The synthesis and structural characterization of the first [1.1]chromarenophanes and the first [1.1]molybdarenophanes are described. A salt-metathesis reaction of [2-(Me2NCH2)C6H4]AlCl2 with freshly prepared [Cr(LiC6H5)(2)] center dot TMEDA (TMEDA = N,N,N',N'-tetramethylethylenediamine) resulted in the dial umina[1.1]chromarenophane [{2-(Me2NCH2)-C6H4)Al(eta(6)-C6H5)(2)Cr](2) (2a). The poor solubility of 2a in organic solvents prompted us to synthesize the new intramolecularly coordinated aluminum- and gallium dichlorides [5-tBu-2-(Me2NCH2)C6H3]ECl2 [E = Al (3a), Ga (3b)] in which the phenyl group was equipped with a tert-butyl group. Salt-metathesis reactions of 3a and 3b, respectively, with freshly prepared [M(LiC6H5)(2)] center dot TMEDA (M = Cr, Mo) resulted in four new [1.1]metallarenophanes of the general type [{5-tBu-2-(Me2NCH2)C6H3)E(eta(6)-C6H5)(2)M](2) [E = Al, M = Cr (4a); E = Ga, M = Cr (4b); E = Al, M = Mo (5a); E = Ga, M = Mo (5b)]. 2a, 4a,b, and 5a,b have been structurally characterized by single-crystal analysis [2a center dot 1/2C(6)H(12): C48H56Al2Cr2N2%, monoclinic, P2(1/c), a = 9.9117(9)angstrom, b = 19.9361(16) angstrom, c = 10.638(2) angstrom, alpha = 90 degrees, beta = 112.322(5)degrees, gamma = 90 degrees, Z = 2; 4a center dot 2C(6)H(6): C62H72Al2Cr2N2, monoclinic, P2(1/c), a = 10.9626(9) angstrom , b = 19.3350(18) angstrom, c = 12.4626(9) angstrom, alpha = 90 degrees, beta = 100.756(5)degrees, gamma = 90 degrees, Z = 2; 4b center dot 2C(6)H(6): C62H72Cr2Ga2N2, monoclinic, P2(1/c), a = 10.8428(2) angstrom, b 19.4844(4) angstrom, c = 12.4958(2) angstrom, alpha = 90 degrees, beta = 100.6187 degrees, gamma = 90 degrees, Z = 2; 5a.2C(6)H(6): C62H72Al2Mo2N2, triclinic, P (1) over bar, a = 10.4377(4) angstrom, b = 11.6510(4) angstrom, c = 11.6514(4) angstrom, alpha = 73.545(3)degrees, beta = 89.318(2)degrees, gamma = 76.120(2)degrees, Z = 1; 5b center dot 2C(6)H(6): C62H72Ga2Mo2N2, triclinic, P (1) over bar, a = 10.3451(5) angstrom, b = 11.6752(6) angstrom, c = 11.6900(5) angstrom, alpha = 73.917(3)degrees, beta = 89,550(3)degrees, gamma = 76.774(2)degrees, Z = 1]. All five [1.1]metallarenophanes 2a, 4a,b, and 5a,b crystallize as anti isomers with both Me2N donor groups in exo positions (C-i point group symmetry), The new [1.1] metallarenophanes show NMR spectra that can be interpreted as being caused by time-averaged C-2h symmetrical species, which is consistent with the findings of their molecular structures in the solid state. Variable-temperature H-1 NMR measurements for 4a,b and 5a,b (500 MHz; -90 to 90 degrees C) revealed only peak broadening in the lower temperature range of -70 to -90 degrees C. 1H NMR saturation transfer difference experiments did not show an expected anti-to-anti isomerization, rendering the new [1, 1]metallacyclophanes rigid on the NMR time scale. Electrochemical measurementswere performed for 4a,b and 5a,b. However, reproducible cyclic voltammograms could only be obtained for the two gallium species 4b and 5b, revealing the expected weak communication between the two transition-metal atoms in both compounds (class II).