ln = Sc, n = 0 (2Sc); Y, n = 1 (2Y)) with NCsp3N pincer type diphenylmethanido ligand were synthesized by the selective sp3 CH‐bond activation of the central CH2 group in 1 by Ln(CH2SiMe3)3(THF)2. According to the X‐ray data the diphenylmethanido ligands in 2K and 2Sc perform a tridentate pincer‐type κ3‐N,C,N coordination. Complexes 2Ln were evaluated as catalysts for isoprene polymerization and hydrosilylation of alkenes and alkynes. [ABSTRACT FROM AUTHOR]

Complexes [(2-MeOC6H4N)C(tBu)N(2,6-Me2C6H3)]2LnN(SiMe3)2 (Ln = Y (2), Sm (3)) and [(2-MeOC6H4N)C(tBu)N(2,6-Me2C6H3)]CaN(SiMe3)2(THF) (4) were obtained by reacting Ln[N(SiMe3)2]3 (Ln = Y, Sm) or Ca[N(SiMe3)2]2 with [2-MeOC6H4N]C(tBu)NH(2,6-Me2C6H3) (1) in 1 : 2 or 1 : 1 molar ratios, respectively, and were isolated in 76 (2), 68 (3) and 63% (4) yields. In complexes 2 and 3, the amidinate ligands are tridentate due to the intramolecular coordination of the 2-MeO-group to the metal center. Complex 4 exhibits an unusual κ2-N,O:η3-arene coordination mode of the amidinate ligand. Complexes 2–4 initiate ring-opening polymerization (ROP) of rac-lactide (rac-LA) and ε-caprolactone (ε-CL) at room temperature and allow for conversion of 1000 equivalents of monomer into polymer within 180–230 min for rac-LA and 1–7 min for ε-CL. Complexes 2 and 3 enable the formation of atactic polymers (Pr = 0.52–0.58) featuring moderate polydispersities (PDI = 1.30–3.06 for polylactide; PDI = 1.48–2.84 for polycaprolactone). When 4 was applied, PDIs were somewhat narrower (1.28–2.43 for PLA; 1.24–2.48 for PCL). Application of the initiating systems 2–4/iPrOH (1 : 1) leads to the formation of the polymers having close values of the experimental and calculated molecular weights however does not affect strongly the molecular weight distribution. In the presence of 5 equivalents of iPrOH, complexes 2–4 initiate immortal polymerization for both rac-LA and ε-CL. The polymers feature a good match with the experimental and calculated Mn but have moderate polydispersities (PDI = 1.28–1.90 for polylactide; PDI = 1.24–1.96 for polycaprolactone). [ABSTRACT FROM AUTHOR]

We report on the synthesis, structure and investigation of magnetic properties of a series of six heteroleptic complexes of the general formula [Ln(Tpm)X3]·yMeCN (Tpm = tris(3,5-dimethylpyrazolyl)methane; Ln = Tb, Dy, Er; X− = NO3−, Cl− and y = 1 or 2). We demonstrate that the observation of a field-induced slow relaxation of magnetization is highly dependent on the anion's nature. While nitrate moieties appear to be suitable to stabilize the oblate electronic density of Dy3+, chloride ions generate an equatorial crystal-field allowing the slow relaxation of the prolate Er3+ ions. [ABSTRACT FROM AUTHOR]

Lithium silylamides 1,8-C10H6[N(SiMe3)Li(L)]2 (L = Et2O (UGRAPHIC DISPLAY="INLINE" ID="UGT1" SRC="UGT1"/); L = TMEDA (1TMEDA)), when treated with PhC≡N, formed the adducts 1,8-C10H6[N(SiMe3)Li(N≡CPh)(OEt2)][N(SiMe3)Li(OEt2)] (UGRAPHIC DISPLAY="INLINE" ID="UGT2" SRC="UGT2"/) and 1,8-C10H6[N(SiMe3)Li(N≡CPh)][N(SiMe3)Li(TMEDA)] (2TMEDA) containing one benzonitrile molecule coordinated to Li ion while the second molecule retains a coordinated L ligand. The salt metathesis reactions of LnCl3 (Ln = Y, Sm) with equimolar amounts of UGRAPHIC DISPLAY="INLINE" ID="UGT3" SRC="UGT3"/ and 2TMEDA (THF, 4 h, 40 °C) resulted in benzonitrile insertion and formation of new dianionic amido-amidinate ligands. The reactions of UGRAPHIC DISPLAY="INLINE" ID="UGT4" SRC="UGT4"/ with LnCl3 afforded ionic chloro complexes [{1,8-C10H6[NSiMe3][NC(Ph)NSiMe3]}{1,8-C10H6[N(H)SiMe3][NC(Ph)NSiMe3]}LnCl][Li(L)n] (Ln = Y, L = THF, n = 4 (3Y), Ln = Sm, L = DME, n = 3 (3Sm)), while the reaction of 2TMEDA and YCl3 leds to the formation of the neutral salt-free yttrium chloro complex {1,8-C10H6[NSiMe3][NC(Ph)NSiMe3]}YCl(TMEDA) (4). The treatment of 3Y and 4 with tBuOK enabled the synthesis of tert-butoxides [{1,8-C10H6[NSiMe3][NC(Ph)NSiMe3]}{1,8-C10H6[N(H)SiMe3][NC(Ph)NSiMe3]}YOtBu][Li(THF)4] (7) and {1,8-C10H6[NSiMe3][NC(Ph)NSiMe3]}YOtBu(TMEDA) (8). Complexes 7 and 8 were evaluated as initiators for the ring opening polymerization of rac-lactide. Neutral tert-butoxide complex 8 demonstrated significantly higher activity compared to that of ionic 7. [ABSTRACT FROM AUTHOR]

Introduction of four tBu groups into a carbazol-ylframework leads to switching of the metal–ligand bonding inthe Ln(II) and Ca complexes from σ to π. Complexes [(tBu4Carb)2Ln] (Ln = Sm, Eu, Yb, Ca)are amido analogues of metallocenes, which adopt the sandwich structureswith parallel disposition of the aromatic ligands and strong contributionof η3-mode into η5metal–ligandbonding. The DFT calculations demonstratedthat the geometry is due to steric effects (presence of the bulky tBu groups) as well as the maximization of the overlap betweenthe Sm 4f orbital and the π-type nitrogen lone pairof the carbazol-yl ligand. Coordination of DME to the metal centersin [(tBu4Carb)2M] (M = Sm,Yb) results in the heterolytic dissociation of the metal–ligandπ-bond and the formation of ionic complexes [tBu4Carb–]2[Ln2+(DME)n]. [ABSTRACT FROM AUTHOR]

A synthetic approach to rare-earth amido complexes coordinated by an ansa bis(amidinate) ligand with a 1,8-naphthalene linker was developed and allowed for the synthesis of a series of complexes [1,8-C10H6{NC(tBu)N-2,6-Me2C6H3}2]LnN(SiMe3)2(THF)n (Ln = Y, n = 0 (2); Ln = Sm, n = 1 (3); Ln = Nd, n = 1 (4)) in reasonable yields. Complexes 2–4 initiate ring-opening polymerization (ROP) of rac-lactide and enable complete conversion of 100–250 equiv. of monomer within 60–90 min at 25 °C. The obtained polylactides feature atactic structures and moderate molecular-weight distributions (Mw/Mn = 1.30–2.12). The experimental Mn values of the obtained polymers are found to be significantly higher than the calculated ones due to a slow initiation stage. Effective immortal ROP of lactide with 3–5 equiv. of isopropanol per metal center was performed using complexes 2–4 as the catalysts. The systems 2–4/iPrOH exhibit higher activities in ROP and allow for complete conversion of 100–300 equiv. of rac-lactide to polymer within 30–60 min at 25 °C and provide a living polymerization mode and very narrow polydispersities (Mw/Mn = 1.13–1.27). Complexes 2–4 as well as related borohydrides [1,8-C10H6{NC(tBu)N-2,6-Me2C6H3}2]Ln(BH4)(μ-BH4)Li(THF)2 (Ln = Sm, Nd) catalyze hydrophosphonylation of aldehydes at room temperature with good reaction rates and hydrophosphonylation of benzylideneacetone at 65 °C. [ABSTRACT FROM AUTHOR]

The reaction of Ap9MeLu(CH2SiMe3)2(thf) (Ap9Me = (2,4,6-trimethylphenyl)[6-(2,4,6-triisopropylphenyl)-pyridine-2-yl]amido ligand) with two molar equivalents of PhSiH3 affords a trinuclear alkyl-hydrido cluster [(Ap9MeLu)3(μ²-H)3(μ³-H)2(CH2SiMe3)(thf)2]. The analogous reactions with Ap9MeLn(CH2SiMe3)2(thf) (Ln = Y, Yb) are more complex and result in the formation of mixtures of two types of trinuclear alkyl-hydrido complexes [(Ap9MeLn)3(μ²-H)3(μ³-H)2(CH2SiMe3)(thf)2] and [(Ap9MeLn)3(μ²-H)3(μ³-H)2(CH2SiH2Ph)(thf)2] differing in the alkyl group. The DFT calculations of [(Ap*Y)3(μ²-H)3(μ³-H)2(CH2SiMe3)(thf)2] (Ap* = (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) confirm localization of the HOMO on the Ap*-Y(1A)-CH2SiMe3 fragment, thus explaining its enhanced reactivity. Analysis of the electron density distribution reveals the Y-H and H-H bonding interactions in the (Y)3(μ²-H)3(μ³-H)2 moiety. The NMR studies of diamagnetic complexes [(Ap9MeLu)3(μ²-H)3(μ³-H)2(CH2SiMe3)(thf)2] and [(Ap*Y)3(μ²-H)3(μ³-H)2(CH2SiMe3)(thf)2] demonstrated that the trinuclear cores are retained in the solution and revealed exchange between μ³- and μ²-bridging hydrido ligands. Complexes [(Ap*Ln)3(μ²-H)3-(μ³-H)2(CH2SiMe3)(thf)2], the cationic yttrium hydrido cluster [(Ap*Y)3(μ²-H)3(μ³-H)2(thf)3]+[B(C6F5)4]- as well as [(Ap9MeLn)3(μ²-H)3(μ³-H)2(CH2SiMe3)(thf)2] proved to be active in catalysis of ethylene polymerization under mild conditions. [ABSTRACT FROM AUTHOR]

A series of lanthanide monoborohydrido complexes {C6H4-1,2-[NC(R)NR′]2}Ln(BH4)(L) n (Ln = Y, Nd, Sm; R = tBu, Ph; R′ = 2,6-Me2C6H3, SiMe3; L = dme = dimethoxyethane, n = 1; L = thf, n = 2), in which lanthanides are coordinated by bulky ansa-bis(amidinato) ligand systems with a conformationally rigid o-phenylene linker ({C6H4-1,2-[NC(R)NR′]2}2-), were synthesized by the salt metathesis reactions of equimolar amounts of Ln(BH4)3(thf)3 and {C6H4-1,2-[NC(R)NR′]2}X2(thf) n (X = Li, Na) in thf. X-ray diffraction studies revealed that the complexes are monomeric. Depending on the denticity of the donor ligand (L = dme or thf), the terminal borohydrido ligand coordinated to the metal ion can be located in either an equatorial (L = thf) or an apical (L = dme) position. All complexes are efficient catalysts for the ring-opening polymerization of rac-lactide, which allows to convert up to 1000 equiv. of monomer into a polymer at room temperature within 10-150 min and affords atactic polylactides with high molecular weights and moderate molecular-weight distributions (1.28-2.16). Yttrium-borohydrido complexes coordinated by the {C6H4-1,2-[NC( tBu)N(2,6-Me2C6H3)]2}2- ligand system showed enhanced catalytic activity compared to that of the analogue complexes containing the {C6H4-1,2-[NC(Ph)NSiMe3]2}2- ligand. The obtained borohydrido complexes catalyze the hydrophosphonylation of benzaldehyde at room temperature with good reaction rates. [ABSTRACT FROM AUTHOR]

The reactions of the lithium silylarylamides [1,2-C6H4(NSiMe3)2Li2]2 and [1,3-C6H4(NSiMe3)2Li2] with two equivalents of PhCN [tetrahydrofuran (thf), room temp.] is an efficient synthetic approach to the ansa-bis(amidinate) ligand systems [1,2-C6H4{NC(Ph)NSiMe3}2Li2(thf)]2 and [1,3-C6H4{NC(Ph)NSiMe3}2Li2(thf)2]2, which were isolated in 54 and 60 % yields, respectively. However, lithium silylarylamide [2,6-C5H3N(NSiMe3)2Li2] containing a pyridine fragment does not undergo PhCN insertion even at elevated temperatures (thf, toluene), and the reaction affords the silylarylamido complex [2,6-C5H3N{NSiMe3}2Li2]3 ·(C6H5CN)4, which contains a coordinated benzonitrile molecule. The different reactivity of the compounds correlates with the changes in the molecular orbital energies estimated by DFT calculations. The salt metathesis reaction of anhydrous YCl3 with lithium amidinate [1,2-C6H4{NC(Ph)NSiMe3}2Li2(thf)]2 in 2:1 molar ratio (thf, 20 °C) afforded a neutral bis(amidinate) chloro yttrium complex [1,2-C6H4{NC(Ph)NSiMe3}2]YCl(thf)2 in 80 % yield. With NdCl3, the analogous reaction resulted in a trinuclear neodymium chloro ate complex with a rather unusual μ-bridging lateral coordination of the amidinate fragment [1,2-C6H4{NC(Ph)NSiMe3}2Nd(thf)(μ-Cl)(1,2-C6H4{NC(Ph)NSiMe3}2Nd{μ-Cl}2)][Li(thf)2]. [ABSTRACT FROM AUTHOR]

The outcome of salt metathesis reactions between the equimolar amounts of LnCl 3 and dimeric potassium diphenylmethanide {[2,2′-(4-MeC 6 H 3 NMe 2) 2 CH]K(THF)} 2 depends on the rare-earth metal ion. In the case of ScIII and YIII, the reactions afford chlorido-bis(diphenylmethanido) complexes {[2,2′-(4-MeC 6 H 3 NMe 2) 2 CH] 2 LnIII(μ-Cl)} 2 , in which the diphenylmethanido ligands perform bidentate κ2-CN coordination according to the X-ray data. For YbIII and SmIII, these reactions result in the spontaneous reduction of LnIII to LnII and the formation of known bis(diphenylmethanido) complexes [2,2′-(4-MeC 6 H 3 NMe 2) 2 CH] 2 LnII and the product of oxidative coupling of diphenylmethanido anions. [ABSTRACT FROM AUTHOR]

Heteroleptic Ln(II) and Ca(II) amides [tBuC(NC6H3-iPr2-2,6)2]MN(SiMe3)2(THF) (M = Yb (1Yb), Ca (1Ca)), [2-MeOC6H4NC(tBu)N(C6H3-iPr2-2,6)]LnN(SiMe3)2(THF) (Ln = Sm (2Sm), Yb (2Yb)), and [2-Ph2P(O)C6H4NC(tBu)N(C6H3-Me2-2,6)]YbN(SiMe3)2(THF) (3Yb) coordinated by bi- and tridentate amidinate ligands were obtained by the amine elimination reactions of M[N(SiMe3)2](THF)2 (M = Yb, Sm, Ca) with parent amidines in good yields. Complex [tBuC(NC6H3-iPr2-2,6)2]SmN(SiMe3)2 can be obtained only by a salt metathesis reaction of [tBuC(NC6H3-2,6-iPr2)2]SmI(THF)2 with NaN(SiMe3)2. Unlike 1Yb and 1Ca in 1Sm the amidinate ligand is coordinated to metal ion in κ¹-amido:η6-arene fashion preventing THF coordination. The derivatives of tridentate amidinate ligands bearing pendant donor 2-MeOC6H4 or 2-Ph2P(O)C6H4N groups feature nonconventional κ¹-N,κ²-O,η6-arene coordination mode. Complexes 1Ca, 1Sm, 1Yb, 2Sm, 2Yb, and 3Yb proved to be efficient catalysts for styrene hydrophosphination with PhPH2 and Ph2PH. In styrene hydrophosphination with PhPH2 all the catalysts perform excellent chemoselectivity and afford a monoaddition product--secondary phosphine (PhCH2CH2)PhPH. Moreover, all the catalysts perform hydrophosphination reactions regioselectively with exclusive formation of the anti-Markovnikov addition product. Within the series of complexes coordinated by the same amidinate ligand catalytic activity decreases in the following order 1Ca ≥ 1Sm>1Yb. The turnover frequencies were in the range of TOF ≈ 0.3-0.7 h-1. However, application of tridentate amidinate ligand allowed one to increase catalytic activity significantly: for 2Sm TOF was found to be 8.3 h-1. For the addition of PhPH2 to para-substituted styrenes catalyzed by 2Sm it was found that electron-withdrawing substituents (Cl, F) do not affect the reaction rate while electron-donating groups (tBu, OMe) noticeably slow down the reaction. [ABSTRACT FROM AUTHOR]

• Monoanionic β-triketiminate ligands feature bidentate coordination mode and are coordinated to a metal center only through two nitrogen atoms. • The ternary systems based on these complexes exhibit catalytic activity in isoprene polymerization. • The ternary systems provide very high content of cis -1,4 units (98.9%). Deprotonation of β-triketimines (2,6-Me 2 C 6 H 3 N = CMe) 3 CH (1), (2,6-Me 2 C 6 H 3 N = CMe) 2 CH(2-MeOC 6 H 4 N = C t Bu) (2), (2,6-Me 2 C 6 H 3 N = CMe) 2 CH(2,6-Me 2 C 6 H 3 N = C t Bu) (3) by equimolar amount of n -BuLi afforded lithium triketiminate complexes [(2,6-Me 2 C 6 H 3 N = CMe) 3 C]Li(THF) (4), [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]Li(THF) 2 (5), [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]Li(THF) 2 (6) in 70–80% yields. The salt metathesis reactions of LnCl 3 (Ln = Y, Nd) with 6 lead to the formation of neutral triketiminate dichloro complexes [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]LnCl 2 (THF) 2 (Ln = Y (7), Nd (8)) in 78 and 70% yields, while the analogous reaction of YCl 3 with 5 resulted in triketiminate yttrium chloro ate complex [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]Y(THF)Cl(µ2-Cl) 2 Li(THF) 2 (9). The reactions of the potassium derivatives of the related triketimines 2 , 3 with YbI 2 (THF) 2 resulted in the formation of mononuclear triketiminate iodo Yb(II) complexes [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]YbI(THF) 2 (10) and [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]YbI(TMEDA) (11). X-ray analysis revealed that in 4 and rare-earth metals complexes 7 – 11 the monoanionic β-triketiminate ligands [(2,6-Me 2 C 6 H 3 N = CMe) 3 C]−, [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]−, [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]− feature bidentate coordination mode and are coordinated to a metal center only through two nitrogen atoms. The ternary systems 7–9 /Al i Bu 3 /[CPh 3 [B(C 6 F 5) 4 exhibit catalytic activity in isoprene polymerization, allowing to carry out polymerization of 1000 equivalents in 2 h with 91–100% conversion. The obtained polyisoprenes feature high molecular weights (M n = 12.8 × 104–20.2 × 104) and moderate polydispersities (M w / M n = 2.7–3.6), however excellent control of regio- and stereoselectivities (up to 9.9% cis -1,4 units) was observed. [ABSTRACT FROM AUTHOR]

A range of stable ytterbium(II) amino ether-phenolato amido complexes of the type {LONxOy}Yb{N(SiMe3)2}, together with a congeneric samarium(II) and two calcium and strontium amido and alkyl derivatives, have been synthesized. They constitute very active, fully regioselective (anti-Markovnikov), and chemoselective precatalysts for the intermolecular hydrophosphination of styrene derivatives with PhPH2, achieving TONs up to 2150, TOFs up to 30 h-1 and chemoselectivities in the region of 95-99%. The ytterbium(II) precatalysts, among which is most prominently {LONO4}Yb{N(SiMe3)2} (3), where the ligand possesses a 15-c-5-aza-crown ether side arm, outperform their related calcium analogues, and the activity of the catalyst increases substantially with the denticity of the ligand. The rate law rate = k[p-tBu-styrene][3] was established following kinetic monitoring of the hydrophosphination of p-tBu-styrene and PhPH2 catalyzed by 3. The kinetic studies also revealed that the reactions are entropically driven and that reaction rates increase when electron-withdrawing groups are introduced at the para position of the styrenic substrate. It is proposed that these catalyzed hydrophosphination reactions proceed by rate-limiting olefin insertion into the [Yb]-phosphide bond. The chemoselective one-pot, two-step double hydrophosphination of PhPH2 with 2 equiv of styrene yields tertiary phosphines. It obeys an unusual kinetic profile where formation of the tertiary phosphine starts only when complete consumption of PhPH2 is first ensured. This sequence was used to obtain asymmetric tertiary phosphines with excellent selectivity. [ABSTRACT FROM AUTHOR]