(H[sub 2]NC[sub 4]H[sub 8]NH[sub 2])[(VO)[sub 2](PO[sub 4])[sub 2]] and (H[sub 2]NC[sub 4]H[sub 8]NH[sub 2])[sub 2][(VO)[sub 3](HPO[sub 4])[sub 2](PO[sub 4])[sub 2]][center dot]H[sub 2]O: Novel layered vanadium phosphates with distorted and defected VOPO[sub 4] layers