R. W. Rudolph

SYNTHESIS OF CYCLIC AND POLYMERIC DERIVATIVES OF 1,2-DITHIOL-o-CARBORANE

Summary Cyclic compounds containing two symmetrically placed 1,2-dicarbaclosododecaboranyl or two 7,8-dicarbaundecaborate( 10) moieties have been synthesized. The bridges between the carborane cages are S-S or S-CH,-CH,-S for the undegraded species, and S-CH,-S or S-CH,CH,-S for the degraded ones. The sulfur atoms in all cases are bonded to the carborane carbons. Unlike preparations previously reported in the literature, degradation to the partially degraded o-carborane cages proceeds without requiring treatment by a conventional base. Ring closure and the presence of sulfur atoms linked to the o-carborane carbons are believed to be necessary in order for the degradation to occur. When the number of bonds involved in the bridge between the two cages was seven, no cyclization occurred despite the presence of a square planar nickel template, the reaction instead producing a polymeric material.

The nature of PtSnCl3− salts in solution by multinuclear NMR. Unusually large spin-spin coupling, cluster size, fluxionality, and a caveat

It was recently shown that even when tin envirnoments are averaged by intramolecular rearrangement, the number of tin atoms in the molecule can be deduced from the ll9sn NMR because of the fortuitous presence of ll9sn-ll7sn coupling (i). We recently have extended these principles to an investigation of the platinum trichlorostannates which are effective homogeneous catalysts for a variety of reactions (2,3). A few examples are noteworthy at this time.

Directive effects in the electrophilic substitution of deltahedral boranes and heteroboranes. Deuteration and halogenation of 1-thiadecaborane(9) and thiadodecaborane(11)

Because of a moderate reaction rate, it is possible to determine the course of the sequential electrophilic halogenation of 1-SB/sub 9/H/sub 9/. The directive effect of the sulfur heteroatom does not correlate with the ground-state charge distribution of 1-SB/sub 9/H/sub 9/. It appears that initial attack is at the 6 position instead of the anticipated 10 position. In the care of monobromination and monoiodination there is a significant degree of rearrangement to also give the thermodynamically more stable 10 isomer in the reaction mixture (..delta..H/sub isomerization/ = 6.8 kcal/mol). Only the 6 isomer results from monochlorination. Rearrangement is also a significant factor as halogenation becomes more extensive. The initial halogenation of SB/sub 11/H/sub 11/ is analogous to that of 1-SB/sub 9/H/sub 9/. The site of initial deuteration was not established clearly, but under forceful conditions deuteration was not complete and 6,7,8,9,10-D/sub 5/-1-SB/sub 9/H/sub 4/ and 7,8,9,10,11,12-D/sub 6/-1-SB/sub 11/H/sub 5/ were obtained.

Chirale titan- und zirkoniumkomplexe mit dem 1-(8-Chinolyl)-2,3-dimethylcyclopentadienyl-Liganden

Abstract Reaction of 8-lithioquinoline with 2,3-dimethylcyclopent-2-en-1-one leads to 1-(8-quinolyl)-2,3-dimethyl-cyclopentadiene (1) after hydrolysis and H2O elimination in acidic solution. With strong bases 1 is deprotonated to the intensively red coloured anion 2.2 was converted to the trimethylsilyl derivative 3, which could be characterized by crystal structure analysis, 3 reacts with group 4 transition metal chlorides to the chiral trichlorotitanium and trichlorozirconium complexes 4 and 5. 4 was examined by crystal structure analysis and shows the expected interaction between the quinolyl nitrogen atom and the metal centre.

Direct effects in the electrophilic substitution of deltahedral boranes and heterboranes. Deuteration and halogenation of 1-SB/sub 9/H/sub 9/ and SB/sub 11/H/sub 11/

Because of a moderate reaction rate, it is possible to determine the course of the sequential electrophilic halogenation of 1-SB/sub 9/H/sub 9/. The directive effect of the sulfur heteroatom does not correlate with the ground-state charge distribution of 1-SB/sub 9/H/sub 9/. It appears that initial attack is at the 6 position instead of the anticipated 10 position. In the care of monobromination and monoiodination there is a significant degree of rearrangement to also give the thermodynamically more stable 10 isomer in the reaction mixture (..delta..H/sub isomerization/ = 6.8 kcal/mol). Only the 6 isomer results from monochlorination. Rearrangement is also a significant factor as halogenation becomes more extensive. The initial halogenation of SB/sub 11/H/sub 11/ is analogous to that of 1-SB/sub 9/H/sub 9/. The site of initial deuteration was not established clearly, but under forceful conditions deuteration was not complete and 6,7,8,9,10-D/sub 5/-1-SB/sub 9/H/sub 4/ and 7,8,9,10,11,12-D/sub 6/-1-SB/sub 11/H/sub 5/ were obtained.

Coordination chemistry of neutral quinolyl- and aminophenylcyclopentadiene derivatives

Abstract The cyclopentadiene and indene derivatives 1 – 4 being functionalised by a dimethylaniline and quinolyl group, respectively, were treated with metal carbonyl complexes. Whereas cyclopentadienes (C 5 R 5 H) normally loose one hydrogen atom prior or during metal complex formation, leading to negatively charged cyclopentadienide ligands, the compounds 1 – 4 are able to act as neutral ligands without hydrogen loss. Consequently transition metal complexes with coordination of the nitrogen donor and a CC double bond of the five membered ring have been obtained. In some cases a hydrogen atom is eliminated and the expected η 5 -(C 5 R 5 ) complexes are formed. Reaction of Ru 3 (CO) 12 with 2 leads to the binuclear η 6 -fulvene complex 8 . The octahedral molybdenum complex 9 and the square planar rhodium(I) complexes 10 and 11 which were obtained from Mo(CO) 6 and [Rh(CO) 2 Cl] 2 , respectively, are rare examples of η 2 -(C 5 R 5 H) coordination to metal atoms.

Molecular structure of F2POPF2: an electron diffraction study

Abstract The most important geometric parameters and associated uncertainties (2σ) determined for F 2 POPF 2 are the distances ( r g ) P-O = 1.631 ± 0.010 A, P-F = 1.568 ± 0.004 A, and angles POP = 135.2 ± 1.8°, OPF = 97.6 ± 1.2°, and FPF = 99.2 ± 2.4°. Amplitudes of vibration were also found. The large POP angle and relatively short P-O bond length are consistent with a significant degree of p π- d π bonding. Our structure interpretation differs from an earlier one reported by Arnold and Rankin in the relative P-O and P-F bond lengths and in the conclusion that the molecule exists in a distribution of not very rigid, probably staggered, conformers instead of one fairly rigid structure.

Di- and triheteronuclear metal cluster anions containing transition metals

Preparation, reactions, spectres RMN de Na 5 [L 2 PtTlSn 8 ] et Na 5 [L 2 PdTlSn 8 ], avec LIPPh 3

Electrophilic alkylation of 1-SB9H9

Abstract Reaction of closo -1-SB 9 H 9 with either ethyl or methyl iodide in the presence of A1C1 3 produces alkylated derivatives of the type 1-SB 9 H (9-x) R x (R  C 2 H 5 , CH 3 ; x  15), which were identified by GC/MS, 11 B and 1 H NMR spectroscopy. The initial product is 6-R-1-SB 9 H 8 rather than the 10-R-1-SB 9 H 8 predicted on the basis of ground-state charge considerations. Thus, these results are as found for halogenation of 1-SB 9 H 9 but differ from the precedent set by substitution reactions in closo -carboranes.

The Nature of Naked Metal Clusters in Solution

Recently, Chini and Heaton investigated the nature of [Ptn (CO) 2n]2- (n=3, 6, 9) and [Rh5Pt(CO)15]- clusters in solution by 195Pt NMR. The results showed that these metal polyhedra are fluxional and static, respectively (1, 2) in solution.