•Silyl iron complex prepared from silazane and iron(0) complex.•Reactivity of iron hydrido complex with haloalkane, Hacac and formic acid.•Silazane as preligand.The preligand pyridine-2-amino(methyl)-dimethylsilane (1) was used to synthesize silyl iron hydride. Iron(II) hydride FeH(N(κN-C5H4N)Me(SiMe2))(PMe3)3 (2) was obtained through the reaction of 1 and Fe(PMe3)4 via the activation of one SiH bond and the coordination of nitrogen atom of pyridine. The substitution reaction of complex 2 with haloalkane (CH3I and EtBr) delivered complexes FeX(N(κN-C5H4 N)Me(SiMe2))(PMe3)3 (X = I (3); Br (4)). Complex 2 reacting with acetylacetone resulted in the formation of Fe(acac)(N(κN-C5H4N)Me(SiMe2))(PMe3)3 (5). However, the insertion products Fe(η3-OCOH)(N(κN-C5H4N)Me(SiMe2))(PMe3)3 (6) and Fe(η3-Ph-NCOH)(N(κN-C5H4N)Me(SiMe2))(PMe3)3 (7) were formed through the insertion of the unsaturated bonds into FeH bond. Complex 6 could also be synthesized through the substitution reaction of 2 with HCOOH. The molecular structures of complexes 2 and 4–7 were determined by single crystal X-ray diffraction.The synthesis and properties of silyl iron hydride bearing silazaneligand via SiH activation was reported. The chemical reactivity of silyl iron hydride was also explored.

The new N-heterocyclic σ-silyl pincer ligand HSiMe(NCH2PPh2)2C6H4 (1) was designed. A series of tridentate silyl pincer Fe and Co complexes were prepared. Most of them were formed by chelate-assisted Si–H activation. The typical iron hydrido complex FeH(PMe3)2(SiMe(NCH2PPh2)2C6H4) (2) was obtained by Si–H activation of compound 1 with Fe(PMe3)4. The combination of compound 1 with CoMe(PMe3)4 afforded the Co(I) complex Co(PMe3)2(SiMe(NCH2PPh2)2C6H4) (3). The Co(III) complex CoHCl(PMe3)(SiMe(NCH2PPh2)2C6H4) (5) was generated by the reaction of complex 1 with CoCl(PMe3)3 or the combination of complex 3 with HCl. However, when complex 3 was treated with MeI, the Co(II) complex CoI(PMe3)(SiMe(NCH2PPh2)2C6H4) (4), rather than the Co(III) complex, was isolated. The catalytic performance of complex 5 for Kumada coupling reactions was explored. With a catalyst loading of 5 mol %, complex 5 displayed efficient catalytic activity for Kumada cross-coupling reactions of aryl chlorides and aryl bromides with Grignard reagents. This catalytic reaction mechanism is proposed and partially experimentally verified.

C,N-coupling reactions of aryl chlorides and aryl amines catalyzed by a nickel catalyst are reported. 17 new amines are synthesized in yields of 57–99%. 2,6-Dichloro substituted imines can be selectively aminated. Both mono- and di-aminated products are obtained. Different substrates and amines are tested to look into the influence of electronic effects and steric hindrance to the reaction. An inexpensive and convenient base, NaOH, is used. It is an efficient way to gain access to new amines and imines.

Csp3–H bond activation in diphosphinito pincer ligand (Ph2PO(o-C6H2-(4,6-tBu2)))2CH2 (1) (POCH2OP) was achieved by Fe(PMe3)4 and CoMe(PMe3)4 to afford complexes (POCHOP)Fe(H) (PMe3)2 (2) and (POCHOP)Co(PMe3)2 (4) under mild conditions. Hydrido iron complex 2 reacted with iodomethane via the elimination of methane to deliver complex (POCHOP)FeI(PMe3) (3). The ligand replacement in Ni(PMe3)4 by 1 gave rise to nickel(0) complex (POCH2OP)Ni(PMe3)2 (5) without Csp3–H bond activation of the pincer ligand (1). It was confirmed that the hydrosilylation of aldehydes and ketones could be effectively catalyzed by hydrido iron complex 2. Complexes 2–5 were characterized by spectroscopic methods and X-ray single crystal diffraction analysis.

•Activation of the vinylic C–Cl bond.•Nickel complexes supported by trimethylphosphine ligands.•β-Chlorinated vinylic aldehyde.•β-Chlorinated cycloalkenyl acetals.The vinylic C–Cl bonds of ortho-chlorinated cycloalkenyl aldehydes (1–4) and ortho-chlorinated cycloalkenyl acetal derivatives (5–6) were successfully activated by nickel(0) and nickel(II) complexes supported by trimethylphosphine ligands. Except one trans-five-coordinate nickel(II) chloride complex trans-[Ni(PMe3)2Cl{(C5H6)CHO}] (7) as a cyclometalation product with coordination of the aldehyde group, the other six four-coordinate nickel(II) chloride complexes trans-[Ni(PMe3)2Cl{(C5H6)CHO}] (8), trans-[Ni(PMe3)2Cl{(C6H8)CHO}] (9), trans-[Ni(PMe3)2Cl{(C6H7Memeta)CHO}] (10), trans-[Ni(PMe3)2Cl{(C6H7Bu-tmeta)CHO}] (11), trans-[Ni(PMe3)2Cl{(C6H8)CH(OCH2CH2O)}] (12) and trans-[Ni(PMe3)2Cl{(C6H7Bu-t-meta)CH(OCH2CH2O)}] (13) as C–Cl bond activation products were obtained without coordination of the aldehyde groups. These complexes were characterized by IR and NMR. The crystal and molecular structures of complexes 8, 9 and 12 were determined by single crystal X-ray diffraction.Seven nickel(II) chlorides 7–13 as activation products of the vinylic C–Cl bond were successfully synthesized. The molecular structures of complexes 8, 9 and 12 were determined by X-ray single crystal diffraction.

A benzyne cobalt complex, Co(η2-C6Cl4)(PMe3)3 (2), was generated from the reaction of hexachlorobenzene with 2 equiv. of Co(PMe3)4 through selective activation of two C–Cl bonds of hexachlorobenzene. Meanwhile, the byproduct CoCl2(PMe3)3 was also confirmed by IR spectra. The cobalt(II) complex, CoCl(C6Cl5)(PMe3)3 (1), as an intermediate in the formation of aryne complex 2, was also isolated by the reaction of hexachlorobenzene with the stoichiometric amount of Co(PMe3)4. Complex 2 could be obtained by the reaction of 1 with Co(PMe3)4. Under similar reaction conditions, the reaction of Ni(PMe3)4 with hexachlorobenzene afforded only a mono-(C–Cl) bond activation nickel(II) complex, NiCl(C6H5)(PMe3)2 (5). The expected benzyne nickel complex was not formed. The structures of complexes 2 and 5 were determined by X-ray single crystal diffraction. Successful selective hydrodechlorinations of hexachlorobenzene were studied and in the presence of Co(PMe3)4 or Ni(PMe3)4 as catalysts and sodium formate as a reducing agent pentachlorobenzene and 1,2,4,5-tetrachlorobenzene were obtained. The catalytic hydrodechlorination mechanism is proposed and discussed.

Three novel [CNN]-pincer nickel(II) complexes with NHC-amine arms were synthesized in three steps. Complex 5b was proven to be an efficient catalyst for the Kumada coupling of aryl chlorides or aryl dichlorides under mild conditions.

A new PC(sp3)P ligand N,N′-bis(diphenylphosphino)dipyrromethane [PCH2P] (1) was prepared and its iron, cobalt and nickel chemistry was explored. Two pincer-type complexes [PCHP]Fe(H)(PMe3)2 (2) and [PCHP]Co(PMe3)2 (4) were synthesized in the reaction of 1 with Fe(PMe3)4 and Co(Me)(PMe3)4. 1 reacted with Co(PMe3)4 and Ni(PMe3)4 to afford Co(0) and Ni(0) complexes [PCH2P]Co(PMe3)2 (3) and [PCH2P]Ni(PMe3)2 (5). The structures of complexes 2–5 were determined by X-ray diffraction.

•Synthesis and characterization of carbonyl organoiron(II) phenolate complex•CO bond activation and subsequent decarbonylation of ester•Iron(0) complex supported by trimethylphosphine ligandsThe reactions of 8-quinolinyl esters with iron(0) complex supported by trimethylphosphine ligands afforded four hexa-coordinate chelate-[C,N] iron(II) carbonyl complexes 5–8 via CacylO bond activation and subsequent decarbonylation. Complexes 5–8 were characterized through IR, 1H NMR, 31P NMR and elemental analysis. The crystal structures of complexes 5–8 were determined by X-ray diffraction.The reactions of 8-quinolinyl esters with iron(0) complex supported by trimethylphosphine ligands afforded four hexa-coordinate chelate-[C,N] iron(II) carbonyl complexes 5–8 via CacylO bond activation and subsequent decarbonylation. The crystal structures of complexes 5–8 were determined by X-ray diffraction.

•Synthesis and characterization of sulfur-coordinated acyl nickel(II) complexes.•C–H bond activation.•Trimethylphosphine ligands.•C,S-coupling.Two sulfur-coordinated acyl nickel(II) complexes 3 and 4 Ni(S^CO)(PMe3)3 (^ = phenyl (3), 5-methylphenyl (4)) were synthesized by reactions of thiosalicylaldehyde (1) and 5-methylthiosalicylaldehyde (2) with NiMe2(PMe3)3. Complex 3 reacted with excess iodomethane affording (2-methyl-mercapto-phenyl)nickel(II) complex 5. The mechanisms of formation of 3–5 were proposed and discussed. The molecular structures of 4 and 5 were determined by X-ray diffraction.The reaction of 2-mercaptobenzaldehyde 1 (or 2-mercapto-5-methylbenzaldehyde 2) with NiMe2(PMe3)3 delivered the corresponding (acylthiophenolato)nickel(II) complexes 3 (or 4). Treatment of complex 3 with excess iodomethane afforded (2-methyl-mercapto-phenyl)nickel(II) complex 5 and no related Ni(IV) complex was found. The related mechanisms of formation of complexes 3–5 were proposed. The molecular structures of complexes 4 and 5 were determined by X-ray single crystal diffraction.

•Kumada cross-coupling reaction.•Non-activated aryl chlorides.•Grignard reagents.•Pincer [PCP]-nickel complexes.A series of pincer Ni(II) complexes were prepared and utilized in the cross-coupling reaction of non-activated aryl chlorides with Grignard reagents (The Kumada reaction). Catalytic studies revealed that complex 5 ([Ph-PNCNP-Ph]-Ni-Cl) showed the highest catalytic activity for the cross-coupling reaction in the presence of 2 mol% catalyst under mild reaction condition.A series of pincer nickel(II) complexes were prepared and utilized in the cross-coupling reaction of non-activated aryl chlorides with Grignard reagents (The Kumada reaction). Catalytic study revealed that complex 5 ([Ph-PNCNP-Ph]-Ni-Cl) showed the highest catalytic activity for the cross-coupling reaction in the presence of 2 mol% catalyst under mild reaction condition.

The reactivity of Ni(PMe3)4 with CO2, CS2 and SCNPh was studied. Although CO2 is structurally homologous compound with CS2 and SCNPh, its reactivity with Ni(PMe3)4 shows a different result with those of CS2 and SCNPh. Reactions of Ni(PMe3)4 with carbon disulfide and phenyl isothiocyanate in THF give the tetrahedral coordinate complexes (Me3P)3Ni(η2-CS2) (1) and (Me3P)3Ni(η2-SCNPh) (3), characterized by standard spectroscopic methods and X-ray diffraction. Nickel(0) complexes 1 and 3 are stabilized by the strong donor ligand PMe3. In the case of CO2, attempts to isolate the expected nickel(0) complex (Me3P)3Ni(η2-CO2) (4) proved to be unsuccessful. To further extend the utility of our nickel catalysts, the catalytic coupling of organozinc bearing different functionalities with CS2 was explored. With 10 mol% of 1 as the catalyst, MeZnMe, EtZnEt and PhZnBr coupled with CS2 to form the corresponding methyl dithiocarboxylate following esterfication of the initial products.Graphical abstractReactions of Ni(PMe3)4 with carbon disulfide and phenyl isothiocyanate in THF give the tetrahedral coordinate complexes (PMe3)3Ni(η2-CS2) (1) and (PMe3)3Ni(η2-SCNPh) (3), characterized by standard spectroscopic methods and X-ray diffraction. Reaction of Ni(PMe3)4 with carbon dioxide results in the reduction of CO2 to CO, while trimethylphosphine served as reductant giving OPMe3. The catalytic coupling reactions of organozinc with CS2 were explored with complex 1 as catalyst.Highlights► Reaction of heterocumulenes (CO2, CS2 and SCNPh) under mild conditions. ► C–S bond activation of carbon disulfide by nickel(0) complex, Ni(PMe3)4. ► C–S bond activation of phenyl isothiocyanate by nickel(0) complex, Ni(PMe3)4. ► Reduction of carbon dioxide to carbon monoxide by nickel(0) complex, Ni(PMe3)4. ► Catalytic coupling reactions of organozinc with carbon disulfide.

The synthesis and characterization of a series of Ni, Co, and Fe complexes bearing a tridentate bis(phosphino)silyl ligand (κ3-(2-Ph2PC6H4)2SiMeH, [PSiP]-H, 1) are reported. 1 reacted with Ni(PMe3)4 to afford the mononuclear nickel(0) complex [η2(Si–H)-PSiP]Ni(PMe3) (2). The halogeno nickel complexes [PSiP]Ni(X)(PMe3) (X = Cl (3), Br (4), I (5)) were synthesized in the reactions of 2 with Me3SiCl or MeHSiCl2, EtBr, and MeI. Complex 2 underwent ligand substitution of PMe3 by CO to give [η2(Si–H)-PSiP]Ni(CO) (6). Complex 3 reacted with NaOMe to deliver [PSiP]Ni(OMe)(PMe3) (7) through anionic ligand substitution, while the neutral ligand replacement of PMe3 by CO in 3 afforded the rare hexacoordinate 20-electron nickel(II) complex [PSiP]Ni(Cl)(CO)2 (8). Unexpectedly, reaction of 1 with NiMe2(PMe3)3 produced the tetracoordinate nickel(0) complex [Me2PSiP]2Ni (9). The complex [Me2PSiP]Ni(CO)2 (10) was acquired from 9 after the substitution of one [PSiP] ligand by two carbonyl ligands. 1 reacted with Co(PMe3)4 or CoCl(PMe3)3 to afford the hydrido cobalt(II) complex [PSiP]CoH(PMe3) (11) or hydrido cobalt(III) complex [PSiP]Co(H)(Cl)(PMe3) (13). Complex 12, [PSiP]Co(H)(I)(PMe3), could be obtained from the reaction of MeI with 11 or 13. Treatment of 13 with 1 equiv of MeLi or n-BuMgBr in THF resulted in the clean formation of cobalt(I) complex [PSiP]Co(PMe3)2 (14) via reductive elimination. The simple anhydrous inorganic salt NiCl2 or CoCl2 could also react with 1 in the presence of PMe3 to form the corresponding silyl complexes 3 and [PSiP]Co(Cl)(PMe3) (15) via Si–H bond cleavage. 1 reacted with Fe(PMe3)4 to form the hexacoordinate octahedral hydrido iron(II) complex [PSiP]Fe(H)(PMe3)2 (16). The molecular structures of complexes 2–5, 10, 12, 13, 15, and 16 were determined by X-ray single crystal diffraction. 16 has excellent catalytic reactivity for the reduction of aldehydes and ketones.

The C–Cl bonds of ortho-chlorinated benzamides Cl-ortho-C6H4C(O)NHR (R = Me (1), nBu (2), Ph (3), (4-Me)Ph (4) and (4-Cl)Ph (5)) were successfully activated by tetrakis(trimethylphosphine)nickel(0) and tetrakis(trimethylphosphine)cobalt(0). The four-coordinate nickel(II) chloride complexes trans-[(C6H4C(O)NHR)Ni(PMe3)2Cl] (R = Me (6), nBu (7), Ph (8) and (4-Me)Ph (9)) as C–Cl bond activation products were obtained without coordination of the amide groups. In the case of 2, the ionic penta-coordinate cobalt(II) chloride [(C6H4C(O)NHnBu)Co(PMe3)3]Cl (10) with the [Cphenyl, Oamide]-chelate coordination as the C–Cl bond activation product was isolated. Under similar reaction conditions, for the benzamides 3–5, hexa-coordinate bis-chelate cobalt(III) complexes (C6H4C(O)NHR)Co(Cl-ortho-C6H4C(O)NR)(PMe3)2 (11–13) were obtained via the reaction with [Co(PMe3)4]. Complexes 11–13 have both a five-membered [C,N]-coordinate chelate ring and a four-membered [N,O]-coordinate chelate ring with two trimethyphosphine ligands in the axial positions. Phosphonium salts [Me3P+-ortho-C6H4C(O)NHR]Cl− (R = Ph (14) and (4-Me)Ph (15)) were isolated by reaction of complexes 8 and 9 as a starting material under 1 bar of CO at room temperature. The crystal and molecular structures of complexes 6, 7 and 9–12 were determined by single-crystal X-ray diffraction.

Reactions of 1,1′-bis(dipheny1phosphino)cobaltocene with Co(PMe3)4, Ni(PMe3)4, Fe(PMe3)4, Ni(COD)2, FeMe2(PMe3)4 or NiMe2(PMe3)3 afford a series of novel dinuclear complexes [((Me3P)Co(η5-C5H4PPh2))((Me3P)M(η5-C5H4PPh2))] (M = Co(1), Ni(2) and Fe(3)) [Co(η5-C5H4PPh2)2Ni(COD)](4), [Co(η5-C5H4PPh2)2Ni(PMe3)2] (5) and [((Me3P)Co(Me)(η5-C5H4PPh2))((Me3P)Fe(Me)(η5-C5H4PPh2))] (6). Reactions of 1,1′-bis(dipheny1phosphino)ferrocene with Ni(PMe3)4, NiMe2(PMe3)3, or Co(PMe3)4 gives rise to complexes [Fe(η5-C5H4PPh2)2M(PMe3)2] (M = Ni (7), Co (8)). The complexes 1–8 were spectroscopically investigated and studied by X-ray single crystal diffraction. The possible reaction mechanisms and structural characteristics are discussed. Density functional theory (DFT) calculations strongly support the deductions.

Successful hydrodechlorinations of aryl chlorides were carried out in the presence of palladium catalyst supported by dppf (1,1′-bis(diphenylphosphino)ferrocene) and sodium formate in DMA (N,N-dimethylacetamide). A series of substituted aryl chlorides as substrates were studied to investigate the influence of electronic effects on the reaction. It was found that the substrates with electron-donating groups are more active than those with electron-withdrawing groups. A proposed mechanism of hydrodechlorination via decarboxylation and reductive elimination was discussed with the supported of in situ IR data. It is suggested that the decarboxylation is the key step of the reaction. This inference of the mechanism is consistent with the results from the in situ IR experiments.Successful hydrodechlorinations of a series of substituted aryl chlorides as substrates were carried out in the presence of palladium catalyst supported by dppf (1,1′-bis(diphenylphosphino)ferrocene) and sodium formate in DMA (N,N-dimethylacetamide). A proposed mechanism of hydrodechlorination was discussed with the supported of in situ IR data.

The ortho-chelated iron(II) complexes [FeCl(PMe3)3((C6H3Cl-ortho)CH═N-R)] (R = Me, Ph) (3, 4) and [FeCl(PMe3)3(C6H4-CH═N-R)] (R = Ph, n-Bu) (7, 8) were prepared through oxidative addition of the C−Cl bond of ortho-chlorinated imine using iron(0) complexes, [Fe(PMe3)4]. The reactions of 3, 4, and 8 with CO delivered the carbonyl Fe(II) complexes 9−11. A one-pot reaction of [FeMe2(PMe3)4] with (C6H3Cl2-2,6)CH═N-Ph in CO atmosphere resulted in carbonyl Fe(II) complexes [FeMe(CO)(PMe3)2((C6H3Cl-ortho)CH═N-Ph)] (12). The crystal and molecular structures of complexes 3, 4, 7−9, and 12 were determined by X-ray diffraction.

A new PC(sp3)P ligand N,N′-bis(diphenylphosphino)dipyrromethane [PCH2P] (1) was prepared and its iron, cobalt and nickel chemistry was explored. Two pincer-type complexes [PCHP]Fe(H)(PMe3)2 (2) and [PCHP]Co(PMe3)2 (4) were synthesized in the reaction of 1 with Fe(PMe3)4 and Co(Me)(PMe3)4. 1 reacted with Co(PMe3)4 and Ni(PMe3)4 to afford Co(0) and Ni(0) complexes [PCH2P]Co(PMe3)2 (3) and [PCH2P]Ni(PMe3)2 (5). The structures of complexes 2–5 were determined by X-ray diffraction.

C,N-coupling reactions of aryl chlorides and aryl amines catalyzed by a nickel catalyst are reported. 17 new amines are synthesized in yields of 57–99%. 2,6-Dichloro substituted imines can be selectively aminated. Both mono- and di-aminated products are obtained. Different substrates and amines are tested to look into the influence of electronic effects and steric hindrance to the reaction. An inexpensive and convenient base, NaOH, is used. It is an efficient way to gain access to new amines and imines.

A benzyne cobalt complex, Co(η2-C6Cl4)(PMe3)3 (2), was generated from the reaction of hexachlorobenzene with 2 equiv. of Co(PMe3)4 through selective activation of two C–Cl bonds of hexachlorobenzene. Meanwhile, the byproduct CoCl2(PMe3)3 was also confirmed by IR spectra. The cobalt(II) complex, CoCl(C6Cl5)(PMe3)3 (1), as an intermediate in the formation of aryne complex 2, was also isolated by the reaction of hexachlorobenzene with the stoichiometric amount of Co(PMe3)4. Complex 2 could be obtained by the reaction of 1 with Co(PMe3)4. Under similar reaction conditions, the reaction of Ni(PMe3)4 with hexachlorobenzene afforded only a mono-(C–Cl) bond activation nickel(II) complex, NiCl(C6H5)(PMe3)2 (5). The expected benzyne nickel complex was not formed. The structures of complexes 2 and 5 were determined by X-ray single crystal diffraction. Successful selective hydrodechlorinations of hexachlorobenzene were studied and in the presence of Co(PMe3)4 or Ni(PMe3)4 as catalysts and sodium formate as a reducing agent pentachlorobenzene and 1,2,4,5-tetrachlorobenzene were obtained. The catalytic hydrodechlorination mechanism is proposed and discussed.

The C–Cl bonds of ortho-chlorinated benzamides Cl-ortho-C6H4C(O)NHR (R = Me (1), nBu (2), Ph (3), (4-Me)Ph (4) and (4-Cl)Ph (5)) were successfully activated by tetrakis(trimethylphosphine)nickel(0) and tetrakis(trimethylphosphine)cobalt(0). The four-coordinate nickel(II) chloride complexes trans-[(C6H4C(O)NHR)Ni(PMe3)2Cl] (R = Me (6), nBu (7), Ph (8) and (4-Me)Ph (9)) as C–Cl bond activation products were obtained without coordination of the amide groups. In the case of 2, the ionic penta-coordinate cobalt(II) chloride [(C6H4C(O)NHnBu)Co(PMe3)3]Cl (10) with the [Cphenyl, Oamide]-chelate coordination as the C–Cl bond activation product was isolated. Under similar reaction conditions, for the benzamides 3–5, hexa-coordinate bis-chelate cobalt(III) complexes (C6H4C(O)NHR)Co(Cl-ortho-C6H4C(O)NR)(PMe3)2 (11–13) were obtained via the reaction with [Co(PMe3)4]. Complexes 11–13 have both a five-membered [C,N]-coordinate chelate ring and a four-membered [N,O]-coordinate chelate ring with two trimethyphosphine ligands in the axial positions. Phosphonium salts [Me3P+-ortho-C6H4C(O)NHR]Cl− (R = Ph (14) and (4-Me)Ph (15)) were isolated by reaction of complexes 8 and 9 as a starting material under 1 bar of CO at room temperature. The crystal and molecular structures of complexes 6, 7 and 9–12 were determined by single-crystal X-ray diffraction.

Reactions of 1,1′-bis(dipheny1phosphino)cobaltocene with Co(PMe3)4, Ni(PMe3)4, Fe(PMe3)4, Ni(COD)2, FeMe2(PMe3)4 or NiMe2(PMe3)3 afford a series of novel dinuclear complexes [((Me3P)Co(η5-C5H4PPh2))((Me3P)M(η5-C5H4PPh2))] (M = Co(1), Ni(2) and Fe(3)) [Co(η5-C5H4PPh2)2Ni(COD)](4), [Co(η5-C5H4PPh2)2Ni(PMe3)2] (5) and [((Me3P)Co(Me)(η5-C5H4PPh2))((Me3P)Fe(Me)(η5-C5H4PPh2))] (6). Reactions of 1,1′-bis(dipheny1phosphino)ferrocene with Ni(PMe3)4, NiMe2(PMe3)3, or Co(PMe3)4 gives rise to complexes [Fe(η5-C5H4PPh2)2M(PMe3)2] (M = Ni (7), Co (8)). The complexes 1–8 were spectroscopically investigated and studied by X-ray single crystal diffraction. The possible reaction mechanisms and structural characteristics are discussed. Density functional theory (DFT) calculations strongly support the deductions.

Three novel [CNN]-pincer nickel(II) complexes with NHC-amine arms were synthesized in three steps. Complex 5b was proven to be an efficient catalyst for the Kumada coupling of aryl chlorides or aryl dichlorides under mild conditions.