We report the structural and magnetic characterizations of Ba 3 TeCo 3 P 2 O 14 , Pb 3 TeCo 3 P 2 O 14 , and Pb 3 TeCo 3 V 2 O 14 , compounds that are based on the mineral dugganite, which is isostructural to langasites. The magnetic part of the structure consists of layers of Co 2+ triangles. Nuclear and magnetic structures were determined through a co-refinement of synchrotron and neutron powder diffraction data. In contrast to the undistorted P321 langasite structure of Ba 3 TeCo 3 P 2 O 14 , a complex structural distortion yielding a large supercell is found for both Pb 3 TeCo 3 P 2 O 14 and Pb 3 TeCo 3 V 2 O 14 . Comparison of the three compounds studied along with the zinc analog Pb 3 TeZn 3 P 2 O 14 , also characterized here, suggests that the distortion is driven by Pb 2+ lone pairs; as such, the Pb compounds crystallize in a pyroelectric space group, P2. Magnetic susceptibility, magnetization, and heat capacity measurements were performed to characterize the magnetic behavior. All three compounds become antiferromagnetic with Néel temperatures T N ≈21K (Ba 3 TeCo 3 P 2 O 14 ), ≈13K (Pb 3 TeCo 3 P 2 O 14 ), and ≈8K (Pb 3 TeCo 3 V 2 O 14 ), and they exhibit magnetic transitions at high applied magnetic fields, suggesting intrinsically complex magnetic behavior for tetrahedrally coordinated d 7 Co 2+ in this structure type.