Two new nickel() complexes were synthesized with an S 4 coordination environment. These complexes were synthesized by in situ deprotection of thiouronium salts in the presence of nickel(). The ligands used are 4-mercapto-3,3-methyl-1-phenyl-2-thiabutane (Hbsms) and α,αЈ-bis(4-mercapto-3,3-methyl-2-thiabutyl)-o-xylene (H 2 xbsms). The former is a didentate ligand containing one thioether and one thiolate group and the latter is a dithioether dithiolate tetradentate ligand. The differences between these ligands upon coordination to nickel have been investigated. During the synthesis of these ligands, an unprecedented spontaneous rearrangement occurs, which is very fast and selective to a single product. The complexes were characterized by analytical, spectroscopic and electrochemical methods. The geometry of the nickel complexes is square planar according to the single-crystal X-ray structures. In [Ni(bsms) 2 ] the two ligands are coordinated with the thiolates in trans positions towards each other; in [Ni(xbsms)] the thiolates are in enforced cis positions. [Ni(bsms) 2 ] crystallizes in the triclinic space group P1 and has one centrosymmetric molecule in the unit cell. [Ni(xbsms)] crystallizes in the monoclinic space group P2 1 /c with two independent molecules in the asymmetric unit, however, the differences between these two molecules are very small. The Ni-S distances are 2.1730(4)-2.1909(6) Å and in the common range for thiolates and chelating thioethers.
The rhenacarborane salt Cs[Re(CO)3(η
5-7,8-C2B9H11)] (1) has been synthesized in excellent
yield using a new procedure. Treatment of CH2Cl2 solutions of 1 with [RuCl2(PPh3)3] yields
the exo-closo complex [Re(CO)3(η
5-2,3,10-(μ-H)3-exo-{RuCl(PPh3)2}-7,8-C2B9H8)] (2a). In this
molecule a [RuCl(PPh3)2]+ moiety is exopolyhedrally bound via three B−H⇀Ru bonds to a
closo-3,1,2-ReC2B9 system. An X-ray diffraction study revealed that one of these agostic
interactions utilizes a β-B−H bond in the coordinating
face of the cage, while the
source of the remaining two B−H⇀Ru bonds is in the B5 belt. The anion of salt 1 also binds
exopolyhedral [Rh(PPh3)2]+ and [Rh{Fe(η-C5H4PPh2)2}]+ fragments in the complexes [Re(CO)3(η
5-5,10-(μ-H)2-exo-(RhL2)-7,8-C2B9H9)] (L2 = (PPh3)2 (3a), {Fe(η-C5H4PPh2)2} (3b)).
Reaction of 1 with the salts [M(CO)2(THF)(η-C5H5)][BF4] (M = Fe, Ru) and [Fe(CO)2(THF)(η-C5Me5)][BF4] gives the complexes [Re(CO)3(η
5-n-(μ-H)-exo-{M(CO)2(η-C5R5)}-7,8-C2B9H10)]
(M = Fe, R = H, n = 10 (4a); M = Ru, R = H, n = 10 (4b); M = Fe, R = Me, n = 10 (4c), 9
(4d)) with isomers 4c and 4d formed as an inseparable mixture. An X-ray structural study
on 4b revealed that there was no Re−Ru bond and that an exo-[Ru(CO)2(η-C5H5)]+ fragment
is bound to the rhenacarboranyl anion by a single unsupported B−H⇀Ru interaction with
an unusually long B−Ru distance (2.695(13) Å). The compounds [ReM(μ-10-H-η
5-7,8-C2B9H10)(CO)3(PPh3)] (M = Cu (5a), Ag (5b)) were isolated from the reaction of 1 with sources of the
fragments [M(PPh3)]+ (M = Cu, Ag). X-ray structure determinations of both species 5 revealed
the presence of direct Re−M (M = Cu, Ag) connectivities bridged by carborane β-B−H⇀M
interactions. In solution the complexes 5 are highly dynamic on the NMR time scale, even
at low (−90 °C) temperatures.
A novel strategy for the synthesis of bis(ortho-amine)chelated monoanionic bisaminoaryl−metal complexes is presented. This method constitutes the exchange
of a monoanionic, NCN-pincer ligand (NCN = [C6H3(CH2NMe2)2-2,6]-) between a stable arylgold(I) phosphine,
[Au(η1-C-NCN)(PPh3)] (2), and a transition metal halide.
This transmetalation results in the quantitative formation of [M(NCN)] organometallic compounds (M = AuIII,
NiII, PdII, PtII, TiIV, and FeIII) and [AuCl(PPh3)] as the
only coproduct that can be recovered.
Rhodium complexes of unsymmetrical diphosphines of the type Ph 2 PCH 2 CH 2 PAr 2 are catalysts for the carbonylation of methanol; several features of the catalysis are reminiscent of iridium carbonylation catalysts.
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