Alkyl Transfer Reactivity in the First Octahedral Isocyanide Complex of Nickel(II)

Abstract

[Ni{S2P(OEt)2}2] (1) reacts with 2 equiv of CNXyl (Xyl = 2,6-dimethylphenyl) to afford [Ni{S2P(OEt)2}2(CNXyl)2] (2), which, as confirmed by X-ray crystallography, is the first octahedral isocyanide complex of Ni(II). Reaction of 2 with PCy3 (2 equiv) produces square-planar [Ni{S2P(O)(OEt)}(PCy3)(CNXyl)] (3). When 2 is reacted with only 1 equiv of PCy3, the final product is the square-planar complex [Ni{S2P(O)(OEt)}(CNXyl)2] (4), containing two isocyanide ligands. Compound 4 reacts with 2-fold excess PCy3 to give 3 via isocyanide displacement. Both 3 and 4 contain one ethyldithiophosphate ligand, which is produced by the transfer of one ethyl group from a coordinated diethyl dithiophosphate of complex 2 to the leaving diethyl dithiophosphate ligand. Experimental evidence indicates that the phosphine plays a significant role in the alkyl transfer. Moreover, reaction of 1 with 2 equiv of N - p-tolyl-2-iminopyridine affords octahedral [Ni{S2P(OEt)2}{2-pyCHNC6H4-Me-4}2][S2P(OEt)2] (5), in which both free and coordinated diethyl dithiophosphate coexist without any transfer of alkyl.

Electrocatalytic Proton Reduction by Dimeric Nickel Complex of a Sterically Demanding Pincer-type NS2 Aminobis(thiophenolate) Ligand

“…Although there is not a significant degree of backbonding from the metal center to the π* orbital of the isocyanide, the high oxidation state of the nickel ion is likely responsible for this observation. Despite the fact that 3 has a relatively high ν(CN) frequency, complexes with related ancillary ligands give rise to even higher stretching frequencies (and less backdonation), with ν(CN) values at 2181 cm –1 , a 2192 cm –1 , and 2196 cm –1 , so that the (NS 2 )Ni moiety can be considered electron-rich among analogous Ni 2+ complexes.…”

Synthesis, structural characterization, and reactivity of late transition-metal complexes bearing linked cyclopentadienyl–carboranyl ligands

“…The average M-C ring bond distances of 2.074(3)/2.099(4) Å in Co (9)/Ni (10) are comparable to those of 2.085(3)/2.145(6) Å observed in 4/5, and the M-C cage bond distances of 1.922(3)/1.898(3) Å in 9/10 are slightly shorter than those of 1.989(3)/1.975(5) Å found in 4/5. The M-C bond distances of 1.838(3)/1.790(3) Å in 9/10 compare to those of 1.87(1)/1.89(1) Å in [Co(L C=O : N 2 (SO) 2 )(CNt-Bu) 2 ] -, 19 to 1.772(18)/1.963(18) Å in CoBr(PhCOCH)(CNC 6 H 3 Me 2 -2,6) 6 , 20 to 1.787(3) Å in Ni(triphos)(CNC 6 H 3 Me 2 -2,6), 21 to 1.820(4) Å in Ni{S 2 P(O)(OEt)}(CNC 6 H 3 Me 2 -2,6)(PCy 3 ), 22 and to 1.789(9)/ 1.789(8) Å in [Ni(m-t-Bu 2 As)(p-tol-NC) 2 ] 2 . 23 Reaction of 4 or 5 with 1 equiv of NHC (1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene) in toluene at room temperature afforded [h 5 :s-Me 2 C(C 5 H 4 ) (C 2 B 10 H 10 )]M[C(2,6-i-Pr 2 C 6 H 3 -NCH) 2 ] (M = Co (11) or Ni (12)) in 51% and 60% isolated yield, respectively (Scheme 2).…”

Alkylation of a Dimolybdenum SO Bridge, Subsequent Reactions, and Characterization of the Thioperoxide Bridge

“…Compounds 6 are represented by BnS{Mo 2 (PO)}SOEt; in addition to the thioperoxide ligand, this compound also provides another structural characterization of a dianionic, monoalkyl dithiophosphate ligand. The additional interest therein lies in the fact that there are few structural studies known for this ligand, − in stark contrast to the extensive characterization of monoanionic, dialkyl dithiophosphate ligands.…”