Heinrich Vahrenkamp

Metallorganische Lewis-basen : XI. Versuche zum Aufbau dreikerniger Metall-Carbonyl-Komplexe☆

The compounds cis-(CO)4M[As(CH3)2Cl]2 (I) and cis-(CO)4M[P(C6H5)2Cl]2(II)(M  Cr, Mo) were prepared. The arsine derivatives (I) react with NaMn(CO)5. The resulting chromium cis-(CO)4Cr[As(CH3)2Mn(CO)5]2 (IIIa) is very stable and is converted thermally into the trans isomer (IIIb). Of the analogous molybdenum compound only rearrangement products could be isolated. Attempts to isolate (CO)5MnP(CH3)2Mn(CO)4P(CH3)2Cr(CO)5 and its arsenic analogue, which is a third isomer of (III), also resulted in rearrangement reactions.

Metallorganische lewis-basen III. Thio-dimethylborane☆

Abstract The preparation of the thiodimethylboranes RnX-S-B(CH3)2 with RnX=H, CH3, C6H5, B(CH3)2, Sn(CH3)3, P(C6H5)2, As (CH32 and Mn(CO)4 is described. The high Lewis basicity of the sulfur atom in (CH3)2B-S-B(CH3)2 and (CH3)3Sn-S-B(CH3)2 leads to slow polymerisation of these compounds. (C6H5)2P-S-B(CH3)2 probably is a dimer with a six-membered B-S-P ring. [(CO)4Mn-S-B(CH3)2]2 is the first thermally stable transition metal complex of a boron-sulfur compound. The Lewis acidity of the thio dimethylboranes is responsible for adduct formation with Lewis bases. Their Lewis basicity is not sufficient for the formation of sulfonium salts [(R2B)2−nSRn+1]+X−. Electrophiles, instead, cleave the boron-sulfur bond.

Metallorganische lewis-basen IV. Schwingungsspektroskopische untersuchungen zur natur der bor-schwefel-bindung☆

Abstract The infrared and Raman spectra of the boron-sulfur compounds B (SCH3)3, CH3B(SCH3)2, C6H5B(SCH3)2, (CH3)2B-SCH3, (CH3)2B-SH, (CH3)2B-SC6H5, (C6H5)2B-SCH3 and (CH3)2B-S-B(CH3)2 are reported, assigned, and discussed. B-S valence force constants are calculated for three typical compounds. They indicate that, in contrast to the corresponding boron-chlorine compounds, no π bonding occurs between boron and sulfur.