Bis(isothiocyanato)bis(phosphine) complexes of group 10 metals: reactivity toward organic isocyanides

Abstract

Treatment of Ni(NCS)2(PMe2Ph)2 with organic isocyanides CN-R gave five-coordinate isocyanide Ni(II) complexes, Ni(CN-R)(NCS)2(PMe2Ph)2 (R = C6H3-2,6-Me2 (1), t-Bu (2)). Interestingly, the corresponding reaction of Ni(NCS)2(P(n-Pr)3)2 with 2 equiv. of CN-t-Bu gave an unusual compound, which exists as an ion pair of the trigonal bipyramidal cation [Ni(P(n-Pr)3)2(CN-t-Bu)3]2+ (3) and the dinuclear NCS-bridged anion [Ni(1,3-micro-NCS)(NCS)3]2(2-) (4). In contrast, Pd(NCS)2(P(n-Pr)3)2 underwent substitution with 2 equiv. of CN-t-Bu to give the four-coordinate mono(isocyanide) Pd(II) complex Pd(NCS)(SCN)(CN-t-Bu)(P(n-Pr)3) (5) via phosphine dissociation. Reactions of M(NCS)2L2 (M = Pd, Pt; L = PMe3, PEt3, PMePh2, P(n-Pr)3) with two equiv. of CN-R (R = t-Bu, i-Pr, C6H3-2,6-Me2) gave the corresponding bis(isocyanide) complexes [M(CN-R)2(PR3)2](SCN)2 (7-13), except for Pd(NCS)2(PEt3)2 that reacted with CN-R' (R' = i-Pr, C6H3-2,6-Me2) and produced the mono(isocyanide) Pd(II) complexes [Pd(CN-R')(SCN)(PEt3)2](SCN) (14 and 15). Finally, treatment of M(NCS)2(PMe3)2 (M = Ni, Pd, Pt) with sterically bulky isocyanide CN-C6H3-2,6-i-Pr2 gave various products, (16-18) depending on the identity of the metal.

Polymorphism and reactivity of [Ni(pyridine)4(NCS)2]: Two new supramolecular isomers and one macro-ionic derivative

“…Calcd for 3: C, 40.10;H, 3.36; N, 17.53%. Found: C, 39.90;H,3.328; N, 17.52%. IR adsorptions of the coordinated SCN À and pyridine: for 1, 768 vs (C-S stretch), 481 vw (SCN bend), 2106 s and 2085 vs (C-N stretch), 1599 m and 1486 w and 1440 s and 692 m (pyridine); for 2, 769 w (C-S stretch), 481 vw (SCN bend), 2084 vs (C-N stretch), 1598 m and 1483 w and 1438 m and 712 w (pyridine); for 3, 770 vs and 684 s (C-S stretch), 469 m and 446 m (SCN bend), 2122 vs and 2097 vs (C-N stretch), 1628 s and 1580 w and 1486 s and 682 s (pyridine).…”

“…Whereas the distances of Ni-N(NCS) bonds (2.04 Å ) in 1 are almost equal to the corresponding value of 2.05 Å in 2 and the value of 2.06 Å in the known structure [6]. Turn to the dihedral (2); Ni1-N2 2.157(2); Ni1-N3 2.108 (3); Ni1-N4 2.158 (3);N3-Ni1-N4 180; N3-C11-S1 179.0(2); 2, Ni1-N1 2.151 (2); Ni1-N2 2.164 (2); Ni1-N3 2.050 (2);N1-C1-S1 179.7 (3). Dihedral angles between the pyridine rings and the mean plane of four coordinated pyridine nitrogen atoms (representative pyridine nitrogen): 1, 71.5 (N2); 55.6 (N3); 37.6 (N4); 71.5 (N2A); 2, 57.1 (N1); 65.0 (N2).…”

“…Significantly, it is found that the conductivity value (205 K M ) of complex 3, performed on DDS-11A conductometer at 25°C in methanol (c = 10 À3 M), is very high, which almost doubles the value (106 K M ) of the dinuclear complex ½NiðPðn-PrÞ 3 Þ 2 ðCN-t-BuÞ 3 2þ Á ½Niðl 1;3 -SCNÞ-ðNCSÞ 3 2À 2 , even exceed the value (181 K M ) of ionic salt [Pt(depe) 2 ](SCN) 2 [3]. Presumably, the effectively conductive property of complex 3 in methanol solution results from its unique structure.…”

“…Thiocyanate (or isothiocyanate) complexes have attracted a great attention due to their structural versatility and potential for development of optical, electrical, organic zeolite, magnetic and conductive materials [1][2][3]. However, research efforts are primarily focused on their synthesis, magnetism and coordination isomerism.…”

“…Recently, Modec and Lin [5] found that methylation reaction between pyridine and methanol under acidic solvothermal conditions could lead to the formation of unusual ionic complexes [methylpyridinium] 3 ] n . However, to the best of our knowledge, no example of similar transformation has as yet been identified for thiocyanate complexes.…”