A series of paramagnetic (S = 3/2) chromium half-sandwiches of the type CpCrX 2 D (D = donor) were synthesized by starting from [CpCrX 2 ] 2 , Cp 2 Cr, CpCrCl 2 (THF), and Cp*Cr(CH 3 ) 2 [P(CH 3 ) 3 ]. Besides the parent cyclopentadienyl (Cp) the alkylated derivatives CH 3 C 5 H 4 , (CH 3 ) 5 C 5 (Cp*), and C 2 H 5 (CH 3 ) 4 C 5 were bound to chromium. The electronegative substituent was X = F, Cl, Br, I, and triflate, while the donors were three ethers, four ketones, dimethylsulfoxide, acetonitrile, methylisocyanide, pyridine, and seven molecules ER 3 where E = N, P, As, Sb. The half-sandwiches were partly isolated and partly established in solution. The 13 C and 1 H NMR spectra showed strongly shifted signals which allowed to quantitatively investigate the equilibrium between CpCrX 2 D and the anti ferromagnetic species [CpCrX 2 ] 2 . The NMR signals of CpCrX 2 D and its substituted derivatives appeared in characteristic ranges thus providing a means of rapid identification. Considerable spin density was found to be induced on the ligands; it is negative in the Cp π system. As for the donors, inter- and intramolecular dynamic behavior as well as selective spin transfer to the γ protons of acetonitrile, methylisocyanide, and ketones was detected.