Reactions of Sodium Tetrahydroborate and Cyanotrihydroborate With Divalent Co, Ni, Cu, Pd, and Pt Chlorides In the Presence of Tertiary Phosphines

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The reactions between a variety of Ni(II) compounds and NaBH4 have been studied in the presence of triphenylphosphine (P) and the bidentate phosphines 1,2-bis(diphenylphosphino)-ethane (diphos), bis(diphenylphosphino)methane (dppm), and cis-1,2-bis(diphenylphosphino)-ethylene (vpp). In ethanol, NiCl2•6H2O, P, and NaBH4 give [Ni(BH4)P3]2 while NiX2P2 X = Cl, Br, I) and NaBH4 produce Ni(BH4)P1.5. Further reactions of the former complex leading to [Ni2P6](PF6)2 and [NiP4](PF6) have been studied. Reactions of Ni(ClO4)2•6H2O, P, and NaBH4 produce Ni(ClO4)P3 and [NiP4](ClO4). The bidentate phosphines, Ni(ClO4)2•-6H2O and NaBH4 in ethanol all lead to quite different products. For example, with diphos, Ni(II) is stabilized and [HNi(diphos)2](ClO4) is formed, but with the other two bidentate phosphines, reduction occurs. With dppm, [Ni2(dppm)4](ClO4)2 is produced, while vpp produces [Ni(vpp)2](ClO4). Physical properties, possible structures, and suggested mechanisms of reduction are discussed.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Production of Ni(I) complexes from reactions between Ni(II) and NaBH₄ in the presence of triphenylphosphine and some bidentate phosphines

Holah¹,

Hughes²,

Hui³

et al. 1978

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“…1, Table 2). These spectra show 110 similarities with those of either tetrahedral (4,18) or square planar (19) Ni(1) complexes and are probably therefore due either to five-coordinated metal, to which the spectra have some similarities (20), or to extensively distorted 6-coordinated structures. In either case, the weakly interacting, BH,-or PF,-groups dissociate in dilute solutions producing the 1 : 1 electrolytes [Niphen,]+-BH,-and P-[Niphen,]+PF,-.…”

Section: Physical Datamentioning

confidence: 91%

Ligand effects upon the reactions of Ni(II) with sodium tetrahydroborate: Ni(I) complexes of bipyridyl and 1,10-phenanthroline

Holah¹,

Hughes²,

Hui³

1977

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. Can. J. Chem. 55, 4048 (1977). The reactions between NaBH, and Ni(I1) have been studied in the presence of a variety of ligands in an effort to determine (a) the conditions under which reduction occurs, (b) the extent of the reduction (e.g. to Ni(I), Ni(0) complexes, or to Ni metal or boride), and (c) whether intermediate Ni complexes can be isolated.With ligands having no n-bonding capabilities (NH3, ethylenediamine, edta, citrate), reduction depends upon the Ni:ligand ratio and, in the presence of an excess of the ligand, reduction of Ni(1I) is very slow. When vacant coordination sites exist on the metal through dissociation of, for example, Ni(NH,),'+, allowing for the interaction of the BH4 group with the metal, then rapid reduction to the metal (or boride) takes place.With the K-bonding N-donor ligands 1,lO-phenanthroline (phen) and 2,2'-bipyridyl (bipy) reduction of the stable ML,'+ complexes probably occurs via an outer-sphere electron transfer mechanism but, in these cases, new species of the type NiL2X (L = phen, bipy; X = BH4, PF6, BPh4), which formally contain Ni(I), have been isolated. Lorsque les ligands n'ont pas de capacitt de liaisons n (NH,, tthylknediamine, edta, citrate), la reduction depend du rapport Ni : ligand et, en prtsence d'un exces de ligand, la reduction de Ni(I1) est tres lente. Quand des sites de coordination vacants existent sur le metal par I'intermtdiaire d'une dissociation, par exemple de Ni(NH,),'+, permettant une interaction du groupe BH4 avec le metal, il y a alors une rtduction rapide conduisant au mttal (ou borure).Avec des ligands donneurs par l'azote et pouvant crter des liens K comme la phtnanthroline-1,10 (phen) et bipyridyl-2,2' (bipy) la reduction des complexes stables ML,,+ se produit probablement par l'intermkdiaire d'un mtcanisme de transfert Clectronique au niveau de la sphere exttrieure mais dans ces cas on peut isoler de nouvelles esfices du type NiL,X (L = phen, bipy; X = BH,, PF,, BPh4) qui contiennent d'une f a~o n formelle du Ni(1). [Traduit par le journal] IntroductionIt is known that the presence of certain ligands prevents the rapid reduction by NaBH, of metal salts to the metal or to the insoluble borides (1). Without doubt, reactions between NaBH, and transition metal complexes containing phosphines are best documented and, in the case of nickel, these proceed by two different routes.

“…W e therefore felt that the introduction of a second T acceptor molecule, like C O , into these systems may significantly modify the course of events (5). This paper reports on reactions between (Co(II), NaBH3CN, and Ph2PCH2CH2PPh2 (Diphos) in the presence of CO; the results obtained prompted a reinvestigation of the same system in the absence of CO (6).…”

Section: Introductionmentioning

confidence: 99%

Reactions between Co(II), 1,2-bis(diphenylphosphino)ethane, and NaBH₃CN in the presence and absence of CO. The crystal structure of bis(cyanotrihydroborato)tetrakis(N,N-dimethylformamide)cobalt(II)

Elliot¹,

Haukilahti²,

Holah³

et al. 1988

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Reactions between Co(II), Diphos, and NaBH3CN lead to Co(BH3CN)2(Diphos)2, 1, or [Co(BH3CN)(Diphos)2]X, 2 (X = ClO4 or BPh4), and, in certain solvents, 2 reacts to produce [Co(CN)(Diphos)2](ClO4). Compound 1 can be reversibly converted to Co(BH3CN)2(DMF)4, 4, via Co(BH3CN)2(Diphos)(DMF). In addition, 1 reacts with CO to form the Co(I) and Co(III) compounds [Co(Diphos)2](CO)]X and [Co(Diphos)2(CN)2]X (X = BH3CN or BPh4). Single crystal X-ray diffraction studies of 4 show that the compound crystallizes in the triclinic space group [Formula: see text], with unit cell parameters a = 7.572(6), b = 9.695(6), c = 9.395(6) Å, α = 81.06(4), β = 68.46(5), γ = 68.19(5)°, V = 595.5 Å3, Z = 1, and dcalcd = 1.202 g cm−3. The structure converged to a conventional R factor of 0.040 for 2841 observations and showed an octahedral arrangement of four O atoms from DMF molecules and two trans N-bound BH3CN groups around the Co(II) center.