•Three titanium(IV) imido complexes with dianionic triazapentadienyl were synthesized.•Their formation involved N-centred nucleophile, metathesis and elimination reactions.•Complexes 1 and 2 showed moderate catalytic activity in ethylene polymerization.The reaction of PhN(Li)SiMe3 with dimethylcyanamide or 1-piperidinecarbonitrile and further with one third equiv of TiCl4(THF)2 led via Me3SiCl elimination to novel five-coordinate titanium(IV) triazapentadienates L1L2TiCl (L1 = [N(Ph)C(R)NC(R)N(R′)]−, L2 = [N(Ph)C(R)NC(R)N]2−; 1, R = dimethylamino, R′ = H; 2, R = 1-piperidino, R′ = SiMe3; 3, R = dimethylamino, R′ = SiMe3). The crystal structure studies of 1–3 revealed dianionic triazapentadienate binding of the metal center. The very short bond length of TiN implies the multiple bond character and imido feature of the ligand. The catalytic activity of selected complexes 1 and 2 in the polymerization of ethylene is reported.Novel titanium(IV) imido complexes containing dianionic triazapentadienyl derivative ligand were synthesized and characterized. Their formation and catalytic potential in ethylene polymerization were also involved.

•A N-functionalized organoamide zirconium complex was prepared.•The complex has been characterized by single crystal X-ray diffraction.•The catalytic behaviors of the complex were investigated.Treatment of anhydrous ZrCl4 with 3 equiv of lithium 2-(trimethylsilyl) amino-pyridine (TMS-Apy) afforded [(TMS-Apy)3ZrCl] (1) in high yield. The structure of 1 was characterized by spectroscopic and X-ray crystallographic method. The X-ray analysis revealed that 1 was a mononuclear zirconium complex with seven-coordinate metal center and the η2-coordinated aminopyridinato ligands arranged in a propeller-like fashion. Complex 1 activated with methylaluminoxane (MAO) showed good activity towards ethylene polymerization.A novel N-functionalized organoamide zirconium complex [(TMS-Apy)3ZrCl] (1) has been prepared and characterized. Complex 1 was found to be active for ethylene polymerization.

The reaction of PhN(Li)SiMe3 with 2 equiv. of dimethylcyanamide with further addition of 2 equiv. of CpTiCl3 led via Me3SiCl elimination to dinuclear titanium(IV) compound 1. The reaction of DippN(Li)SiMe3 with 1 equiv. of dimethylcyanamide with further addition of 1 equiv. of CpTiCl3 afforded centrosymmetric dimeric titanium(IV) compound 2 and mononuclear 3 with the elimination of Me3SiCl. The zirconium(IV) compound 4 was obtained by the addition reaction of PhN(Li)SiMe3 with 2 equiv. of dimethylcyanamide and metathesis reaction with ZrCl4. X-ray diffraction studies of 1–4 establish the dinuclear titanium(IV) structure in 1, half-titanocene of 2 and 3, and a propeller-like complex fragment of 4. Complexes 2 and 4 show moderate or high activities in the polymerization of ethylene upon activation with methylaluminoxane (MAO).

•Three triazapentadienyl zinc and aluminum complexes were prepared.•Their structures were confirmed by single crystal X-ray diffraction.•The catalytic properties of the complexes were investigated.Bis(1,3,5-triazapentadienate)zinc complexes [N(Ph)C(R)NC(R)N(SiMe3)]2Zn (R = NMe2, 1; 1-piperidino, 2) and (1,3,5-triazapentadienate)aluminum dichloride [N(Ph)C(NMe2)NC(NMe2)N(SiMe3)]AlCl2·C9H18N6 (3) were synthesized and structurally characterized by X-ray crystallography and spectroscopic techniques. The X-ray structures of 1–3 showed that they crystallize in the triclinic system and prefer coordination to the zinc and aluminum centers via the terminal N atoms of the NCNCN ligand backbone, affording tetrahedral geometry. The catalytic properties of 1 and 2 were evaluated.Three 1,3,5-triazapentadienate–zinc and 1,3,5-triazapentadienate–aluminum complexes are reported. Their structural features are discussed and their catalytic properties have been evaluated.

A novel non-symmetric aliphatic benzamidinato zirconium complex, [{CyNC(Ph)(NSiMe3)}2ZrCl2] (Cy = cyclohexyl) (1) has been readily prepared via the reaction of freshly prepared aliphatic lithium benzamidinate with zirconium tetrachloride. Complex 1 has been characterized by various spectroscopic techniques, elemental analysis, and single-crystal X-ray diffraction analysis. Complex 1 has a distorted pseudo-octahedral structure. Catalytic studies showed that the zirconium complex was active for ethylene polymerization with the activity of 6.66 × 104 g PE/mol Zr h. The influences of Al/Zr molar ratios, ethylene pressures and reaction temperature on the activities were investigated.A novel non-symmetric aliphatic benzamidinato zirconium complex [{CyNC(Ph)(NSiMe3)}2ZrCl2] (Cy = cyclohexyl) (1) has been prepared and characterized. Complex 1 was found to be active for ethylene polymerization.Highlights► A novel non-symmetrical aliphatic zirconium benzamidinate was prepared. ► The complex has been characterized by single crystal X-ray diffraction. ► The catalytic behaviors of the complex were investigated.

Addition reactions of MN(R)SiMe3 (R = Ph or SiMe3, M = Li or Na) to 2 equivalents of α-hydrogen-free 1-piperidinecarbonitrile generated [M{N(R)C(R′)NC(R′)N(SiMe3)}]2 [(1a), R = SiMe3, R′ = 1-piperidino, M = Li; (1b), R = Ph, R′ = 1-piperidino, M = Li; (1c), R = Ph, R′ = 1-piperidino, M = Na] which further reacted with MCl2 (M = Fe, Co) to give M[{N(SiMe3)C(R′)}2N]2 [R′ = 1-piperidino, M = Fe (2); Co (3)] and M[N(Ph)C(R′)NC(R′)N(SiMe3)]2 [R′ = 1-piperidino, M = Fe (4); Co (5)], respectively. In each of the crystalline complexes 2–5 the MNCNCN rings are planar. The Fe and Co centers in 2–5 feature a tetrahedral environment in N, N′-1,5-chelated fashion. The molecular structures of 2–5 are presented. Furthermore, the thermal properties of the four complexes have been investigated.Four iron and cobalt complexes bearing 1,3,5-triazapentadienyl ligands have been synthesized from insertion reactions of the amido ligands into the –CN functionality, followed by 1,3-silyl migrations. These six-electron monoanionic ligands are bound to the metal center in N,N′-1,5-chelated fashion as good σ- and π-donors.

Addition reactions of lithium bis(trimethylsilyl)amide with dimethylcyanamide lead to novel lithium salts of 6-((trimethylsilyl)amido)-2,4-bis(dimethylamino)[1,3,5]triazines [LLi(D)]2 (L = NC(NMe2)NC(NMe2)NC(NSiMe3); D = Me2NCN (1), Et2O (2)) and to the Mn and Co complexes [LL′M] (L′ = N{N(SiMe3)C(NMe2)}2; M = Mn (3), Co (4)); the structures of crystalline 1, 3, and 4 are reported. Their formation involves trimethylsilyl shifts, ring formation, and unusual Me2NSiMe3 elimination.

The reaction of a Et2O solution of LiN(Cy)SiMe3 (Cy = cyclohexyl) with PhCN in the presence of the Lewis-base donor tetrahydrofuran (THF) or Me2N(CH2)2NMe2 (TMEDA) gave the THF- or TMEDA-solvated unsymmetrical aliphatic lithium benzamidinato compound [{PhC(NCy)(NSiMe3)}Li(THF)]2 (1) or [{PhC(NCy)(NSiMe3)}Li(TMEDA)] (2). Treatment of LiN(Cy)SiMe3 with PhCN in diethyl ether, and further with CuCl, MgBr2(THF)2 or ZrCl4 at a ratio of 1:1, 2:1 and 3:1 allowed the formation of novel metal complexes [{PhC(NCy)(NSiMe3)}Cu]2 (3), [{PhC(NCy)(NSiMe3)}2Mg(OEt2)] (4) and [{PhC(NCy)(NSiMe3)}3ZrCl] (5), respectively. The X-ray structures of complexes 1–4 are presented. Complex 5/MAO system allows the moderate polymerization of ethylene.

Treatment of the appropriate lithium or sodium 2,4-N,N′-disubstituted 1,3,5-triazapentadienate [RNC(R′)NC(R′)N(SiMe3)M]2 (R = Ph, 2,6-iPr2−C6H3(Dipp) or SiMe3; R′ = NMe2 or 1-piperidino; M = Li or Na) with one or half equivalent portion of MgBr2(THF)2 in Et2O under mild conditions furnishes in good yield the first structurally characterized molecular magnesium 2,4-N,N′-disubstituted 1,3,5-triazapentadienates [DippNC(NMe2)NC(NMe2)N(SiMe3)MgBr]2 (1), [{RNC(R′)NC(R′)N(SiMe3)}2Mg] (R = Ph, R′ = NMe2 2; R = Ph, R′ = 1-piperidino 3; R = SiMe3, R′ = 1-piperidino 4). The solid-state structure of 1 is dimeric and those of 2, 3, and 4 are monomeric. The ligand backbone NCNCN in 1 adopts a W-shaped configuration, while in 2, 3 and 4 adopts a U-shaped configuration.

2,4-N,N′-Disubstituted 1,3,5-triazapentadienyl ligands as their lithium salts [Li{(N(R)C(R′))2N}]2 [where R = SiMe3 here and hereafter and R′ = dimethylamino (1) or 1-piperidino (2)] were synthesized via the reactions of LiN(SiMe3)2 with 2 equiv of the α-hydrogen-free carbonitrile dimethylcyanamide or 1-piperdinecarbonitrile and used in the isolation of the two-coordinate copper(I) complexes [Cu{(N(R)C(R′))2N}]2 [R′ = dimethylamino (3) and 1-piperidino (4)]. Complex 2 features a twisted W-shaped ligand backbone in the solid state. Complexes 3 and 4 show an unusual 12-membered ring dinuclear copper(I) triazapentadienyl and a less expressed ability to form a stable delocalized triazapentadienyl system.

Addition reaction of ArN(SiMe3)M (Ar = Ph or 2,6-iPr2−C6H3 (Dipp); M = Li or Na) to 2 equivalents of α-hydrogen-free nitrile RCN (R = dimethylamido) gave the dimeric [M{N(Ar)C(NMe2)NC(NMe2)N(SiMe3)}]2 (1a, Ar = Ph, M = Li; 1b, Ar = Ph, M = Na; 1c, Ar = Dipp, M = Li). 1d was obtained by hydrolysis of 1c at ambient temperature. Treatment of a double ratio of 1a or 1b with anhydrous MCl2 (M = Mn, Fe, Co) yielded the 1,3,5-triazapentadienato complexes [M{N(Ph)C(NMe2)NC(NMe2)N(SiMe3)}2] (M = Mn, 2; Fe, 3; Co, 4) and with NiCl2·6H2O gave [M{N(Ph)C(NMe2)NC(NMe2)N(H)}2] (M = Ni, 5). Treatment of an equiv of 1c with anhydrous CuCl in situ and in air led to complexes [{N(Dipp)C(NMe2)NC(NMe2)N(SiMe3)}CuPPh3] 6 and [Cu{N(Dipp)C(NMe2)NC(NMe2)N(H)}2] 7, respectively. 1c, 1d, and 2−7 were characterized by X-ray crystallography and microanalysis. 1c, 1d, 5, and 6 were well characterized by 1H, 13C NMR, 1c by 7Li, and 6 by 31P NMR as well. The structural features of these complexes were described in detail.