Bor-stabilisierte Ν,Ο-Carbene, II Röntgenstrukturanalyse von (trans-4,5-Dimethyloxazolidin-2-yliden)triphenylbor und N-Alkyliengen / Boron Stabilized Ν,Ο-Carbenes, II X-Ray Structure of (trans-4,5-Dimethyloxazolidin-2-ylidene)triphenylboron and N-Alkylations